RP8 Plant responses

Question 1

describe how you would investigate the effect of light on the growth of newly germinated seedling

Answer 1

• incubate seeds in 3 petri dishes and allow them to germinate
• place one dish in full sunlight, one in partial sunlight and one in complete darkness
• measure the height of each seedling each day for a week and calculate the mean height for each day
• plot graph of mean seedling height (y) against day (x)

Question 2

which group of seedlings would you expect to grow the most and why?

Answer 2

the group in full sunlight - light is required for photosynthesis and these plants will not have light intensity as a limiting factor

Question 3

what growth substance in plants is affected by light?

Answer 3

auxins - the distribution of auxins in seedling stems is affected by light. this impacts the seedling’s direction of growth

Question 4

why is it necessary to find the mean height of the seedlings?

Answer 4

some seedlings may be much shorter/longer than others in the same dish - calculating a mean makes the values more representative and allows comparison between groups