4. Bioenergetics

Question 1

What can the glucose made during photosynthesis be used for?

Answer 1

1. Respiration
2. Stored as starch for later

Question 2

What is the molecular formula for glucose?

Answer 2

C6H12O6.

Question 3

How do plants get the carbon dioxide required for photosynthesis?

Answer 3

It diffuses from the air into the leaves via stomata

Question 4

How do plants get the water required for photosynthesis?

Answer 4

It diffuses from the soil into the root hair cells by osmosis

Question 5

What makes starch a useful long term storage molecule?

Answer 5

1. It can easily be broken down when needed
2. It is compact
3. It is insoluble in water

Question 6

One use of glucose is to make amino acids.
What else do plants need to make amino acids?

Answer 6

Nitrate ions

Question 7

What are the main uses of glucose in plants?

Answer 7

1. Cellular respiration - break down the glucose to release energy
2. Make cellulose - which is used to make strong cell walls
3. Make starch - which is used to store glucose for a later time
4. Make amino acids - which are used to make proteins
5. Make lipids - these store the energy as fats or oils for later use

Question 8

Which useful energy transfer or conversion happens overall in photosynthesis?

Answer 8

Light ➔ chemical

Question 9

Why may plants produce insufficient chlorophyll?

Answer 9

1. They have a disease like Tobacco Mosaic Virus
   2.They lack the required nutrients

Question 10

Describe and explain how the rate of photosynthesis varies with temperature.

Answer 10

At first the rate of photosynthesis rises with temperature as the particles have more energy and move more quickly. This means they can react more quickly and so the rate is higher.
However, as temperature rises above the optimum temperature for the enzymes involved, the enzymes may start to break down. This decreases the rate until it falls to zero (when the enzymes are denatured).

Question 11

Is respiration an exothermic or endothermic reaction?

Answer 11

Exothermic

Question 12

Which process in plants produces the glucose required for respiration?

Answer 12

Photosynthesis

Question 13

Give two examples of how cells use the energy from respiration.

Answer 13

1. To maintain our body temperature
2. For muscle contraction

Question 14

What is the word equation for aerobic respiration?

Answer 14

Glucose + oxygen ➔ carbon dioxide + water

Question 15

What is glucose converted to during anaerobic respiration in animals?

Answer 15

Lactic acid

Question 16

What are the two reasons animals cells prefer aerobic respiration to anaerobic respiration?

Answer 16

1.Anaerobic respiration doesn’t break down the glucose molecule completely, and so releases less energy than aerobic respiration
2. Anaerobic respiration produces lactic acid which can damage cells and leads to an oxygen debt

Question 17

Which type of respiration requires oxygen, aerobic or anaerobic?

Answer 17

Aerobic respiration

Question 18

Which type of respiration leads to an oxygen debt, aerobic or anaerobic?

Answer 18

Anaerobic respiration

Question 19

Which type of respiration leads to the build up of lactic acid, aerobic or anaerobic?

Answer 19

Anaerobic respiration

Question 20

Which organ in the body removes the lactic acid from the blood.

Answer 20

Liver