Form 2:
Respiration kcse questions

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1. The diagram below shows a set up that was used to demonstrate fermentation. Glucose solution was boiled and oil added on top of it. The glucose solution was then allowed to cool before adding the yeast suspension.

a) Why was the glucose solution boiled before adding the yeast suspension? (1mk)

To derive off air or oxygen

b) What was the importance of cooling the glucose solution before adding the yeast suspension? (1mk)

To avoid killing yeast/Denaturing enzymes in yeast

c) What was the use of the oil in the experiment? (1mk)

To prevent air from getting into the yeast and glucose mixture.

d) What observation would be made in test tube B at the end of the experiment (1mk)

Lime water turn to white precipitate

e) Suggest a control for this experiment (1mk)

Use boiled yeast/glucose without yeast/yeast without glucose

2. Give two reasons why accumulation of lactic acid during vigorous exercise lead to an increase in heart beat. (2mks)

-Lactic acid is toxic to tissues and must be removed from muscles to liver.

-To increase supply of oxygen to tissues

3. A process that occurs in plants is represented by the equation below.

C6H12O6 2C2

Glucose Ethanol Carbon Dioxide

a) Name the process (1mk)

Anaerobic respiration

b) State the economic importance of process name in (a) above. (1mk)

Brewing/Beer making

4. Other than carbon dioxide, name the other products of anaerobic respiration in plants. (2mks)


-Energy (ATP)

5. Name the substance which accumulates in muscles when respiration occurs with insufficient oxygen. (1mk)

Lactic acid

6. a) In what form is energy stored in muscles? (1mk)

Adenosine triphosphate (ATP)

b) State the economic importance of anaerobic respiration in plants.

i) Beer brewing/wine making

ii) Baking using yeast.

7. State four ways in which respiratory surfaces are suited to their function. (4mks)

- Have thin epithelium/wall to reduce distance of diffusion of the gases.

- Moist to dissolve the diffusing gases

- Highly folded to increase surface area for diffusion of gases.

- Well supplied with blood or vascularized to help maintain high concentration gradient.

8. a) A dog weighing 15.2kg requires 216kJ while a mouse weighing  50g requires 2736KJ per day. Explain. (2mks)

A mouse has high surface area to volume ratio and tends to lose heat faster. It required more energy to replace it. A dog has low surface area to volume ratio and lose less heat. Less energy is required to replace it

b) What is the end product of respiration in animals when there is insufficient oxygen supply? (1mk)

Lactic acid

9 a) Name the products of anaerobic respiration in:

i) Plants (1mk)

Ethanol and carbon (IV) oxide.

ii) Animals (1mk)

Lactic acid

b) What is oxygen debt? (1mk)

It is the state when human body undergoes anaerobic respiration producing lactic acid. Oxygen has to be taken into the body to break the lactic acid.

10. 5C51H98O6 + 145O2 1 O2CO2 + 98 H2O + energy

The above equation shows an oxidation reaction of food substances. (2mks)

a) What do you understand by the term respiratory quotient? (1mk)

Ratio of carbon dioxide produce to oxygen used up during breakdown of a food substrate.

b) Determine respiratory quotient of the oxidation of food substance.  (2mks)

c) Identify the food substances. (1mk)

Fat/ Lipid

11 Write differences between aerobic respiration and photosynthesis. (4mks)

12. Below is a diagram of an organelle that is involved in aerobic respiration.

a) Name the organelle (1mk)


b) Name the parts labeled A, B, and C. (3mks)

A - Outer membrane

B - Inner membrane

C - Matrix

D - Cristae

c) What is the purpose of the folding labeled D? (1mk)

Increase surface area over which respiration takes place:

d) Give the chemical compound which is formed in the organelle and forms the immediate source of energy.