Taxis and kinesis and response to the enviroment

Question 1

what is a stimulus

Answer 1

detectable change in the enviroment that leads to a response

Question 2

how does respondng lead to an increase of survival

Answer 2

move away from predator and survive por move towards food and survive

Question 3

how does it influence natural selection

Answer 3

those best adapted to detecting and responding to changes in the enviroment are more likely to survive and reproduce passing on alleles to the offsprings

Question 4

desribe a receptor

Answer 4

it is detects stimulus and is specific to one type of stimulus

Question 5

what is a coordinator

Answer 5

formulates an appropriate response

Question 6

what is an effector

Answer 6

a response producer at a molecular or larger level

Question 7

what is taxis

Answer 7

directional movement of an organism body as a result of a directional stimulus towards favourable or away from unfavourable one

Question 8

what is kinesis

Answer 8

change in speed and turning as a result of enviromental stimulus in order to find a more favourable enviroment

Question 9

when does it occur

Answer 9

when the stimulus does not have a specific direction

Question 10

what is tropism

Answer 10

directional growth in response to directional stimulus towards favourable condition

Question 11

how to shoots grow

Answer 11

they are positive phototropism as they grow towards the light

Question 12

how do roots grow

Answer 12

they are positive gravitropism as they grow towards the gravity

Question 13

why do plants grow towards light

Answer 13

in order to maximise capturing of light for photosynthesis

Question 14

why do plants grow towards gravity

Answer 14

they need to be firmly anchored into the soil

Question 15

why do plants grow towards water

Answer 15

needed for photosynthesis

Question 16

so how is directional growth achieved by plants

Answer 16

by a group of hormones called auxins iaa that act on the cells that release them

Question 17

describe photropism

Answer 17

the iaa is produced in the growing part of the plant - the tip of the shoot
it then diffuses evenly throughout the plant
when the light hits the iaa moved to the shaded side of the plant
greater concentration of iaa in shaded side compared to lit side
in the shoots iaa promote cell elongation so the shaded side grows at a fster rate and bends towards the ligth

Question 18

describe gravitropism

Answer 18

iaa is produced in the tip of the roots
distributed evenly throughtout the roots
then move to the lower side of the root as influenced by gravity
greater concentration of iaa in the root inhibit cell elongation \
upper side of the root grows at a faster rate compared to lower side and then bend towards gravity

Question 19

what happens to young plants vs old plants

Answer 19

old plants are rigid and less flexible so cells cannot elongate

Question 20

what is the acid hypothesis

Answer 20

the hydrogen ions are actively transported from the cytoplasm to the cell wall space and leads to the elongation of the cell walls