3 Plants and Photosynthesis

Question 1

Photosynthesis equation (word, symbol and balanced)

Answer 1

carbon dioxide + water → glucose + oxygen
CO2 + H2O → C6H12O6 + O2
6CO2 + 6H2O → C6H12O6 + 6O2

Question 2

Light energy is absorbed by a _____ substance called ____________, which is found in the ____________ of some plants cells and algae.

Answer 2

1) green
2) chlorophyll
3) chloroplasts

Question 3

Where does carbon dioxide for photosynthesis come from?

Answer 3

The air.

Question 4

Where does water for photosynthesis come from?

Answer 4

The soil.

Question 5

1) What is glucose?

2) What is oxygen in photosynthesis?

Answer 5

1) Glucose is a sugar.

2) A by-product.

Question 6

What do plants use glucose (in photosynthesis) for? (5)

Answer 6

• Respiration (for energy)
• Converting into insoluble starch for storage
• For producing cellulose which strengthens cell walls
• To produce amino acids for protein synthesis
• To produce proteins for plant growth and repair

Question 7

Plant tissues are gathered together to form ______. The ____ is a plant organ.

Answer 7

1) organs

2) leaf

Question 8

Stomata

Answer 8

Allows diffusion of gases in and out of the leaf and can be opened and closed by guard cells.

Question 9

Why is there lots of air space in leaves?

Answer 9

So gases can diffuse.

Question 10

Why are there many chloroplasts close to the top of the leaf?

Answer 10

To trap as much sunlight as possible.

Question 11

Epidermis

Answer 11

Covers the outer surface of the plant for protection.

Question 12

Palisade mesophyll

Answer 12

The main site of photosynthesis in the leaf.

Question 13

Spongy mesophyll

Answer 13

Air spaces between cells allow gases to diffuse through the leaf.

Question 14

Xylem vessels (3)

Answer 14

• Transports water and minerals through the plant from roots to leaves
• Supports the plant
• Composed of hollow tubes strengthened by lignin adapted for water transport in the transpiration stream

Question 15

Phloem vessels (2)

Answer 15

• Transports dissolved food materials through the plant.

* Translocation

Question 16

State factors affecting photosynthesis. (4)

Answer 16

• Temperature
• Carbon dioxide concentration
• Light intensity
• Chlorophyll concentration

Question 17

Limiting factors (2)

Answer 17

• “The rate of any given process will be determined by the factor that is in the shortest supply.”
• It is the factor that stops the reaction from going any faster

Question 18

Meristem tissue

Answer 18

Found mainly at tips of roots and shoots where it can produce new cells for growth.

Question 19

The rate of photosynthesis may be limited by what? (3)

Answer 19

• Shortage of light
• Low temperature
• Shortage of carbon dioxide

Question 20

Transpiration (3)

Answer 20

• The movement of water up through a plant (by evaporation) and its loss from the leaves
• Xylem
• Up only

Question 21

Translocation (3)

Answer 21

• The movement of sugars/dissolved food materials through a plant
• Phloem
• Both ways

Question 22

Photosynthesis is an ___________ reaction where energy is transferred from the environment to the ____________ by _____.

Answer 22

1) endothermic
2) chloroplasts
3) light

Question 23

How is a root hair cell adapted to its function? (2)

Answer 23

• Long projection increases surface area to absorb water and minerals
• Lots of mitochondria for active transport of minerals

Question 24

How is the phloem adapted to its function? (2)

Answer 24

• End walls of cells allow sugars through but also support the tubes (sieve plate)
• Companion cells provide energy

Question 25

How are xylem cells adapted to their function? (2)

Answer 25

• Cell wall is strengthened and supported by lignin (wood)

* Cells are arranged end to end but end walls break down to form continuous, hollow tubes