Plant Response RPA

Question 1

Effect of light intensity on height of seedlings IV

Answer 1

Light intensity

Question 2

Effect of light intensity on height of seedlings DV

Answer 2

Height of seedlings

Question 3

How to find the effect of light intensity on height of seedlings

Answer 3

• place cotton wool in 3 Petri dishes and soak with equal volumes of water
• place 10 mustard seeds in each dish
• leave dishes in warm place and allow seeds to germinate
• water seeds everyday with same volume of water
• make sure dishes have same number of seedlings
• use ruler to measure height of seedling
• make sure they’re straight
• place dishes in diff conditions
  = bright, partial sunlight and darkness
• measure height of seedling everyday

Question 4

Effect of light intensity on height of seedlings CV

Answer 4

Volume of water
Type of seed

Question 5

Why is full and partial sunlight similar

Answer 5

Chlorophyll is very efficient at absorbing light energy
= plants don’t need full sunlight to grow

Question 6

Why do seedlings grow towards sunlight

Answer 6

Phototropism

Question 7

Why do seedlings in the dark grow longest

Answer 7

Seeds usually germinate underground and they grow rapidly to reach the light

Question 8

Why are leaves small and yellow in darkness

Answer 8

Once seedlings have used all energy stores they can’t photosynthesise in the dark

Question 9

How to find effects of gravity on seedlings

Answer 9

• dish of seedlings placed on its side in the dark
• shoots grow upwards, against direction of gravity, roots grow downwards
  = gravity causes auxin to build up on lower side of the root
  = grows more slowly than upper side
  = makes root grow in direction of gravity