B2: Photosynthesis

Question 1

What is the equation for photosynthesis?

Answer 1

6CO₂ + 6H₂O = C₆H₁₂O₆ + 6O₂

Question 2

Why is glucose stored as starch?

Answer 2

Glucose is stored as starch as it is a more compact molecule. Furthermore starch is insoluble meaning it will not effect osmosis and prevents water loss.

Question 3

What are other uses of glucose?(4)

Answer 3

• reacts with nitrates to make proteins
• used for respiration
• makes cellulose
• stored as starch

Question 4

Are plants able to respire at night?

Answer 4

Plants ARE able to respire at night as long as starch or glucose is present. This is because respiration does not require light, unlike photosynthesis.

Question 5

What are the limiting factors of photosynthesis?(3)

Answer 5

• concentration of CO₂ light intensity

- volume of water

Question 6

What is the function of the waxy cuticle?

Answer 6

It protects the plant

Question 7

What is the function of the guard cells?

Answer 7

They open and close, so gases can enter the cell through diffusion

Question 8

What is the function of the palisade cells?

Answer 8

Large surface area for light absorption

Question 9

What is the function of the spongy mesophyll?

Answer 9

Allows gases to pass through

Question 10

What is the function of the epidermis?

Answer 10

Allows light to pass through

Question 11

What is the function of the veins?

Answer 11

They carry water

Question 12

What is the function of the chlorophyll?

Answer 12

It gives the plant its green colour

Question 13

The phloem(4)

Answer 13

• has companion cells which store all the organelles, meaning it controls the cell functions
• has end walls with pores in them to allow sugars and amino acids to pass through
• has a source cell for substances to made
• substances go upwards and downwards

Question 14

Xylem(3):

Answer 14

• has thick walls that are made of dead cells to withstand high water pressure
• water only travels in one direction
• has NO end cells so water can pass through easily

Question 15

Define translocation

Answer 15

The movement of sugars and amino acids through the phloem

Question 16

Define transpiration

Answer 16

The movement of water in a plant

Question 17

Define diffusion

Answer 17

The movement of particles from a high to low concentration

Question 18

Define osmosis

Answer 18

The movement of water particles through a partially Permeable membrane

Question 19

Define active transport

Answer 19

The movement of particles against the concentration gradient

Question 20

Define hydroponics

Answer 20

When plants are grown under water as there is a prefect balance in mineral ions

Question 21

Greenhouses

Answer 21

+ protects plant +clear, allows light to pass through +lights at night + controlled CO₂
- expensive - ruins the look of the countryside - use a lot of energy

Question 22

Why might some farmers prefer to use poly tunnels?

Answer 22

Polytunnels are cheaper as they are made of plastic. Some polytunnels can even control the concentration of CO₂ and light intensity

Question 23

What is the adaption of a root hair cell?

Answer 23

They have a large surface area to absorb more water

Question 24

Describe the transport of water through a plant from the roots to the atmosphere(3):

Answer 24

• Water goes from the root hair cell to the xylem through osmosis
• It moves up the xylem by transpiration
• It is then carried by the veins to the leaves where it evaporates into the atmosphere