Photosynthesis

Question 1

How is photosynthesis essential for survival?

Answer 1

Plants are known as producers as they produce their own food (Start of the food chain)
Without photosynthesis plants would die.

Question 2

Describe 2 stage process of photosynthesis

Answer 2

1) Energy transferred by light is used to split water into oxygen gas and hydrogen ions
2) carbon dioxide gas combines with hydrogen ions to make glucose

Question 3

What is the location of the reaction of photosynthesis

Answer 3

In chloroplasts containing chlorophyll which absorb light

Question 4

Describe photosynthesis as an endothermic reaction.

Answer 4

Energy is transferred from the environment to chloroplasts

Question 5

Describe an experiment to investigate photosynthesis

Answer 5

Oxygen production.

Pondweed is left to photosynthesise
Oxygen collected during the process will be collected in a capillary tube

At the end of the experiment, the syringe is used to draw the gas bubble in the tube up alongside a ruler.

The length of the gas bubble is measured

Experiment repeated to test a range of values for the factor being investigated
e.g a range of different temperatures.

Variables other than the one being tested should be kept the same

Question 6

Explain effect of light intensity and C02 concentration on the rate of photosynthesis

Answer 6

light intensity: Without enough light, the rate of photosynthesis is limited.

With enough light, the rate of photosynthesis levels out and light intensity is no longer the limiting factor

C02 concentration: If the concentration of carbon dioxide is increased, the rate of photosynthesis will increase.

Eventually, the rate of photosynthesis levels out and C02 concentration is no longer the limiting factor.

Question 7

Describe plants as main producers of food and biomass for life on earth

Answer 7

Plants are known as producers
They make their own food through photosynthesis
Using this food to grow they increase their biomass.

Question 8

Word and symbol equation for photosynthesis?

Answer 8

Carbon dioxide + water → Glucose + Oxygen
6C02 + 6H20 → C6H1206 602

Question 9

Describe and explain how the rate of photosynthesis varies with temperature.

Answer 9

Rate initially increases with temperature

because particles have more energy and move faster, so react more frequently

Highest rate is at optimum temperature for enzyme

At higher temperatures the rate decreases as bonds holding the enzyme together begin to break, and so the enzyme changes shape

Rate falls to zero as enzymes denature