CBSE Class 10 Science Advanced Biology Nutrition Very Short Answer Questions Set 01

Very Short Answer Type

Question 1. Why do insectivorous plants eat insects ?
Answer:
Insectivorous plants such as the pitcher plant and Drosera grow in soil that is poor in nitrogen. They trap and digest insects to get the nitrogen (in the form of proteins) that they cannot get from the soil. They still make their carbohydrate food by photosynthesis.
In simple words: They eat insects to get the nitrogen that their soil lacks.

Teacher's Note:
1. Insects give the nitrogen; photosynthesis gives the carbohydrates.
2. Do not call these plants heterotrophs; they are green and make food too.

Question 2. Define compensation point.
Answer:
The compensation point is the light intensity at which the CO₂ used in photosynthesis becomes equal to the CO₂ released in respiration. It occurs at low light, in the morning and in the evening.
In simple words: It is the light level at which photosynthesis and respiration just cancel each other's gas exchange.

Teacher's Note:
1. At the compensation point there is no net release of CO₂ or O₂.
2. It occurs at dawn and dusk.

Question 3. Write down the types of leucoplast.
Answer:
Leucoplasts are the colourless plastids of the underground parts. They are of three types according to what they store:
1. Aleuroplast stores protein.
2. Elaioplast stores oil (fat).
3. Amyloplast stores starch.
In simple words: Aleuroplasts store protein, elaioplasts store oil and amyloplasts store starch.

Teacher's Note:
1. Learn the three prefixes: aleuro (protein), elaio (oil), amylo (starch).
2. The other plastids are chromoplasts (coloured) and chloroplasts (green).

Question 4. Define photons.
Answer:
Photons (also called quanta) are the tiny packets or bundles of energy in which light energy is delivered. Chlorophyll in the thylakoid membranes traps solar energy in the form of photons.
In simple words: A photon is one small packet of light energy.

Teacher's Note:
1. Light behaves as particles of energy as well as waves.
2. A photon excites a chlorophyll molecule in the light reaction.

Question 5. Write down one function of bile juice.
Answer:
Bile juice makes the acidic food that comes from the stomach alkaline, so that the pancreatic enzymes can act on it. (Its salts also break fats into tiny globules, which is called emulsification.)
In simple words: Bile makes the food alkaline and breaks fat into small droplets.

Teacher's Note:
1. Any one of the two functions is enough for one mark.
2. Bile has no enzymes.

Question 6. Define succus entericus
Answer:
Succus entericus is the intestinal juice, secreted by the glands in the wall of the small intestine. It contains the enzymes that complete the digestion of carbohydrates, proteins and fats in the ileum.
In simple words: Succus entericus is another name for the intestinal juice.

Teacher's Note:
1. It completes digestion.
2. Its source is the intestinal glands (crypts of Lieberkuhn).

Question 7. What is the need of lacteal in digestive system.
Answer:
A lacteal is a lymph capillary inside each villus. The products of fat digestion (fatty acids and glycerol) are absorbed into the lacteals, which carry them away in the lymph. So lacteals are needed for the absorption of fats.
In simple words: Lacteals absorb the digested fat.

Teacher's Note:
1. Glucose and amino acids go into the blood capillaries instead.
2. Lacteals get their name from the milky colour of fat-rich lymph.

Question 8. "All plants give out oxygen during day and carbon dioxide during night". Do you agree with this statement ? Give reason.
Answer:
Yes, broadly I agree, but it needs one correction.
In the day, photosynthesis goes on faster than respiration, so the oxygen produced is more than the plant needs and the extra oxygen is given out, while the CO₂ produced in respiration is used in photosynthesis.
At night there is no light, photosynthesis stops, and only respiration continues, so the plant takes in oxygen and gives out CO₂.
The correction: plants respire during the day also, but the exchange of gases of photosynthesis hides it.
In simple words: More photosynthesis in the day means a net release of oxygen; at night only respiration remains, so CO₂ is released.

Teacher's Note:
1. Say that respiration goes on all the time and photosynthesis only in light.
2. This is why sleeping under a tree at night is not advised.

Question 9. How do the guard cells regulate opening and closing of stomatal pores ?
Answer:
Guard cells are kidney-shaped, with a thick inner wall (facing the pore) and a thin outer wall.
Opening: when water flows into the guard cells by osmosis, they become turgid and bulge outwards, and the thin outer wall stretches more than the thick inner wall, so the pore opens.
Closing: when water leaves the guard cells, they become flaccid and straighten, and the pore closes.
In simple words: Guard cells open the pore when they take in water and swell, and close it when they lose water.

Teacher's Note:
1. Mention both the wall difference and the movement of water.
2. A diagram of an open and a closed stoma earns full marks.

Question 10. Is 'nutrition' a necessity for an organism ? Discuss
Answer:
Yes. Nutrition is a necessity for every living organism, because the nutrients give:
1. Energy for all life activities such as movement, respiration and keeping warm.
2. Raw material for growth and for the repair of worn-out cells and tissues.
3. Protection against diseases (for example, vitamins and minerals keep the body healthy).
Without nutrition an organism cannot live, grow or reproduce.
In simple words: Without food an organism gets neither energy nor material for growth and repair.

Teacher's Note:
1. Three points are enough: energy, growth and repair, and protection.
2. Add an example, such as the stored fat used during fasting.

Question 11. 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 stomach that acts on proteins.
Answer:
(a) Photosynthesis
(b) Autotrophs
(c) Chloroplast
(d) Guard cells
(e) Heterotrophs
(f) Pepsin
In simple words: Photosynthesis, autotrophs, chloroplast, guard cells, heterotrophs and pepsin.

Teacher's Note:
1. Write only the names for one-word items.
2. Pepsin works in the acidic stomach.

Question 12. How do autotrophs obtain CO₂ and H₂O to make their food ?
Answer:
Carbon dioxide: land plants take it from the air through the tiny pores (stomata) on their leaves. Aquatic plants take the CO₂ dissolved in water through the general surface of the body.
Water: plants absorb water from the soil by osmosis through their roots, and the xylem carries it up to the leaves.
In simple words: Leaves take CO₂ from the air through stomata, and roots take water from the soil.

Teacher's Note:
1. Give the organ and the process for each raw material.
2. Aquatic plants do not need stomata for CO₂.

Question 13. Name the site of light and dark reaction of photosynthesis ?
Answer:
The light reaction takes place in the grana of the chloroplast and the dark reaction takes place in the stroma of the chloroplast.
In simple words: Light reaction in grana, dark reaction in stroma.

Teacher's Note:
1. Grana contain chlorophyll to trap light.
2. Stroma contains the enzymes for the dark reaction.

Question 14. What is the product formed during C₃ cycle of dark reaction of photosynthesis ?
Answer:
The C₃ cycle (Calvin–Benson cycle) fixes CO₂ into a three-carbon compound (3-phosphoglyceric acid, PGA) and finally forms glucose, with the RuBP regenerated for the next turn.
In simple words: The product of the cycle is glucose.

Teacher's Note:
1. C₃ means that the first stable product has three carbon atoms.
2. The book gives glucose as the product of the dark reaction.

Question 15. Name the different steps involved in digestion process.
Answer:
The steps in the nutrition of an animal are ingestion, digestion, absorption, assimilation and egestion.
In simple words: Ingestion, digestion, absorption, assimilation and egestion.

Teacher's Note:
1. The question says 'digestion process', but the answer is the five steps of nutrition.
2. Learn them in this order.

Question 16. Name the different parts of large intestine.
Answer:
The large intestine has three parts: caecum, colon and rectum. (The colon is further divided into ascending, transverse, descending and sigmoid parts.)
In simple words: Caecum, colon and rectum.

Teacher's Note:
1. The appendix hangs from the caecum.
2. The rectum ends at the anus.

Question 17. Where does the absorption of food takes place ?
Answer:
The absorption of digested food takes place mainly in the small intestine, through the villi and microvilli of its wall. Water is absorbed mostly in the large intestine.
In simple words: Digested food is absorbed in the small intestine.

Teacher's Note:
1. Villi make the absorption quick.
2. Mention the large intestine for water.

Question 18. Name five different types of glands involved in human digestive system.
Answer:
1. Salivary glands, 2. Gastric glands, 3. Liver, 4. Pancreas, 5. Intestinal glands.
In simple words: Salivary, gastric, liver, pancreas and intestinal glands.

Teacher's Note:
1. The liver and the pancreas are the two big glands.
2. Each gland adds its own juice to the food.

Question 19. Where does digestion of fat take place in our body ?
Answer:
Fat is digested in the small intestine. In the duodenum bile emulsifies the fat, and the lipase of the pancreatic juice breaks it into fatty acids and glycerol. The digestion is completed in the ileum by the intestinal juice.
In simple words: Fats are digested in the small intestine.

Teacher's Note:
1. There is no fat-digesting action in the mouth.
2. Without bile, fat digestion would be slow.