B4 - Organising plants

Question 1

What is the function of epidermal tissue?

Answer 1

• Covers and protects leaf
• top is called upper epidermis
• bottom is called lower epidermis

Question 2

What is the function of the waxy cuticle and what is it?

Answer 2

• Prevents water loss from top of the leaf
• Thin waterproof layer of lipids

Question 3

What are stomata?

Answer 3

• Small pores on the underside of the leaf that allow gases like O2, CO2 and water vapour to diffuse through

Question 4

How does stomata prevent water loss?

Answer 4

• Open for as short a time as possible

Question 5

What 3 roles do guard cells play in water loss?

Answer 5

• Full of water = larger gap= more CO2
• No water = closed stomata = no CO2, conserves water vapour
• Close at night as sensitive to water

Question 6

How is the upper epidermis adapted?

Answer 6

• cells transparent for sunlight
• waxy cuticle - reduces evaporation of water, no drying up

Question 7

How is the lower epidermis adapted?

Answer 7

• tiny pores called stomata - gas exchange
• control water vapour
• guard cells that open and close stomata

Question 8

What is the function of the palisade mesophyll?

Answer 8

• absorb light for photosynthesis

Question 9

How is palisade tissue adapted?

Answer 9

• Close towards upper surface of the leaf
• packed with chloroplasts for photosynthesis

Question 10

What is the function of spongy mesophyll?

Answer 10

• Gas exchange

Question 11

How is the spongy mesophyll adapted?

Answer 11

• Cells packed loosely to allow gaps for easier diffusion
• Cells covered by a thin layer of water which gases dissolve in

Question 12

What is the function of the xylem?

Answer 12

• Transport water and dissolved minerals around the plant
• Water for photosynthesis

Question 13

How is the xylem adapted?

Answer 13

• Dead hollow tube
• Strengthened by lignin

Question 14

What is the function of the phloem?

Answer 14

• Transport sugars around the plant
• Translocation

Question 15

How is the phloem adapted?

Answer 15

• Pores for cell sap movement
• Supported by companion cells
• End has a sieve plate for free movements of substances
• Up or down

Question 16

What is the function of meristems?

Answer 16

• have plant stem cells that differentiate to specialised cells throughout the life of the plant

Question 17

Where are meristems found in the plants?

Answer 17

• Shoots and roots

Question 18

How is a root hair cell adapted (3)?

Answer 18

• Large surface area
• Thin surface emmbrane for short diffusion pathway
• Lots of mitochondria

Question 19

What is transpiration?

Answer 19

• Evaporation of water from leaves

Question 20

What happens to rate of transpiration when temperature increases and why?

Answer 20

• Increases too
• Water molecules have more energy

Question 21

What happens to the rate of transpiration when air movement increases and why?

Answer 21

• Increases too
• Concentration gradient is kept high
• Air flow removes water vapour from leaves so more water diffuses from leaf

Question 22

What happens to the rate of transpiration when there is more humid air?

Answer 22

• Transpiration decreases
• Amount of water in air decrease concentration gradient
• Less water diffuses out

Question 23

What happens to the rate of transpiration when light intensity increases and why?

Answer 23

• Increases
• More photosynthesis happening during day - more stomata is open

Question 24

What happens to the rate of transpiration when light intensity decreases and why?

Answer 24

• Decreases
• No photosynthesis - stomata closed - no water leaves

Question 25

What is translocation?

Answer 25

- Movement of sugar through phloem both upwards and downwards - Pores found in phloem tubes which allow cell sap(sugar + water) to move - This can be used directly for energy or stored