Topic 4: Bioenergetics

Question 1

Limiting factors of photosynthesis (3)

Answer 1

1) Shortage of light - at night
2) Shortage of carbon dioxide - warm and bright
3) Temperature - in winter

Question 2

Light and the rate of photosynthesis (2)

Answer 2

1) Light increases = rate increases

2) IF limiting factor is CO2 or temperature then increasing light has no effect

Question 3

CO2 and the rate of photosynthesis (2)

Answer 3

1) CO2 increases = rate increases

2) IF limiting factor is light or temperature then increasing CO2 has no effect

Question 4

Temperature and the rate of photosynthesis (3)

Answer 4

1) When temperature is too low = slow rate as enzymes work best warm
2) (pre-45C) Temperature increases = rate increases as enzymes work best warm
3) (post-45C) Temperature increases = rate decreases as enzymes denature

Question 5

PONDWEED PRACTICAL

Answer 5

-

Question 6

Use of glucose in plants (6)

Answer 6

1) Produce energy through respiration
2) Produce fats for storage in seeds
3) Produce cellulose to strengthen cell wall
4) Produce proteins by combining glucose with nitrate ions
5) Produce insoluble starch

Question 7

Light intensity is proportional to…

Answer 7

1/Distance^2

Question 8

Metabolism

Answer 8

The sum of all the chemical reactions in a cell or organism which are controlled by enzymes

Question 9

Reactions: small molecules –> large molecules (3)

Answer 9

1) Glucose –> Starch
2) Glycerol + 3 fatty acids –> Lipids
3) Glucose + Nitrate ions –> Amino acids

Question 10

Reactions: large molecules –> small molecules (2)

Answer 10

1) Glucose –> energy

2) Excess protein –> Urea

Question 11

Respiration

Answer 11

The process of transferring energy from the breakdown of glucose which continuously occurs in every cell’s mitochondria

Question 12

Use of energy released in respiration

Answer 12

1) Build larger molecules from small ones
2) Contract muscles (animals)
3) Build up sugars, nitrates and other nutrients into amino acids then proteins (plants)
4) Maintain steady body temperature (mammals)

Question 13

Why is anaerobic respiration only used in emergencies?

Answer 13

It is the incomplete breakdown of glucose which means it doesn’t transfer as much energy as aerobic respiration

Question 14

Why is the anaerobic respiration of yeast useful in the food and drink industry

Answer 14

Called fermentation, it used to make bread and alcoholic drinks as the CO2 released makes bread rise and the ethanol released is used in beer and wine

Question 15

Oxygen debt (2)

Answer 15

1) The extra oxygen needed to react with lactic acid, form CO2 and oxygen and remove it from the body
2) Causes you to continue breathing heavily after exercising

Question 16

Why does your pulse and breathing rate stay high after exercising

Answer 16

There is still an oxygen debt as there are high levels of lactic acid