Photosynthesis

Question 1

What is Photosynthesis?

Answer 1

This the process in which photosynthetic organisms, such as green plants and algae, use energy from the sun to make glucose.

Question 2

Explain how photosynthesis contributes to a plant’s biomass

Answer 2

Photosynthesis produces glucose, which is then use to make large, complex molecules that make up the mass of the plant’s living material.

Question 3

How do we investigate the effect of light intensity on the rate of photosynthesis?

Answer 3

The rate at which the pondweed produces oxygen corresponds to the rate at which it’s photosynthesising.

Question 4

How is the experiment to investigate the effect of light intensity on rate of photsynthesis carried out?

Answer 4

1. The apparatus is set up, with the gas syringe being empty, in the conical flask, water and sodium hydrogencarbonate[ which releases CO2 for plant]
2. White light at a specific distance placed from the pondweed.
3. The pond weed is left to photosynthesise over a set period of time.
4. As it photosynthesise, O2 gas is colled in gas syringe, for accurate measurement if volume of O2 produced.
5. Control variable that could affect result e.g temperature, put conical flask in a thermostatically controlled waterbath, and set amount of NaHCO3 to a set volume of water.
6. Repeat experiment with the light source at different distance from pondweed. Calculate rate of Oxygen produced (Volume produced at each distance÷time taken at each distance)

Question 5

Describe the relationship between intensity and rate of photosynthesis.

Answer 5

As light intensity increases, the rate of photosynthesis increases steadily, up to a certain point where it won’t make a difference, as it’ll either be temperature or the CO2 level which is the limiting factor, as a result the rate is no longer increasing so the graph flattens out.

Question 6

What does the inverse square law mean?

Answer 6

It means that if you halve the distance, the light intensity will be four time greater. And if you double the distance, the light intensity will be four times smaller.

Question 7

How is the inverse square law written?

Answer 7

1/d²

Question 8

Describe the relationship between the Concentration of CO2 and the rate of Photosynthesis.

Answer 8

As Concentration of CO2 increases, the rate of photosy thesis increases up to a point, after which the graph flattens out, indicating that CO2 is no longer the limiting factor, the light or temp need to be increased.

Question 9

Describe the relationship between Temperature and Photosynthesis.

Answer 9

Low temp, causes enzymes needed for photosynthesis to work more slowly, High temp, causes plant to get too hot and enzymes denature as a result. This happens at about 45°C, except greenhouse can get that if if not careful.