biology - plant responses

Question 1

how to investigate the effect of light on the growth of newly germinates seedlings?

Answer 1

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

Question 2

Which group of seedlings would you expect to grow the most?

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 seedlings direction of growth

Question 4

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

Answer 4

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