B8

Question 1

Photosynthesis

Answer 1

• endothermic reaction
• During photosynthesis energy is transferred from the environment to the chloroplast by light it is used to convert CO2 and water into sugar

Question 2

photosynthesis equation

Answer 2

carbon dioxide + water -> glucose + oxygen

Question 3

leaf adaptations

Answer 3

• broad, giving a big surface area for light to fall on
• thin so diffusion distances for gases are short
• chlorophyll in chloroplasts to absorb light
• gaurd cells regulate gas exchange

Question 4

rate of photosynthesis - light

Answer 4

• plenty of light means lots pf photosynthesis can take place
• if there is little or no light, photosynthesis will stop, whatever the other conditions around the plant is
• brighter the light the faster the rate of photosynthesis

Question 5

rate of photosynthesis - temperature

Answer 5

• as temperature rises the rate of photosynthesis increases as the reaction speeds up
• most enzymes are denatured once temp reaches 40-50
• if temp gets too high the enzymes controlling photosynthesis are denatured and rate of photosynthesis will fall

Question 6

rate of photosynthesis - carbon dioxide concentration

Answer 6

• plants need CO2 to make glucose
• CO2 often limits rate of photosynthesis
• increases CO2 conc. will increase rate of photosynthesis

Question 7

using glucose

Answer 7

plant and algal cells use the glucose produced during photosynthesis for respiration to convert into insoluble starch and fats for storage, cellulose to strengthen cell walls and to produce amino acids for protein synthesis

Question 8

starch

Answer 8

• stored in the leave cells to provide energy store for when light levels are low
• helps them survive winter

Question 9

nitrates, proteins and carnivorous plants

Answer 9

• plant and algal cells need nitrate ions absorbed from the soil or water to make the amino acids used to make proteins
• carnivorous plants adapt to live in nitrate poor soil by obtaining nutrients from insects that they catch

Question 10

greenhouses

Answer 10

• help trap suns heat and ensure temp. doesn’t become limiting
• artificial light is used for photosynthesis after the sun goes down to give plants more photosynthesis time

Question 11

greenhouse economics

Answer 11

The increased income from a larger crop and the ability to grow more crops each year has to be balanced against the cost of setting up and maintaining the system