irritability in plants

Question 1

state two types of movements in plants

Answer 1

part movements
growth movements (tropisms)

Question 2

what is part movement brought about by

Answer 2

a change in turgidity of cells due to movement of water

Question 3

list 4 examples of part movements

Answer 3

leaves respond to touch or strong winds by folding liek mimosa pudica

leaves respond to changing light intensities by folding at night and opening in morning like tamarind

flowers open in morning and close at night responding to light intensities like hibiscus or night flowering cactus

parts of insectivorous plants move to trap prey like sundew or venus flytrap

Question 4

what is tropisms

Answer 4

growth movement
permanent and relatively slow

Question 5

what is growth in response to light called

Answer 5

phototropism

Question 6

what is growth in response to gravity called

Answer 6

geotropism

Question 7

explain growth in plant stems and roots

Answer 7

growth in shoots happens in region just behind shoot tip
while in roots just behind root tip

regions called meristems

Question 8

what is growth controlled by

Answer 8

plant growth hormones which is produced in tip but moved back away from tip affecting cell elongation

Question 9

explain phototropism

Answer 9

shoots grow towards unilateral light positive phototropism
because plant growth hormone accumulates on shaded side of stem increasing cell elongation in that area so stem bends towards light

roots grow downwards away from light negative phototropism
allow root to grow towards water and minerals in soil

Question 10

negative geotropism

Answer 10

shoots grow upwards against gravity
if placed horizontally plant growth hormone accumulates on lower side of stem increasing cell elongation in that area so stem bends upwards against gravity

Question 11

positive geotropism

Answer 11

roots grow downwards with gravity
allow root to grow downward to anchor the plant in the soil and to grow towards water and minerals in soil