Bioenergetics

Question 1

Using glucose in plants - respiration

Answer 1

Transfers energy from glucose which enables the plant to convert the rest of the glucose into various other useful substances

Question 2

Using glucose in plants - making cellulose

Answer 2

Glucose is converted into cellulose for making strong cell walls

Question 3

Using glucose in plants - making amino acids

Answer 3

Glucose is combined with nitrate ions to make amino acids

Question 4

Using glucose in plants - stored as oils or fats

Answer 4

Glucose is turned into lipids for storing in seeds

Question 5

Using glucose in plants - stored as starch

Answer 5

Glucose is turned into starch and stored in roots

Question 6

When is light the limiting factor?

Answer 6

Night time

Question 7

When is temperature the limiting factor?

Answer 7

Winter

Question 8

When is the carbon dioxide concentration the limiting factor?

Answer 8

When it’s warm and bright enough

Question 9

Limiting factors - light intensity

Answer 9

As the light intensity increases, the rate of photosynthesis increases steadily

Question 10

Limiting factors - carbon dioxide concentration

Answer 10

As the concentration of carbon dioxide increases, the rate of photosynthesis increases steadily

Question 11

Limiting factors - temperature

Answer 11

If the temperature gets too high, the enzymes will denature - 45 degrees
If the temperature is too low, the enzymes will work very slowly

Question 12

What is light intensity inversely proportional to?

Answer 12

Distance²

Question 13

Greenhouses - temperature

Answer 13

Help to trap the sun’s heat and ensure the temperature doesn’t become a limiting factor
Heaters are used in winter to maintain a high temperature
Ventilation is used in summer to prevent the temperature increasing too much

Question 14

Greenhouses - light intensity

Answer 14

Artificial light is used after the sun goes down - gives the plant more quality photosynthesis time

Question 15

Greenhouses - carbon dioxide concentration

Answer 15

Paraffin heaters help increase the concentration of carbon dioxide - as the paraffin burns, it creates carbon dioxide as a by-product

Question 16

Other benefits of greenhouses

Answer 16

1) Easier to keep the plants free from pests
2) Fertilisers help provide all the minerals needed for healthy growth

Question 17

What is respiration?

Answer 17

The process of transferring energy from glucose which goes on in every cell

Question 18

Is photosynthesis endothermic or exothermic?

Answer 18

Endothermic - energy is transferred from the environment

Question 19

Is respiration endothermic or exothermic?

Answer 19

Exothermic - transfers energy to the environment

Question 20

How do organisms use the energy transferred by respiration?

Answer 20

1) To build up larger molecules from smaller ones e.g. proteins from amino acids
2) In animals, it’s used to allow the muscles to contract
3) In mammals and birds, the energy is used to keep their body temperature steady in colder surroundings

Question 21

Aerobic respiration

Answer 21

Respiration using oxygen
Goes on constantly in plants and animals
Most of the reactions happen inside mitochondria

Question 22

Aerobic respiration equation

Answer 22

Glucose + oxygen –> carbon dioxide + water

Question 23

Anaerobic respiration - animals

Answer 23

Respiration without oxygen
Incomplete breakdown of glucose
Happens when your body can’t supply enough oxygen to your muscles during vigorous exercise
Doesn’t transfer as much energy as aerobic respiration - glucose isn’t fully oxidised

Question 24

Anaerobic respiration equation - animals

Answer 24

Glucose –> lactic acid

Question 25

Anaerobic respiration - plants & yeasts

Answer 25

In yeasts
Fermentation is used to make bread and alcohol drinks

Question 26

Anaerobic respiration equation - plants and yeasts

Answer 26

Glucose –> ethanol + carbon dioxide

Question 27

What three things increase with increased respiration?

Answer 27

1) Breathing rate
2) Breath volume
3) Heart rate

Question 28

What happens during increased respiration?

Answer 28

More oxygen diffuses into the blood which causes carbon dioxide to be removed more quickly

Question 29

What does anaerobic respiration lead to?

Answer 29

Oxygen debt - the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells

Question 30

What forms when oxygen reacts with lactic acid?

Answer 30

Carbon dioxide and water

Question 31

How else does the body cope with a high level of lactic acid?

Answer 31

The blood that enters your muscles transports the lactic acid to the liver. Here, the lactic acid is converted back to glucose

Question 32

Oxygen Production - Method

Answer 32

1) A source of white light is placed at a specific distance from the pondweed
2) The pondweed is left to photosynthesise for a set amount of time. As it photosynthesises, the oxygen released will collect in a capillary tube
3) At the end of the experiment, the syringe is used to draw the gas bubble in the tube up alongside a ruler & the length of the gas bubble is measured. This is proportional to the volume of O2 produced
4) Any variable that could affect the results should be controlled
5) The experiment is repeated twice with the light source at the same distance & the mean volume of O2 produced is calculated
6) Then, the whole experiment is repeated with the light source at different distances from the pondweed

Question 33

What are lipid molecules made up of?

Answer 33

One molecule of glycerol & three fatty acids

Question 34

What is metabolism?

Answer 34

The sum of all the reactions that happen in a cell or in the body

Question 35

What is muscle fatigue?

Answer 35

When over long periods of exercise, the muscles get tired & stop contracting efficiently