Responding To Change

Question 1

What is osmoregulation

Answer 1

Regulating water content in the body

Question 2

What is homeostasis

Answer 2

Maintaining a stable internal environment
Eg water content
Temperature
Blood glucose regulation

Question 3

What is thermoregualtion

Answer 3

Regulating the internal body temperature

Question 4

What is negative feedback

Answer 4

Changes in the environment trigger a response that counteracts the change
This means the internal environment will stay normal
It only works within certain limits

Question 5

How is body temperature controlled

Answer 5

In the hypothalamus there are receptors that are sensitive to blood temperature in the brain and it receives impulses from the skin about the skin temp
When the hypothalamus detects a change it sends a response to the dermis

Question 6

What happens when we’re too hot

Answer 6

Erector muscles relax and hairs lie flat
Lots of sweat is produces so when it evaporates it transfers heat to the environment and cools us down
Blood vessels close to the surface dilate this is vasodilation and allows more more blood to go to the surface of the skin so more heat can be transferred to the surroundings this gives us a red face

Question 7

What happens when we’re too cold

Answer 7

Erector muscles contract so hairs stand up trapping a layer of warm air keeping us warm
Very little sweat is produced
Blood vessels vasoconstrict so less blood flows near the surface so less heat is transferred to the surroundings and more blood goes to the internal organs to keep them warm

Question 8

What are hormones

Answer 8

A slow chemical message that travels in the blood and acts for a long time in a general way

Question 9

What is the structure of a Neurone

Answer 9

Lots of dendrons to connect with other neurones
The main part of the cell has a nucleus
The electrical impulse moves along the axon
Th myelin sheath insulates the axon which speeds up the impulse and stops it leaving the cell
The neurones are long to increase the speed the Impulse can travel

Question 10

What is a synapse

Answer 10

The connection between two neurones
The impulse is transmitted by chemical neurotransmitters which diffuse across the gap to the next neurone
They set off a new electrical impulse in the next neurone

Question 11

What is a nerve

Answer 11

A fast electrical message that acts for a short time on a precise area

Question 12

What receptors do the five sense organs have

Answer 12

Eyes   light 
Ears   sound and balance 
Nose   smell 
Tongue   taste
Skin    touch pressure and temperature

Question 13

How does the body respond to a stimulus

Answer 13

Stimulus 
Receptor 
Sensory neurones 
Central nervous system 
Brain and spinal chord 
Motor neurone 
Effector cell
Response

Question 14

What is the sensory neurone like

Answer 14

Long dendrons and short axon to carry the nerve impulse to the cns

Question 15

What is the relay neurone like

Answer 15

Many short dendrons and axons surrounding the nucleus

Question 16

What is the motor neurone like

Answer 16

Many short dendrons and one long axon

Question 17

What is the effector

Answer 17

Muscles respond in different ways and contract in response to a nervous impulse

Question 18

What are reflexes for

Answer 18

They are automatic responses to certain stimuli which reduce our chances of being injured
This is known as the reflex arc
They’re much quicker than normal responses because we have no time to think about it

Question 19

What is the reflex arc

Answer 19

Stimulus eg bee sting 
Pain receptor
Sensory neurones 
Relay neurone in the spine
Motor neurone 
Effector 
Response eg move away

Question 20

How is oxygen removed from the blood in s normal person

Answer 20

Metabolism of cells

Vigorous exercise

Question 21

What happens when our blood glucose level is too high

Answer 21

Blood with too much glucose
Insulin secreted by pancreas
Too much glucose and insulin go in the blood to the liver
Glucose is removed by the liver
Insulin causes it to be changed to glycogen
Blood glucose levels are reduced so insulin stops being secreted

Question 22

What happens when our blood glucose level is too low

Answer 22

Blood with too little glucose
Glucagon is secreted by pancreas
Blood with too little glucose and glucagon travel in the blood to the liver
Glucagon turns glycogen to glucose in the liver
Glucose is released back to the blood and the levels increase

Question 23

What is type one diabetes

Answer 23

A condition where the pancreas produces little or no insulin so there is no way of the blood sugar levels being brought down

Question 24

How is type one diabetes overcome

Answer 24

Limit the intake of foods rich in simple carbohydrates
Insulin is injected often at meal times to make sure the excess glucose is removed quickly after eating
The insulin is injected into subcutaneous fat
A healthy diet and regular exercise reduce the amount of insulin needed

Question 25

What is type two diabetes

Answer 25

A condition where the pancreas doesn’t produce enough insulin or when the person becomes resistant to insulin so the blood sugar level rises
People with a BMI over 30 have an increased risk of developing type 2 diabetes

Question 26

BMI=

Answer 26

Body mass/(height)2
Mass in kg
Height in m

Question 27

How is type 2 diabetes controlled

Answer 27

Eating a healthy diet and regular exercise to lose weight and reduce BMI
Medication or insulin injections can be used

Question 28

What is phototropism

Answer 28

The growth of a plant in response to light

Shoots are positively phototrophic they grow towards the light

Question 29

What is gravitropism

Answer 29

The growth of s plant in response to gravity

Roots are positively phototrophic and grow downwards

Question 30

What is auxin

Answer 30

It is a plant growth hormone that promotes growth at the tips of roots and shoots
It stimulates the tips just behind the tips to elongate
If the tip of the shoot is removed then no auxin is available so the plant will stop growing
It promotes growth in the shoot but inhibits growth in the roots

Question 31

How does auxin make a shoot phototrophic

Answer 31

When the shoot is exposed to light more auxin accumulates on the side in the shade so it promotes cell elongation in this side causing the plant to grow towards the light
This allows plants to absorb more light for photosynthesis

Question 32

How does auxin make plant roots gravitrophic

Answer 32

Gravity causes more auxin to fall tot he bottom of the root
But the extra auxin inhibits growth so the cells on top elongate faster and the root bends down wards
This allows plants to anchor themselves into the soil so they can absorb more water and minerals

Question 33

What is gibberilin

Answer 33

It is a plant growth hormone
It stimulates seed germination stem growth and flowering
allows plants to grow tall
Auxin and gibberilin can work together to have big impacts on plant growth

Question 34

How are plant hormones used as selective weed killers

Answer 34

Most weeds are broad leafs and grasses and cereals are narrow leaved
Selective weedkillers only kill broadleaf plants
They disrupt the normal growth pattern and soon kills them whilst leaving the other crops untouched

Question 35

How is rooting powder used to grow cuttings

Answer 35

A cutting is a part of a plant being cut off
If you put a cutting in a soil with rooting powder roots are produced quickly and start growing
This allows clones to be produced quickly

Question 36

How are plant hormones used In the ripening of fruit

Answer 36

It can control the ripening of fruit while they’re still on the plant or in transport
This means the fruit can be picked while it’s still unripe so firmer and less easily damaged
Ripening hormone is then added and the fruit will ripen on the way to the supermarket

Question 37

How are plant hormones used to produce seedless fruits

Answer 37

If a plant isn’t pollinated then fruit seeds won’t grow
If growth hormones are given to unpollinated flowers then the fruit will grow but the seeds won’t
Seedless grapes and citrus can be made in this way