On the basis of the characteristics of the processes given in the brackets in each case, differentiate between the following:
(a) Products of breakdown of pyruvate in aerobic and anaerobic respiration in human beings (product(s) of the processes)
(b) Respiration and photosynthesis in plants (gas released)
(c) Respiration in terrestrial animals and fishes (organs involved)
On the basis of the characteristics of the processes given in the brackets in each case, differentiate between the following:
(a) Products of breakdown of pyruvate in aerobic and anaerobic respiration in human beings (product(s) of the processes)
(b) Respiration and photosynthesis in plants (gas released)
(c) Respiration in terrestrial animals and fishes (organs involved)
(a) Products of breakdown of pyruvate in aerobic and anaerobic respiration in human beings:
| Aerobic respiration | Anaerobic respiration (in human muscle cells) |
|---|---|
| Pyruvate (3-carbon) is broken down completely in the mitochondria using oxygen | Pyruvate (3-carbon) is broken down without oxygen |
| Products: carbon dioxide + water + a large amount of energy | Product: lactic acid (a 3-carbon compound) + a small amount of energy |
As the chapter states: 'Breakdown of pyruvate using oxygen takes place in the mitochondria. This process breaks up the three-carbon pyruvate molecule to give three molecules of carbon dioxide. The other product is water... Sometimes, when there is a lack of oxygen in our muscle cells, another pathway for the break-down of pyruvate is taken. Here the pyruvate is converted into lactic acid.'
(b) Respiration and photosynthesis in plants (gas released):
| Respiration | Photosynthesis |
|---|---|
| Carbon dioxide () is released as glucose is oxidised for energy | Oxygen () is released as a by-product when water molecules are split during the light reaction |
In plants, respiration occurs all the time (day and night) and releases , while photosynthesis occurs only in the presence of sunlight and releases . During the day, the produced by respiration is largely used up in photosynthesis itself, so oxygen release dominates; at night, with no photosynthesis, elimination is the major gas-exchange activity.
(c) Respiration in terrestrial animals and fishes (organs involved):
| Terrestrial animals | Fishes |
|---|---|
| Use lungs to absorb oxygen from the atmosphere; air reaches the lungs via nostrils, throat and air passages, and gas exchange occurs across the fine, moist surface of alveoli | Use gills to absorb oxygen dissolved in water; fishes take in water through the mouth and force it past the gills, where dissolved oxygen is taken up by the blood |
As the chapter notes, terrestrial organisms breathe atmospheric oxygen through lungs (with alveoli maximising surface area), whereas aquatic organisms such as fishes use gills, and because the amount of dissolved oxygen in water is much lower than in air, fishes must breathe (open and close mouth/gill-slits) much faster than terrestrial organisms do.
Marking Scheme
- 11 mark for correctly differentiating pyruvate breakdown products (CO2 + water in aerobic vs lactic acid in anaerobic, in humans).
- 21 mark for correctly differentiating the gas released (CO2 in respiration vs O2 in photosynthesis).
- 31 mark for correctly identifying the organs (lungs in terrestrial animals vs gills in fishes).
Hint
For each pair, focus only on the specific criterion given in brackets — don't describe the whole process, just the asked-for feature.
Analysis & Explanation
This 3-mark question requires differentiating three related pairs of life-process concepts, one mark for each correctly and clearly differentiated pair, based directly on the chapter's sections on Respiration and Transportation. Each part must be answered strictly on the criterion specified in the brackets — products for (a), gas released for (b), and organs involved for (c) — since the marking scheme rewards addressing exactly that criterion rather than a general description.
Common Mistakes
- 1In (a), confusing anaerobic respiration in yeast (which gives ethanol + CO2) with anaerobic respiration in human muscle cells (which gives only lactic acid).
- 2In (b), stating that plants either only release CO2 or only release O2, forgetting that both occur depending on time of day/light conditions.
- 3In (c), describing the whole respiratory process instead of specifically naming the organs involved (lungs vs gills).
Interesting Facts
The build-up of lactic acid from anaerobic respiration in muscle cells during vigorous exercise is what causes the sensation of muscle cramps.
Because dissolved oxygen in water is far less concentrated than oxygen in air, fishes must pass a much larger volume of water over their gills per unit time than terrestrial animals breathe air, which is why fish open and close their mouths and gill-slits much more rapidly.
Spotted a mistake or something unclear?
Tell us — we fix reported answers fast.
Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2025?
This question carries 3 marks in the CBSE Class 10 Science 2025 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 "Respiration — Aerobic vs Anaerobic Respiration; Gaseous Exchange in Plants; Respiratory Organs in Terrestrial Animals and Fishes" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2025 paper?
This is a Short Answer question from Section C in the CBSE Class 10 Science 2025 paper.