plant growth factors NEEED TO FINISH

Question 1

explain positive phototropism when the light is evenly distributed

Answer 1

IAA produces by cells in shoot tips

1. IAA moves evenly to all short cells
2. all cells have same concentration
3. cell elongation is equal on all sides
4. shoots grows straight upwards

Question 2

explain positive phototropism when the light shines on one side

Answer 2

1. light causes IAA to move to one side
2. higher concentration of IAA on a shaded side compared to the light side
3. IAA causes cells to elongate more on one side
4. shaded side elongate faster than light side causing shoot to grow towards light

Question 3

explain positive phototropism when the shoot tip removed and unidirectional light

Answer 3

1. no response
2. tip has been removed so source of IAA has been removed
3. cell elongation not stimulated
4. so even cell growth

Question 4

describe the role of IAA in root gravitropism

Answer 4

• uneven distribution of IAA
• IAA at a higher concentration on the side closer to ground
• IAA inhibits cell growth on the lower side closer to the ground
• this causes the cells on the opposite side to elongate a faster rate
• this causes the root to grow in the direction of gravity
• positive geotropism