Section 2 - Photosynthesis

Question 1

Describe the process of photosynthesis

Answer 1

Photosynthesis is the process in which energy, form the sunlight, is used to create glucose. Light energy is absorbed by chlorophyll in the leaves of the plant. It is then used to convert carbon dioxide (from the air) and water (from the soil) into glucose; which is used for respiration. Oxygen is a by-product of this process.

Question 2

What is the importance of photosynthesis in the conservation of light energy to chemical energy in plants?

Answer 2

Photosynthesis uses light energy, from the sun, to create chemical energy (glucose); which conserves the energy from the sun. This energy is then passed through the food chain, which is why plants are called the producer (producing the chemical energy in the chain from the sun light).

Question 3

What is the word equation for photosynthesis?

Answer 3

Carbon Dioxide + Water > Glucose + Oxygen

Question 4

What is the balanced chemical symbol equation for photosynthesis?

Answer 4

6CO₂ + 6H₂O > C₆H₁₂O₆ + 6O₂

Question 5

How does varying the carbon dioxide concentration affect the rate of photosynthesis?

Answer 5

If there is insufficient amounts of carbon dioxide, a plant will not be able to photosynthesis to its full potential. As there is less carbon dioxide (the reactant), there has to be less product being made.

Question 6

How does varying the light intensity affect the rate of photosynthesis?

Answer 6

If the light is at a low intensity, the rate of photosynthesis is lowered because the energy that the light provides is less, so the reaction is slowed down. A higher light intensity will enable photosynthesis to occur faster.

Question 7

How does varying the temperature affect the rate of photosynthesis?

Answer 7

In colder temperatures, the rate of photosynthesis will decrease. If the temperature is too high however, the plant will not be able to photosynthesis

Question 8

How is the structure of the leaf adapted for photosynthesis?

Answer 8

• Leaves have a large surface area; this allows them to absorb more sunlight
• They are also thin, this means that carbon dioxide has a shorter way to travel
• The stomata allows the entrance of carbon dioxide
• The epidermis is thin and is transparent; this means that more light can reach the palisade cells underneath the upper epidermis
• The palisade cells are at the top of the leaf, so they can absorb more of the light. (They contain chloroplasts so that they can absorb the light)
• The spongy layer has air spaces in it; this allows the carbon dioxide to diffuse through the leaf and they increase the surface area
• The wax cuiticle is thin and made out of wax so it doesn’t stop the sunlight from getting through

Question 9

Describe an experiment used to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll?

Answer 9

Use a pond weed, which is placed uner water then factors are varied

1. A lamp is moved further away form the plant
2. Baking powder is added to the water (increasing CO₂)
3. A white leaved plant is tested against a green leaved plant (green has more chlorophyll)

The gas it gives off (the product of photosynthesis) can be counted as bubbles or measured by downwards displacement. This shows the speed of photosynthesis under different conditions. Iodine cause be used to test the production of starch.