(A) (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

OR

(B) (i) What is double circulation?

(ii) Why is the separation of the right side and the left side of the heart useful? How does it help birds and mammals?

Life Processes

Nutrition and Transportation

Official Answer

Option (A)

(i) Nutrition in Paramecium:

Paramecium is a unicellular organism with a definite shape. It takes in food at a specific spot on its cell surface. Food is moved to this spot by the coordinated movement of hair-like projections called cilia, which cover the entire surface of the cell.

(ii) Roles in the Human Digestive System:

(a) Hydrochloric acid: It creates an acidic medium in the stomach which facilitates the action of the protein-digesting enzyme pepsin. It also helps kill harmful bacteria ingested with food.
(b) Trypsin: Secreted by the pancreas into the small intestine, it is an enzyme responsible for digesting proteins into simpler peptides/amino acids.
(c) Muscular walls of stomach: They contract rhythmically (churning) to mix the food thoroughly with gastric digestive juices.
(d) Salivary amylase: Secreted by the salivary glands in the mouth, this enzyme breaks down starch (a complex carbohydrate) into simple sugars.

OR

Option (B)

(i) Double Circulation:

Double circulation is a circulatory system pathway where blood travels through the heart twice during one complete cycle of the body. It consists of:

Pulmonary Circulation: Deoxygenated blood from the right side of the heart goes to the lungs for oxygenation and returns as oxygenated blood to the left side of the heart.
Systemic Circulation: Oxygenated blood from the left side of the heart is pumped to all body tissues and returns as deoxygenated blood to the right side of the heart.

(ii) Utility of Separation of Heart Chambers:

Prevents Mixing: The complete separation of the right side (deoxygenated blood) and the left side (oxygenated blood) of the heart prevents the mixing of oxygenated and deoxygenated blood.
High Efficiency: This separation allows a highly efficient supply of oxygen to the body cells.
Help to Birds and Mammals: Warm-blooded animals like birds and mammals have high energy requirements to constantly maintain a constant body temperature. The highly efficient oxygen delivery provided by double circulation helps meet these high metabolic energy demands.

CiliaSpecific spotHydrochloric acidPepsinTrypsinMuscular wallsSalivary amylaseDouble circulationOxygenatedDeoxygenatedWarm-bloodedBody temperature

Marking Scheme

1Option A (i): State that Paramecium uses cilia covering its surface to move food to a specific spot. (1 mark)
2Option A (ii): Correctly state the roles of (a) Hydrochloric acid, (b) Trypsin, (c) Muscular walls of stomach, and (d) Salivary amylase (0.5 marks each). (2 marks)
3Option B (i): Define double circulation as blood passing through the heart twice in one complete cycle. (1 mark)
4Option B (ii): Explain that separation prevents mixing of oxygenated and deoxygenated blood, providing highly efficient oxygen supply to meet the high energy demands of warm-blooded birds and mammals to maintain body temperature. (2 marks)

Hint

For (A), remember how cilia differ from pseudopodia, and match each digestive agent to its specific location (mouth, stomach, small intestine). For (B), think about why warm-blooded animals need more oxygen than cold-blooded ones.

Quick Oral Answer

In Paramecium, tiny hair-like cilia sweep food into a specific spot. In our digestive system, salivary amylase breaks down starch in the mouth, HCl creates an acidic environment in the stomach for pepsin, stomach muscles churn the food, and trypsin digests proteins in the small intestine. Double circulation means blood goes through the heart twice per cycle, keeping oxygen-rich and oxygen-poor blood separate to give birds and mammals the high energy they need to stay warm.

Analysis & Explanation

This question offers two choices testing core physiological mechanisms in 'Life Processes'.

Option A focuses on heterotrophic nutrition: comparing unicellular ingestion (Paramecium's cilia) with specialized chemical and mechanical digestion in humans (enzymes, acid, and muscular churning).

Option B focuses on the efficiency of the circulatory system in multicellular organisms. Separation of oxygenated and deoxygenated blood is an evolutionary adaptation for homeothermic (warm-blooded) animals to sustain high metabolic rates.

Common Mistakes

1Confusing Paramecium's food intake (cilia) with Amoeba's food intake (pseudopodia/finger-like extensions).
2Confusing the site of action of trypsin (small intestine) with pepsin (stomach).
3Forgetting to link double circulation to the maintenance of constant body temperature in birds and mammals.

Interesting Facts

Unlike mammals and birds, amphibians and reptiles have a 3-chambered heart where some mixing of oxygenated and deoxygenated blood occurs because they do not need to use energy to maintain a constant body temperature!

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2023?

This question carries 3 marks in the CBSE Class 10 Science 2023 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Life Processes" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Nutrition and Transportation" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2023 paper?

This is a Short Answer question from Section C in the CBSE Class 10 Science 2023 paper.