Past Paper Questions

Question 1

How to test for oxygen

Answer 1

• remove the test tube
• cover with finger so the gas doesn’t escape
• insert a glowing split into the test tube
• if the splint glows brighter then there is oxygen

Question 2

Why pond water/ sodium bicarbonate is added to the investigation

Answer 2

To supply carbon dioxide for photosynthesis

Question 3

Control for a photosynthesis experiment

Answer 3

Set up the apparatus exactly the same but out it in a dark cupboard

Question 4

Hydrogen Transfer System

Answer 4

1. In the mitochondria
2. In the inner membrane
3. Energy from the hydrogens are removed step by step to form ATP
4. The exhausted hydrogens bond with oxygen
5. Will form water
6. Each hydrogen has enough energy to form 3 ATP’s
7. 12 x 3 = 36 ATP

Question 5

How many ATPs form from 1 glucose molecule

Answer 5

(36 + 2) = 38

Question 6

Why is cotton wool used instead of an airstopper

Answer 6

• cotton wool legs carbon dioxide escape
• Build - up of carbon dioxide will slow down respiration
• to allow oxygen to enter
• respiration needs oxygen

Question 7

Why must the seeds be boiled in the control experiment

Answer 7

In order to denature the enzymes in the seeds to stop respiration from taking place

Question 8

Why must the seeds be sterilised

Answer 8

To remove all other cells like bacteria and yeast which may respire and mess with the results

Question 9

Why use flasks

Answer 9

• they prevent loss of heat

- they prevent heat from entering

Question 10

Explain why there was an increase in lactic acid in blood

Answer 10

• the muscles do not receive enough oxygen
• the muscles cells therefore have to respire anaerobically
• only glycolysis takes place
• glucose is broken down
• only pyruvic acid is formed
• only 2 ATP’s are formed
• due to lack of oxygen the pyruvic acid does not go into the mitochondria
• instead the pyruvic acid is converted into lactic acid