Coordination and Response

Question 1

Homeostasis & Examples

Answer 1

The maintenance of a constant internal environment
E.g: Body water content, Body temperature

Question 2

Co-ordinated response requires:

Answer 2

Stimulus, Receptor, (Coordination center), Effector

Question 3

Roots

Answer 3

Positively Geotropic, Negatively Phototropic

Question 4

Stems/Shoot

Answer 4

Negatively Geotropic, Positively Phototropic

Question 5

Phototropic so
Geotropic so

Answer 5

P: Leaves have a greater surface area facing light, so more absorbed for photosynthesis
G: Roots can grow downwards for water and minerals in the darkness, Shoot grows upwards away from soil

Question 6

Auxin in phototropic response of stems:

Answer 6

Auxin mostly made in tips of shoots and diffuses down the shoot
Auxin stimulates cells in a region to elongate
If light shines evenly, the auxin is distributed evenly and the cells grow at the same rate
If light shines (more) from one side, auxin concentrates on the shaded side, making those cells grow faster than the brighter side
This causes the shoot to bend and grow towards the light

Question 7

Endocrine System

Answer 7

Hormones secreted from glands into blood stream
They travel in blood to target cells/organs
Bind to correct receptors on target cells, bringing about a response/triggering a chemical reaction
Used to control slower responses

Question 8

Nervous System

Answer 8

Information sent through neurones as electrical responses
Impulses travel along neurones at very high speeds up to 100m/s
This allows rapid responses to stimuli
Nervous system coordinates receptors, decision making centres in CNS and effectors
Used to control rapid responses

Question 9

Nervous vs Endocrine

Answer 9

N: involves Brain, spinal cord, neurones, E: Glands
N: Electrical impulse, E: Chemical hormone
N: Transmitted by neurones, E: Bloodstream
N: Muscle or gland effectors, E: target cells in specific tissues
N: Fast transmission, E: slower
N: Short & localised effect, E: Long and widespread

Question 10

Nerve:

Answer 10

Bundle of neurones

Question 11

CNS

Answer 11

Central Nervous System - brain and spinal cord
acts as central coordinating center

Question 12

PNS

Answer 12

Peripheral Nervous System - all of the nerves in the body

Question 13

Reflex Arc:

Answer 13

Receptor -> Sensory Neurone(PNS) -> Relay neurone(CNS) then synapses with -> Motor neurone -> Impulse to Effector -> Response - (fraction of a second)

Question 14

Sensory Neurone Structure

Answer 14

Long, cell body middle of axon
Myelin sheath
Connected to receptor cell and CNS neurones

Question 15

Relay Neurone Structure

Answer 15

Short, small cell body at one end with many dendrites
No Myelin sheath
Connects sensory and motor neurons

Question 16

Motor Neurone Structure

Answer 16

Long, large cell body with long dendrites
Myelin sheath
Connected to CNS neurones and effectors

Question 17

Dendrites function

Answer 17

Extend out of cell body and end of axon
Alows neurones to connect to many other neurones and recieve impulses

Question 18

Synapse

Answer 18

Gap between dendrites of 2 neurones

Question 19

Role of Neurotransmitters

Answer 19

Electrical impulses cannot travel directly from one neurone to the next
Electrical signal briefly converted to chemical signal, transferred across the synapse by Neurotransmitter molecules
Once the Neurotransmitters cross the synapse, the signal is converted back into an electrical impulse, which passes along the neurone

Question 20

How is an impulse passed across a synapse

Answer 20

Electrical impulse travels along the presynaptic neurone
Vesicles at the end of the presynaptic neurone release neurotransmitters
Neurotransmitters diffuse across the synapse and bind with receptors on the postsynaptic membrane, stimulating electrical impulse in it to the next neurone.

Question 21

Cornea Function

Answer 21

Transparent lens that refracts light as it enters the eye

Question 22

Iris Function

Answer 22

Controls how much light enters the pupil

Question 23

Lens Function

Answer 23

Transparent disc that changes shape to focus light onto the retina

Question 24

Retina Function

Answer 24

Contains Light Receptor Cells - Rods (Detect light intensity) and Cones (Detect color)

Question 25

Optic Nerve

Answer 25

Sensory neurone that carries impulses between the eye and brain

Question 26

Accommodation (Close up)

Answer 26

Ciliary muscles contract
Suspensory ligaments loosen, stopping them from pulling on lens
Lens becomes more convex
Light refracted more, converges on retina

Question 27

Pupil

Answer 27

Hole that allows light to enter the eye

Question 28

Accommodation (Far away)

Answer 28

Ciliary muscles relax
Suspensory ligaments tighten, pulling on the lens
Lens becomes thinner (less convex)
Light refracted less, converges on retina

Question 29

Pupil reflex (dim light)

Answer 29

Photoreceptors detect light intensity (dark)
Radial muscles Contract
Circular muscles Relax
Pupil Dilates (Widens)
More light enters the eye

Question 30

Pupil reflex (bright light)

Answer 30

Photoreceptors detect light intensity (bright)
Radial muscles Relax
Circular Muscles Contract
Pupil Constricts (Narrows)
Less light enters the eye

Question 31

Vasodilation

Answer 31

Hot temperature
Arterioles supplying capillaries near the surface of the skin dilate (widen)
Blood flow through capillaries increases
More energy/heat lost to environment

Question 32

Vasoconstriction

Answer 32

Cold temperature
Arterioles supplying capillaries near the surface of the skin constrict
Blood flow through capillaries decreases
Less energy/heat lost to environment

Question 33

Sweating

Answer 33

Sweat secreted from sweat glands
As sweat evaporates, the heat from the body is used to convert liquid water into water vapour

Question 34

Flattening of hairs

Answer 34

Hair erector muscles relax, causing hairs to lie flat
This stops them from forming an insulating layer by trapping air

Question 35

Why cant body temperature differ too much

Answer 35

2°C change can be fatal, as enzymes do not function properly.

Question 36

Adrenaline

Answer 36

-Adrenal Glands (near kidney)
Increased breathing and heart rate, more oxygen and (glucose) reaches muscles quickly
Blood diverted away from gut to muscles
Glycogen in liver broken down, more glucose available in blood to reach muscles
Increased rate of respiration, more ATP produced - greater contraction of muscles
Pupils dilate for more light into retina for visual sensitivity to movement
Body hair stands on end for “increased size”
Mental awareness increased - faster reactions

Question 37

Insulin

Answer 37

-Pancreas
Lowers glucose concentration in blood
Converts glucose into glycogen, stored in liver and skeletal muscle

Question 38

Testosterone

Answer 38

-Testes
Controls development of male secondary sexual characteristics
Growth of penis and testes
Growth of facial and body hair
Muscle development
Breaking of voice

Question 39

Progesterone

Answer 39

-Ovaries
Regulates menstrual cycle
Completes development of uterus lining
Inhibits FSH and LH

Question 40

Oestrogen

Answer 40

-Ovaries
Controls development of female secondary sexual characteristics
Stimulates thickening of uterus lining
Inhibits FSH, stimulates LH

Question 41

FSH

Answer 41

-Pituitary Gland
Causes egg to mature in ovary

Question 42

LH

Answer 42

-Pituitary Gland
Triggers ovulation