B2.3 Photosynthesis

Question 1

Describe the process of photosynthesis

Answer 1

light energy is absorbed by a green substance called chlorophyll which is found in chloroplasts in some plant and algae cells

This energy is used by converting carbon dioxide from the air and water from the soil into sugar

oxygen in released as a by product

Question 2

How may the rate of photosynthesis be limited by?

Answer 2

• shortage of light
• low temperature
• shortage of carbon dioxide

Question 3

How can you change the light intensity to increase the rate of photosynthesis?

Answer 3

artificial lighting

Question 4

How can you change the temperature to increase the rate of photosynthesis?

Answer 4

to warm up- heater or greenhouse - traps sun’s heat

to cool down- shades, ventilation

Question 5

How can you change the carbon dioxide concentration to increase the rate of photosynthesis?

Answer 5

use a paraffin heater. As paraffin burns it makes carbon dioxide as a by product

Question 6

What may some of the glucose produced in photosynthesis be converted into?

Answer 6

insoluble starch for storage

• ready for use when photosynthesis is not occurring like in winter

Question 7

What is the equation for photosynthesis?

Answer 7

carbon dioxide + water —– glucose + oxygen

Question 8

What are the 5 ways that plants use glucose?

Answer 8

• respiration
• making cellulose which strengthens cell walls
• making proteins
• to produce fat or oil for storage
• stored as insoluble starch

Question 9

To produce proteins, what do plants also need?

Answer 9

nitrate ions that are absorbed from the soil

Question 10

About what temperature do enzymes start to become damaged in plants?

Answer 10

45 degrees

Question 11

Why do biologists use models in their research?

Answer 11

• it is possible to mimic large scale events on a small scale
• can be used to predict changes

Question 12

Describe what factors a farmer should consider when building tunnels to grow plants in

Answer 12

consider limiting factors- CO2, temp, light

• light changes with type of plastic, colour and thickness of tunnels
• hight need heating or ventilation to control temp
• needs to have a source of CO2 gas

Question 13

What do farmers need to consider before making decisions about the growing conditions for their plants?

Answer 13

• The cost of providing the conditions

- The effect of the conditions on profit

Question 14

What happens if a plant does not get enough nitrates?

Answer 14

stunted growth

Question 15

Name the 2 reactants in photosynthesis and state where each one comes from

Answer 15

carbon dioxide- air

water- soil

Question 16

Where is chlorophyll found?

Answer 16

in chloroplasts in some plant and algae cells

Question 17

What is the function of chlorophyll?

Answer 17

absorbs light energy which is used to convert carbon dioxide and water to glucose and oxygen

Question 18

Name the substance that glucose can be converted into for storage and describe how you can test for the presence of this substance

Answer 18

insoluble starch

test with iodide: changes from brown to blue-black if starch is present

Question 19

Why might a farmer put a paraffin heater in a greenhouse?

Answer 19

to increase carbon dioxide concentration to increase the rate of photosynthesis

Question 20

How do plants produce proteins for growth?

Answer 20

use nitrate ions that are absorbed from the soil to make amino acids that are then joined to make proteins

This process require glucose from photosynthesis

Question 21

Describe the shape of the rate of photosynthesis on a light intensity graph

Answer 21

As the light intensity increases the rate of photosynthesis increases up to a peak point- optimum

After this point any further increase in light intensity does not increase the rate of photosynthesis

Question 22

Explain the effect of increasing the temperature has on the rate of photosynthesis

Answer 22

Increasing the temperature increases the rate up to a max production at 40 degrees

this is because enzymes have more energy and up to 40 degrees, temperature is a limiting factor

Increasing the temperature over 40 degrees decreases the rate of photosynthesis

because the high temperature denatures enzymes in the plant

Question 23

Suggest how receiving more sunlight could result in plants producing more flowers per stalk

Answer 23

more energy is available for growth

Question 24

Why do plants need magnesium ions for healthy growth?

Answer 24

to make chlorophyl which traps light energy

for photosynthesis