Raw Materials For Photosynthesis

Question 1

What does chlorophyll do?

Answer 1

Absorbs light energy. Chlorophyll is in the chloroplasts of the leaf.

Question 2

What does carbon dioxide do?

Answer 2

Diffuses into the leaves from the air.

Question 3

What does water do?

Answer 3

Water is absorbed by the roots from the soil.

Question 4

What happens if a plant cannot carry out photosynthesis?

Answer 4

It will not make starch. But we must make sure that the plant has no starch to begin with.

Question 5

How do we de-starch a plant?

Answer 5

By leaving it in the dark for 24 hours.

Question 6

Where is sugar made?

Answer 6

Leaf

Question 7

How do we prove plants need water for photosynthesis?

Answer 7

Scientists can give plants a special form of water called ‘heavy water’. They can trace this water and see where it goes. They can show that it is taken up and used in photosynthesis.

Question 8

What is glucose used for?(3)

Answer 8

• some of the glucose is used in respiration to give the plant energy
• some of the glucose is changed to starch and stored in the roots for future use
• some of the glucose is used to make cellulose. This is needed fro plant cell walls.

Question 9

How can glucose be converted into other substances?(2)

Answer 9

• Plants can get nitrogen by absorbing nitrates from the soil. Glucose and nitrogen can form amino acids.
• Fats and oils are used for storage in seeds.

Question 10

What are amino acids?

Answer 10

Proteins are built from amino acids and plants need proteins for growth and cell repair.

Question 11

Oxygen is also a product of photosynthesis. This replaces oxygen that is used up in ______.

Answer 11

Respiration

Question 12

What is respiration?

Answer 12

A process in living organisms involving the production of energy, with the intake of oxygen as release or carbon dioxide.

Question 13

Why are plants important in the making of medicines?

Answer 13

Medicines have been extracted from hundreds of species of flowering plants. Tropical rainforests are the main source of these plants.

Question 14

How are plants important in terms of habitats?

Answer 14

Only make up 6% of the Earth’s land surface but support more half the world’s species of plants and animals .

Question 15

Why are plants important for atmospheric gasses?

Answer 15

Atmospheric gases are kept stable by photosynthesis. Without green plants, carbon dioxide in the air would increase and oxygen would decrease.

Question 16

Plants also provide us with important building materials like wood. Fuels like ____, ____ and peat have coke from fossil plants.

Answer 16

Oil

Coal

Question 17

How can the rate of photosynthesis be measured?

Answer 17

By how much glucose is made in a given time.

Question 18

Why do scientists try to increase the rate of photosynthesis?

Answer 18

Increase the yield of a crop.

Question 19

How does light affect the rate of photosynthesis?

Answer 19

Increase when light gets brighter but only to a point. When a certain light intensity is reached the rate of photosynthesis stays constant

Question 20

True or false

If light is too strong it can damage chloroplasts

Answer 20

True

Question 21

What are shade plants?

Answer 21

A plant that grows normally in a shaded habitat where it only receives only light of low intensity

Question 22

What are the 2 main phases of photosynthesis?

Answer 22

Light dependent phase-convert the light energy into chemical energy
Light independent phase-uses the chemical energy to synthesize glucose

Question 23

What is photosynthesis?

Answer 23

The making of carbohydrates from carbon dioxide and water using radiant energy from the sun that is absorbed by chlorophyll. Oxygen is released as a by-product.