Plants Growth

Question 1

IAA

Answer 1

Indoleacetic acid
A type of auxin
Controls cell elongation in shoots + inhibit cell growth in roots
Made in the tip/ roots and shoots
Can diffuse to other cells

Question 2

Positive Phototropism

Answer 2

Light is needed for LDR in photosyn.
Shoot tho cells produce IAA = cell elongation (plant growth upwards and IAA goes down)
IAA diffused to other cells
Unilateral light = IAA diffuses towards shaded side of shoot = higher conc of IAA there
Cells on shaded side elongate more = PLANT BENDS TOWARDS LIGHT SOURCE

Question 3

Negative phototropism

Answer 3

Roots don’t photosynthesise = don’t require light
High conc of IAA on shaded side of roots = cells without high IAA elongate (lighter side) = roots bend away from light
ANCHOR PLANT DEEP IN SOIL

Question 4

Positive + negative Gravitropism

Answer 4

IAA diffuses from upper side to lower side of shoot (towards gravity)
VERTICAL = plant cells elongate + plant grows upwards

IAA moves to lower side of roots - upper side elongates = root BENDS DOWN + anchors
POSITIVE

ON SIDE = shoot will bend upwards
NEGATIVE