Topic 6

Question 1

the student observed that the stomata were open.

describe how stomata open

Answer 1

guard cells take in water by osmosis and they become turgid

Question 2

describe the effect of light intensity on the rate of photosynthesis

Answer 2

as light intensity increases so does rate of photosynthesis

Question 3

explain the effect of temperature on the rate of photosynthesis

Answer 3

as temperature increases so does rate of photosynthesis. above optimum temperature enzymes become denatured (photosynthesis decreases)

Question 4

figure 18 shows an investigation into the growth of plant shoots.

give one variable that must have been controlled for the plant shoot to grow vertically, as shown in experiment 2

Answer 4

direction of light

Question 5

figure 18 shows an investigation into the growth of plant shoots.

state one conclusion that could be made based on these two experiments

Answer 5

the tip controls growth

Question 6

which plant hormone causes growth in the plant shoot?

A) auxin
B) ethene
C) gibberellin
D) chlorophyll

Answer 6

A) auxin

Question 7

water enters a plant though root hair cells. root hair cells have:

A) a small surface area and thin cell walls
B) a small surface area and thick cell walls
C) a large surface area and thin cell walls
D) a large surface area and thick cell walls

Answer 7

C) a large surface area and thin cell walls

Question 8

glucose is made by photosynthesis. glucose is converted to another sugar to be transported in the plant. what is the name of this sugar?

A) glycerol
B) ribose
C) sucrose
D) starch

Answer 8

C) sucrose

Question 9

describe how this sugar is transported from the leaves to the flowers of the water lily

Answer 9

in the phloem its dissolved in water by translocation using active transport

Question 10

some weed killer contain plant hormones.

explain how plant hormones work as weed killers

Answer 10

weed killer contains auxins causing them to overgrow. selective weed killer doesn’t kill grass plants

Question 11

explain how phototropism is controlled in plant shoots

Answer 11

phototropism is controlled by the hormone auxin. auxins move to the shaded side of the shoot causing cell elongation

Question 12

explain how substances are moved through a plant by transpiration and translocation

Answer 12

in transpiration, water is moved from the root through the plant to the dead cells of the xylem, driven by evaporation of water from the leaves through the stomata. it flows in only one direction.

in translocation, sugars move from the leaves through the plant as sucrose and through the living sieve cells of the phloem to sinks in the plant where sucrose is needed. flow is bidirectional however in transpiration flow is only in one direction