A scientist monitored the changes in the $$$\mathrm{pH}$$$ in muscles before, during and after two minutes of vigorous exercise. The changes in $$$\mathrm{pH}$$$ are caused by the production of lactic acid. Complete the sentences to describe and explain the results in Fig. 6.1. The pH decreases from to to. during vigorous exercise. There is not enough supplied to the muscles. The body respires anaerobically. The lactic acid produced builds up in the muscles causing an debt. It takes minutes for the muscle $$$\mathrm{pH}$$$ to return to its initial level after exercise. The $$$\mathrm{pH}$$$ value increases after vigorous exercise has ended, as lactic acid is transported in the . to the During this time the breathing rate and rate remain high.

Biology

IGCSE&ALevel

CAIE

Exam No：0610_s23_qp_41 Year：2023 Question No：6(a)

Answer:

Knowledge points:

12.2.1 Define aerobic respiration as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

12.2.2 State the word equation for aerobic respiration as glucose + oxygen → carbon dioxide + water

12.2.3 Investigate the uptake of oxygen by respiring organisms, such as arthropods and germinating seeds

12.2.4 State the balanced chemical equation for aerobic respiration as

12.2.5 Investigate the effect of temperature on the rate of respiration of germinating seeds

12.3.1 Define anaerobic respiration as the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

12.3.2 State the word equations for anaerobic respiration in muscles during vigorous exercise (glucose → lactic acid) and the microorganism yeast (glucose → alcohol + carbon dioxide)

12.3.3 State that anaerobic respiration releases much less energy per glucose molecule than aerobic respiration

12.3.4 State the balanced chemical equation for anaerobic respiration in the microorganism yeast as

12.3.5 State that lactic acid builds up in muscles and blood during vigorous exercise causing an oxygen debt

Answer:

Knowledge points:

Solution:

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