parts and functions of a leaf

Question 1

cuticle

Answer 1

• it is transparent > allows light to pass through
• waxy , waterproof > prevents excessive evaporation of water

Question 2

upper epidermis

Answer 2

• protective layer of cells
• transparent >allows light to reach the mesophyll cells

Question 3

palisade mesophyll cells

Answer 3

• closely packed , large number of chloroplasts to absorb max light energy
• carries out the most photosynthesis

Question 4

spongy mesophyll cells

Answer 4

• less chloroplasts , less photosynthesis
• loosely packed with air spaces to facilitate rapid diffusion of co2 into the leaves
• wall coated w layer of moisture to allow co2 to dissolve first before diffusing into cells

Question 5

xylem (part of vascular bundle)

Answer 5

• transports water and mineral salts from roots to other parts of the plant
• supports the plant prevents it from collapsing

Question 6

phloem (part of vascular bundle)

Answer 6

• transports sucrose and amino acids from leaves to all parts of plant ( translocation)
• mitochondria respires to release energy needed for translocation

Question 7

lower epidermis

Answer 7

• protective layer of cells
• presence of stomata for gaseous exchange

Question 8

guard cells

Answer 8

• controls size/opening of stomata

Question 9

root hair cell

Answer 9

• elongated protrusion
  > increases surface area to volume ratio for faster absorption of water and mineral salts
• concentrated cell sap
  > provides a steep water potential gradient for water to move from the soil into the root hair cell by osmosis

Question 10

temperature

Answer 10

the higher the temperature , the faster the water evaporates. hence , transpiration is faster

Question 11

wind speed

Answer 11

wind blows away the water vapour molecules surrounding the leaf > concentration of wv lowers > creates steep concentration gradient >less water diffuses out > rate of transpiration decreases

Question 12

humidity

Answer 12

more humidity > higher concentration of wv > creates less steep concentration gradient > less water diffuses out > rate of transpiration decreases

Question 13

light intensity

Answer 13

higher light intensity > the bigger stomata opens > more wv diffuses out > faster rate of transpiration

Question 14

wilting (how it occurs)

Answer 14

rate of water loss greater than water uptake during transpiration

Question 15

translocation

Answer 15

transport of food such as sucrose and amino acids by phloem from leaves to other partsof the plant