Chapter 14

Question 1

stimulus definition

Answer 1

change in the external or internal environment that is detected by a receptor

Question 2

Effect of indoleacetic acid during gravitropism in the roots

Answer 2

In the roots, the IAA collects along the bottom and slows down cell elongation causing the roots to bend down

Question 3

Effect of indoleacetic acid during gravitropism in the shoots

Answer 3

IAA collects at the bottom and stimulates more cell elongation causing the shoot to bend upwards

Question 4

Taxis definition

Answer 4

directional response to a stimulus

Question 5

Kinesis definition

Answer 5

non-directional response to a stimulus

Question 6

Basic sequence of events

Answer 6

stimulus, receptor, coordinator, effector, response

Question 7

Tropism definition

Answer 7

the growth of a plant in response to a stimulus

Question 8

sensory neurons

Answer 8

carry nerve impulses from receptors towards the CNS

Question 9

motor neurons

Answer 9

carry nerve impulses away from the CNS to effectors

Question 10

CNS

Answer 10

made up of the brain and spinal cord
Receiving, processing, repsonding to sensory information

Question 11

PNS

Answer 11

made up of pairs of nerves that originate from the brain or spinal cord
Feeds information from senses to CNS

Question 12

Reflex arc

Answer 12

stimulus, receptor, sensory neuron, coordinator, motor neurone, effector, response

Question 13

Benefits of reflex arcs

Answer 13

involuntary, protect body from harm, fast

Question 14

what does a pacinian corpuscle respond to

Answer 14

mechanical pressure

Question 15

Generator potential definition

Answer 15

stimulation of a receptor

Question 16

How is an action potential generated in a pacinian corpuscle

Answer 16

the cell surface membrane becomes deformed due to a change in pressure, widening the stretch-mediated sodium channels to widen. This allows sodium ions to diffuse through into the neurone changing the potential difference across the membrane. The membrane depolarises creating a generator potential. If sufficient sodium ions enter the cell, the threshold will be reached and initiate an action potential

Question 17

what happens once an action potential has been generated

Answer 17

it travels along the neurone and then onto the nervous system via other neurones

Question 18

habituation definition

Answer 18

you get used to the stimulus and cease to be aware of it

Question 19

resolution

Answer 19

how close together two stimuli have to be before they are detected as a single stimulus

Question 20

4 characteristics of cones

Answer 20

three different types that respond to 3 different wavelengths to give colour vision, each cone cell has its own neurone, contains the pigment iodopsin, high visual acuity

Question 21

4 characteristics of rods

Answer 21

produce monochromal images, many rods to one neurone, contains the pigment rhodopsin, low visual acuity

Question 22

cardiac output =

Answer 22

heart rate x stroke volume

Question 23

Myogenic definition

Answer 23

the hearts ability to initiate its own muscle contraction

Question 24

process of myogenic stimulation

Answer 24

an action potential is initiated by the SAN (in the right atria), the AP sets up a wave of electrical activity through the walls of the atria, the AP is channelled through the AVN and down through the bundle of His and then the purkinjie fibres