6. Life Processes SEBA/ASSEB Class 10 Science– Important Questions and Answers | Assam HSLC

SEBA/ASSEB Class 10 Science Chapter 6: Life Processes Important Questions and Answers | HSLC Assam

Chapter 6: Life Processes

Multiple Choose Question and Answer:

Question : Emulsification of fat molecule is carried out by :

(a) Trypsin (b) Pepsin (c) Bile salts (d) Amylase

Answer : (c) Bile salts

[The emulsification of fat molecules is carried out by bile salts. ]

Question : Anaerobic respiration occurs in – [SEBA 2016]

(a) Mitochondria (b) Chloroplast (c) Nuclcus (d) Cytoplasm

Answer : (d) Cytoplasm

[Anaerobic respiration occurs in the cytoplasm. ]

Question: The enzyme which converts starch to simple sugar is [SEBA 2017]

(a) Amylase (b) lipase (c) pepsin (d) trypsin

Answer : (a) Amylase .

[The enzyme that converts starch to simple sugars is amylase. ]

Question : The name of the process with the help of which carbon and energy requirements of an autotrophic organism are fulfilled ,is : [SEBA 2018]

(a) Photosynthesis (b) transpiration (c) translocation (d) Photophosphorylation

Answer : (a) Photosynthesis.

[The process with the help of which carbon and energy requirements of an autotrophic organism are fulfilled is photosynthesis.]

Question : The enzyme contained by our saliva is called [SEBA 2019]

(a) amylase (b) lipase (c) trypsin (d) pepsin

Answer : (a) Amylase.

[The enzyme contained in our saliva is called amylase. ]

Question : Anaerobic respiration takes place in – [SEBA 2020]

(a) Mitochondria (b) Chloroplast (c) Nuclcus (d) Cytoplasm

Answer : (d) Cytoplasm

[Anaerobic respiration takes place in the cytoplasm. Anaerobic respiration is the process by which cells generate energy without the use of oxygen.]

Question : Sphygmomanometer is an instrument which is used to measure the of a man .[SEBA 2021]

(a) blood pressure (ii) level in the blood (iii) blood sugar level (d) level of urea in the blood

Answer : (a) blood pressure

Question : Breakdown of glucose into pyruvate takes place in the [SEBA 2023]

(a) Cell cytoplasm (b) Mitochondria (c) Cell membrane (d) Golgi body

Answer : (a) Cell cytoplasm.

[The breakdown of glucose into pyruvate takes place in the cell cytoplasm.]

Question : The energy currency for most of the cellular processes is : [SEBA 2023]

(a) ADP (b) AMP (c) ATP (d)

Answer : (c) ATP

[The energy currency for most cellular processes is ATP (adenosine triphosphate).]

Question: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in [2025]

(a) cytoplasm (b) mitochondria (c) chloroplast (d) nucleus

Answer: (b) Mitochondria

[ The breakdown of pyruvate in the presence of oxygen to produce carbon dioxide, water and energy takes place in the mitochondria. ]

Question: The kidney in human beings are a part of the system for [2025]

(a) excretion (b) transportation (c) nutrition (d) respiration

Answer: (a) excretion

Question: In human beings , the normal systolic pressure is about [2025]

(a) 120 mm of Hg (b) 100 mm of Hg (c) 90 mm of Hg (d) 105 mm of Hg

Answer: (a) 120 mm of Hg

[The normal systolic pressure is about 120 mm of Hg ]

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

(a) Pepsin (b) Mucus (c) Salivary amylase (d) Bile

Answer : (b) Mucus

[ Mucus serves as a protective layer on the inner lining of the stomach, preventing it from being damaged by the acidic gastric juices, including hydrochloric acid. ]

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

(a) Stomach (b) Mouth cavity (c) Large intestine (d) Small intestine

Answer : (d) Small intestine

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

(a) nutrition. (b) respiration. (c) excretion. (d) transportation.

Answer: (c) excretion .

[ Kidneys filter blood to remove wastes like urea, excess salts, and water, forming urine, which is part of the excretory system.]

Question: When air is blown from 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

Answer : (b) Carbon dioxide

[ Carbon dioxide reacts with lime water to form calcium carbonate, which is insoluble and gives the milky appearance.]

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

(a) Stomach (b) Small intestine (c) Large intestine (d) Oesophagus

Answer : (b) Small intestine

Question: The xylem in plants are responsible for

(a) transport of water. (b) transport of food. (c) transport of amino acids. (d) transport of oxygen.

Answer: (a) transport of water .

[ Xylem carries water and minerals from the roots to the leaves, while phloem transports food. ]

Question: During respiration exchange of gases take place in

(a) trachea and larynx (b) alveoli of lungs (c) alveoli and throat (d) throat and larynx

Answer : (b) Alveoli of lungs .

[ During respiration, the exchange of gases (oxygen and carbon dioxide) takes place specifically in the alveoli of the lungs. ]

Question: The autotrophic mode of nutrition requires

(a) carbon dioxide and water. (b) chlorophyll. (c) sunlight. (d) all of the above.

Answer: (d) all of the above

[ Autotrophic nutrition, like photosynthesis, needs carbon dioxide, water, sunlight, and chlorophyll to make food. All three are essential for the process.]

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

(a) cytoplasm. (b) mitochondria. (c) chloroplast. (d) nucleus.

Answer: (b) mitochondria

[ After glycolysis in the cytoplasm, pyruvate enters the mitochondria, where it is fully broken down during the Krebs cycle and electron transport chain to produce carbon dioxide, water, and energy (ATP).]

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: (a) Carbon dioxide + water.

[ Aerobic respiration (when oxygen is available): Glucose → Carbon dioxide + Water + Energy (This is the complete oxidation process in mitochondria.)

Anaerobic respiration (when oxygen is not available):

In yeast/plants (alcoholic fermentation): Glucose → Carbon dioxide + Alcohol (Ethanol)

In animal muscles: Glucose → Lactic acid

Water is not produced in anaerobic conditions.

Therefore, Carbon dioxide + Water are not formed together when oxygen is unavailable. ]

Question: 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

Answer : (a) cytoplasm.

[ During the deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the cytoplasm. ]

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)

[ (i) Complex substances are not broken down into simpler substances
Incorrect — even single-celled organisms digest food, so complex substances are broken down.

(ii) Simple diffusion is sufficient for exchange of gases
Correct — since they are very small, diffusion is enough for oxygen and carbon dioxide exchange.

(iii) Specialised tissues perform different functions
Incorrect — they don’t have tissues at all (only one cell!).

(iv) Entire surface is in contact with the environment for taking in food
Correct — the whole cell surface helps in exchange and intake. ]

Question: 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)

Answer : (c) (i) and (iv)

[ (i) Pyruvate can be converted into ethanol and carbon dioxide by yeast, a process known as alcoholic fermentation. (iv) Fermentation is a form of anaerobic respiration.]

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

[ Plants remove wastes in different ways:

Resins and gums → stored or secreted as waste

Dry leaves → wastes get stored and removed when leaves fall

Excess water → removed through transpiration

But urea is a nitrogenous waste found in animals, not in plants. ]

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 .

(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 wrongly written because in the correct procedure, plants must be kept in sunlight before the starch test, not after. ]

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

Answer: (b) Type of food consumed

[ A deer is a herbivore (plant eater). Plant food like cellulose is hard to digest, so it needs a longer small intestine for proper digestion and absorption.

A tiger is a carnivore (meat eater). Meat is easier to digest, so its small intestine is shorter.

So, the difference is because of the type of food they consume. ]

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 .

(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 .

(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 is the first enzyme to mix with food in the digestive tract?

(a) Pepsin (b) Cellulase (c) Amylase (d) Trypsin

Answer : (c) Amylase .

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

(a) oxygen (b) temperature (c) water in guard cells (d) concentration of in stomatal

Answer : (c) Water in guard cells

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

(a)

(b)

(c)

(d)

Answer : (c)

[ This equation represents the process of photosynthesis, where carbon dioxide and water, in the presence of chlorophyll and sunlight, are converted into glucose and oxygen.]

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: An organism which breaks down the food material outside the body and then absorbs it is: [2023]

(a) a plant parasite , cuscuta (b) an animal parasite, tapeworm (c) a bacteria, Rhizobium (d) a fungi, Rhizopus

Answer: (d) a fungi, Rhizopus.

[ Fungi like Rhizopus secrete digestive enzymes to break down food externally and then absorb the nutrients, a process known as extracellular digestion.]

Question: Consider the following statements about ,small intestine and select the which is not correct: [2023]

(a) The length of the small intestine in animals differs as it depends on the type of food they eat.

(b) The small intestine is the site of complete digestion of food.

(d) The villi of the small intestine absorb water from the unabsorded food before it gets removed from the body via the anus.

Answer: (d) The villi of the small intestine absorb water from the unabsorbed food before it gets removed from the body via the anus.

[ Water absorption primarily occurs in the large intestine, not the small intestine. The villi in the small intestine mainly absorb nutrients, not water.]

Question: The filtration units of kidneys are called

(a) ureter (b) urethra (c) neurons (d) nephrons

Answer : (d) Nephrons

[ The filtration units of the kidneys are called nephrons ]

Question: The internal (cellular) energy reserve in autotrophic is

(a) glycogen (b) protein (c) starch (d) fatty acid

Answer : (c) Starch

[ Starch is the primary internal (cellular) energy reserve in autotrophic . ]

Question: Oxygen liberated during photosynthesis comes from

(a) water (b) chlorophyll (c) carbon dioxide (d) glucose

Answer : (a) Water

[ During photosynthesis, oxygen is liberated as a byproduct, and it comes from the splitting of water molecules. ]

Question: The blood leaving the tissues becomes richer in

(a) carbon dioxide (b) water (c) heamoglobin (d) oxygen

Answer : (a) Carbon dioxide

[ The blood leaving the tissues becomes richer in carbon dioxide.]

Question : The process by which some organisms fulfill their carbon and energy requirements and yields their stored form of energy is . [2023]

Answer : photosynthesis .

Assertion (A) and Reason (R) Question and Answer :

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) .

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

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

[ Assertion (A): Nitrogen is essential for plant growth and is absorbed as nitrates or nitrites.
This is true — plants cannot take nitrogen directly from air, so they absorb it from soil in these forms.

Reason (R): Soil is the main source of raw materials like nitrogen, phosphorus, and minerals. This is also true.]

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) .

(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): Hydrochloric acid helps in digestion in the stomach.
True — it plays an important role in digestion.

Reason (R): Hydrochloric acid creates an acidic medium to activate protein-digesting enzymes (like pepsin).
True — this is exactly how it helps in digestion. ]

Short Questions and Answers (From 1 Mark to 2 Marks)

Question: What is the role of saliva in the digestion of food? [1M]

Answer: Saliva helps in digestion by moistening food to make it easy to swallow and by breaking down starch into sugar with the help of the enzyme salivary amylase.

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 ? [1M]

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: Explain the role of mouth in digestion of food.

Answer : The mouth helps in the digestion of food by chewing it into smaller pieces with the help of teeth. The tongue mixes the food with saliva and helps in swallowing it. Saliva contains an enzyme called salivary amylase, which breaks down starch into simpler sugars. Thus, digestion of carbohydrates begins in the mouth.

Question: How are fats digested in our bodies? Where does this process take place? [2M]

Answer: Fats are digested in the small intestine. Bile from the liver breaks large fat globules into smaller ones, a process called emulsification, which helps enzymes act efficiently. The pancreas secretes lipase, an enzyme that breaks these emulsified fats into fatty acids and glycerol. This complete digestion occurs in the small intestine with the help of bile and pancreatic juice.

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

Answer : The gastric glands present in the wall of the stomach secrete hydrochloric acid (HCl), pepsin and mucus. Hydrochloric acid makes the medium acidic and kills harmful bacteria. Pepsin helps in the digestion of proteins. Mucus protects the inner lining of the stomach from the action of hydrochloric acid and digestive enzymes.

Question: What are the components of the transport system in human beings? What are the functions of these components? [2M]

Answer: The transport system in human beings consists of blood, heart, and blood vessels.

The functions are : (i) Blood carries oxygen, nutrients, hormones, and waste products to and from the body cells.

(ii) Heart acts as a pump that pushes blood through the blood vessels to all parts of the body.

(iii) Blood vessels form a network of arteries, veins, and capillaries that carry blood to and from the heart and body tissues.

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

Answer : Yes, nutrition is essential for organisms. It provides the energy and nutrients required for growth, repair, and maintenance of bodily functions. Without adequate nutrition, organisms cannot sustain life processes, resulting in poor health or death. Nutrients support metabolic activities and overall well-being.

Question: What are the differences between autotrophic nutrition and heterotrophic nutrition? [2M]

Answer: The differences between Autotrophic and Heterotrophic nutrition are :

Autotrophic Nutrition	Heterotrophic Nutrition
Organisms make their own food from simple substances.	Organisms cannot make their own food.
Uses sunlight, carbon dioxide, and water.	Depends on plants or other animals for food.
Food is prepared by photosynthesis.	No photosynthesis occurs.
Found in green plants and algae.	Found in animals, fungi, and humans.
Chlorophyll is present.	Chlorophyll is absent.

Question: Where do plants get each of the raw materials required for photosynthesis? [2M]

Answer: Plants get the raw materials for photosynthesis from different sources. Carbon dioxide comes from the air through small pores called stomata in the leaves. Water is absorbed from the soil by the roots and transported to the leaves through xylem tissues. Sunlight is obtained from the Sun and is trapped by chlorophyll present in green leaves. These raw materials together help plants to prepare their food by photosynthesis.

Question: What is the significance of emulsification of fats?

Answer : Emulsification of fats is the process of breaking down large fat globules into smaller droplets by bile salts present in bile juice. It increases the surface area of fats, allowing the enzyme lipase to act on them more effectively and digest them into fatty acids and glycerol.

Question: What is the role of the acid in our stomach? [2M]

Answer: The acid in our stomach, released by the gastric glands, creates an acidic medium which facilitates the action of the enzyme pepsin to digest proteins. It also helps protect the inner lining of the stomach under normal conditions with the mucus secreted by the glands.

Question: What is the function of digestive enzymes? [2M]

Answer: The function of digestive enzymes is to break down complex food molecules into simpler substances that can be easily absorbed by the body. For example, enzymes like amylase break down starch into sugar, pepsin breaks down proteins into smaller peptides, and lipase breaks down fats into fatty acids and glycerol. This helps the body to get nutrients from the food we eat.

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: (a) Blood : Transports oxygen, nutrients, hormones, and wastes throughout the body.

(b) Blood platelets : Help in clotting of blood to stop bleeding.

(d) Heart : Pumps blood to all parts of the body.

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: Potassium hydroxide (KOH) . KOH absorbs carbon dioxide (CO₂) present inside the flask.
Since CO₂ produced during respiration is absorbed by KOH, the pressure inside the flask decreases. This causes the liquid (like water) in the delivery tube to move inward, showing that CO₂ is being produced during respiration.

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

Answer : ATP (Adenosine Triphosphate) is called the energy currency of living organisms.

It is produced during cellular respiration, mainly in the mitochondria of the cell. ATP is also produced in the cytoplasm during glycolysis.

Question: Name the correct substrates for the following enzymes

(a) Trypsin (b) Amylase (c) Pepsin (d) Lipase

Answer : (a) Trypsin: Proteins

(b) Amylase: Starch

(d) Lipase: Fats (lipids)

Question: What is biological catalyst ? Which enzyme is contained by the saliva secteted by the salivary gland of humans ? [SEBA 2025 2M]

Answer: A biological catalyst is a substance that speeds up a biochemical reaction in living organisms without being used up in the reaction.

Saliva secreted by the salivary glands in humans contains an enzyme called salivary amylase, which helps in breaking down starch into simpler sugars.

Question: Give the differences between blood and lymph. [ SEBA 2025 2M

Answer: The differences between blood and lymph :

Blood	Lymph
(i) Blood is red in colour due to the presence of haemoglobin in red blood cells.	(i) Lymph is a colourless or pale yellow fluid.
(ii) It contains red blood cells, white blood cells, platelets and plasma.	(ii) It mainly contains white blood cells and lacks red blood cells and platelets in normal conditions.
(iii) It transports oxygen, carbon dioxide, nutrients, hormones and waste products.	(iii) It transports absorbed fats and helps return excess tissue fluid to the blood.

Question: Mention the major events during photosynthesis.

Answer : The major 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.

Long Questions and Answers (From 3 Marks to 5 Marks)

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

Answer : Carbohydrates are broken down into simple sugars by enzymes like salivary amylase in the mouth and other enzymes in the small intestine. Proteins are digested into amino acids by enzymes such as pepsin in the stomach and trypsin in the small intestine. Fats are broken down into fatty acids and glycerol in the small intestine. Bile juice emulsifies fats, while lipase helps digest them.

Question: (a) (i) State the role of ATP in cellular respiration.

(ii) what ensures sufficient exchange of gases in plants ?

(iii) State the conditions on which the direction of diffusion of gases in plant depend upon. [3M, 2023]

Answer: (a) (i) ATP acts as the main energy currency of the cell. It stores and supplies energy needed for various cellular processes like growth, movement, and active transport.

(ii) Stomata and lenticels ensure proper exchange of gases (O₂ and CO₂) between the plant and the environment.

(iii) The direction of diffusion of gases in plants depends on the concentration gradient of gases. Gases move from a region of higher concentration to a region of lower concentration. It also depends on whether the plant is carrying out photosynthesis or respiration, which changes the relative levels of oxygen and carbon dioxide.

Question: (a) (i) What is the internal energy reserve in plants and animals ?

(ii) How desert plants perform photosynthesis if their stomata remain closed during the day ? [3M, 2023]

Answer: (a) (i) The internal energy reserve in plants is primarily stored in the form of starch, while in animals, it is stored as glycogen and fat. These reserves are used to provide energy when needed.

(ii) Desert plants keep their stomata (tiny openings on leaves) closed during the day to save water. Instead, they open their stomata at night to take in carbon dioxide (CO₂) and store it as an acid. During the day, they use this stored CO₂ to perform photosynthesis, even with their stomata closed.

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: In human beings, oxygen is transported by haemoglobin in red blood cells. It binds with oxygen in the lungs and carries it to all body parts. Carbon dioxide is transported mainly in dissolved form in blood plasma and also by haemoglobin back to the lungs.

The lungs are designed with millions of tiny air sacs called alveoli. These alveoli provide a large surface area, have thin walls, and are surrounded by capillaries, which helps in efficient exchange of gases.

Question: Draw a neat labeled diagram of the longitudinal section of the human heart and show the path of the flow of blood through it with the arrow marks. Mention the role of the valves present in the system . [SEBA 2025 3M]

Answer: The labelled diagram of the longitudinal section of the human heart :

Valves present in the circulatory system prevent the backward flow of blood and ensure that blood flows in one direction through the heart and blood vessels.

Question: Explain the process of nutrition in Amoeba.

Answer: Amoeba takes in food with the help of finger-like projections called pseudopodia. These projections surround the food and engulf it, forming a food vacuole. Digestive enzymes break down the food into simpler substances, which are absorbed and used for growth and energy. The undigested waste is expelled through the cell membrane. This process of taking in food, digesting it, absorbing nutrients and removing waste is called holozoic nutrition.

Question: What is transpiration ? How does it help in the absorption and upward movement of water, minerals ,etc, from the root to the leaves of a plant ? [SEBA 2025 3M]

Answer: Transpiration is the process by which plants lose water in the form of water vapour from their aerial parts, mainly through the stomata of leaves.

Transpiration helps in the absorption and upward movement of water and minerals from the roots to the leaves. The loss of water through stomata creates a suction force called transpiration pull, which pulls water upwards through the xylem vessels. This helps in the continuous transport of water and dissolved minerals from the roots to different parts of the plant.

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

Answer: The three pathways of breakdown in living organisms are:

(i) In the presence of oxygen (Aerobic respiration): Glucose breaks down into carbon dioxide and water, releasing a large amount of energy. It mainly occurs in the mitochondria.

i.e. , Glucose (6-carbon molecules) Pyruvate (3-carbon molecules) + Energy Carbon dioxide + Water + Energy .

(ii) In the absence of oxygen (Anaerobic respiration): Glucose breaks down into ethanol and carbon dioxide in yeast, releasing energy.

i.e. , Glucose (6-carbon molecules) Pyruvate (3-carbon molecules) + Energy Ethanol + Carbon dioxide + Energy .

(iii) Lack of oxygen in muscles: Glucose breaks down into lactic acid, releasing energy during vigorous exercise.

i.e. , Glucose (6-carbon molecules) Pyruvate (3-carbon molecules) + Energy Lactic acid + Energy .

Question: Describe the process of urine formation in kidneys.

Answer: Urine formation in the kidneys takes place in functional units called nephrons. The blood is filtered through a cluster of thin-walled blood capillaries, and the filtrate enters a cup-shaped structure. Useful substances such as glucose, amino acids, salts and most of the water are selectively reabsorbed into the blood as the filtrate passes through the tubule. The remaining waste, mainly urea, forms urine. It passes through the ureters into the urinary bladder, where it is stored until it is released through the urethra.

Question: What are the differences between the transport of materials in xylem and phloem ? [3M]

Answer: The differences between the transport of materials in xylem and phloem are as follows.

Xylem	Phloem
(i) Xylem transports water and minerals from the roots to the aerial parts of the plant, such as the leaves and stems.	(i) Phloem transports organic nutrients, such as sugars and amino acids, from the photosynthetic parts (source) to the non-photosynthetic parts (sink) of the plant.
(ii) Xylem consists of non-living cells called tracheids and vessel elements, which form long tubes for water transport.	(ii) Phloem consists of living cells called sieve elements (sieve tube elements and companion cells) connected end-to-end to form sieve tubes.
(iii) The flow rate in xylem is unidirectional and relatively slow.	(iii) The flow rate in phloem can be bidirectional, allowing for the movement of materials both upwards and downwards in the plant.

Question: Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning. [3M]

Answer: The structure and functioning of alveoli in the lungs and nephrons in the kidneys are :

Alveoli (Lungs)	Nephrons (Kidneys)
Small balloon-like sacs at the end of bronchioles	Small filtering units in kidneys
Surrounded by capillaries for gas exchange	Surrounded by blood vessels for filtration and reabsorption
Thin walls allow easy diffusion of oxygen into blood and carbon dioxide out	Tubular structure allows selective reabsorption of water, salts, and useful substances
Main function: exchange of gases	Main function: excretion of wastes and regulation of water and salts
Provides large surface area for efficient oxygen absorption	Provides large surface area for maximum filtration and reabsorption

Question: What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration. [3M]

Answer: The differences between aerobic and anaerobic respiration are :

Aerobic Respiration	Anaerobic Respiration
Requires oxygen	Does not require oxygen
Glucose is completely broken down into CO₂ and H₂O	Glucose is partially broken down into lactic acid (in animals) or ethanol and CO₂ (in plants/yeast)
Releases more energy	Releases less energy
Occurs in mitochondria	Occurs in cytoplasm
Examples: Humans, animals, plants	Examples: Yeast, bacteria, some muscle cells (during intense exercise)

Some organisms using anaerobic respiration include yeast and certain bacteria.

Question: Describe double circulation in human beings. Why is it necessary? [3M]

Answer: Double circulation in humans means that blood passes through the heart twice in one complete cycle of the body. The right side of the heart pumps deoxygenated blood to the lungs to get oxygen, while the left side pumps oxygenated blood to the rest of the body. This separation prevents mixing of oxygen-rich and oxygen-poor blood, ensuring an efficient supply of oxygen to meet high energy needs. It is a key feature of mammals and birds.

It is necessary because it keeps oxygen-rich and oxygen-poor blood separate, ensuring efficient oxygen supply to all body cells.

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

Answer : The flow of blood through the human heart begins with deoxygenated blood from the body entering the right atrium. When the atrium contracts, blood moves into the right ventricle, which then pumps it to the lungs for oxygenation. The oxygen-rich blood returns to the left atrium, and on contraction, it enters the left ventricle. The strong left ventricle then pumps this blood to the entire body. Valves in the heart prevent backward flow, and the thicker walls of ventricles help pump blood efficiently to the lungs and body.

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6. Life Processes SEBA/ASSEB Class 10 Science– Important Questions and Answers | Assam HSLC

SEBA/ASSEB Class 10 Science Chapter 6: Life Processes Important Questions and Answers | HSLC Assam

Chapter 6: Life Processes

Multiple Choose Question and Answer:

Assertion (A) and Reason (R) Question and Answer :

Short Questions and Answers (From 1 Mark to 2 Marks)

Long Questions and Answers (From 3 Marks to 5 Marks)

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