CBSE Class 10 Science Life Processes VBQs Set 04

Nutrition

Question. Opening and closing of stomata is due to
(a) high pressure of gases inside the cells
(b) movement of water in and out of the guard cells
(c) stimulus of light in the guard cells
(d) diffusion of \( CO_2 \) in and out of the guard cells.
Answer: (b) movement of water in and out of the guard cells

Question. Assertion (A) : The inner walls of the small intestine have finger like projections called villi which are rich in blood.
Reason (R) : These villi have a large surface area to help the small intestine in completing the digestion of food.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true and (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: (c) (A) is true but (R) is false.

Question. Water in the root enters due to
(a) the function of the root to absorb water
(b) difference in the concentration of ions between the root and the soil
(c) excess water present in the soil
(d) diffusion of water in the roots.
Answer: (b) difference in the concentration of ions between the root and the soil

Read the following and answer the questions from :
Take a healthy potted plant with elongated leaves. Select a leaf and insert about one half of this leaf in a test tube containing KOH and make it air tight. Place the set-up in sun for two hours. Take out the leaf from the test tube and dip it in boiling water for a few minutes. Put this leaf in a beaker with alcohol and boil it in a water bath. Wash the leaf with water and then dip the leaf in iodine solution for a few minutes. The portion of the leaf dipped in KOH solution will not show any change when dipped in iodine solution.

Question. The function of KOH taken in the test tube is to absorb
(a) released water vapours
(b) released \( CO_2 \)
(c) released \( O_2 \)
(d) chlorophyll.
Answer: (b) released \( CO_2 \)

Question. On the basis of this activity, we may conclude that the factor for photosynthesis is
(a) carbon dioxide
(b) oxygen
(c) chlorophyll
(d) water vapour.
Answer: (a) carbon dioxide

Question. The event that does not occur in photosynthesis is
(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.
Answer: (c) oxidation of carbon to carbon dioxide

Question. Iodine solution gives blue-black colour with
(a) starch
(b) proteins
(c) glucose
(d) fats.
Answer: (a) starch

Question. The correct statements with reference to single celled organisms are
(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)

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 nearest and richest source of raw materials like nitrogen, phosphorus and other minerals for the plants.
(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).

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
(a) mode of 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

Question. Most of the digestion and absorption of the food takes place in the
(a) small intestine
(b) liver
(c) stomach
(d) large intestine.
Answer: (a) small intestine

VSA

Question. Name an enzyme present in pancreatic juice.
Answer: Trypsin (or pancreatic amylase or pancreatic lipase).

Question. What causes movement of food inside the alimentary canal in human beings?
Answer: Rhythmic contraction and expansion of the muscles of the alimentary canal, called peristalsis (peristaltic movement).

Question. Mention the raw materials required for photosynthesis.
Answer: The raw materials required for photosynthesis are carbon dioxide (\( CO_2 \)), water, sunlight, and chlorophyll.

Question. State the location and function of gastric glands.
Answer: Gastric glands are located in the wall of the stomach. Their function is to secrete gastric juice, which contains hydrochloric acid (\( HCl \)), pepsin (a protein-digesting enzyme), and mucus.

SA I 

Question. Two green plants are kept separately in oxygen free containers, one in the dark and other in sunlight. It was observed that plant kept in dark could not survive longer. Give reason for this observation.
Answer: The plant kept in sunlight survives longer because it can perform photosynthesis and release oxygen as a byproduct, which is then used for its respiration. The plant in the dark cannot perform photosynthesis and will eventually use up all available oxygen for respiration and die.

Question. List the events in proper sequence that takes place during the process of photosynthesis.
Answer: 1. Absorption of light energy by chlorophyll.
2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

Question. Name the glands present in the wall of the stomach that release secretions for digestion of food. Write the three components of secretion that are released by these glands.
Answer: Gastric glands are present in the wall of the stomach. The three components they release are:
1. Hydrochloric acid (\( HCl \))
2. Pepsin (enzyme)
3. Mucus

SA II 

Question. (i) How does Paramecium obtain its food?
(ii) List the role of each of the following in our digestive system :
(a) Hydrochloric acid
(b) Trypsin
(c) Muscular walls of stomach
(d) Salivary amylase
Answer: (i) Paramecium uses its cilia to move food particles along with water current towards its oral groove or cytostome.
(ii) (a) Hydrochloric acid: Creates an acidic medium for the activation of pepsin and kills bacteria.
(b) Trypsin: Digests proteins into amino acids in the small intestine.
(c) Muscular walls of stomach: Helps in churning and mixing the food thoroughly with digestive juices.
(d) Salivary amylase: Breaks down starch into maltose (sugar) in the mouth.

Question. (a) With the help of an activity, explain the action of saliva on the food we eat.
(b) Why is bile juice important in the process of digestion?
Answer: (a) Activity: Take two test tubes A and B. Put 1 mL starch solution in both. Add saliva to tube A and nothing to B. After 20-30 mins, add iodine. Tube B turns blue-black (starch present), tube A does not (saliva converted starch to sugar).
(b) Bile juice is important because it emulsifies large fat globules into small droplets, increasing the surface area for enzyme action, and it makes the acidic food from the stomach alkaline for pancreatic enzymes.

Question. In the human body the site of absorption of digested food is the small intestine. How is the process of absorption carried out and why is absorption of digested food necessary?
Answer: Absorption is carried out by tiny finger-like projections called villi in the small intestine, which increase the surface area for absorption and are rich in blood vessels. It is necessary so that nutrients can reach all body cells for energy, growth, and repair.

Question. Complete the following flow chart as per the given instructions.
Gastric glands present in the wall of stomach.
Secretions: a, b, c
Functions: d, e, f
Answer: a = Hydrochloric acid (\( HCl \)), b = Pepsin, c = Mucus.
d = Makes medium acidic for enzyme action and kills bacteria.
e = Digests proteins into peptones.
f = Protects the inner lining of the stomach from the action of acid.

Question. (a) State the role played by the following in the process of digestion :
(i) Enzyme trypsin
(ii) Enzyme lipase
(b) List two functions of finger-like projections present in the small intestine.
Answer: (a) (i) Trypsin: Digests proteins into smaller peptides/amino acids.
(ii) Lipase: Breaks down emulsified fats into fatty acids and glycerol.
(b) 1. Increase surface area for absorption. 2. Rich in blood vessels to transport absorbed food to all parts of the body.

Question. (a) Write the function of the following in the human alimentary canal :
(i) Saliva
(ii) HCl in stomach
(iii) Bile juice
(iv) Villi
(b) Write one function each of the following enzymes :
(i) Pepsin
(ii) Lipase
Answer: (a) (i) Saliva: Moistens food and breaks down starch to sugar. (ii) HCl: Activates pepsin and kills germs. (iii) Bile juice: Emulsifies fats and provides alkaline medium. (iv) Villi: Absorb digested food.
(b) (i) Pepsin: Digests proteins in acidic medium. (ii) Lipase: Digests emulsified fats.

Question. Explain the significance of photosynthesis. Write the balanced chemical equation involved in the process.
Answer: Significance: It is the primary source of food for all living organisms and maintains oxygen-carbon dioxide balance in the atmosphere.
Balanced equation: \( 6CO_2 + 12H_2O \xrightarrow{\text{Sunlight, Chlorophyll}} C_6H_{12}O_6 + 6H_2O + 6O_2 \)

Question. Differentiate between autotrophs and heterotrophs and give one example of each.
Answer: Autotrophs: Organisms that make their own food from inorganic substances (e.g., green plants).
Heterotrophs: Organisms that depend on others for food (e.g., humans, animals).

Question. Explain with the help of neat and well labelled diagrams the different steps involved in nutrition in Amoeba.
Answer: Steps: 1. Ingestion (using pseudopodia), 2. Digestion (in food vacuole), 3. Absorption (diffusion into cytoplasm), 4. Assimilation (use of food), 5. Egestion (rupture of cell membrane).

LA 

Question. (a) Why is nutrition necessary for the human body?
(b) What causes movement of food inside the alimentary canal?
(c) Why is small intestine in herbivores longer than in carnivores?
(d) What will happen if mucus is not secreted by the gastric glands?
Answer: (a) For energy, growth, repair, and protection against diseases.
(b) Peristalsis (rhythmic muscle contractions).
(c) Herbivores eat grass (cellulose), which is difficult to digest and requires a longer time/length.
(d) The inner lining of the stomach would be damaged or corroded by the hydrochloric acid.

Question. (a) State the form in which the following are stored:
(i) Unused carbohydrates in plants.
(ii) The energy derived from food in humans.
(b) Describe the process of nutrition in Amoeba with the help of diagram.
Answer: (a) (i) Starch, (ii) Glycogen.
(b) Amoeba uses pseudopodia to engulf food particles into a food vacuole where digestion occurs by enzymes. Absorbed nutrients diffuse into the cytoplasm, and waste is expelled through the cell membrane.

Respiration

Question. As compared to terrestrial organisms, the rate of breathing in aquatic organism is
(a) faster because they need more oxygen for their survival
(b) faster because the amount of dissolved oxygen in water is fairly low
(c) slower because the amount of dissolved oxygen in water is fairly low
(d) slower because the capacity of water of dissolving atmospheric air is limited
Answer: (b) faster because the amount of dissolved oxygen in water is fairly low

Question. The sequence of anaerobic respiration in our muscle cells during heavy exercise is
(a) Glucose \( \xrightarrow{\text{Cytoplasm}} \) Pyruvate \( \xrightarrow{\text{Muscle cells}} \) Lactic acid + Energy
(b) Glucose \( \xrightarrow{\text{Mitochondria}} \) Pyruvate \( \xrightarrow{\text{Muscle cells}} \) Carbon dioxide + Water
(c) Glucose \( \xrightarrow{\text{Cytoplasm}} \) Pyruvate \( \xrightarrow{\text{Muscle cells}} \) Ethanol + Carbon dioxide
(d) Glucose \( \xrightarrow{\text{Mitochondria}} \) Pyruvate \( \xrightarrow{\text{Muscle cells}} \) Ethanol + Lactic acid.
Answer: (a) Glucose \( \xrightarrow{\text{Cytoplasm}} \) Pyruvate \( \xrightarrow{\text{Muscle cells}} \) Lactic acid + Energy

Question. The energy released during cellular respiration is used to synthesise
(a) ribosomes
(b) RBC
(c) ATP
(d) mitochondria.
Answer: (c) ATP

Question. Assertion (A) : The rate of breathing in aquatic organisms is much slower than that seen in terrestrial organisms.
Reason (R) : The amount of oxygen dissolved in water is very low as compared to the amount of oxygen in air.
(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: (d) (A) is false, but (R) is true.

Question. Assertion (A) : In human beings, when air is taken into the body through the nostrils and passed through the throat, the air passage does not collapse.
Reason (R) : Rings of cartilage present in the throat ensure that the air passage does not collapse.
(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).

Question. The function of the lining of mucus in the nasal passage of human beings is to
(a) increase the temperature of inhaled air
(b) move the air in and out
(c) filter the air that we breathe in
(d) absorb oxygen from the air.
Answer: (c) filter the air that we breathe in

Question. In living organisms during respiration which of the following products are not formed if oxygen is not available?
(a) Carbon dioxide + Water
(b) Carbon dioxide + Alcohol
(c) Lactic acid + Alcohol
(d) Carbon dioxide + Lactic Acid
Answer: (a) Carbon dioxide + Water

Question. Anaerobic process
(a) takes place in yeast during fermentation
(b) takes place in the presence of oxygen
(c) produces only energy in the muscles of human beings
(d) produces ethanol, oxygen and energy.
Answer: (a) takes place in yeast during fermentation

VSA 

Question. Diffusion is insufficient to meet the oxygen requirement of multicellular organisms like human. State reason.
Answer: Multicellular organisms like humans have a very large body size and high metabolic demands. Diffusion is a slow process and cannot supply oxygen to all the cells located deep inside the body, as they are not in direct contact with the environment.

SA I 

Question. Write two different ways in which glucose is oxidised to provide energy in human body. Write the products formed in each case.
Answer: The two ways glucose is oxidised in the human body are:
1. Aerobic Respiration (in the presence of oxygen): Occurs in mitochondria. Products are carbon dioxide, water, and energy.
2. Anaerobic Respiration (in the lack of oxygen): Occurs in muscle cells during vigorous exercise. Products are lactic acid and energy.