Life Processes

The maintenance of living organisms is essential even if they are moving, resting, or even sleeping. The processes that together maintain life are known as life processes.
The various life processes which take place in living organisms are called metabolic activities or metabolism. These life processes can either be anabolic or catabolic in nature.
Nutrition, respiration, transportation, and excretion are some of the life processes that are essential for the functioning as well as maintenance of living organisms.

Life Processes

Nutrition

Nutrition is defined as a process by which living organisms procure food or synthesize it and convert it into simple absorbable form by a series of biochemical processes.
Nutrient can be defined as a substance that an organism obtains from its surroundings and use as a source of energy as well as providing raw materials for the biosynthesis of body constituents.
There are two basic modes of nutrition: autotrophic and heterotrophic.

Autotrophic Nutrition

Autotrophic organisms meet their carbon and energy needs through photosynthesis. This process involves the conversion of external substances into stored energy.
During photosynthesis, autotrophs absorb carbon dioxide and water, converting them into carbohydrates with the help of sunlight and chlorophyll.
Carbohydrates produced are used as an energy source for the plant's activities.
Excess carbohydrates are stored as starch, acting as an internal energy reserve for the plant's future needs.
In a similar manner, humans store energy from food as glycogen.

Photosynthesis

Photosynthesis can be defined as the synthesis of organic compounds (carbohydrates) from CO2 and H2O using radiant energy or solar energy by chlorophyll molecules.

The process of photosynthesis involves two phases: Light Reaction and Dark Reaction.

The following events occur during the process of photosynthesis:

Absorption of light energy by chlorophyll.
Conversion of light energy to chemical energy as well as splitting of water molecules into hydrogen and oxygen.
Reduction of carbon dioxide to carbohydrates.

However, these stages do not have to occur directly one after the other. For instance, some desert plants absorb carbon dioxide at night and then use the energy captured by chlorophyll during the day.

Inside some cells, there are green structures known as chloroplasts that contain chlorophyll. A large amount of gas exchange occurs in the leaves through tiny openings called stomata during photosynthesis.

Photosynthesis

Experiment Activity:

Take a potted plant with variegated leaves, such as a money plant or crotons.
Place the plant in a dark room for three days to deplete starch reserves.
Expose the plant to sunlight for about six hours.
Pluck a leaf, mark the green areas, and trace them on a sheet of paper.
Boil the leaf in water and then immerse it in alcohol.
Heat the alcohol in a water-bath until it boils.
Observe color changes in the leaf and solution.
Dip the leaf in a dilute iodine solution and compare colors with the initial tracing.
Draw conclusions about starch presence in different leaf areas.

Heterotrophic Nutrition

Heterotrophic organisms cannot prepare their food. They are dependent on plants, animals or on dead decaying organic materials for their food. Saprophytes derive their nourishment from dead decaying matter.

Organisms adapt to their environment, and their nutrition methods vary based on food type, availability, and how it's acquired.
For instance, the nature of the food source (stationary like grass or mobile like a deer) influences how it's accessed.
Differences exist in the nutritive apparatus used by animals like cows and lions.
Organisms employ various strategies to acquire and utilize food.
Some organisms externally break down food before absorption, for example, fungi such as bread molds, yeast, and mushrooms.
Others ingest whole material and break it down internally, based on body design and function.
Some organisms obtain nutrition from plants or animals without causing harm, employing parasitic strategies.
Parasitic nutrition is observed in organisms like cuscuta, ticks, lice, leeches, and tapeworms which depend on a host for nutrition.

Holozoic nutrition is a mode of nutrition that involves swallowing solid food material. Ingestion, digestion, absorption, assimilation, and egestion are the various steps involved in holozoic nutrition.

MULTIPLE CHOICE QUESTION

Try yourself: Green plants use ____________ mode of nutrition.

Heterotrophic

CORRECT ANSWER

Autotrophic

Holozoic

Parasitic

Correct Answer: B

Green plants make their own food through the process of photosynthesis and hence use autotrophic mode of nutrition.

Nutrition in Humans & Other Organisms

In animals, procurement of food is highly variable. The process of nutrition becomes more complex in multicellular organisms as compared to unicellular organisms. In single-celled organisms like Amoeba, the food is taken in through the general body surface.
In humans, the digestive system consists of a long alimentary canal and digestive glands. Various parts of the alimentary canal in sequence are the mouth, esophagus, stomach, small intestine and large intestine.
In the mouth, food is crushed by teeth and mixed with saliva, secreted by salivary glands. Saliva contains an enzyme called salivary amylase that breaks down starch into simple sugar.
When we swallow the food (bolus), it is further pushed forward by rhythmic contraction and relaxation of muscles present inlining of the alimentary canal. These movements are called peristaltic movements. Thus, the food is carried to the stomach through the food pipe or esophagus.
The stomach is a large C-shaped hollow organ that expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly, with the gastric secretions.
The gastric glands present in the wall of the stomach secrete hydrochloric acid, a protein-digesting enzyme called pepsin and mucus.
Hydrochloric acid facilitates the action of the enzyme pepsin as this enzyme works in an acidic medium. Apart from it, hydrochloric acid prevents the fermentation of food and also kills harmful microorganisms present in the food. Mucus protects the inner wall of the stomach from excoriation by highly acidic HCl.
From the stomach, the partially digested food (chyme) enters the small intestine. The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.

Digestive System

The length of the small intestine differs in various animals depending on the feeding habit. Herbivores have a longer small intestine (due to the high bulk of vegetal matter and cellulose) as compared to carnivores (due to the smaller bulk of animal food).
The small intestine is the site of the complete digestion of carbohydrates, proteins and fats. The proximal part of the small intestine referred to as the duodenum receives partially digested acidified food from the stomach. Duodenal glands secrete an alkaline mucus-containing juice that helps in neutralising the chyme and protects the duodenal wall from corrosion.

MULTIPLE CHOICE QUESTION

Try yourself: Where does the complete digestion of carbohydrates, fats, and protiens takes place in a human body?

Large intenstine

Stomach

Liver

CORRECT ANSWER

Small intestine

Correct Answer: D

The small intestine is where the complete digestion of carbohydrates, fats, and proteins takes place in the human body:

Digestive juices
The small intestine produces digestive juice, which mixes with pancreatic juice and bile to break down food.
Absorption
The small intestine absorbs nutrients, water, and minerals from digested food.
Enzymes
The small intestine contains bacteria that produce some of the enzymes needed to digest carbohydrates. The pancreas secretes digestive enzymes into the duodenum that break down protein, fats, and carbohydrates.

The small intestine is about 5.5 meters long and is divided into three parts: the duodenum, jejunum, and ileum.

A common hepatopancreatic duct opens into the duodenum. It is formed of the common bile duct from the liver and gall bladder as well as a pancreatic duct from the pancreas.
Fats are present in the form of large globules in the small intestine which makes it difficult for enzymes to act on them. Bile juice from the liver contains bile pigments and bile salts. Bile salts break fats into small globules by a process called emulsification and thus increase the efficiency of enzyme action (lipase).
The pancreas secretes slightly alkaline pancreatic juice which contains three major following enzymes:

(i) Trypsin which digests proteins.
(ii) Lipase which digests fats.
(iii) Amylase which digests carbohydrates.
The walls of the small intestine contain glands that secrete intestinal juice. The enzymes present in it, finally convert the proteins into amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol.
The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption of digested food. The villi are richly supplied with blood vessels that take the absorbed food to every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old ones.

Small Intestine

The undigested food is sent into the large intestine where more water is reabsorbed from undigested food. The rest of the undigested food material is removed from the body via the anus. The anal sphincter regulates the exit of this waste material.
The food material taken in during the process of nutrition is used by cells to provide energy for various life processes.
Some organisms use oxygen to bring about the complete breakdown of glucose in cells into carbon dioxide and water (aerobic respiration).
Respiration is a biochemical catabolic process that involves:
(i) Intake of molecular oxygen from the environment
(ii) Stepwise oxidation of food with incoming oxygen
(iii) Elimination of carbon dioxide produced during oxidation and
(iv) Release of energy.

MULTIPLE CHOICE QUESTION
Try yourself: What is the primary function of villi in the small intestine?
A
Secretion of digestive enzymes
CORRECT ANSWER
B
Absorption of digested food
C
Breaking down large food particles
D
Excretion of waste products
Correct Answer: B
Explanation: The inner lining of the small intestine has numerous finger-like projections called villi, which increase the surface area for absorption of digested food. The villi are richly supplied with blood vessels that take the absorbed food to every cell of the body, where it is utilized for obtaining energy, building up new tissues, and the repair of the old ones.

What are Life Processes?

Maintenance of living organisms is essential even if they are moving, resting, or even sleeping. The processes which together perform the function of maintenance of 'life' are known as life processes.

Nutrition, respiration, circulation, and excretion are examples of essential life processes.
In unicellular organisms, all these processes are carried out by a single cell.
In multicellular organisms, well-developed systems are present to carry out the processes.

Types of Life Processes

Biology is the study of living things, encompassing plants and animals. Determining if something is alive involves seven life processes:

Types of Life Processes

1. Movement: Both plants and animals can exhibit movement, although in different ways.

2. Respiration: The process of obtaining energy from food, occurring in the mitochondria of cells.

3. Sensitivity: Living things are responsive to stimuli in their environment.

4. Growth: All living organisms undergo a growth process, with plants continuing to grow throughout their lives.

5. Excretion: Removal of metabolic waste, with plants eliminating waste through falling leaves and animals through various means.

6. Reproduction: The production of offspring for the survival of the species, occurring through sexual or asexual means.

7. Nutrition: The intake of food for energy and growth, achieved through photosynthesis in plants and consumption of other organisms in animals.

Let us study Nutrition and Metabolism in detail.

What is Nutrition?

Nutrition is the process of taking in food and converting it into energy and other vital nutrients required for life.

Nutrients are inorganic as well as organic substances which the organisms obtain from their surroundings in order to synthesize their body constituents and use them as a source of energy. The process of intake of nutrients and their utilization by an organism in various biological activities.
A process to transfer a source of energy from outside the body of the organism (food), to the inside is called nutrition.
There are various types of nutrients on the basis of function they perform:
(a) Energy foods: Carbohydrates and fats
(b) Bodybuilding foods: Proteins and mineral salts
(c) Regulating foods: Vitamins and minerals

MULTIPLE CHOICE QUESTION

Try yourself: Which of the following are energy foods?

CORRECT ANSWER

Carbohydrates and fats

Proteins and mineral salts

Vitamins and minerals

Water and roughage

Correct Answer: A

Human food should consist of a variety of nutrients such as carbohydrates, minerals, fats, proteins, vitamins and fibre.
However, carbohydrates provide the human body with maximum energy.
Carbohydrates are broken down into various forms of glucose which act as the best source of energy.
Fats are also a very good source of energy.

Modes of Nutrition

The method of obtaining food by the organism is called the mode of nutrition.

Modes of Nutrition

1. Autotrophic (Holophytic) Nutrition

The mode of nutrition in which the organisms prepare (or synthesize) their own organic food by using inorganic raw material (CO2 & H2O). They are also called Autotrophs.
(Auto = self, trophic = food)
Example: Plants, Photosynthetic and chemosynthetic bacteria and cyanobacteria etc.

- Light energy absorption by chlorophyll.

- Light energy is converted to chemical energy, and water molecules are divided into hydrogen and oxygen.

- Carbon dioxide is converted to carbohydrates.

(i) Photoautotroph: Those which utilize sunlight for preparing their food

(ii) Chemoautotroph: Those which utilize chemical energy for preparing their food.

Autotrophic Nutrition

Photosynthesis

Photosynthesis is an important process by which food in plants is formed.
The plants make food using sunlight and water, which provides nourishment to other organisms and themselves.

Process of Photosynthesis
Chlorophyll present in the green parts absorbs light energy.
This light energy is used to split water into hydrogen and oxygen.
Carbon dioxide is reduced to form glucose during photosynthesis, and the source of hydrogen is water.
Chlorophyll is essential for photosynthesis and stomata to facilitate the intake of carbon dioxide.

Stomata

Stomata are pores on the leaves that help in the exchange of gases.
They are mostly found on the underside of the leaf.
Each stoma is guarded by guard cells, which control the opening and closing of the pore.
Stomata
The water content of the guard cells is responsible for their function.

2. Heterotrophic Nutrition

The mode of nutrition in which the organisms derive their nutrition from other organisms. They take ready-made organic food from other dead or living plants or animals. The living organisms showing heterotrophic nutrition, are called heterotrophs.

(Hetero = different ; trophic = food)

Example: All animals, fungi, many bacteria and some non-green plants (insectivorous plants), and man.

Types of Heterotrophic Nutrition

(i) Holozoic nutrition (Holo-Complete + Zoon-animal)

The mode of nutrition in which all animals take in complex solid food material is called holozoic nutrition.
Example: All animals including vertebrates and Invertebrates.
It contains the following steps:
(i) Ingestion: Taking in complex organic food through the mouth opening.
(ii) Digestion: Change of complex food into simple diffusible form by the action of enzymes.
(iii) Absorption: Passing of simple, soluble nutrients into blood or lymph.
(iv) Assimilation: Utilization of absorbed food for various metabolic processes.
(v) Egestion: Expelling out the undigested food.

Depending upon the type of food habit, animals are divided into three categories:
(i) Herbivores: Animals that depend upon green plants are known as herbivores.
Example: Goat, Cow, Deer, Rabbit.
(ii) Carnivores: Animals that eat the flesh of other animals as food are called carnivores.
Example: Lion, Tiger.
(iii) Omnivores: Animals that eat both plants and animals as food are known as omnivores.
Example: Rat, Pigs, Crows, Cockroaches and Humans.

(ii) Saprotrophic (Sapro - Rotten; Trophos - Feeder) Nutrition

In this type of nutrition, the organisms obtain their food from decaying organic substances. Organisms are also called Saprotrophs.
Example: Bacteria, Fungi.
Saprotrophs

(iii) Parasitic Nutrition (para-other)

The mode of nutrition in which one organism (called parasite) derives its food from other living organisms (Host) is called parasitic nutrition.
Example: Tapeworm, Ascaris, Plasmodium, Liver flukes, Cuscuta etc.

(iv) Mutualistic nutrition

Mutualistic nutrition can be defined as the interdependent nutrition in which each organism is dependent mutually on the other.
Example: The lichens share mutualistic nutrition between a fungus and an Algae.

Differences between Autotrophic and Heterotrophic Nutrition

Differences between Holozoic and Saprotrophic Nutrition

Note:
Animals that depend upon the blood of other animals known as sanguines.
Example: Bedbug, Mosquito, Leech etc.
Some organisms take in predigested food through their body wall by the process of diffusion. This process of nutrition is known as osmotrophic nutrition.
Example: Tapeworm, Trypanosoma.

MULTIPLE CHOICE QUESTION

Try yourself: The mode of nutrition found in fungi is:

Parasitic nutrition

Holozoic nutrition

Autotrophic nutrition

CORRECT ANSWER

Saprotrophic nutrition

Correct Answer: D

Saprophytic: The mode of nutrition in which organisms feed on dead and decaying matter. Example fungi. In the saprotrophic mode of nutrition, the vital nutrients required for their body are collected from dead and decaying matter. The other organisms which are saprotrophic are Rhizopus, Yeast, and Mushroom.

Nutrition in Unicellular Organism (Amoeba)

Amoeba is a holozoic and omnivorous animal. It feeds upon microscopic organisms like bacteria, Paramecium, Diatoms, Algae and dead organic matter.

Nutrition in Amoeba

Nutrition in Amoeba involves the following steps:

Ingestion: Amoeba has no mouth, so ingestion may occur at any point of body surface but generally it occurs at the advancing end of the body. Ingestion occurs with the help of pseudopodia. The opening of the food cup gradually becomes narrower and narrower, and finally closes. So the food is finally enveloped and taken inside a food-vacuole (called phagosome) along with a drop of water.
Digestion: Amoeba shows intracellular and vacuolar digestion. In the cytoplasm, food vacuole fuses with lysosomes containing digestive enzymes. In this, the complex and non-diffusible nutrients are changed into simple and diffusible nutrients. Medium inside the food vacuole is first acidic but later becomes alkaline (as in the alimentary canal of man).
Absorption and assimilation: In absorption, the diffusible nutrients pass through the vacuolar membrane into the cytoplasm by diffusion and are then distributed to all the body parts by streaming movements of the cytoplasm called cyclosis. Due to this, the size of the food vacuole gradually decreases.
In the cytoplasm, a part of the absorbed food is oxidised to produce energy, most of the simple nutrients are combined to synthesize complex compounds.
Egestion: Amoeba has no anus, so egestion may occur at any point on the body surface.

MULTIPLE CHOICE QUESTION

Try yourself: In amoeba, food is digested in the:

CORRECT ANSWER

Food vacuole

Mitochondria

Pseudopodia

Chloroplast

Correct Answer: A

Digestion in Amoeba mainly takes place in the food vacuole. Food vacuole is formed when food is engulfed through phagocytosis. These vacuoles are pushed deeper into the cytoplasm where they join with the lysosome to form secondary lysosomes.

What is Metabolism?

Metabolism refers to a series of chemical reactions that occur in a living organism to sustain life.

Metabolism is a word used to describe the sum total of all the chemical and physical changes that are constantly taking place in living matter and are necessary for life.
The word metabolite refers to a substance that undergoes various changes during metabolism.
Example: Carbon dioxide and water are metabolites used in the process of photosynthesis.

Types of Metabolic Process

There are two types of metabolic processes:

Catabolism
Anabolism

1. Anabolic pathways or Biosynthetic pathways: In which biosynthesis of organic compounds occurs, or in other words, complex substances are synthesized from simpler ones.

Example: Photosynthesis

In anabolic pathways or processes of anabolism, energy is used (endothermic reactions)

2. Catabolic pathways in which the breakdown of complex organic substances into simpler ones occurs.

Example: Respiration

In catabolic pathways or catabolism, energy is released (exothermic reactions).

Important Terms to Learn

Nutrition: The processes by which organisms obtain and utilise nutrients (food).
Food: The substance which is palatable, delicious enough, and energy provider is called food.
Chemically food consists of six essential components:
(i) Carbohydrates
(ii) Fats
(iii) Proteins
(iv) Minerals
(v) Vitamins
(vi) Water
Digestion: Digestion is a catabolic process, in which the complex, non-diffusable, and larger components of the food are broken down into their respective simpler, diffusible and smaller forms with the help of various hydrolytic enzymes in the alimentary canal of living organisms.
Intracellular and Extracellular Digestion
(a) Intracellular Digestion: This type of digestion occur inside the cell cytoplasm. The food inside the cell occurs as a food vacuole. The digestive enzyme in this case is secreted inside the cell. They digest the contents of the food vacuole. So the entire process of digestion occurs inside the cell.
Example: Protozoans [Amoeba], Sponges.
(b) Extracellular Digestion: It takes place outside the cell [i.e. in the intercellular space or a cavity formed by many cells or tissue]. In all animals, this cavity is found as a large canal, called the Alimentary canal.
Hydrolysis: It is a kind of catabolic reaction in which a compound is broken [lysis means break] down into smaller compounds, with the help [addition] of water [hydro = water].
Carbohydrates: These are the hydrates of carbon in which the ratio among carbon, hydrogen & oxygen is 1: 2: 1. Carbohydrates are the quickest source of energy.
On the basis of their composition, carbohydrates are of the following types:
(a) Monosaccharides: The simplest sugars are called monosaccharides. These sugars cannot be further degraded to produce more sugars.
Example: Glucose, Fructose, Galactose, Ribose, and Deoxyribose.
(b) Oligosaccharides: These are complex sugars, formed by the polymerisation of a few [1 to 10] units of monosaccharides.
Sucrose - Glucose + Fructose
Maltose - Glucose + Glucose
Lactose - Glucose + Galactose
(c) Polysaccharides: These are the most complex carbohydrates, which are the polymers of thousand of units of monosaccharides.
Example: Starch Stored food in plants, Glycogen Stored food material in Animals.
Cellulose: Constituent of the cell wall.
Fats: These are energy-rich compounds. These are the esters of higher fatty acids. [Esters are formed by the addition of alcohol with acids]. Glycerol is a type of alcohol.
Proteins: Proteins are the polymers of amino acids. Amino acids are held together by means of a peptide bond to form polypeptide chains.
On the basis of the gross size of food, the mechanism in different animals may be of two main types:
(a) Microphagy: Feeding on microscopic organisms.
Example: Amoeba, Paramecium.
(b) Macrophagy: Feeding on larger forms of organisms.
Example: Majority of non-chordates and some chordates.
In Paramecium, ingestion is aided by the beating of cilia. It has a definite food passage, including a mouth (cytostome) and an anus (cytopyge).
Food vacuole is commonly called the temporary stomach as it is the site of storage of food.
The most common mode of ingestion in Amoeba is circumvallation. In this, pseudopodia extend and form a cup-like structure, called a food cup, around the prey.

Respiration

Organisms like yeast perform anaerobic respiration, breaking down glucose into ethanol, carbon dioxide, and energy without using oxygen. Since this process occurs without air (oxygen), it is called anaerobic respiration.
During vigorous exercise, when oxygen is limited, muscles perform anaerobic respiration, producing lactic acid and energy. The accumulation of lactic acid in our muscles during sudden activity causes cramps.
Aerobic and Anaerobic Respiration

Glycolysis

The first step in the breakdown of glucose-a six-carbon molecule-into a three-carbon molecule called pyruvate occurs in the cytoplasm of the cell. This step is common to both aerobic and anaerobic respiration.
Breakdown of pyruvate using oxygen takes place in the mitochondria. This process breaks up the three-carbon pyruvate molecule to produce three molecules of carbon dioxide and water, along with the release of energy. Since this process occurs in the presence of air (oxygen), it is called aerobic respiration.
The energy released during cellular respiration is immediately used to synthesize a molecule called ATP (Adenosine triphosphate), which is used to fuel all other activities in the cell.

The energy released during aerobic respiration is significantly greater than that released during anaerobic respiration. In these processes, ATP is broken down to provide energy for various endothermic reactions taking place in the cell.

MULTIPLE CHOICE QUESTION

Try yourself: Where does the breakdown of pyruvate take place in the presence of oxygen?

Glycolysis

Anaerobic respiration

CORRECT ANSWER

Mitochondria

Lactic acid formation

Correct Answer: C

The breakdown of pyruvate in the presence of oxygen takes place in the mitochondria. Mitochondria are known as the power-house of the cell because they are responsible for producing energy through aerobic respiration. During this step, pyruvate is further broken down into carbon dioxide and water, releasing a large amount of energy. This energy is then used by the cell for various metabolic processes. The mitochondria's ability to carry out this process makes it crucial for aerobic respiration to occur.

Respiration in Humans

In human beings, air enters the body through the nostrils. As it passes through, fine hairs filter the air, ensuring it is free of dust and other impurities.
From the nostrils, air moves through the pharynx and into the lungs via the trachea.
The trachea contains incomplete C-shaped rings of cartilage, preventing the air passage from collapsing when no air is present.
The trachea divides into bronchi and bronchioles within the lungs, culminating in thin-walled, balloon-like structures called alveoli, where gas exchange occurs due to their extensive network of blood vessels.
Respiration in humans
Upon inhalation, the chest cavity expands. The contraction of external intercostal muscles pushes the rib cage outward and upward, while the diaphragm flattens.
This increase in chest cavity volume results in decreased pressure, causing air to rush into the lungs through the external nostrils. This process is known as inspiration or inhalation.
During expiration or exhalation, stale air rich in carbon dioxide is expelled.
Inspiration and expiration
This occurs due to the relaxation of inspiratory muscles, pulling the rib cage inward. The diaphragm relaxes, taking a dome shape, which reduces the size of the thoracic cavity and compresses the lungs.
The respiratory pigment hemoglobin in red blood cells (RBCs) has a high affinity for both O2 and CO2. Carbon dioxide is primarily transported as bicarbonate ions in the plasma, with some dissolved or bound to hemoglobin.
The upper respiratory tract, including the trachea, bronchi, and bronchioles, is lined with small hair-like cilia that help remove germs and dust from inhaled air.

Transportation in Human Beings

Blood carries numerous substances such as salts, vitamins, hormones, and waste products. The transportation system in humans includes the heart, blood vessels (arteries, veins, and capillaries), and circulatory fluids (blood and lymph).

Our pump- The Heart

The heart is a muscular organ approximately the size of a fist. A mammalian heart consists of four chambers: the upper chambers, known as auricles or atria, and the lower chambers called ventricles.
Double circulation occurs in humans, meaning the same blood passes through the heart twice to complete one cycle.
The right side of the heart receives deoxygenated blood, while the left side pumps oxygenated blood. There is no mixing of these blood types.
Deoxygenated blood returns to the right auricle via two large veins: the superior and inferior vena cava.
When the right atrium contracts, the right ventricle dilates, allowing blood to flow into it before being pumped to the lungs for oxygenation.
The left ventricle's contraction sends oxygenated blood to the body through the aorta, the largest artery.
The walls of the ventricles are thicker than those of the auricles because they pump blood under higher pressure to the lungs (right ventricle) and the rest of the body (left ventricle). Valves prevent backflow of blood during contractions.
Double circulatory system
In mammals and birds, the separation between the left and right sides of the heart is advantageous because it prevents the mixing of oxygenated and deoxygenated blood. This is crucial for animals with high energy demands, like birds and mammals, which need to maintain body temperature.
Fish have a two-chambered heart with one auricle and one ventricle. In single circulation, blood is pumped to the gills for oxygenation and then directly to the body, passing through the heart once per cycle.

[Intext Questions]

Blood Pressure

Blood pressure is the force exerted by blood against the walls of blood vessels. This pressure is significantly higher in arteries compared to veins.
The heart's contraction is known as systole, while its relaxation is referred to as diastole. Blood pressure during systole is called systolic pressure, and during diastole, it is termed diastolic pressure. The standard systolic pressure is 120 mm of Hg, and diastolic pressure is 80 mm of Hg.
Blood pressure is measured using a device called a sphygmomanometer. High blood pressure, or hypertension, arises from the narrowing of arterioles, leading to greater resistance to blood flow. This condition can cause an artery to rupture, resulting in internal bleeding.
Systolic and Diastolic Pressure

Blood Vessels

Arteries transport blood away from the heart to various body organs. Due to the high pressure of blood exiting the heart, arteries possess thick, elastic walls.
Veins return deoxygenated blood from the body's organs back to the heart. They have thinner walls since the blood within is not under high pressure, and they feature valves that ensure blood flows in one direction.
When reaching organs or tissues, arteries branch into smaller vessels to deliver blood to individual cells. The smallest vessels, known as capillaries, have walls that are just one cell thick, facilitating material exchange between blood and surrounding cells.
Capillaries converge to form veins, which carry blood away from the organ or tissue and back to the heart.

Arteries, Veins and Capillaries

Lymph

Another important fluid involved in transportation is lymph, also known as tissue fluid. Plasma, proteins, and blood cells escape through the pores in capillary walls into intercellular spaces, forming tissue fluid or lymph.
Lymph resembles blood plasma but is colorless and contains less protein. It enters lymphatic capillaries from intercellular spaces, which merge to form larger lymph vessels that eventually connect to larger veins.

Lymph plays a crucial role in carrying digested and absorbed fats from the intestine and draining excess fluid from the extracellular space back into the blood.
Lymph is a colorless, light yellow, viscous fluid formed when some fluid passes from blood capillaries into intercellular spaces in the tissues through pores in the capillary walls. It contains less protein than blood plasma.
Lymph drains into lymphatic capillaries from intercellular spaces, joining to form larger lymph vessels that eventually open into larger veins.
Lymph carries digested and absorbed fat from the intestine and drains excess fluid from the extracellular space back into the blood.

Transportation in Plants

Xylem transports minerals and water from roots to other parts of the plant, while phloem transports the products of photosynthesis from leaves to other parts and storage organs.
Xylem tissue consists of four components: xylem vessels, xylem tracheids, xylem fibers, and xylem parenchyma.
Water and minerals are conducted from roots to other parts due to root pressure, transpirational pull, and cohesion-adhesion forces.
The transport of soluble products of photosynthesis is called translocation and occurs in the part of the vascular tissue known as phloem. Phloem also transports amino acids and other substances to storage organs.
Translocation of food and other substances takes place in the sieve tubes with the help of adjacent companion cells, in both upward and downward directions. Material like sucrose is transferred into phloem tissue using energy from ATP, which increases the osmotic pressure of the tissue, causing water to move into it. This pressure moves the material in the phloem to tissues with less pressure.

MULTIPLE CHOICE QUESTION

Try yourself: Which type of blood vessel carries oxygenated blood from the heart to the various organs of the body?

CORRECT ANSWER

Arteries

Veins

Capillaries

Pulmonary artery

Correct Answer: A

Arteries are the blood vessels that carry oxygenated blood from the heart to the various organs of the body, except for the pulmonary artery. They have thick and elastic walls to withstand the high pressure of the blood being pumped from the heart. Veins, on the other hand, collect deoxygenated blood from the organs and bring it back to the heart. Capillaries, the smallest vessels, allow for the exchange of materials between the blood and surrounding cells. So, the correct answer is Option A: Arteries.

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Excretion in Humans

The biological process involved in the removal of harmful metabolic wastes from the body is known as excretion. Different organisms employ various strategies for this purpose. In complex multicellular organisms like humans, specialized organs carry out this function.

The excretory system of humans comprises a pair of kidneys, a pair of ureters, a urinary bladder, and a urethra. The kidneys are situated in the abdomen, one on each side of the backbone. Urine produced in the kidneys travels through the ureters to the urinary bladder, where it is stored until it is expelled through the urethra.

Functions of the Kidneys

Each kidney contains numerous filtering units called nephrons, densely packed together.
Each nephron consists of a cup-shaped structure known as Bowman's capsule (which contains a cluster of capillaries called glomerulus), a convoluted tube, and a collecting duct.
As the glomerular filtrate moves through the nephron's tubular part, useful substances such as glucose, amino acids, mineral ions, and water are reabsorbed by the blood capillaries surrounding the nephron.
Each kidney filters approximately 180 liters of plasma daily, producing about one to two liters of urine, as most of the filtrate is reabsorbed by the kidney tubules.
The kidneys play a crucial role in excretion, filtering soluble nitrogen compounds as waste products.
Kidneys perform two essential functions: (i) filtering nitrogenous waste from the blood, and (ii) osmoregulation, which maintains the appropriate balance of water and ions in the body.
An artificial kidney is utilized to filter the blood of patients. The process of purifying blood using an artificial kidney is referred to as hemodialysis.
The urinary bladder is muscular and regulated by the nervous system, allowing for the control of the urge to urinate.

Excretion in Plants

Plants employ completely different strategies for excretion than those of animals. Oxygen itself can be thought of as a waste product generated during photosynthesis! We have discussed earlier how plants deal with oxygen as well as carbon dioxide. They can get rid of excess water by transpiration.

Waste Management Strategies

Plants use the fact that many of their tissues consist of dead cells.
They can even lose some parts, such as leaves.
Many plant waste products are stored in cellular vacuoles.
Waste products may also be contained in leaves that fall off.
Other waste products are stored as resins and gums, especially in old xylem.
Plants also excrete some waste substances into the soil around them.

Olympiad Notes: Life Processes (Introduction, Nutrition)

Introduction

Differentiating between living and non-living entities can sometimes be challenging, but certain characteristics can help us make this separation. While the visible movement, such as breathing or growth, is often associated with living beings, it is not always a definitive indicator. Even a motionless plant or an animal that breathes without visible movement can still be considered alive. Organisms are organized structures that require constant maintenance and repair to sustain. As these structures are composed of molecules, the continuous movement of molecules is necessary for the maintenance processes in living organisms.

Life Processes

What are Life Processes?

Life processes are one of the most important parts of living beings which collective help us to sustain. These simple points capture the basic ideas that explain what life processes are in living things.

Continuous Maintenance: Even when at rest, living organisms require ongoing maintenance processes to prevent damage and breakdown.
Energy Source: Energy for maintenance comes from external sources called food. The process of transferring energy from food to the body is called nutrition.
Growth Requirements: For growth, additional raw materials are needed from the environment, often carbon-based substances.
Nutritional Diversity: Different organisms use various nutritional processes based on the complexity of carbon sources.
Energy Transformation: External energy sources vary, so they are broken down or transformed into a uniform energy source for sustaining cellular functions and growth.
Chemical Reactions: Chemical reactions inside the body are necessary for breaking down molecules. Oxidising-reducing reactions are common, often involving oxygen, known as respiration.
Multi-cellular Challenges: As organisms grow larger and more complex, specialized tissues handle food and oxygen uptake. This complexity requires a transportation system to distribute these essentials.
Waste Management: Energy-generating reactions produce waste by-products. Specialized tissues for waste elimination require a transportation system to remove waste from cells.

Nutrition

The process by which an organism takes food and utilizes it, is called nutrition.

Organisms need the energy to perform various activities. The energy is supplied by the nutrients. They need various raw materials for growth and repair. These raw materials are provided by nutrients. Carbohydrates, proteins and fats are the main nutrients and are called macronutrients. Minerals and vitamins are required in small amounts and hence are called micronutrients.

How do living things get their food?

All organisms have a general requirement for energy and materials. This requirement is fulfilled in different ways.
Some organisms, called autotrophs, use simple food materials obtained from inorganic sources like carbon dioxide and water. Autotrophs include green plants and some bacteria.
Other organisms, called heterotrophs, utilize complex substances. These complex substances need to be broken down into simpler ones before they can be used for the upkeep and growth of the body. To achieve this, organisms use enzymes, which are bio-catalysts. Therefore, the survival of heterotrophic organisms depends directly or indirectly on autotrophs. Heterotrophic organisms include animals and fungi.

Categorization

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Autotrophic Nutrition

The mode of nutrition in which an organism prepares its own food is called autotrophic nutrition. Green plants and blue-green algae follow the autotrophic mode of nutrition.

The term "autotrophic" is formed by the combination of two terms, "auto" meaning self, and "trophic" meaning nutrition. The literal meaning of this term is self-nutrition.

MULTIPLE CHOICE QUESTION

Try yourself: Which mode of nutrition involves an organism preparing its own food?

CORRECT ANSWER

Autotrophic nutrition

Heterotrophic nutrition

Macronutrient nutrition

Micronutrient nutrition

Correct Answer: A

- Autotrophic nutrition is the mode of nutrition in which an organism prepares its own food.

- Green plants and blue-green algae are examples of organisms that follow autotrophic nutrition.

- Autotrophs, such as green plants, are capable of producing their own food by converting carbon dioxide and water into carbohydrates in the presence of sunlight and chlorophyll.

- This process is known as photosynthesis, where sunlight provides the energy source for the conversion.

- In photosynthesis, carbon dioxide and water are the raw materials, and the chloroplasts within the cells of autotrophs are the sites where food is made.

- Autotrophic nutrition is essential for the growth and survival of green plants and other autotrophic organisms as it provides them with the necessary energy and raw materials for their various activities.

- Therefore, the correct answer is option A: Autotrophic nutrition.

What is Photosynthesis?

Autotrophic nutrition is fulfilled by the process by which autotrophs intake CO2 and H2O and convert these into carbohydrates in the presence of chlorophyll and sunlight, which is called photosynthesis.

Photosynthesis Equation

Main Events of Photosynthesis

Chlorophyll absorbs light energy.
The absorbed light energy is converted into chemical energy.
Water molecules are split into hydrogen and oxygen during this conversion process.
Carbon dioxide is reduced to form carbohydrates.

Process of Photosynthesis

Site of Photosynthesis: Chloroplast in the leaf. Chloroplast contains chlorophyll (green pigment)

Stomata

Stomata are tiny pores in the epidermis of leaf or stem through which gaseous exchange and transpiration occur.

Functions of stomata

Exchange of gases, O2 and CO2.
Loses a large amount of water (water vapour) during transpiration.
Stomata

Opening and closing of stomatal pores

The opening and closing of stomatal pores are controlled by the turgidity of guard cells.
When guard cells uptake water from surrounding cells, they swell to become a turgid body, which enlarges the pore in between (Stomatal Opening).
While, when water is released, they become flaccid shrinking to close the pore (Stomatal Closing).

How do other raw materials for photosynthesis become available to the plant?

Autotrophs not only require energy but also other raw materials for building their bodies.

Water used in photosynthesis is obtained by terrestrial plants from the soil through their roots.
Nitrogen, phosphorus, iron, and magnesium are other materials that autotrophs need, which are also obtained from the soil.
Nitrogen is an essential element for the synthesis of proteins. It is mostly absorbed from the soil in the form of nitrates.
Alternatively, autotrophs can also obtain nitrogen in the form of organic compounds that have been prepared by bacteria from atmospheric nitrogen.

Heterotrophic Nutrition

Heterotrophic nutrition refers to the mode of nutrition where an organism obtains food from other living organisms.

Different organisms have different ways of obtaining food, depending on whether the food source is stationary or mobile.
Some organisms externally break down the food material and then absorb it, like bread molds, yeast, and mushrooms.
Other organisms take in whole material and break it down internally.
The ability to take in and break down food depends on the organism's body design and functioning.
Some organisms derive nutrition from plants or a wide variety of other organisms, such as cuscuta, ticks, lice, leeches, and tapeworms.

How do Amoeba Obtain their Nutrition?

Amoeba is a unicellular animal. Digestion happens in five steps, viz. ingestion, digestion, absorption, assimilation and egestion.

Nutrition in Amoeba

The cell membrane of amoeba keeps on protruding into pseudopodia.
Amoeba surrounds a food particle with its pseudopodia and forms a food vacuole.
The food vacuole contains food particles and water.
Digestive enzymes are secreted in the food vacuole and digestion takes place.
After digestion, the food is absorbed from the food vacuole.
Finally, the food vacuole moves near the cell membrane and undigested food is expelled out.

MULTIPLE CHOICE QUESTION

Try yourself: How do green plants obtain the raw materials required for photosynthesis?

Through the process of respiration

Through the absorption of sunlight

CORRECT ANSWER

Through the roots and stomata

Through the process of transpiration

Correct Answer: C

- Green plants obtain water and dissolved minerals from the soil through their roots.

- The water is transported through the xylem tissue in the roots and stems.

- Carbon dioxide enters the leaves through small openings called stomata.

- Stomata are located on the surface of the leaves and allow for the exchange of gases.

- The raw materials, water and carbon dioxide, are then available in the chloroplasts of the leaf cells where photosynthesis takes place.

- It is through this process that green plants are able to convert sunlight into chemical energy and produce carbohydrates.

- Therefore, the correct option is C: Through the roots and stomata.

Nutrition in Human Beings

Human beings possess a sophisticated digestive system, consisting of both an alimentary canal and several accessory glands. The alimentary canal is a long, hollow tube that is divided into various parts, including the esophagus, stomach, small intestine, large intestine, rectum, and anus. Meanwhile, the accessory glands, namely the salivary gland, liver, and pancreas, are located outside the alimentary canal and play essential roles in the digestive process.

Structure of the Human Digestive System

The human digestive system comprises of the alimentary canal and associated digestive glands.

Structure of digestive system

Alimentary Canal

It comprises of mouth, oesophagus, stomach, small intestine and large intestine.

1. Mouth or Buccal Cavity

The mouth has teeth and tongue. Salivary glands are also present in the mouth which help by secreting saliva.
The tongue has gustatory receptors which perceive the sense of taste.
The tongue helps in turning over the food so that saliva can be properly mixed in it.
Teeth help in breaking down the food into smaller particles so that, swallowing of food becomes easier.
There are four types of teeth in human beings. The incisor teeth are used for cutting the food. The canine teeth are used for tearing the food and for cracking hard substances. The premolars are used for the coarse grinding of food. The molars are used for fine grinding of food.

2. Oesophagus

Food is taken from the mouth to the stomach by peristaltic movement.
Rhythmic contraction of muscles of the lining of the alimentary canal to push the food forward is called Peristaltic movement.

3. Stomach

Stomach is a bag-like organ. Highly muscular walls of the stomach help in churning the food.
The walls of the stomach secrete hydrochloric acid. Hydrochloric acid kills the germs which may be present in food.
Moreover, it makes the medium inside the stomach as acidic. The acidic medium is necessary for gastric enzymes to work.
The enzyme pepsin, secreted in the stomach, does partial digestion of protein.
The mucus, secreted by the walls of the stomach saves the inner lining of the stomach from getting damaged from hydrochloric acid.

4. Small Intestine

The highly coiled, tube-like structure known as the small intestine is longer than the large intestine, although its lumen is smaller in comparison.

5. Large Intestine

Large intestine is smaller than the small intestine.
Undigested food goes into the large intestine.
Some water and salt are absorbed by the walls of the large intestine. After that, the undigested food goes to the rectum, from where it is expelled out through the anus.
Large Intestine absorb excess of water. The remaining material is expelled from the body through the anus as egestion.

Associated Glands

The main associated glands are the Salivary gland, Gastric Glands, Liver and Pancreas.

1. Salivary glands

Saliva makes the food slippery which makes it easy to swallow the food.
Saliva also contains the enzyme salivary amylase or ptyalin. Salivary amylase digests starch and converts it into sucrose, (maltose).

2. Liver

Liver is the largest organ in the human body.
The liver manufactures bile, which gets stored in the gall bladder.
From the gall bladder, bile is released as and when required.
Liver

3. Pancreas

Pancreas is situated below the stomach.
It secretes pancreatic juice which contains many digestive enzymes.
The duodenum receives both bile and pancreatic juice through a common duct called the hepatopancreatic duct.
Bile plays a crucial role in breaking down fats into smaller particles, a process known as emulsification.
Following this, the enzyme lipase acts on the emulsified fats, breaking them down into fatty acids and glycerol.
Moreover, the enzymes trypsin and chymotrypsin are responsible for digesting proteins into amino acids, while complex carbohydrates are broken down into glucose.
The duodenum is the primary site for these digestive processes, where the major part of digestion occurs.

No digestion occurs in the jejunum: Inside the ileum, the inner wall has numerous finger-like structures known as villi. These villi serve two important functions: first, they increase the surface area of the ileum, allowing for efficient nutrient absorption. Second, they help reduce the lumen of the ileum, which allows food to stay inside for a longer time, facilitating better absorption. The digested food is then absorbed through these villi.

Excretion in Human Beings

Excretion is the process by which the body removes harmful metabolic wastes, primarily produced during cellular activities. In humans, the main excretory organs are the kidneys, which filter nitrogenous wastes like urea from the blood and expel them in the form of urine. The excretory system also includes ureters, the urinary bladder, and the urethra, which help in transporting and storing urine before its removal. Along with kidneys, organs like the lungs (which remove carbon dioxide), skin (which releases sweat), and liver (which detoxifies harmful substances) also assist in excretion.

Short & Long Answer Questions: Life Processes

Q1. Define nutrition. What are the different modes of nutrition?

Ans: Nutrition is the process by which living organisms obtain and use food for growth and health. There are three main modes of nutrition:

Autotrophic Nutrition: Organisms create their own food using water, carbon dioxide, and sunlight through processes like photosynthesis.
Heterotrophic Nutrition: Organisms consume organic matter from other sources. This includes:
1. Herbivores: eat plants.
2. Carnivores: eat animals.
3. Omnivores: eat both plants and animals.
4. Detritivores: feed on dead organic matter.
5. Saprotrophs: act as decomposers.

These modes of nutrition help organisms acquire the essential nutrients and energy needed for survival and growth in various environments.

Q2. What is the mode of nutrition in fungi?

Ans: Saprophytic nutrition is the primary mode of nutrition in fungi.

Q3. Name the pigment, which can absorb solar energy.

Ans: (i) The pigment that can absorb solar energy is called chlorophyll.

(ii) It is found in the chloroplasts of plant cells and is essential for photosynthesis.

(iii) Chlorophyll absorbs light in the blue and red parts of the spectrum and reflects green light, giving plants their characteristic colour. This ability has practical applications in fields such as solar energy production.

Q4. Write the stages of photosynthesis.

Ans:

Absorption of light energy
Conversion of light energy to chemical energy and splitting of water
Reduction of carbon dioxide to carbohydrates

Photosynthesis

Q5. Name the factors, that affect Photosynthesis.

Ans: The factors that affect photosynthesis include:

Light - Essential for the process to occur.
Water - A critical raw material.
Temperature - Influences the rate of photosynthesis.
Carbon dioxide - Necessary for the production of glucose.
Chlorophyll - Presence of this pigment is necessary for photosynthesis.

Q6. Define a Herbivore and a Carnivore.

Ans: Herbivore: Animals that feed exclusively on plants are known as herbivores.

Carnivore: Animals that consume only flesh are referred to as carnivores.

Q7. How does Amoeba engulf its food?

Ans: Amoeba engulfs its food by extending pseudopodia. This process is known as phagocytosis.

The amoeba stretches its membrane to form temporary arms called pseudopodia.
These extensions surround the food particle.
Once engulfed, the food is enclosed in a food vacuole.
The amoeba then digests the food within this vacuole.

Q8. Name the parts of the digestive system of a grasshopper.

Ans: The parts of the digestive system of a grasshopper are the Mouth, Salivary glands, Esophagus, Crop, Gizzard, Stomach, Intestines, Rectum, and Anus.

Q9. What are the functions of the liver and the pancreas?

Ans: The liver and pancreas play crucial roles in digestion and metabolism:

Liver functions:

Secretes bile, which includes bile pigments and salts.
Bile is stored in the gall bladder until needed in the duodenum.
Helps in emulsifying fats in food.

Pancreas functions:

Located parallel to and beneath the stomach.
Secretes digestive enzymes and hormones, including insulin and glucagon.
Enzymes like trypsin digest proteins, while pancreatic amylase breaks down starch.

Both bile and pancreatic juice enter the duodenum through a common duct.

Q10. Define Breathing.

Ans: Breathing is the physical process by which an organism takes in oxygen from the surroundings (inhalation) and gives out carbon dioxide (exhalation).

Q11. How is respiration different from breathing?

Ans:

Q12. In which kind of respiration is more energy released?

Ans: Aerobic respiration releases more energy compared to other types of respiration. This is due to the fact that most cells in the body depend on aerobic processes to produce the energy they require for normal functioning.

Q13. Which part of the roots is involved in the exchange of respiratory gases?

Ans: Root hair is the part of the roots that plays a key role in the exchange of respiratory gases.

Q14. What are

(i) stomata

(ii) lenticels

Ans: (i) Stomata are small openings on the surface of leaves that help control the exchange of gases, such as oxygen and carbon dioxide, as well as transpiration (the loss of water vapour).

(ii) Lenticels are raised pores found in the bark of woody plants. They facilitate gas exchange between the atmosphere and the plant's internal tissues.

Q15. Give two points of differences between respiration in plants and respiration in animals.

Ans: Respiration in plants differs from respiration in animals in two main ways:

Gas transport: Plants have minimal transport of gases between different parts, whereas animals actively transport gases throughout their bodies.
Respiration rate: Plant respiration occurs at a much slower rate than that of animals.

Q16. Name the respiratory organs of

(i) fish

(ii) mosquito

(iii) earthworm

(iv) dog

Ans: The respiratory organs of:

(i) fish - gills

(ii) mosquito-tracheoles

(iii) earthworm-skin

(iv) dog - lungs.

Q17. From where do the following take in oxygen?

(i) prawn

(ii) rat

Ans: (i) Prawns take in oxygen that is dissolved in water through their gills.

(ii) Rats breathe in oxygen from the atmosphere using their lungs.

Q18. State the function of epiglottis.

Ans: The epiglottis serves several important functions:

It prevents food from entering the trachea.
This flap of tissue is located in the throat and stops food and liquids from entering the windpipe and lungs during swallowing.

It closes over the opening of the windpipe (the glottis) and directs food towards the oesophagus.

Q19. Define Photolysis.

Ans: The term photolysis is derived from Greek, where photo means light and lysis means to break apart. It refers to the process of breaking down substances using light energy.

Specifically, photolysis involves:

The breakdown of water molecules in the chloroplasts of plants when exposed to light.
Generation of oxygen gas as a by-product of this process.

Q20. What are the living organisms that cannot make their food called?

Ans: The living organisms that cannot make their own food are called heterotrophs.

Q21. What are Chemotrophs?

Ans: Chemotrophs are organisms that do not need light to survive. Instead, they produce their own food using inorganic substances. They obtain energy from the oxidation of simple inorganic compounds, such as:

Iron
Sulphur

An example of a chemotroph is the bacterium Nitrosomonas.

Q22. What is Compensation Point?

Ans:

The compensation point is the specific level of light at which the rate of photosynthesis equals the rate of respiration. At this point:

The absorption of CO2 by photosynthesis matches the release of CO2 through respiration.
The uptake of O2 by respiration equals the O2 released by photosynthesis.
This condition typically occurs in the early morning and late evening.

Q23. Other than chlorophyll, which another pigment is necessary for photosynthesis?

Ans: Carotenoids are essential pigments for photosynthesis, aside from chlorophyll. They are:

Yellow, orange, red, or brown pigments.
Responsible for absorbing sunlight.
Assist in transferring energy to chlorophyll.

While carotenoids do not directly perform photosynthesis, they play a crucial role in the process.

Q24. Where does digestion begin?

Ans:

Digestion begins in the mouth. When we eat:

Our teeth break food into smaller pieces.
This food mixes with saliva.
Saliva contains enzymes that convert complex carbohydrates into simpler sugars.

Q25. What is the name given to the process of using the absorbed food for producing energy?

Ans: The process of using absorbed food to produce energy is called cellular respiration.

Q26. What happens to the visible light of the Sun when it falls on chlorophyll?

Ans: Visible light from the Sun includes seven colours: violet, indigo, blue, green, yellow, orange, and red.

Chlorophyll interacts with this light as follows:

It primarily absorbs blue, violet, red, and orange light.
It does not absorb green light.

The reflection of green light is why plants appear green.

NCERT Solutions: Life Processes

Page No. 81

Q1: Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Ans: Multicellular organisms such as humans possess complex body designs. They have specialized cells and tissues for performing various necessary functions of the body, such as intake of food and oxygen. Unlike unicellular organisms, multicellular cells are not in direct contact with the outside environment. Therefore, diffusion cannot meet their oxygen requirements.

Q2: What criteria do we use to decide whether something is alive?

Ans: Living organisms are identified by the presence of life processes. The essential criterion is the presence of metabolic activities (molecular movements) that maintain life.

Even if visible movement is absent, internal processes like respiration, nutrition, and excretion indicate that the organism is alive.

Characteristics of life

Q3: What are outside raw materials used for by an organism?

Ans: An organism uses outside raw materials, mostly in the form of food and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.

Q4: What processes would you consider essential for maintaining life?

Ans: Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.

Page No. 87

Q1: What are the differences between autotrophic nutrition and heterotrophic nutrition?

Ans:

Q2: Where do plants get each of the raw materials required for photosynthesis?

Ans: The following raw materials are required for photosynthesis:

Carbon Dioxide: Plants get CO2 from the atmosphere through stomata.
Water: Plants absorb water from the soil through roots and transport it to leaves.
Sunlight: Sunlight, which is absorbed by the chlorophyll and other green parts of the plant.

Q3: What is the role of the acid in our stomach?

Ans: Following are the roles of acid in our stomach:

(i) It creates an acidic medium for the action of the proteolytic enzyme pepsin.

(ii) HCl converts inactive pepsinogen into active pepsin.

(iii) Kills harmful bacteria present in the food.

Q4: What is the function of digestive enzymes?

Ans: Digestive enzymes such as amylase, lipase, pepsin, trypsin, etc. help in the breakdown of complex food particles into simple ones. These simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.

Q5: How is the small intestine designed to absorb digested food?

Ans: The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the bloodstream. From the bloodstream, the absorbed food is delivered to each and every cell of the body.

Fig: Longitudinal section of villi

Page No. 91

Q1: What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Ans: Terrestrial organisms take up oxygen from the atmosphere, whereas aquatic animals obtain oxygen from water. Air contains more O2 as compared to water. Since the content of O2 in the air is high, terrestrial animals do not have to breathe faster to get more oxygen. Therefore, unlike aquatic animals, terrestrial animals do not need adaptations for gaseous exchange.

Q2: What are the different ways in which glucose is oxidized to provide energy in various organisms?

Ans: At first, glucose (6 carbon molecules) is broken in the cytoplasm of cells of all organisms. This process yields a 3-carbon molecule compound called pyruvate.

Further breakdown of pyruvate takes place in different manners in different organisms.

Anaerobic Respiration: This process takes place in the absence of oxygen, e.g., in yeast during fermentation. In this case, pyruvate is converted into ethanol and carbon dioxide.
Aerobic Respiration: In aerobic respiration, the breakdown of pyruvate takes place in the presence of oxygen to give rise to 3 molecules of carbon dioxide and water. The release of energy in aerobic respiration is much more than anaerobic respiration.
Lack of Oxygen: Sometimes, when there is a lack of oxygen, especially during vigorous activity, in our muscles, pyruvate is converted into lactic acid (3-carbon molecule compounds). The formation of lactic acid in muscles causes cramps.

Q3: How is oxygen and carbon dioxide transported in human beings?

Ans: (i) Transport of oxygen : Haemoglobin present in the blood takes up the oxygen from the air in the lungs. It carries the oxygen to tissues which are deficient in oxygen before releasing it.

(ii) Transport of carbon dioxide : Carbon dioxide is more soluble in water. Therefore, it is mostly transported from body tissues in the dissolved form in our blood plasma to lungs. Here it diffuses from blood to air in the lungs.

Q4: How are the lungs designed in human beings to maximize the area for the exchange of gases?

Ans:

The lungs are an important part of the body. The passage inside the lungs divides into smaller and smaller tubes, which finally terminate in balloon-like structures called alveoli.
The alveoli provide a surface where the exchange of gases can take place. The walls of the alveoli usually contain an extensive network of blood vessels. We know that when we breathe in, we lift our ribs, flatten our diaphragm and the chest cavity becomes larger.
Because of this action, the air is sucked into the lungs and fills up the expanded alveoli.

Page No. 96

Q1: What are the components of the transport system in human beings? What are the functions of these components?

Ans: The main components of the transport system in human beings are the heart, blood, and blood vessels.

Heart: The heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from the various body parts and sends this impure blood to the lungs for oxygenation.

Blood: Blood helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.

Blood Vessels: The blood vessels (arteries, veins, and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.

Q2: Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Ans: It is necessary to separate oxygenated and deoxygenated blood to ensure an efficient supply of oxygen to the body.

Mammals and birds have a high metabolic rate and need large amounts of energy to maintain a constant body temperature.

Separation prevents mixing of blood and allows maximum oxygen delivery for efficient respiration.

Q3: What are the components of the transport system in highly organized plants?

Ans: In highly organized plants, there are two different types of conducting tissues - xylem and phloem. Xylem conducts water and minerals obtained from the soil (via roots) to the rest of the plant. The phloem transports food materials from the leaves to different parts of the plant body.

Q4: How are water and minerals transported in plants?

Ans: The components of xylem tissue (tracheids and vessels) of roots, stems, and leaves are interconnected to form a continuous system of water-conducting channels that reaches all parts of the plant. Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells of the roots. Then, there is a steady movement of water from the root xylem to all the plant parts through the interconnected water-conducting channels.

Fig: Xylem tissue

Q5: How is food transported in plants?

Ans: Phloem transports food materials from the leaves to different parts of the plant body. The transportation of food in phloem is achieved by utilizing energy from ATP. As a result of this, the osmotic pressure in the tissue increases, causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant. For example, the food material, such as sucrose, is transported into the phloem tissue using ATP energy.

Fig: Phloem tissue

Page No. 98

Q1: Describe the structure and functioning of nephrons.

Ans: Nephrons are the basic filtering units of the kidneys. Each kidney possesses a large number of nephrons, approximately 1-1.5 million. The main components of the nephron are the glomerulus, Bowman's capsule, and a long renal tubule.

Fig: Structure of Nephron

Functioning of a nephron:

The blood enters the kidney through the renal artery, which branches into many capillaries associated with the glomerulus.

The water and solute are transferred to the nephron at Bowman's capsule.

In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed, and unwanted molecules are added in the urine.

The filtrate then moves down into the loop of Henle, where more water is absorbed.

From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collects urine from many nephrons.

The urine formed in each kidney enters a long tube called a ureter. From the ureter, it gets transported to the urinary bladder and then into the urethra.

Q2: What are the methods used by plants to get rid of excretory products?

Ans: Plants can get rid of excess water by transpiration.

For other wastes, plants use the fact that many of their tissues consist of dead cells and that they can even lose some parts, such as leaves. Many plant waste products are stored in cellular vacuoles. Waste products may be stored in leaves that fall off.

Other waste products are stored as resins and gums, especially in old xylem. Plants also excrete some waste substances into the soil around them.

Q3: How is the amount of urine produced regulated?

Ans: The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors, such as habitat of an organism and hormone such as Antidiuretic hormone (ADH), also regulates the amount of urine produced.

Page No. 99

Exercise

Q1: The kidneys in human beings are a part of the system for

(a) nutrition

(b) respiration

(d) transportation

Ans: (c) In human beings, the kidneys are a part of the system for excretion.

Q2: The xylem in plants are responsible for

(a) transport of water

(b) transport of food

(d) transport of oxygen

Ans: (a) In a plant, the xylem is responsible for transport of water.

Q3: The autotrophic mode of nutrition requires

(a) carbon dioxide and water

(b) chlorophyll

(d) all of the above

Ans: (d) The autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll and sunlight.

Q4: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) cytoplasm

(b) mitochondria

(d) nucleus

Ans: (b) The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

Q5: How are fats digested in our bodies? Where does this process take place?

Ans: Digestion of fats takes place in the small intestine.

Bile juice secreted by the liver poured in the intestine along with pancreatic juice. The bile salts present in the bile juice emulsify fhe large globules of fats. Therefore, by enulsification large globules break down into fine globules to provide larger surface area to act upon by the enzymes.

Lipase enzyme present in the pancreatic juice causes break down of emulsified fats. Glands present in the wall of small intestine secrete intestinal juice which contains lipase enzyme that converts fats into fatty acids and glycerol.

Q6: What is the role of saliva in the digestion of food?

Ans: Saliva is secreted by the salivary glands, located under the tongue. It moistens the food for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

Q7: What are the necessary conditions for autotrophic nutrition and what are its by-products?

Ans: Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. O2 is the by-product of photosynthesis.

Q8: What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Ans:

Examples: Yeast and some bacteria use anaerobic respiration.

Q9: How are the alveoli designed to maximize the exchange of gases?

Ans: The alveoli are the small balloon-like structures present in the lungs. The walls of the alveoli consist of an extensive network of blood vessels. Each lung contains 300-350 million alveoli, making it a total of approximately 700 million in both lungs. The alveolar surface, when spread out, covers about 80 m2 area. This large surface area makes the gaseous exchange more efficient.

Fig: Alveoli and capillaries

Q10: What would be the consequences of a deficiency of hemoglobin in our bodies?

Ans: Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Therefore, a deficiency of hemoglobin in the blood can affect the oxygen-supplying capacity of blood. This can lead to a deficiency of oxygen in the body cells. It can also lead to a disease called anemia.

Q11: Describe double circulation in human beings. Why is it necessary?

Ans:

Double circulation means, in a single cycle, blood goes twice in the heart. The process helps in separating oxygenated and deoxygenated blood to maintain a constant body temperature.

Fig: Flow of blood

Schematic diagram of blood circulation in humans

The double circulatory system of blood includes

Pulmonary circulation
Systemic circulation.

Pulmonary circulation

The right ventricle pumps deoxygenated blood into the lungs, where it is oxygenated. The oxygenated blood is brought back to the left atrium, and from there, it is pumped into the left ventricle. Finally, blood goes into the aorta for systemic circulation.

Systemic circulation

The oxygenated blood is pumped to various parts of the body from the left ventricle. The deoxygenated blood from different parts of the body passes through the vena cava to reach the right atrium. The right atrium transfers the blood into the right ventricle.

Necessity of double circulation: The right side and the left side of the human heart are useful to keep deoxygenated and oxygenated blood from mixing. This type of separation of oxygenated and deoxygenated blood ensures a highly efficient supply of oxygen to the body. This is useful in case of humans who constantly need energy to maintain their body temperature.

Q12: What are the differences between the transport of materials in xylem and phloem?

Ans:

Q13: Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Ans:

Alveoli	Nephrons
Structure	Structure
Alveoli are tiny balloon-like structures present inside the lungs.	Nephrons are tubular structures present inside the kidneys.
The walls of the alveoli are one cell thick and it contains an extensive network of blood capillaries.	Nephrons are made of glomerulus, bowman's capsule, and a long renal tube.
Function	Function
The exchange of 02 and C02 takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli.	The blood enters the kidneys through the renal artery. The blood is entered here and the nitrogenous waste in the form of urine is collected by collecting duct.
Alveoli are the site of gaseous exchange.	Nephrons are the basic filtration unit.

MCQ Questions

Q1: Pair of spongy organs lying in the chest cavity is called

(a) hearts

(b) kidneys

(d) bronchioles

Ans: (c)

Lungs

The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). They play a crucial role in the respiratory system by taking in oxygen when we inhale and releasing carbon dioxide when we exhale.

Q2: Which of the following structures increase the total surface area for the exchange of gases in the lungs?

(a) Bronchi

(b) Alveoli

(d) Trachea

Ans: (b)

These tiny, balloon-shaped air sacs located at the end of the bronchial tubes deep within the lungs provide a large surface area for the exchange of oxygen and carbon dioxide.

Q3: Bile is produced by

(a) pancreas

(b) liver

(d) stomach

Ans: (b)

The liver produces bile, a digestive fluid that helps in the breakdown of fats during digestion.

Q4: Which of the following represents the correct sequence of air passage during inhalation?

(a) Nostrils→ larynx → pharynx → alveoli → lungs

(b) Nostrils → trachea → pharynx → larynx → lungs

(d) Nostrils → alveoli → pharynx → larynx → lungs

Ans: (c)

The sequence of air passage during inhalation starts from the nostrils, proceeds to the pharynx (throat), then to the larynx (voice box), followed by the trachea (windpipe), and finally reaches the alveoli in the lungs.

Q5: Balloon-like structures present inside the lungs are called

(a) alveoli

(b) bronchioles

(d) alveolar ducts

Ans: (a)

These are small, balloon-like structures present inside the lungs where the exchange of gases occurs.

Q6: Haemoglobin, the respiratory pigment is not found in

(a) WBC

(b) RBC

(d) plasma

Ans: (a)

White blood cells (WBC) are part of the immune system and help the body fight infections. Unlike red blood cells (RBC), they do not contain the respiratory pigment haemoglobin.

Q7: Pacemaker is meant for:

(a) transporting liver.

(b) transplanting heart.

(d) regulation of blood flow.

Ans: (c)

Pacemaker

A pacemaker is a small device that's placed in the chest to help control abnormal heart rhythms. It uses electrical pulses to prompt the heart to beat at a normal rate.

Q8: Veins can be differentiated from arteries because the veins

(a) have valves

(b) have hard walls.

(d) have thick walls.

Ans: (a)

Veins are blood vessels that carry blood towards the heart. They have valves that prevent the backflow of blood, which is a feature that differentiates them from arteries.

Q9: The rate at which oxygen moves from the alveoli of our lungs into our blood

(a) depends on the difference in oxygen concentration between the alveoli and the bloo(d)

(b) depends on the color of the alveoli.

(d) none of the above

Ans: (a)

The rate at which oxygen moves from the alveoli of our lungs into our blood depends on the difference in oxygen concentration between the alveoli and the blood.

Q10: Heart beat can be initiated by

(a)Sino-atrial (SA) node

(b) Sino-auricular node

(d) Purkinje's fibres

Ans: (a)

This node is a group of cells situated in the wall of the right atrium of the heart. It has the capacity to initiate a heartbeat and is hence often referred to as the natural pacemaker.

Q11: Erythropoesis may be stimulated by the deficiency of

(a) Iron

(b) Oxygen

(d) None of these

Ans: (b)

Erythropoiesis, the production of red blood cells, may be stimulated by a deficiency of oxygen in the body.

Q12: The chief function of lymph nodes in mammalian body is to

(a) produce RBCs

(b) collect and destroy pathogens

(d) destroy the old and worn out red blood cells

Ans: (b)

Lymph nodes play a crucial role in the body's immune system by trapping and destroying pathogens, such as bacteria and viruses.

Q13: Select the correct statement?

(a) Heterotrophs do not synthesise their own food

(b) Heterotrophs utilise solar energy for photosynthesis.

(d) Heterotrophs are capable of converting carbon dioxide and water into carbohydrates.

Ans: (a)

They depend on other organisms for their food.

Q14: During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the

(a) cytoplasm

(b) chloroplast

(d) golgi body

Ans: (a)

During deficiency of oxygen, pyruvic acid is converted into lactic acid in the cytoplasm of the cell.

Q15: The phenomenon of normal breathing in a human being comprises.

(a) an active inspiratory and a passive expiratory phase.

(b) a passive inspiratory and an active expiratory phase.

(d) both passive inspiratory and expiratory phases.

Ans: (a)

Normal breathing involves an active phase of inspiration, where muscles contract to pull air into the lungs, and a passive phase of expiration, where muscles relax to let air out.

Q16: Filteration unit of kidney is

(a) ureter

(b) urethra

(d) nephron

Ans: (d)

Nephron is the basic structural and functional unit of the kidney. It is responsible for the filtration of blood and the removal of waste products.

Q17: Column of water within xylem vessels of tall trees does not break under its weight because of:

(a) Tensile strength of water

(b) Lignification of xylem vessels

(d) Dissolved sugars in water

Ans: (a)

This refers to the ability of water to resist breaking under tension, which is why the column of water within xylem vessels of tall trees does not break under its weight.

Q18: Roots play insignificant role in absorption of water in:

(a) Pistia

(b) Pea

(d) Sunflower

Ans: (a)

In this water plant, the roots play an insignificant role in the absorption of water as it floats on the water surface and absorbs water directly from its surroundings.

Q19: Human urine is usually acidic because

(a) excreted plasma proteins are acidi(c)

(b) potassium and sodium exchange generates acidity.

(d) the sodium transporter exchanges one hydrogen ion for each sodium ion in peritubular capillaries.

Ans: (c)

This process contributes to the acidity of urine.

Q20: Which one of the following animals has two separate circulatory pathways?

(a) Lizard

(b) Whale

(d) Frog

Ans: (b)

Whales, like all mammals, have a double circulatory system. This means they have two separate pathways for blood flow - one for oxygenated blood and one for deoxygenated blood.

Q21: Cow has a special stomach as compared to that of a lion in order to

(a) absorb food in better manner.

(b) digest cellulose present in the food.

(d) absorb large amount of water.

Ans: (b)

Cows have a complex digestive system with a special stomach to break down cellulose found in their plant-based diet.

Q22: Which of the following is not an enzyme?

(a) Lipase

(b) Amylase

(d) Bilirubin

Ans: (d)

Bilirubin is not an enzyme but a yellowish substance produced by the breakdown of old red blood cells. High levels of bilirubin can lead to jaundice.

Fill in the blanks

Q1: The oxygen picked up by haemoglobin gets _________ with blood to various ________ .

Ans: transported, tissues

The oxygen picked up by haemoglobin gets 'transported' with blood to various 'tissues'. This means that oxygen, after being absorbed by haemoglobin present in the red blood cells, is carried or transferred through the bloodstream to different body tissues that require it for their metabolic activities.

Q2: Amoeba exhibits _______ nutrition.

Ans: holozoic

An amoeba exhibits 'holozoic' nutrition. This indicates that an amoeba feeds in a manner similar to humans, i.e., it ingests solid food particles, digests them internally, and throws out the waste. This type of nutrition is termed as holozoic nutrition.

Q3: Chlorophyll is mainly found in the__________.

Ans: leaves

Chlorophyll is mainly found in the 'leaves'. Chlorophyll is a green pigment that absorbs light energy for photosynthesis, and it's predominantly located in the chloroplasts of leaf cells, where the process of photosynthesis primarily takes place.

Q4: ATP is the ___________ for most cellular processes.

Ans: energy currency

ATP is the 'energy currency' for most cellular processes. This means that Adenosine triphosphate (ATP) is the primary energy carrier in all living organisms. The energy required for various biochemical reactions in the body is stored and transported by ATP.

Q5: The walls of the alveoli contain an extensive network of ____________ .

Ans: blood vessels

The walls of the alveoli contain an extensive network of 'blood vessels'. This network of blood vessels allows for the exchange of gases, with oxygen from the air in the alveoli diffusing into the blood, and carbon dioxide in the blood diffusing out into the alveoli to be exhaled.

Q6: The oral cavity opens into the ____________ .

Ans: pharynx

The oral cavity opens into the 'pharynx'. This means that the mouth or oral cavity leads to the pharynx, a part of the digestive and respiratory systems, which serves as a pathway for food to the esophagus and air to the larynx and trachea.

Q7: _____________ is the first part of small intestine.

Ans: Duodenum

'Duodenum' is the first part of the small intestine. This means that the first section of the small intestine that receives partially digested food from the stomach is called the duodenum. It plays a crucial role in the further digestion of food.

Mark the statements True (T) or False (F)

Q1: Anaerobic reactions after glycolysis produce lactic acid, or ethanol.

Ans: True

In the absence of oxygen, the process of glycolysis in anaerobic respiration is followed by fermentation. In human muscles, lactic acid fermentation happens which leads to the production of lactic acid. In yeast cells, alcoholic fermentation happens which leads to the production of ethanol. Therefore, the statement is true.

Q2: As compared to aerobic respiration, anaerobic respiration produces more energy.

Ans: False

Anaerobic respiration produces less energy compared to aerobic respiration. In aerobic respiration, glucose is completely broken down into carbon dioxide and water, releasing 38 ATP molecules which is a higher amount of energy. In anaerobic respiration, glucose is incompletely broken down and only 2 ATP molecules are generated, hence less energy is produced.

Q3: Stomach serves as a storehouse of food where complete digestion takes place.

Ans: False

The stomach does serve as a storehouse where food can be stored for 2-4 hours, but it is not the site for complete digestion. The process of digestion starts in the stomach with the action of gastric juices but it is completed in the small intestine with the help of various enzymes and intestinal juices.

Q4: Gastric glands are present in small intestine.

Ans: False

Gastric glands are not present in the small intestine. They are located in the stomach. They secrete gastric juice which contains enzymes like pepsin for the digestion of proteins. The small intestine has its own glands called intestinal glands which secrete intestinal juice.

Practice Questions: Transportation in Human Beings

Fill in the Blanks

1. A mineral that helps in the formation of RBCs is _________.

2. Blood vessels with thin walls and no muscles are _________.

3. The first heart sound is called _________.

4. Fishes have a _________ chambered heart.

5. Amphibians have a _________ chambered heart.

6. The _________ heart pumps only deoxygenated blood.

7. Blood goes through the heart twice during each cycle is called _________.

8. High blood pressure is called _________.

9. The force that blood exerts against the wall of a vessel is called _________.

10. Contraction of the heart chambers is called _________.

11. Relaxation of heart chambers is called _________.

12. _________ helps in blood clotting.

13. White colored fluid other than blood that helps in transportation is called _________.

14. Lymph carries digested and absorbed fat from _________.

15. Lymph drains excess fluid from extra cellular space back into _________.

16. Lymph drains into _________ for the intercellular spaces.

17. Lymphatic capillaries join to form _________.

18. The pumping organ in the human body is _________.

19. The fluid medium of blood is called _________.

20. Oxygen is carried by the _________.

21. Blood platelets are also called _________.

22. Covering over heart is called _________.

23. _________ circulation is related to the lungs.

24. The series of events that occur during one complete beat of the heart is known as the _________ cycle.

25. The pressure wave transmitted all through the arterial system is known as _________.

Answer.

1. Iron

2. Capillaries

3. Lub

4. Two

5. Three

6. Fishes

7. Double circulation

8. Hypertension

9. Blood pressure

10. Systole

11. Diastole

12. Platelets

13. Lymph

14. Intestine

15. Blood

16. Lymphatic capillaries

17. Lymph vessels

18. Heart

19. Plasma

20. RBC

21. Thrombocytes

22. Pericardium

23. Pulmonary

24. Cardiac

25. Pulse

Match the Columns

Answer.

1 → (e)

2 → (a)

3 → (b)

4 → (c)

5 → (d)

6 → (g)

7 → (f)

8 → (k)

9 → (i)

10 → (l)

True or False Statements

1. Vessels are able to contract and expand. (True)

2. While there is only one type of RBC, there are many white cell types. (True)

3. All animals have a system of vessels and tubes called a circulatory system. (True)

4. Blood is not a tissue because it is a fluid. (False)

5. Arteries are the widest blood vessels. (True)

6. Humans have an open circulatory system. (False)

7. The exchange of nutrients and waste products between the blood and cells occurs within the arteries. (False)

8. The liquid portion of the blood is called plasma. (True)

9. Living organisms must maintain a constant internal environment. (True)

10. The circulatory system also performs the function of homeostasis. (True)

Very Short Answer Type Questions

1. Name the blood-receiving chamber of the heart.

2. What makes RBCs red?

3. What is pulmonary circulation?

4. Which chamber of the heart has the thickest wall?

5. Name the larger veins that pour blood into right auricle.

6. Name the largest artery of our body.

7. Which chamber of heart receives oxygenated blood from lungs ?

8. Name the valve present between the :

(a) left auricle and left ventricle

(b) right auricle and right ventricle

9. What is normal blood pressure?

10. Name the artery that carries deoxygenated blood and the vein that carries oxygenated blood.

11. What is SA node?

12. Which instrument can record electrical changes during heart beat ?

13. Name the thickest artery.

14. Name the part of the circulatory system that acts as filter for microorganisms.

15. Name the major circulation present in our body.

16. Give the technical term for the white vascular connective tissue.

17. What is the life span of human RBCs ?

18. Why is blood called river of life ?

19. Give the position of human heart ?

20. Why there is no backflow of blood from ventricles to auricles ?

Answer Key:

1. Right auricle

2. Haemoglobin

3. In this, blood completes its circulation from right ventricle to left auricle through the lungs.

4. Left ventricle

5. Superior and inferior vena cava

6. Aorta

7. Left auricle

8. a. bicuspid valve

b. tricuspid valve

9. 120/80 mm Hg

10. pulmonary artery, pulmonary vein

11. Sinoatrial node (pacemaker of the heart)

12. Electrocardiograph

13. Aorta

14. Lymph nodes

15. Systemic circulation

16. Lymph

17. 120 days

18. because it transports the materials and helps in survival of the organism.

19. In thoracic cavity between the lungs

20. due to the presence of atrioventricular valves.