response to stimulus

Question 1

what is a stimulus

Answer 1

a detectable change in the environment

Question 2

what is taxes

Answer 2

simple response in which an organism moves its entire body towards a favourable stimulus

Question 3

what is kinesis

Answer 3

when an organism changes there speed of movement and rate of changing direction

Question 4

what is tropism

Answer 4

given when plants respond via growth to a stimulus

Question 5

types of tropism

Answer 5

phototropism, geotropism, hydrotropism

Question 6

what is IAA

Answer 6

it is a type of auxin that controls cell elongation

Question 7

why do shoots need light

Answer 7

for light dependent reactions

Question 8

how is IAA different in shoots and stems

Answer 8

in shoots it inhibits cell elongation and in the stem it promotes cell elongation

Question 9

where does IAA go

Answer 9

IAA will diffuse to the bottom part of the organism due to gravity. as in the roots the growth will be inhibited, the growth of the top of the plant wont stop, causing it to bend down. unlike in the stem where it will promote growth so the plant will grow upwards as it will grow faster than the top part of the stem.

Question 10

nervous system order

Answer 10

stimulus- receptor- coordination- effector- response

Question 11

what is nervous system made out of

Answer 11

made of the peripheral and the central nervous system

Question 12

where is the CNS

Answer 12

the brain and spinal cord

Question 13

where is the PNS

Answer 13

made of receptor cells, the sensory neurons and motor neurons.

Question 14

what do receptors do

Answer 14

they detect change in the environment

Question 15

three types of receptions

Answer 15

pacinian corpuscle, rods, cones

Question 16

what does the stimulus of receptors lead to

Answer 16

it leads to the establishment of a generator potential which causes a response

Question 17

stages of how to get a reaction

Answer 17

stimulus needs to big enough so it causes an influx of sodium ions into the neuron larger than 55mV. this will then allow the rest of the response to take place as it will react the action potential.

Question 18

what does the pacinian corpuscle respond to

Answer 18

pressure change

Question 19

what is the pacinian corpuscle

Answer 19

it is a single sensory neuron wrapped with layers of tissue separated with gel. it has a special channel proteins in its plasma membrane

Question 20

what are the special channels

Answer 20

they are stretch mediated sodium channels which allows the sodium to enter the sensory neuron by pressure. when not letting sodium in they are closed.

Question 21

what happens to the sensory neuron when there is sodium

Answer 21

it becomes more close to positive as it goes from -70 to -55mV

Question 22

if there is enough sodium ions diffusing in to the sensory neuron what will happen

Answer 22

then it can exceed the threshold and carry out a response because an active potential has been generated.

Question 23

where to find rods and cones

Answer 23

in the retina

Question 24

what are rod cells

Answer 24

they don’t distinguish different wavelengths of light but processes black and white. they can detect light at low light intensities due to retinal convergence

Question 25

what do the rods and cones do

Answer 25

then generate a response when the action potential is high enough

Question 26

what do rod cells do

Answer 26

they absorb the light intensity and the protein pigment rhodopsin will be broken down by the light energy which will go on to trigger a response if enough is broken down.

Question 27

what cells link the rod cells and the sensory neuron

Answer 27

bipolar cells

Question 28

what is retinal convergence

Answer 28

you have multiple rod cells connecting to one bipolar cell. this is good as collectively all of the broken down pigment will allow an action potential even when dark.

Question 29

problem with retinal convergence

Answer 29

the brain can not distinguish between the separate sources of light that stimulated it meaning it gives a low visual acuity.

Question 30

three types of cone cells

Answer 30

red, green and blue which absorb different wavelengths of light. this is how we perceive colour imaging

Question 31

when is iodopsin broken down

Answer 31

when there is a high light intensity so action potential can only be generated with enough light.

Question 32

how are the cones connected

Answer 32

one cone is connected to one bipolar cell. this is why we cannot see colour in the dark as there is no retinal convergence

Question 33

positive of cone cells

Answer 33

as one cone cell is only connected to one bipolar cell they brain can distinguish between separate sources of light so it has a high visual acuity.

Question 34

what id the distribution of rods and cones like

Answer 34

it is uneven

Question 35

what is the light more focused on by

Answer 35

by the lens on the part of the retina opposite the pupil, called the fovea which receives the highest intensity of light.

Question 36

which is it important that the fovea absorbs high light intensity

Answer 36

it tells us where the rod and cone cells will be. as the cones need a high light intensity to reach an action potential, this means that it will be near the fovea whereas the rods need a low level of light so will be further from it.