NCERT Exemplar Solutions Class 10 Science Life Processes

Multiple Choice Questions....................

Question 1:  Which of the following statements about the autotrophs is incorrect?

(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll

(b) They store carbohydrates in the form of starch

(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight

(d) They constitute the first trophic level in food chains 

Solution 1:  (c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight 

To turn carbon dioxide and water into carbohydrates, they require sunlight.

Question 2:  In which of the following groups of organisms, food material is broken down outside the body and absorbed?

(a) Mushroom, green plants, Amoeba

(b) Yeast, mushroom, bread mould

(c) Paramecium, Amoeba, Cuscuta

(d) Cuscuta, lice, tapeworm 

Solution 2: (b) Yeast, mushroom, bread mould 

Saprophytes are organisms that break down food outside of their bodies and absorb it. Yeast, mushrooms, and bread mould are examples of saprophytes.

Question 3:  Select the correct statement

(a) Heterotrophs do not synthesise their own food

(b) Heterotrophs utilise solar energy for photosynthesis

(c) Heterotrophs synthesise their own food

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

Solution 3: (a) Heterotrophs do not synthesise their own food 

Heterotrophs are species that rely on Phototrophs or other organisms for food.

Question 4:  Which is the correct sequence of parts in the human alimentary canal?

(a) Mouth → stomach → small intestine → oesophagus → large intestine

(b) Mouth →oesophagus → stomach → large intestine → small intestine

(c) Mouth → stomach → oesophagus → small intestine → large intestine

(d) Mouth → oesophagus → stomach → small intestine → large intestine 

Solution 4:  (d) Mouth → oesophagus → stomach → small intestine → large intestine 

Question 5:  If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected?

(a) Proteins breaking down into amino acids

(b) Starch breaking down into sugars

(c) Fats breaking down into fatty acids and glycerol

(d) Absorption of vitamins 

Solution 5: (b) Starch breaking down into sugars 

Salivary Amylase, a digestive enzyme, breaks down starch into simpler sugars and aids digestion. As a result, if salivary amylase is deficient, starch breakdown will be hampered.

Question 6:  The inner lining of the stomach is protected by one of the following from hydrochloric acid. Choose the correct one

(a) Pepsin

(b) Mucus

(c) Salivary amylase

(d) Bile 

Solution 6:  (b) Mucus 

The inner lining of the stomach is protected by mucus from hydrochloric acid.

Question 7:  Which part of alimentary canal receives bile from the liver?

(a) Stomach

(b) Small intestine

(c) Large intestine

(d) Oesophagus 

Solution 7:  (b) Small intestine 

The hepta pancreatic duct transports bile from the gall bladder to the small intestine.

Question 8:  A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains

(a) complex proteins

(b) simple proteins

(c) fats

(d) starch 

Solution 8: (d) starch

Amylose and Amylopectin are the two elements of starch. Amylose interacts with iodine to form a blue colour complex when iodine is added to starch-containing water. As Iodine is added to this solution, it turns blue-black, indicating the presence of starch in the rice water.

Question 9:  In which part of the alimentary canal food is finally digested?

(a) Stomach

(b) Mouth cavity

(c) Large intestine

(d) Small intestine 

Solution 9: (d) Small intestine

While the primary digestion process occurs in the mouth and stomach, the majority of digestion occurs in the small intestine, and the large intestine digestion process may not occur.

Question 10:  Choose the function of the pancreatic juice from the following

(a) trypsin digests proteins and lipase carbohydrates

(b) trypsin digests emulsified fats and lipase proteins

(c) trypsin and lipase digest fats

(d) trypsin digests proteins and lipase emulsified fats 

Solution 10:  (d) trypsin digests proteins and lipase emulsified fats 

Lipase breaks down emulsified fat molecules into fatty acids and glycerol, while Trypsin breaks down proteins into polypeptides.

Question 11:  When air is blown from the mouth into a test-tube containing lime water, the lime water turned milky due to the presence of

(a) oxygen

(b) carbon-dioxide

(c) nitrogen

(d) water vapour 

Solution 11: (b) carbon-dioxide 

Lime water becomes milky when carbon dioxide reacts with it.

Question 14:  Which of the following statement(s) is (are) true about respiration?

(i) During inhalation, ribs move inward and diaphragm is raised

(ii) In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air diffuses into blood and carbon dioxide from the blood into the alveolar air

(iii) Haemoglobin has a greater affinity for carbon dioxide than oxygen

(iv) Alveoli increase surface area for exchange of gases

(a) (i) and (iv)

(b) (ii) and (iii)

(c) (i) and (iii)

(d) (ii) and (iv) 

Solution 14: (d) (ii) and (iv) 

Statement (i) is incorrect because during inhalation, the ribs pass outward and the diaphragm is lowered. Option (iii) is also incorrect since haemoglobin has a higher affinity for oxygen than CO₂.

Question 15:  Which is the correct sequence of air passage during inhalation?

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

(b) Nasal passage →trachea →pharynx →larynx →alveoli

(c) larynx →nostrils →pharynx →lungs

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

Solution 15:  (d) Nostrils →pharynx →larynx →trachea→alveoli 

Air enters the respiratory system through the nostrils, then travels through the pharynx, larynx, trachea, and alveoli. Following inhalation, the diaphragm and intercoastal muscles contract, while the thoracic muscles expand, allowing the air to reach the lungs.

Question 16:  During respiration exchange of gases take place in

(a) trachea and larynx

(b) alveoli of lungs

(c) alveoli and throat

(d) throat and larynx 

Solution 16:  (b) alveoli of lungs 

The Trachea and Larynx provide a passage for air to pass through. The Alveoli of the lungs are where gas exchange takes place. Oxygen diffuses into the bloodstream from alveoli, while carbon dioxide is exhaled.

Question 17:  Which of the following statement (s) is (are) true about the heart?

(i) The left atrium receives oxygenated blood from different parts of the body while the right atrium receives deoxygenated blood from lungs

(ii) Left ventricle pumps oxygenated blood to different body parts while right ventricle pumps deoxygenated blood to lungs

(iii) Left atrium transfers oxygenated blood to the right ventricle which sends it to different body parts

(iv) The right atrium receives deoxygenated blood from different parts of the body while the left ventricle pumps oxygenated blood to different parts of the body

(a) (i)

(b) (ii)

(c) (ii) and (iv)

(d) (i) and (iii) 

Solution 17:  (c) (ii) and (iv)

The left side of the heart is where oxygenated blood circulates, while the right side is where deoxygenated blood circulates. The atrium collects blood, while the ventricle pumps it out of the nucleus.

Question 18:  What prevents backflow of blood inside the heart during contraction?

(a) Valves in heart

(b) Thick muscular walls of ventricles

(c) Thin walls of atria

(d) All of the above 

Solution 18: (a) Valves in the heart

The walls of the heart are only responsible for pumping blood; they are not responsible for preventing blood from flowing backwards within the heart during contraction.

Question 19:  Single circulation i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by

(a) Labeo, Chameleon, Salamander

(b) Hippocampus, Exocoetus, Anabas

(c) Hyla, Rana, Draco

(d) Whale, Dolphin, Turtle 

Solution 19:  (b) Hippocampus, Exocoetus, Anabas

Option a) Chameleons are reptiles, while Salamanders are amphibians, all of which have three chambered hearts and partial double circulation. Many of the Amphibians in Option c) have partial double circulation. Option d) is incorrect since the whale is a dolphin and the turtle is a reptile.

Question 20:  In which of the following vertebrate group/groups, the heart does not pump oxygenated blood to different parts of the body?

(a) Pisces and amphibians

(b) Amphibians and reptiles

(c) Amphibians only

(d) Pisces only 

Solution 20: (d) Pisces only

This is due to the heart's single circulation, which pumps deoxygenated blood from all parts of the body into it. It is pumped from the heart to the gills, where it is oxygenated and distributed to other areas of the body. As a result, Pisces will not be receiving oxygenated blood.

Question 21:  Choose the correct statement that describes arteries.

(a) They have thick elastic walls, blood flows under high pressure; collect blood from different organs and bring it back to the heart

(b) They have thin walls with valves inside, blood flows under low pressure and carry blood away from the heart to various organs of the body

(c) They have thick elastic walls, blood flows under low pressure; carry blood from the heart to various organs of the body

(d) They have thick elastic walls without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body. 

Solution 21:  (d) They have thick elastic walls without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body.

Question 22: The filtration units of kidneys are called

(a) ureter

(b) urethra

(c) neurons

(d) nephrons 

Solution 22:  (d) nephrons

The functional unit of the kidney is known as the nephron. It aids in the removal of waste and excess substances from our bodies.

Question 23: Oxygen liberated during photosynthesis comes from

(a) water

(b) chlorophyll

(c) carbon dioxide

(d) glucose 

Solution 23:  (a) water

Water molecules break during photosynthesis to create oxygen and hydrogen ions. Plants expel oxygen, which is then used to reduce carbon dioxide to create carbohydrates.

Question 24:  The blood leaving the tissues becomes richer in

(a) carbon dioxide

(b) water

(c) haemoglobin

(d) oxygen 

Solution 24:  (a) carbon dioxide 

Carbon-dioxide accumulates in tissues as a result of respiration. As a result, the carbon-dioxide content of blood leaving the tissues increases.

Question 25:  Which of the following is an incorrect statement?

(a) Organisms grow with time

(b) Organisms must repair and maintain their structure

(c) Movement of molecules does not take place among cells

(d) Energy is essential for life processes 

Solution 25:  (c) Movement of molecules does not take place among cells 

Molecule movement is an important method. Diffusion, osmosis, and facilitated diffusion are examples of active and passive modes of molecule movement in cells.

Question 26:  The internal (cellular) energy reserve in autotrophs is

(a) glycogen

(b) protein

(c) starch

(d) fatty acid 

Solution 26:  (c) starch 

Animals store energy in the form of glycogen, while plants store energy in the form of starch.

Question 27:  Which of the following equations is the summary of photosynthesis?

(a) 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

(b) 6CO₂ + H₂O + Sunlight → C₆H₁₂O₆ + O₂ + 6H₂O

(c) 6CO₂ + 12H₂O + Chlorophyll + Sunlight → C₆H₁₂O₆ + 6O₂ + 6H₂O

(d) 6CO₂ + 12H₂O + Chlorophyll + Sunlight → C₆H₁₂O₆ + 6CO₂ + 6H₂O 

Solution 27:  (c) 6CO₂ + 12H₂O + Chlorophyll + Sunlight → C₆H₁₂O₆ + 6O₂ + 6H₂O 

Option (a) does not show the photosynthesis-related factors. Option (b) does not result in a balanced equation. Option (d) is incorrect since the products contain CO₂.

Question 28: Choose the event that does not occur in photosynthesis

(a) Absorption of light energy by chlorophyll

(b) Reduction of carbon dioxide to carbohydrates

(c) Oxidation of carbon to carbon dioxide

(d) Conversion of light energy to chemical energy 

Solution 28:  (c) Oxidation of carbon to carbon dioxide 

In the process of photosynthesis chlorophyll absorbs light energy from the sun, carbon-dioxide turns down into carbohydrates, and light energy is converted into chemical energy.

Question 29:  The opening and closing of the stomatal pore depends upon

(a) oxygen

(b) temperature

(c) water in guard cells

(d) concentration of CO₂ in stomata 

Solution 29:  (c) water in guard cells 

The entry of water into guard cells aids in the opening of guard cells. The guard cell becomes turgid as a result of this. Water leaking from guard cells aids in the closing of guard cells. The guard cells would become flaccid as a result of this.

Question 30:  Choose the forms in which most plants absorb nitrogen

(i) Proteins

(ii) Nitrates and Nitrites

(iii) Urea

(iv) Atmospheric nitrogen

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)

(d) (i) and (iv)   

Solution 30:  (b) (ii) and (iii)

Plants are unable to absorb nitrogen from the atmosphere. They can absorb nitrogen from the soil in the form of nitrates, nitrites, and urea.

Question 31:  Which is the first enzyme to mix with food in the digestive tract?

(a) Pepsin

(b) Cellulase

(c) Amylase

(d) Trypsin 

Solution 31: (c) Amylase 

Amylase is produced in the mouth and acts on starch to break it down into smaller molecules. As a result, Amylase is the first enzyme in the digestive tract to interact with food.

Question 32:  Which of the following statement(s) is (are) correct?

(i) Pyruvate can be converted into ethanol and carbon dioxide by yeast

(ii) Fermentation takes place in aerobic bacteria

(iii) Fermentation takes place in mitochondria

(iv) Fermentation is a form of anaerobic respiration

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (iv)

(d) (ii) and (iii) 

Solution 32: (c) (i) and (iv) 

Anaerobes in the cytoplasm carry out the fermentation process. As a result, options (ii) and (iii) are incorrect.

Question 33:  Lack of oxygen in muscles often leads to cramps among cricketers. This results due to

(a) conversion of pyruvate to ethanol

(b) conversion of pyruvate to glucose

(c) non-conversion of glucose to pyruvate

(d) conversion of pyruvate to lactic acid 

Solution 33: (d) conversion of pyruvate to lactic acid

In the presence of oxygen, Pyruvate is broken down in mitochondria, resulting in the formation of Lactic acid. As a result of the exercise, oxygen is used to produce energy, resulting in a loss of oxygen and the creation of lactic acid.

Question 34:  Choose the correct path of urine in our body

(a) kidney → ureter → urethra → urinary bladder

(b) kidney → urinary bladder → urethra → ureter

(c) kidney → ureters → urinary bladder → urethra

(d) urinary bladder → kidney → ureter → urethra  

Solution 34: (c) kidney → ureters → urinary bladder → urethra

Urine from the nephron is transported to the kidneys' collection duct, where it reaches the ureters. Each kidney has two ureters, which open into the urinary bladder. The urinary bladder stores urine, and as the amount of urine produced increases, so does the size of the bladder. As the CNS sends a voluntary message, the bladder muscles contract and the bladder sphincter relaxes, allowing urin to be excreted. 

Question 35:  During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the

(a) cytoplasm

(b) chloroplast

(c) mitochondria

(d) Golgi body 

Solution 35: (a) cytoplasm 

When there is a deficiency in oxygen Pyruvate is broken down in the cytoplasm of muscle cells, resulting in the production of lactic acid.

Short Answer Questions..........................

Question 36:   Name the following

(a) The process in plants that links light energy with chemical energy

(b) Organisms that can prepare their own food

(c) The cell organelle where photosynthesis occurs

(d) Cells that surround a stomatal pore

(e) Organisms that cannot prepare their own food

(f) An enzyme secreted from gastric glands in the stomach that acts on proteins. 

Solution 36:

(a) Photosynthesis is the process in plants that links light energy with chemical energy.

(b) Autotrophs are the organisms that can prepare their own food.

(c) Chloroplast is the cell organelle where photosynthesis occurs.

(d) Guard cells surround the stomatal pore.

(e) Heterotrophs are the organisms that cannot prepare their own food.

(f) Pepsin is the enzyme secreted from gastric glands in the stomach that acts on proteins.

Question 37:  “All plants give out oxygen during day and carbon dioxide during the night”. Do you agree with this statement? Give reason. 

Solution 37:  The argument is incorrect because plants respire and remove carbon dioxide at all times, but they only give out oxygen during the day because photosynthesis can only occur in the presence of sunlight.

Question 38:  How do the guard cells regulate opening and closing of stomatal pores? 

Solution 38:  The entry of water into guard cells aids in the opening of guard cells. The guard cell becomes turgid as a result of this. Water leaking from guard cells aids in the closing of guard cells. The guard cells would become flaccid as a result of this.

When water is introduced into guard cells, the cell becomes turgid, allowing the stomata to open. When water escapes from guard cells, the cell becomes flaccid; this causes the stomata to close.

Question 39: Two green plants are kept separately in oxygen-free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons. 

Solution 39:  Since plats release CO₂ during respiration, plants held in continuous light live longer. In the case of a plant held in the dark, CO₂ causes a lack of oxygen, causing the plant to die sooner.

Question 40:  If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer. 

Solution 40:   If a plant is releasing carbon dioxide and taking in oxygen throughout the day, it is respiring; however, this does not rule out the possibility of photosynthesis. This is due to the fact that photosynthesis and respiration are two separate processes.

Question 41: Why do fishes die when taken out of water? 

Solution 41:  Only dissolved oxygen allows fish to breathe. When we remove fish from the water, they are unable to breathe due to a lack of dissolved oxygen and die.

Question 42:  Differentiate between an autotroph and a heterotroph 

Solution 42:   Autotrophs are the organisms who make their food by themselves. For example plants and certain bacteria.

Whereas heterotrophs are the organisms that cannot make their food by themselves. For example animals, fungi and protozoans.

Question 43:  Is ‘nutrition’ a necessity for an organism? Discuss. 

Solution 43:   Nutrition is important for species since it provides the energy needed to carry out metabolic activities.

Question 44:  What would happen if green plants disappear from earth? 

Solution 44:  Both heterotrophs on the planet depend on green plants for energy. Solar and chemical resources are converted into viable food sources by plants. If plants vanish from the earth, the ecosystem becomes unbalanced, and heterotrophs will starve to death.

Question 45: Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer. 

Solution 45:  Vaseline applied to the leaves of a healthy plant clogs the stomata pores, preventing the plants from breathing and causing them to die.

Question 48:  Differentiate between an artery and a vein. 

Solution 48:   Veins have thin walls, while arteries have thick walls.

Blood is carried away from the heart by arteries, but blood is carried back to the heart by veins.

Valves are absent in arteries but present in veins.

Blood flows under pressure in lungs, so there would be none in veins.

Question 49:  What are the adaptations of leaf for photosynthesis? 

Solution 49:  The leaf's photosynthesis adaptations are as follows:

1. The leaf's surface is smooth to allow for more light exposure.
2. The presence of chlorophyll, which helps to absorb sunlight.
3. The presence of stomata on the lower surface of the leaf allows for fast transpiration.

Question 50:  Why is small intestine in herbivores longer than in carnivores? 

Solution 50:  Herbivores eat mainly cellulose-based foods. Herbivores need the assistance of some bacteria to digest cellulose. Herbivores have a longer small intestine than carnivores to contain bacteria and promote food digestion.

Question 51: What will happen if the mucus is not secreted by the gastric glands? 

Solution 51:   The inner lining of the stomach is protected from HCL by mucus. The inner lining of the stomach is kept moist by mucus. Mucus aids in the smooth passage of food particles into the digestive tract. Food will not easily pass through the digestive system if mucus is not secreted. The stomach lining will be damaged by HCL, and the digestive process will be disrupted.

Question 52:  What is the significance of the emulsification of fats? 

Solution 52:  Emulsification is the breaking down of larger fat molecules into smaller, more digestible fat globules. By breaking larger fat molecules, emulsification helps fat action enzymes.

Question 53:  What causes movement of food inside the alimentary canal? 

Solution 53:  The process of peristalsis is the passage of food through the alimentary canal.

Question 54:  Why does the absorption of digested food occur mainly in the small intestine? 

Solution 54:  Specialized structures in the small intestine aid in the absorption of digested food. The folds in the small intestine increase the absorption space. The small intestine also has microvilli, which are fingerlike projections that are well-supplied by blood vessels.

Question 56:  Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms? 

Solution 56:  Aquatic organisms breathe much faster than terrestrial organisms because oxygen availability in water is lower than on land, so aquatic organisms must work harder to acquire the oxygen they need.

Question 57:  Why is blood circulation in the human heart called double circulation? 

Solution 57:  In one cardiac cycle, blood flows in two directions simultaneously in humans. Oxygenated blood flows from the lungs to the heart, while deoxygenated blood flows from the heart to the lungs. Blood circulation in the human heart is called double circulation because of this double movement.

Question 58:  What is the advantage of having a four-chambered heart? 

Solution 58:  The following are some of the benefits of a four-chambered heart:

• The heart's efficiency will improve.
• The heart separates oxygenated and deoxygenated blood.
• There is a clear division of labour among the various chambers.

Question 59:  Mention the major events during photosynthesis 

Solution 59:  The following are the major photosynthesis events:

1. Light energy absorption by chlorophyll.
2. CO₂ reduction to carbohydrate formation.
3. Water molecule splitting into hydrogen and oxygen.
4. Transformation of light energy into chemical energy.

Question 60: In each of the following situations what happens to the rate of photosynthesis?

(a) Cloudy days

(b) No rainfall in the area

(c) Good manuring in the area

(d) Stomata get blocked due to dust 

Solution 60: 

(a) Because of the lack of sunlight, the rate of photosynthesis would slow.

(b) The rate of photosynthesis is unaffected by rain.

(c) The rate of photosynthesis would not be affected by manuring.

(d) The rate of photosynthesis will be slowed if stomata are blocked, so the supply of carbon dioxide will be reduced.

Question 61:  Name the energy currency in the living organisms. When and where is it produced? 

Solution 61:  The energy currency of living organisms is adenosine triphosphate (ATP). During respiration, it is formed in Mitochondria.

Question 62:  What is common for Cuscuta, ticks and leeches? 

Solution 62:  Both of these are parasites. To receive food from the host, they live on or within another body. Parasites often damage their hosts in order to acquire food.

Question 63:  Explain the role of the mouth in digestion of food.  

Solution 63:  The role of mouth in digestion of food is as follows:

1. Ingestion of food.
2. Breakage of food.
3. With the help of saliva swallowing of food is done.
4. Amylase in the saliva breaks down starch into simpler carbohydrates.

Question 64:  What are the functions of gastric glands present in the wall of the stomach? 

Solution 64:   The gastric gland in the stomach secretes hydrochloric acid, pepsin, and mucus. They have the following capabilities.

HCL kills germs in food and lowers the PH of the stomach, which is essential for digestive enzymes to function properly.

Protein is digested by pepsin.

The inner line of the stomach is protected by mucus from HCL.

Question 66: Name the correct substrates for the following enzymes

(a) Trypsin

(b) Amylase

(c) Pepsin

(d) Lipase 

Solution 66:

(a) Protein

(b) Starch

(c) Protein

(d) Lipid

Question 67:  Why do veins have thin walls as compared to arteries? 

Solution 67:   Vein walls are thin because blood flow into them does not exert pressure on them. The high pressure exerted on arterial walls by blood flow necessitates thick walls.

Question 68:  What will happen if platelets were absent in the blood? 

Solution 68:  Platelets are the cells that cause blood to clot. Blood will not clot if platelets are missing. Blood flow cannot be halted without clotting in the event of an injury, and this can be fatal.

Question 69: Plants have low energy needs as compared to animals. Explain. 

Solution 69:   The majority of plant transport occurs through passive transport, which does not require energy, and plants remain stationary in one location rather than travelling in search of food. In comparison to animals, plants consume less energy.

Question 70:  Why and how does water enter continuously into the root xylem? 

Solution 70:  Water should be continually pumped into the root xylem to aid various processes such as photosynthesis. The transpiration pull causes a constant flow of water through the root xylem.

Question 71:  Why is transpiration important for plants? 

Solution 71:  The following are some of the reasons why plants need to breathe.

(a) It induces a transpiration pull that aids sap ascent.

(b) It aids in the removal of excess water from a plant.

(b) Sap must ascend in order for water to be sufficient for photosynthesis.

Question 72:  How do leaves of plants help in excretion? 

Solution 72:  Since CO₂ is expelled out of the pores of stomata found in the herb, leaves play an important role in plant excretion. Plants shed leaves to rid themselves of excretory products that have accumulated on them.

Long Answer Questions..........................

Question 73:  Explain the process of nutrition in Amoeba. 

Solution 73:   Ingestion, Digestion, Absorption, Assimilation, and Egestion are all part of Amoeba's holozoic nutrition.

Ingestion:

Ameoba traps food particles with pseudopodia, which are fingerlike projections. Pseudopodia is found on the exterior of the animal's body and aids in the intake of food and water.

Digestion:

Food vacuoles are formed after the food has been consumed. For digestion, enzymes are produced in the food vacuole.

Absorption:

Osmosis allows nutrients to reach the cytoplasm after digestion.

Assimilation:

The cell uses nutrients for a variety of purposes.

Egestion:

It occurs as a food vacuole approaches the cell membrane to drain its contents outside the cell. As a consequence, waste materials are ejected from the cell.

Question 74:  Describe the alimentary canal of man. 

Solution 74:

Human Alimentary canal has the following parts

Buccal Cavity:

Also known as the mouth, the buccal cavity is made up of the tongue, teeth, and salivary gland. It is the point at which food enters the digestive system. Mastication breaks down food into simpler molecules in the buccal cavity, and salivary amylase breaks down starch into simpler carbohydrates.

Oesophagus:

The buccal cavity is connected to the Oesophagus, a long tube-like structure. The oesophagus connects the buccal cavity to the stomach and aids in the ingestion of food. A valve in the oesophagus prevents food particles from backflowing.

Stomach:

The stomach is a J-shaped organ that contains gastric glands. The hydrochloric acid, pepsin, and mucus secreted by the gastric glands aid in the digestion of food.

Small Intestine:

The small intestine is a long, coiled structure. The small intestine is responsible for the majority of food absorption. Specialized structures in the small intestine aid in the absorption of digested food. The folds in the small intestine increase the absorption space. The small intestine also has microvilli, which are fingerlike projections that are well-supplied by blood vessels.

Large Intestine:

Its lumen is larger than that of the small intestine and it is shorter than that of the small intestine. The large intestine's primary purpose is to extract water from the remaining indigestible food matter and to remove waste from the body.

Rectum:

The rectum is formed by the opening of the large intestine. The rectum is where waste and undigested food are kept.

Anus:

It's the end of the alimentary canal's opening. Anus is when solid waste products exit the body.

Question 75:  Explain the process of breathing in man. 

Solution 75:   The process of breathing in Human are:

1) Inhalation

2) Exhalation

Inhalation:

The method of taking oxygen is known as inhalation. Ribs come out and the diaphragm goes down during this process. This expands the lungs' volume while lowering the pressure. This causes the air to shift closer to the lungs.

Exhalation:

Exhalation is the act of releasing carbon dioxide from the body. The diaphragm moves up and the ribs move down during this operation. The volume of the lungs is reduced, and the pressure rises. Food is forced out of the lungs as a result.

Question 76:  Explain the importance of soil for plant growth. 

Solution 76:   For the following reasons, soil is very important for plant development:

1. It serves as a water reservoir.
2. Soil contains organic materials that are essential for plant growth.
3. Plants have a symbiotic relationship with soil microorganisms, and these microbes support the plant in its growth and life cycles.
4. Soil contains a variety of minerals that are essential for plant growth. Soil is the only source of nutrients for the soil.
5. Soil offers a medium for root penetration and serves as a foundation for plant development.

Question 77:  Draw the diagram of the alimentary canal of man and label the following parts. Mouth, Oesophagus, Stomach, Intestine 

Solution 77:

Question 78:  How do carbohydrates, proteins and fats get digested in human beings? 

Solution 78:

Carbohydrate Digestion:

Carbohydrate digestion begins in the buccal cavity, where salivary enzymes degrade starch into simple sugar molecules. In the small intestine, other sugar molecules are broken down to glucose.

Protein digestion:

Pepsin, a digestive enzyme secreted by the stomach's gastric glands, helps to partially digest proteins. The pancreatic juice then secretes trypsin and chymotrypsin enzymes into the small intestine, where they are completely digested.

Fat Digestion:

The small intestine is where fats are digested. The liver's bile juice emulsifies the fat, breaking it down into tiny globules. Lipase breaks down these small fat globules into glycerol and fatty acids.

Question 79:  Explain the mechanism of photosynthesis 

Solution 79:   Photosynthesis is the mechanism by which plants use sunlight, CO₂, and water to make their own food. With the evolution of oxygen, CO₂ and water are converted to carbohydrates. The following reaction can be used to describe the photosynthesis reaction.

6CO₂ + 6H₂O ^{Sunlight energy} C₆H₁₂O₆ + 6O₂

The process of Photosynthesis is divided into 4 parts:

1. Light energy absorption by chlorophyll.
2. Conversion of light energy into chemical energy.
3. Hydrogen and Oxygen are separated from water molecules.
4. CO₂ reduction for carbohydrate production.

Question 80:  Explain the three pathways of breakdown in living organisms. 

Solution 80:

Glucose is first broken down into pyruvate, a three-carbon molecule. This process occurs in the cytoplasm of all living things. The following steps further break down pyruvate.

In yeast:

Anaerobic respiration is the mechanism of breaking down pyruvate in the absence of oxygen. Pyruvate is broken down in yeasts to generate CO2 and ethanol.

In Muscle Cells:

The energy demand of our muscles cells increases rapidly during strenuous physical exercise. Anaerobic respiration of muscle cells compensates for this. Pyruvate is converted to lactic acid in muscle cells.

In Mitochondria:

Pyruvate is broken down in mitochondria during aerobic respiration (when oxygen is present). Pyruvate is decomposed here to create H₂O and CO₂. Aerobic respiration is the most common mode of respiration in most species.

Question 81:  Describe the flow of blood through the heart of human beings 

Solution 81:

• The vena cava transports deoxygenated blood from various organs to the right atrium.

• Blood flows from the right atrium to the right ventricle. The tricuspid valve, which connects the right atrium and right ventricle, prevents blood from flowing backward.

• The pulmonary artery transports blood from the right ventricle to the lungs. Carbon dioxide is extracted from the blood and oxygen is added inside the lungs.

• Blood travels from the lungs to the left atrium through the pulmonary vein, and then from the left atrium to the left ventricle.

• Blood is pumped into the aorta from the left ventricle and distributed to various organs.

Question 82:  Describe the process of urine formation in kidneys. 

Solution 82:

The basic filtration device in the kidneys is a cluster of blood capillaries with very thin walls. The cup-shaped end of a coiled tube called Bowman's capsule that collects the filtrate is associated with each capillary cluster in the kidney. The filtration units known as nephrons are found in large numbers in each kidney.

When the urine flows down the channel, certain substances in the initial filtrate, such as glucose, amino acids, salts, and a significant amount of water, are selectively reabsorbed. The amount of water reabsorbed is determined by the amount of excess water in the body as well as the amount of dissolved waste to be excreted. The urine produced by each kidney eventually reaches the ureter, a long tube that connects the kidneys to the bladder.

Urine is contained in the urinary bladder until it is pushed out of the urethra by the weight of the enlarged bladder. Since the bladder is muscular, it is regulated by the nervous system.