B8- Photosynthesis

Question 1

What is photosynthesis

Answer 1

This is an endothermic reaction- it needs an input of energy from the environment. Plants need carbon dioxide from the air, water from roots and sunlight through the chloroplast.

Question 2

What is the equation for photosynthesis

Answer 2

Carbon dioxide + water&raquo_space;»light chloroplast&raquo_space;> glucose + oxygen

Question 3

What happens during photosynthesis

Answer 3

Energy is transferred from the enviroment to the chloroplast by light and is used to convert carbon dioxide and water into glucose. Oxygen is also produced. Light energy is also converted into chemical energy in the form of glucose

Question 4

How are leaves adapted for photosynthesis?

Answer 4

Broad have a big surface area for light to fall on.
Thin so diffusion distance for gas is shorter.
Contain chlorophyll in the chloroplast to absorb light.
Have large veins bring water to produce glucose and take glucose away.
Large air spaces to allow carbon dioxide to get to the cells and oxygen to leave by diffusion.

Question 5

How is the rate of photosynthesis affected?

Answer 5

Light intensity, carbon dioxide levels and temperature and amount if chloroplast.

Question 6

What do plants use glucose for?

Answer 6

Respiration 
To convert glucose to starch for storage because glucose is soluble is water and will affect osmosis in plants and the water balance. This is the opposite to starch however.
To produce fats and oils.
To produce cellulose for cell walls.
To produce amino acids for protein.

Question 7

What else is needed to make amino acids?

Answer 7

Nitrate ions absorbed from the soil or water.

Question 8

Why are limiting factors important in economics?

Answer 8

In enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis and get a good profit.

Question 9

What is the starch test in leaves?

Answer 9

• Take a specially prepared leaf that has been kept in the dark and light.
• Treat the leaves by boiling them in Ethanol to destroy waxy cuticle.
• Rinse in hot water to soften it and get rid of ethanol on the leaf.
• Add iodine solution to both the leaves and see the colour change. If the leaf is blue-black then starch is present and therefore photosynthesis has taken place and chloroplast is needed for photosynthesis.