Chapter 5 : Life Processes

Class 10 Science Chapter 5 : Life Processes Exercise Questions and Answers :

Question: How do autotrophs obtain and to make their food ?    [2008 1M]

Answer : Autotrophs obtain from the atmosphere through photosynthesis and  from nitrogen-fixing bacteria in the soil or water.

Question: What will happen to a plant if its xylem is removed ? [2009 1M]

Answer : If the xylem is removed from a plant, it will be unable to transport water and minerals from the roots to the rest of the plant, causing dehydration and wilting.

Question: What will happen to a plant if its phloem is removed ?

Answer : If the phloem is removed from a plant, it will be unable to transport sugars and other products of photosynthesis, leading to wilting and eventual death.

Question: Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope . What is this green colour due to ? [2010 1M]

Answer :  The green dot-like structures observed in leaf cells are chloroplasts. The green color is due to chlorophyll, the pigment responsible for capturing light energy during photosynthesis.

Question: Consider the following statement in connection with the functions of the blood vessels marked A and B in the diagram of a human heart as show .  [2021 1M]

     

(i) Blood vessel A – It carries carbon dioxide rich blood to the lungs .

(ii) Blood vessel B – It carries oxygen rich blood from the lungs .

(iii) Blood vessel B – Left atrium relaxes as it receives blood from this blood vessel .

(iv) Blood vessel A – Right atrium has thick muscular wall as it has to pump blood to this blood vessel . .

The correct statements are :

(a) (i) and (ii) only   (b) (ii) and (iii) only  (c) (ii) , (iii) and (iv) (d) (i) , (ii) and (iii)

Answer : (d) (i) , (ii) and (iii)

Question: In living organisms during respiration which of the following products are not formed if oxygen is not available ?  [2021 1M]

(a) Carbon dioxide + water   (b) Carbon dioxide + Alcohol  (c) Lactic acid +Alcohol

(d) Carbon dioxide + Lactic Acid

Answer : (c) Lactic acid + Alcohol .

Question: The correct statements with reference to single celled organisms are : [2021 1M]

(i) Complex substances are not broken down into simpler substances .

(ii) Simple diffusion is sufficient to meet the requirement of exchange of gases .

(iii) Specialised tissues perform different functions in the organism .

(iv) Entire surface of the organism is in contact with the environment for taking in food .

(a) (i) and (iii)   (b) (ii) and (iii)  (c) (ii) and (iv)  (d) (i) and (iv)   

Answer : (c) (ii) and (iv)  

[ The correct statements with reference to single-celled organisms are: (ii) Simple diffusion is sufficient to meet the requirement of exchange of gases. (iv) Entire surface of the organism is in contact with the environment for taking in food.]

Question: Which one among the following is not removed  as a waste product from the body of a plant ? [2021 1M]

(a) Resins  and Gums   (b) Urea   (c) Dry leaves   (d) Excess water

Answer :  (b) Urea .

Question: Which of the following statement are correct in reference to the role of A ( show in the given diagram ) during a breathing cycle in human beings ? [2021]

 

(i) It helps to decrease the residual volume of air in lungs .

(ii) It flattens as we inhale   (iii) It gets raised as we inhale . (iv) It helps the chest to become larger .

(a)  (ii) and (iv)   (b) (iii) and (iv)   (c) (i) and  (ii)    (d) (i) , (ii) and (iv)

Answer :  (b) (iii) and (iv)

Question: Which one of the following conditions is true for the state of stomata of a green leaf show in the given diagram ? [2021  1M]

 

(a)  Large amount of water flows into the guard cells .

(b) Gaseous exchange is occurring in large amount .

(c) Large amount of water flows out from the guard cells .

(d) Large amount of sugar collects in the guard cells .

Answer :  (a) Large amount of water flows into the guard cells.

[ Stomata open to allow for gas exchange and transpiration, which involves water flowing into the guard cells to facilitate stomatal opening.]

Question: Assertion (A) : Nitrogen is an essential element for plant growth and is taken up by plants in the form of inorganic nitrates or nitrites .

Reason (R) : The soil is the neatest and richest source of raw materials like Nitrogen, Phosphorus and other minerals for the plants . [2021]

(a) Both (A) and (R) are true and (R) is the correct explanation of (A) .

(b) Both (A) and (R) are true but (R) is not the correct explanation of (A) .

(c) (A) is true , but (R) is false .

(d) (A) is false , but (R) is true .

Answer :  (a) Both (A) and (R) are true and (R) is the correct explanation of (A).

[  Assertion (A) states that nitrogen is essential for plant growth and is taken up by plants in the form of inorganic nitrates or nitrites, which is true.

Reason (R) states that soil is the nearest and richest source of raw materials like nitrogen, phosphorus, and other minerals for plants, which is also true and explains why plants uptake nitrogen from the soil. Therefore, (R) is the correct explanation of (A). ]

Question: Assertion (A) : Hydrochloric acid helps in the digestion of stomach .

Reason (R) : Hydrochloric acid creases and acidic medium to activate protein digesting enzymes . [2021 1M]

(a) Both (A) and (R) are true and (R) is the correct explanation of (A) .

(b) Both (A) and (R) are true but (R) is not the correct explanation of (A) .

(c) (A) is true, but (R) is false .

(d) (A) is false, but (R) is true .

Answer : (a) Both (A) and (R) are true and (R) is the correct explanation of (A).

[  Assertion (A) is true: Hydrochloric acid indeed helps in the digestion of food in the stomach.

Reason (R) is true: Hydrochloric acid creates an acidic environment in the stomach, which is necessary to activate protein-digesting enzymes like pepsin.

Reason (R) logically explains why hydrochloric acid helps in digestion, so it is the correct explanation of Assertion (A).]

Question: A student was asked to write a stepwise procedure to demonstrate that carbon dioxide is necessary for photosynthesis . He wrote the following steps . The wrongly worded step is ; [2021 1M]

 

(a) Both potted plants are kept in dark room for at least three days . 

(b) Bottom of the bell jars is sealed to make them air tight .

(c) Both potted plants are kept in sunlight  after the starch test .

(d) A leaf from both the plants is taken to test the presence of starch .

Answer : (c) Both potted plants are kept in sunlight after the starch test.

This step is incorrect because after the starch test, it would be more appropriate to keep the plants in the presence of light rather than specifically in sunlight to observe the process of photosynthesis.

Question: Respiratory structures of two different animals – a fish and a human being are as show .

Observe (a) and (b) and select one characteristics that holds true for both of them . [2021  1M]

 

(a) Both are placed internally in the body of animal .

(b) Both have thin and moist surface for gaseous exchange .

(c) Both are poorly supplied with blood vessels to conserve energy .

(d) In both the blood returns to the heart after being oxygenated .

Answer : (b) Both have thin and moist surfaces for gaseous exchange.

[ Both fish gills and human lungs have thin epithelial surfaces that allow for the exchange of gases (oxygen and carbon dioxide) between the respiratory surface and the bloodstream.]

Question: Observe the diagram of an actively given below, What does it help to conclude , when the person exhales into the test-tube ? [2021 1M]

  

(a) Percentage of carbon dioxide is more in inhales air .

(b) Fermentation occurs in the presence of oxygen .

(c) Percentage of carbon dioxide is more in the exhaled air .

(d) Fermentation occurs in the presence of carbon dioxide .

Answer : (c) Percentage of carbon dioxide is more in the exhaled air.

[ Exhaled air contains a higher percentage of carbon dioxide compared to inhaled air, which is evident when the carbon dioxide from the exhaled breath reacts with the lime water, turning it milky due to the formation of calcium carbonate.]

Question: The length of small intestine in a deer is more as compared to the length of small intestine of a tiger . The reason for this is [2021 1M]

(a) Mode for intake of food .

(b) Type of food consumed

(c) Presence or absence of villi in intestines .

(d) Presence or absence of digestive enzymes .

Answer : (b) Type of food consumed.

[ Deer are herbivores and consume plant material, which is more difficult to digest and requires a longer digestive tract to extract nutrients efficiently. Tigers, being carnivores, consume meat which is easier to digest, requiring a shorter digestive tract. Therefore, the difference in the type of food consumed is a significant factor in the length of the small intestine.]

Question: Identify the two components of phloem tissue that help in transportation of food in plants . [2021 1M]

(a) Phloem parenchyma and sieve tubes .

(b) Sieve tubes and companion cells

(c) Phloem parenchyma and companion cells

(d) Phloem fibres and sieves tubes .

Answer : (b) Sieve tubes and companion cells.

[ Sieve tubes are responsible for transporting sugars and other organic nutrients, while companion cells support and regulate the function of sieve tubes.]

Question: Case study based Questions (Q17. To Q20) :  [2021 ]

The figure show below represents a common type of dialysis called as Haemodialysis . It removes waste products from the blood such as excess salts and urea which are insufficiently removed by the kidney in patients with kidney failure . During the procedure , the patient’s blood is cleared by filtration through a series of semi-permeable membranes before being of this, answer the following questions :

 

Question: The haemodialyzer has semi-permeable lining of tubes which help  [2021 1M]

(a) To maintain osmotic pressure of blood

(b) To filter nitrogenous waste from the dialyzing solution .

(c) In passing the waste products in the dialyzing solution .

(d) To pump purified blood back into the body of the patient .

Answer : (c) In passing the waste products in the dialyzing solution.

[ The semi-permeable membrane of the hemodialyzer allows waste products from the patient's blood to pass through into the dialyzing solution while retaining essential components like blood cells and proteins.]

Question: Which one of the following is not a function of Artificial Kidney ?

(a) To remove nitrogenous wastes from the blood .

(b) To remove excess fluids from the blood .

(c)  To remove reabsorb essential nutrients from the blood .

(d) To filter and purify the blood .

Answer : (c) To remove reabsorb essential nutrients from the blood.

[ Artificial kidneys are designed to filter and purify the blood by removing nitrogenous wastes and excess fluids, mimicking the function of natural kidneys. They do not selectively reabsorb essential nutrients like natural kidneys do. ]

Question: The ‘used dialysis’ solution is rich in :

(a) Urea and excess salts

(b) Blood cells

(c) Lymph 

(d) Proteins

Answer : (a) Urea and excess salts.

[ During dialysis, the solution used to cleanse the blood accumulates waste products like urea and excess salts that have been removed from the patient's bloodstream. ]

Question: Which part of the nephron inhuman kidney, serves the function of reabsorbtion of certain substances ?

(a) Glomerulus   (b) Bowman’s  capsule  (c) Tubules   (d) Collecting 

Answer : (c) Tubules

[ The renal tubules, including the proximal convoluted tubule, loop of Henle, and distal convoluted tubule, are responsible for reabsorbing essential substances (such as water, glucose, and ions) from the filtrate back into the bloodstream. ]

Question: Write one function each of the following components of the transport system in human beings : [2008 2M]

(a) Blood   (b) Blood platelets   (c) Lymph   (d) Heart  

Answer :  One function for each component of the transport system in human beings:

(a) Blood: Blood transports oxygen, nutrients, hormones, and waste products throughout the body, helping to maintain homeostasis and support cellular functions.

(b) Blood platelets: Blood platelets play a crucial role in blood clotting (hemostasis) by forming clots to prevent excessive bleeding when blood vessels are damaged.

(c) Lymph: Lymph collects excess tissue fluid and proteins from the interstitial spaces, transports fat-soluble vitamins, and facilitates the immune response by carrying lymphocytes and other immune cells.

(d) Heart: The heart pumps blood throughout the body, delivering oxygen and nutrients to tissues and organs while removing carbon dioxide and other waste products. It maintains circulation, ensuring that all parts of the body receive the necessary blood supply for proper function.

Question: Write two different ways in which glucose is oxidized to provide energy in human body . Write the products formed in each case .   [2019 2M]

Answer :  The two different ways in which glucose is oxidized to provide energy in the human body are :

 (i)

The name of product is Lactic acid .

(ii)

 

The name of the products are carbon dioxide and water .

Question: In the experimental set up to show that “ is given out during out during respiration” . Name the substance taken in the small test tube kept in the conical flask . State its function and the consequence of its use . [2019 2M]

Answer :  In the experimental setup to show that " is given out during respiration," the substance taken in the small test tube kept in the conical flask is lime water.

Lime water (calcium hydroxide solution) serves as an indicator for the presence of carbon dioxide. When carbon dioxide is passed through lime water, it reacts to form a white precipitate of calcium carbonate.

The consequence of using lime water is that, in the presence of carbon dioxide released during respiration, the lime water will turn milky due to the formation of calcium carbonate. This change in the appearance of lime water indicates the release of carbon dioxide, providing visual evidence of the respiratory process.

Question: How are oxygen and carbon dioxide transported in human beings ? How are lungs designed to maximize the area for exchange of gases ? [2008 3M]

Answer : Oxygen and carbon dioxide are transported in human beings through the bloodstream. Oxygen binds to hemoglobin in red blood cells and is carried from the lungs to tissues, while carbon dioxide is transported back to the lungs for exhalation.

Lungs are designed to maximize the area for gas exchange through an intricate network of alveoli. The numerous tiny air sacs provide a large surface area and thin walls, facilitating efficient diffusion of gases between air and blood during respiration.

Question: Write three types of blood vessels . Give one important feature of each . [2019  3M]

Answer : Three types of blood vessels are arteries, veins, and capillaries.

The important feature of blood vessels are :

 (i) Arteries carry oxygen-rich blood away from the heart to various parts of the body. They have thick, muscular walls that withstand high pressure from the heart's contractions.

(ii) Veins return oxygen-depleted blood back to the heart. They have valves to prevent backflow and thinner walls compared to arteries.

(iii) Capillaries are tiny blood vessels where gas exchange and nutrient transfer occur.

Question: (a) Draw a diagram of human alimentary  canal and label on it :

Oesophagus , gall bladder , Liver and pancreas

(b) Explain the statement , ‘ Bile does not contain any enzyme but it is essential for digestion ‘ . [2009 5M]

Answer :  (a)  The label diagram of human alimentary canal :

   

(b) The statement is accurate. Bile does not contain enzymes, but it plays a crucial role in digestion. Bile salts in bile help emulsify large fat globules into smaller droplets, increasing the efficiency of enzyme action. This emulsification process aids in the digestion and absorption of fats in the small intestine, facilitating overall digestion.

Question: (a) Draw a diagram of excretory system in human beings and label on it  :

Aorta , vena cava , urinary bladder , urethra

(b) List two vital functions of the kidney . [2009 5M]

Answer :  (a) The label diagram of the excretory system in human beings :

(b)  Two vital functions of the kidneys are:

(i) The kidneys filter waste products, excess ions, and toxins from the bloodstream, excreting them as urine while maintaining the balance of electrolytes and fluid levels in the body.

(ii) The kidneys help regulate blood pressure by adjusting the volume of blood plasma and the concentration of electrolytes in the bloodstream through processes like reabsorption and secretion.

Question: Explain the process of digestion of food in mouth, stomach and small intestine in human body [2010 5M]

Answer : The process of digestion begins in the mouth, where food is crushed by the teeth and moistened with saliva containing an enzyme called salivary amylase. This enzyme breaks down complex starch molecules into simple sugars. The muscular tongue helps in chewing and moving the food around the mouth.

To facilitate proper digestion, the food needs to move in a regulated manner along the digestive tube. The soft lining of the canal has muscles that contract rhythmically, creating peristaltic movements, which push the food forward through the digestive tract.

From the mouth, the partially processed food moves into the stomach through the esophagus. The stomach, a large organ, expands when food enters it. The muscular walls of the stomach mix the food with digestive juices from gastric glands. These juices include hydrochloric acid, pepsin (a protein-digesting enzyme), and mucus. Hydrochloric acid creates an acidic environment to aid pepsin, while mucus protects the stomach lining.

The exit of food from the stomach is regulated by a sphincter muscle, releasing it in small amounts into the small intestine. The small intestine, the longest part of the alimentary canal, is responsible for the complete digestion of carbohydrates, proteins, and fats. It receives secretions from the liver and pancreas. Bile juice from the liver makes the acidic food alkaline and acts on fats, breaking them down into smaller globules. Pancreatic juice, containing enzymes like trypsin and lipase, further digests proteins and fats, respectively.

The walls of the small intestine contain glands that secrete intestinal juice. These enzymes convert proteins into amino acids, complex carbohydrates into glucose, and fats into fatty acids and glycerol. The digested food is absorbed by the walls of the intestine, aided by numerous finger-like projections called villi. Villi increase the surface area for absorption, and the absorbed nutrients are transported by blood vessels to various cells for energy, tissue building, and repair.

Question: (a) List the three events that occur during the process of photosynthesis . Explain the role of stomata in this process .

(b) Describe an experiment to show that ‘‘ sunlight is essential for photosynthesis .’’   [2010 5M]

Answer : (a) Three events during photosynthesis are :

(i) Absorption of light energy by chlorophyll.

(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.

(iii) Reduction of carbon dioxide to carbohydrates.

Stomata play a crucial role in the photosynthesis process by facilitating gaseous exchange in plant leaves. These tiny pores allow the entry of carbon dioxide, essential for photosynthesis, and the release of oxygen produced during the process. The opening and closing of stomatal pores are regulated by guard cells, which respond to changes in water availability, helping to minimize water loss while optimizing carbon dioxide intake for efficient photosynthesis.

(b) To demonstrate that sunlight is essential for photosynthesis, you can conduct the following experiment:

(i) Take two healthy potted plants of similar size. Keep them in a dark room for three days to ensure they are deprived of light and their starch reserves are depleted.

(ii) Place each plant on a separate glass plate. Next to one of the plants, place a watch-glass containing potassium hydroxide (KOH) to absorb carbon dioxide. This step ensures that any carbon dioxide released during respiration by the plant is absorbed, preventing interference with the experiment.

(iii) Cover both plants with separate bell jars, ensuring the setup is airtight. Seal the bottom of the jars to the glass plates with vaseline to prevent any air exchange from outside.

(iv) Place the setup in sunlight for about two hours. Sunlight is essential as it provides the energy needed for photosynthesis to occur.

(v) After exposure to sunlight, pluck a leaf from each plant and perform a starch test. This test involves boiling the leaves in water to soften them and then placing them in a solution of iodine. If starch is present, the iodine will turn blue-black.

Observation: Observe the leaves for the presence of starch. The plant that was exposed to sunlight should show the presence of starch, indicating that photosynthesis occurred in the presence of light. The plant kept in the dark should not show significant starch presence, indicating that photosynthesis did not occur in the absence of light.

This experiment demonstrates that sunlight is essential for photosynthesis to take place, as it provides the energy necessary for the synthesis of glucose from carbon dioxide and water.

Question: (a) Mention any two components of blood .

(b) Trace the movement of oxygenated blood in the body .

(c) Write the function of valves present in between the composition of artery and veins . [2018 5M]

Answer : (a) Two components of blood are:  (i) Red blood cells (erythrocytes)  (ii) Plasma

(b) The movement of oxygenated blood in the body: Oxygenated blood is pumped from the left ventricle of the heart into the aorta, the largest artery. The aorta branches into smaller arteries, which further branch into arterioles. Arterioles deliver oxygenated blood to capillaries in various tissues and organs. In capillaries, oxygen and nutrients are exchanged for carbon dioxide and waste products. Oxygen-depleted blood then returns to the heart via venules, which merge into veins. The superior and inferior vena cava carry the deoxygenated blood back to the right atrium of the heart. From there, it is pumped into the right ventricle and sent to the lungs for oxygenation.

(c) The function of valves present between the compartments of arteries and veins: Valves in the circulatory system, particularly in veins, prevent the backflow of blood. In veins, which transport blood back to the heart against gravity, valves ensure that blood moves in one direction—towards the heart. This prevents the pooling of blood in the extremities and enhances the efficiency of blood circulation. The rhythmic contraction and relaxation of muscles around the veins also assist in pushing blood against gravity, working in conjunction with the valves .

Question: (a) Define excretion .

(b) Name the basic filtration unit present in the kidney .

(c) Draw excretory system in human beings and label the following organs of excretory system which perform following functions :

(i) Form urine   (ii) is a long tube which collects urine from kidney (iii) Store urine unit it is passed out . [2018]

Answer : (a) Excretion is the process by which metabolic waste products and harmful substances are removed from an organism's body. It involves the elimination of waste products produced during cellular metabolism, such as carbon dioxide, urea, and excess salts, to maintain internal homeostasis and prevent the accumulation of toxic substances.

(b) Name the basic filtration unit present in the kidney is nephron.

[ Nephrons are microscopic structures responsible for the filtration of blood and the formation of urine in the kidneys. Each kidney contains millions of nephrons, which play a crucial role in regulating the body's fluid balance, electrolyte levels, and waste excretion.]

(c) The label diagram of the excretory system in human beings :

Kidneys - Form urine.

Ureter - A long tube that collects urine from the kidney.

Bladder - Stores urine until it is passed out.

Question: (a) Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms ? Explain .

(b) Draw a diagram of human respiratory system and label – pharynx , trachea , lungs , diaphragm and alveolar sac on it . [2020   5M]

Answer : The difference in the rate of breathing between aquatic organisms (like fish) and terrestrial organisms (like humans) is primarily due to the availability of oxygen in their respective environments and the efficiency of their respiratory systems.

Factor	Aquatic Organisms	Terrestrial Organisms
Oxygen Availability	Oxygen is dissolved in water .	Oxygen is abundant in the air.
Respiratory System	Gills, which are adapted to extract dissolved oxygen from water but are less efficient in absorbing large volumes of oxygen quickly.	Lungs, which are highly efficient at extracting oxygen from air and have a larger surface area relative to gills.
Breathing Rate	Higher; fish need to pump water continuously over their gills to meet oxygen demands, resulting in a higher breathing rate.	Lower; terrestrial animals can take slower, deeper breaths due to the higher concentration of oxygen in the air.
Energy Expenditure	High; moving water over gills requires more energy due to the density and viscosity of water.	Lower; air is less dense and easier to move in and out of the lungs, reducing energy expenditure.
Gas Exchange Efficiency	Lower; water has a lower oxygen content, and the gill surface must constantly be in contact with water to extract enough oxygen.	Higher; lungs have a larger surface area, allowing more efficient oxygen uptake and carbon dioxide expulsion.
Temperature Influence	Oxygen solubility in water decreases as temperature increases, further reducing available oxygen, which increases the breathing rate.	Air temperature has less impact on oxygen availability, and the breathing rate adjusts primarily with metabolic demands.
Adaptation to Environment	Gills are specifically adapted for oxygen extraction from water, which requires a higher rate of water flow over the gills.	Lungs are adapted to efficiently extract oxygen from the air, allowing slower breathing rates.

(b)  The diagram of human respiratory system and label :

 

 

Question : (a) Name the organs that form the excretory system in human beings .

(b) Describe in brief how urine is produced in human body .

Answer: The organs that form the excretory system in human beings are :

(i) Kidneys

(ii) Ureters

(iii) Urinary bladder

(iv) Urethra

(b) Urine is produced in the human body through the process of filtration, reabsorption, and secretion in the kidneys. Each kidney contains numerous nephrons, which consist of clusters of thin-walled blood capillaries associated with Bowman's capsules. Filtration occurs as blood passes through these capillaries, with waste products and excess substances entering the nephrons. Subsequently, selective reabsorption of essential substances occurs as urine flows through tubules. The formed urine then travels through the ureters to the urinary bladder for storage until it is expelled through the urethra.