Rate of photosynthesis

Question 1

What does the limiting factor in plant photosynthesis depend on?

Answer 1

The conditions

Question 2

At night what would be the limiting factor for photosynthesis?

Answer 2

Light intensity

Question 3

In winter what is likely to be the limiting factor for photosynthesis?

Answer 3

Temperature

Question 4

If the conditions are warm and bright what is likely to be the limiting factor for photosynthesis?

Answer 4

Carbon Dioxide

Question 5

What experiment would be best when trying to work out the ideal conditions for a particular plant?

Answer 5

Using a water plant like Canadian pondweed which is kept in water and then measuring the amount of oxygen produced in a given time to show how fast photosynthesis is happening.

Question 6

How would you measure the amount of oxygen given off in an experiment measuring the rate of photosynthesis with a water plant?

Answer 6

Count the bubbles given off or collect the oxygen in a gas syringe.

Question 7

On a graph showing the rate of photosynthesis in accordance with light intensity, why will it show progression only up to a certain point?

Answer 7

Another factor will be limiting the rate of photosynthesis such as temperature or CO2.

Question 8

In a lab how could you control the light intensity?

Answer 8

By moving a lamp closer or further away

Question 9

What is one way of controlling the amount of CO2 in an experiment?

Answer 9

Dissolving different amounts of sodium hydrogen carbonate in water, which gives of CO2

Question 10

Why is temperature a limiting factor is it’s too low?

Answer 10

The enzymes involved in photosynthesis work more slowly at a low temperature.

Question 11

At what temperature is it too hot for photosynthesis and why?

Answer 11

45 degrees Celsius - The enzymes needed for photosynthesis will be damaged at this temperature and so will not work.

Question 12

Experimentally, what is the best way to control temperature?

Answer 12

Put the flask of the plant you’re measuring in a water bath.

Question 13

What is the most common way to artificially create the ideal environment for plants?

Answer 13

Growing them in a GREENHOUSE

Question 14

Give three ways in which greenhouses help to make sure temperature isn’t the limiting factor.

Answer 14

1) Traps the suns heat
2) Shades and ventilation to stop it getting too hot
3) A heater can be used in the winter

Question 15

How might a farmer control light intensity to aid the rate of photosynthesis?

Answer 15

Use artificial lighting at night to give plants more quality photosynthesis time

Question 16

How does a paraffin heater help to increase the level of carbon dioxide in a greenhouse?

Answer 16

As the paraffin burns it makes carbon dioxide as a by-product.

Question 17

What is the main disadvantage of having a greenhouse?

Answer 17

It costs money.

Question 18

Aside from photosynthesis, what are the two other benefits of having a greenhouse?

Answer 18

1) Keeps plants enclosed and so free from pests and diseases

2) Fertilises can be added to the soil to provide all the minerals needed for healthy growth