a) During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
b) Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid. c) As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration. Anaerobic respirationresults in an oxygen debt that has to be repaid in order to oxidise lactic acid to carbon dioxide and water.
d) If muscles are subjected to long periods of vigorous activity they become fatigued, ie they stop contracting efficiently. One cause of muscle fatigue is the build-up of lactic acid in the muscles. Blood flowing through the muscles removes the lactic acid. Suggested ideas for practical work to develop skills and understanding include the following:
■ investigating the rate of respiration in yeast using carbon dioxide sensors and dataloggers ■ investigating the effect of exercise on pulse rate, either physically or using pulse sensors and dataloggers
■ investigating the link between exercise and breathing rate with a breathing sensor
■ investigating holding masses at arm’s length and timing how long it takes the muscles to fatigue
■ designing an investigation using force meters and dataloggers to find the relationship between the amount of force exerted by a muscle and muscle fatigue.

	Created by banski over 10 years ago

GCSE Science (Biology) Note on Aerobic and Anaerobic Respiration, created by banski on 31/03/2014.