Answers to Hands on Pg 76-79

7.1 : Anaerobic respiration in yeast

Aim : To investigate anaerobic respiration in yeast
Hypothesis : Anaerobic respiration by yeast produces carbon dioxide and ethanol
a) MV : Presence or absence of yeast
b) RV : Change in colour of bicarbonate indicator and smell of ethanol
c) FV : Temperature, volume of solution
Discussion :

1. To remove oxygen
2. To pevent oxygen from dissolving in the solution
3. Carbon dioxide is produced and it will turn limewater cloudy
4. Yes. Ethanol is produced and can be detected through the smell of alcohol.

Conclusion : The hypothesis is accepted. Anaerobic respiration by yeast produces carbon dioxide and ethanol.

7.2 : Effects of vigorous exercising on the rates of respiration and heartbeat

Aim : To study the effects of vigorous exercising on the rates of respiration and heartbeat
Hypothesis : The more vigorous the exercise, the higher the rates of respiration and heartbeat.
a) MV : At rest or vigorous activity
b) RV : Rates of respiration and heartbeat
c) FV : Temperature, student

Condition	Rate of respiration (counts per min)				Rate of respiration (counts per min)
	1	2	3	Mean	1	2	3	Mean
At rest	14	15	14	14	72	71	72	72
After vigorous exercise	27	27	28	27	88	86	88	87

Discussion

1. The rate of respiration increases when the exercise is more vigorous.
2. Vigorous exercise actually increases the rate of heartbeat.
3. An increase in the rate of respiration and the rate of heartbeat will increase the oxygen content in the body. Cell respiration increases due to an increase in oxygen content. This results in an increase in carbon dioxide content in the body as more carbon dioxide is released through cell respiration.

Conclusion

The hypothesis is accepted. The more vigorous the exercise, the higher the rates of respiration and heartbeat