Photosynthesis (4.1)

Question 1

What is the equation for photosynthesis?

Answer 1

Question 2

What are the chemical symbols for carbon dioxide, water, oxygen and glucose?

Answer 2

CO₂, H₂O, O₂, C₆H₁₂O₆

Question 3

Is photosynthesis an endo or exothermic reaction?

Answer 3

endothermic

Question 4

How does the endothermic reaction photosynthesis gain light?

Answer 4

energy is transferred from the environment to the chloroplasts by light

Question 5

What are the limiting factors to the rate of photosynthesis?

Answer 5

• temperature
• light intensity
• carbon dioxide concentration
• amount of chlorophyll

Question 6

On a graph, the rate of photosynthesis will increase as the level of limiting factor increases, then the rate remains constant while the limiting factor continues to increase, why is this?

Answer 6

Due to another limiting factor (running out/not providing enough to continue the rate)

Question 7

What is inverse proportion?

Answer 7

when one variable increases as the other one decreases at the same rate

Question 8

What is inverse square law (for light intensity)?

Answer 8

an example of inverse proportion that links together light intensity and the distance between the light source and a plant

Question 9

What is the equation for inverse square law (for light intensity)?

Answer 9

light intensity = 1 / d²

Question 10

Why are limiting factors important in the economics of enhancing the conditions in greenhouses

Answer 10

in order to gain the maximum rate of photosynthesis while still maintaining profit.

Question 11

5 uses

What are the uses of glucose produced in photosynthesis?

Answer 11

• used for respiration to release energy
• converted into insoluble starch for storage
• used to produce fat or oil for storage
• used to produce cellulose, which strengthens the cell wall
• used to produce amino acids for protein synthesis.

Question 12

In addition to glucose, what do plants need to produce proteins and what is the source of them?

Answer 12

nitrate ions that are absorbed from the soil

Question 13

Why does photosynthesis increase with increasing temperature?

Answer 13

faster movement of particles, which have more energy

Question 14

The lower surface of the leaf was covered in grease. Explain why water loss decreased after this?

Answer 14

Lower surface has most stomata

stomata are now covered by grease

so water cannot evaporate from the stomata

Question 15

Increasing the carbon dioxide concentration increases the rate of photosynthesis until 0.15%, describe why with reference to limiting factors

Answer 15

CO2 is limiting at low CO2 / at first

light is limiting at high CO2 / at end

Question 16

What would have been the effect on oxygen concentration over the five-hour period if a white region of the leaf had been used, instead of a green region? And explain

Answer 16

oxygen falls

oxygen used for respiration