During vigorous exercise, the occurrence of cramps in the outer muscles of an athlete is due to the conversion of pyruvate to :
During vigorous exercise, the occurrence of cramps in the outer muscles of an athlete is due to the conversion of pyruvate to :
Options
The correct option is (c) Lactic acid.
Marking Scheme
- 11 mark for selecting the correct option (c) Lactic acid.
Hint
Think about the anaerobic pathway that occurs in human muscle cells when there is a lack of oxygen during heavy physical exertion.
Quick Oral Answer
During vigorous exercise, our muscle cells do not get enough oxygen. To produce energy quickly, they convert pyruvate into lactic acid. The accumulation of this lactic acid in the muscles leads to painful cramps.
Analysis & Explanation
During vigorous physical activity or exercise, the oxygen supply in our muscle cells becomes insufficient to meet the high energy demand. To overcome this, muscle cells temporarily switch to anaerobic respiration. In this pathway, glucose is first broken down into pyruvate (a 3-carbon molecule) in the cytoplasm, which is then converted into lactic acid (also a 3-carbon molecule) instead of being completely oxidized to carbon dioxide and water. The accumulation of lactic acid in the muscles causes muscle fatigue and cramps.
- Option (a) Glucose is incorrect because glucose is the initial substrate that is broken down, not the product of pyruvate conversion.
- Option (b) Ethanol is incorrect because ethanol is produced during anaerobic respiration (fermentation) in yeast, not in human muscle cells.
- Option (d) Lactose is incorrect because lactose is a disaccharide sugar found in milk and is not involved as a direct product of anaerobic respiration.
Common Mistakes
- 1Students often confuse anaerobic respiration in yeast (which produces ethanol and carbon dioxide) with anaerobic respiration in human muscle cells (which produces lactic acid only).
Interesting Facts
Lactic acid accumulation is a temporary state. Once the vigorous activity stops and oxygen supply returns to normal, lactic acid is transported to the liver where it is converted back into glucose or pyruvate.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2023?
This question carries 1 mark 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 "Respiration" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2023 paper?
This is a MCQ question from Section A in the CBSE Class 10 Science 2023 paper.