B4b-Photosynthesis

Question 1

What is the word equation for photosynthesis?

Answer 1

Carbon dioxide +water –> glucose + oxygen

Light energy
(Chlorophyll)

Question 2

What is the waste product in photosynthesis?

Answer 2

Oxygen

Question 3

What is the balanced symbol equation for photosynthesis?

Answer 3

6CO2 + 6H2O —> C6H12O6 + 6O2

Light energy
(Chlorophyll)

Question 4

What did greek scientists believe about plants?

Answer 4

Plants gained mass by only taking in minerals fron the soil

Question 5

What did Van Helmont believe about plants?

Answer 5

• He concluded from his experiments that plant growth cannot be solely due to nutrients drom the soil
• gain mass by taking in water

Question 6

What did Priestleys experiments show?

Answer 6

Oxygen is produced by plants

Question 7

What was priestleys experiment?

Answer 7

• He placed a burning candle in a sealed container
• the flame went out after a short time
• when he placed a plant in the container the candle could be re lit after a few weeks

Question 8

What are isotopes?

Answer 8

Isotopes are just different forms of the same element

Question 9

Describe the experiment which used isotopes to find out where oxygen came from in photosynthesis

Answer 9

• scientist supplied plant with water containing oxygen 18
• plants received carbon dioxide with oxygen 16
• the plants released oxygen 18 in photosynthesis

Question 10

What did the isotope experiment show?

Answer 10

The oxygen produced by photo synthesis comes from the water and not the carbon dioxide

Question 11

What is photosynthesis?

Answer 11

A 2 stage process where:

1) light energy is used to split water, releasing oxygen gas and hydrogen ions
2) carbon dioxide gas combines with the hydrogen to make glucose

Question 12

What are the 5 uses of glucose in plants?

Answer 12

• respiration(releases energy)
• making cell walls(cellulose)
• stored in seeds(fats and oils)
• starch(storage, used for photosynthesis)
• making proteins(growth and repair)

Question 13

Why is the fact that starch is insoluble good for storing?

Answer 13

• does not move away in solution from storage areas

- does not affect water concentration inside cells

Question 14

How can photosynthesis be increased?

Answer 14

More
Co2
Light
Higher temperature

Question 15

What is the limiting factor?

Answer 15

The restricted factor which controls how quickly photosynthesis occurs and so limits the rate

Question 16

How does light affect the rate?

Answer 16

• Light provides energy needed for photosynthesis

- high light level will increase the rate to a certain point

Question 17

How does carbon dioxide affect the rate?

Answer 17

• Raw material needed for photosynthesis

- high levels will increase photosynthesis to a certain point

Question 18

How does temperature affect the rate?

Answer 18

• photosynthesis works best when its warm but not too hot

- if its too high the plants enzymes will be denatured which decreases the rate (45°C)

Question 19

What do plants do during the day?

Answer 19

• both photosynthesis and respiration
• make more oxygen by photosynthesis than used in respiration
• release oxygen, take in co2

Question 20

What do plants do at night?

Answer 20

Only respiration

-take in oxygen, release co2