B1 Topic 2 Core GCSE - Holgate Ac Papers/B1 Topic 2 Revisio… · B1 Topic 2 Core GCSE The bare...

B1 Topic 2 Core GCSE

The bare essentials

THE NERVOUS SYSTEM

What are the 5 Senses? Where are the receptor cells that detect a change?

What changes do they detect?Sense Sense Organ /

ReceptorTouch Receptor cells in skin

Sight Receptor cells in eye

Smell Receptor cells in nose

Taste Receptor cells on tongue

Hear Receptor cells in ears

Detect changes in…

Pressure / temperature

Light

Chemicals in air

Chemicals in food

Sounds

Sense organs have receptor cellsReceptors (receptor cells) detect changes in your environment.

They are found in your sense organs (eyes, skin, ears, tongue and nose).

The changes in the environment are called stimuli – (one = stimulus).

Can you statewhat makes up the CNS and labelthese parts.

(Grade E)

Can you match senses with their sense organs and what they detect changes in. (Grade D)

Can you establish the nerve pathway to show how the CNS coordinates a response. (Grade C)

Can you modify the pathway to represent what happens in a different situation.

(Grade B)

Can you justifywhy ChristopherReeve can move his eyes but not his legs.

(Grade A)

The Central Nervous System is made of the brain and the spinal cord.

The Central Nervous System controls everything in the body. Your sense organs (eg skin eyes etc) are linked to the brain

and spinal cord by nerves.

2.19 Recall that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves

The brain has the spinal cord attached and runs down the back of the body. Nerves branch from the spinal cord to every part of your

body. Nerves are made up of bundles of neurones. (Like a wire).

Can you statewhat makes up the CNS and labelthese parts.

(Grade E)

Can you match senses with their sense organs and what they detect changes in. (Grade D)


Can you modify the pathway to represent what happens in a different situation.

(Grade B)

Can you justifywhy ChristopherReeve can move his eyes but not his legs.

(Grade A)

The organisation of the nervous system.

1. The CNS controls… your body

2. The CNS is made up of the …brain and spinal cord

3. The spinal cord …connects to the brain

4. It contains …many nerves packed together

5. Nerves are …bundles of neurones (nerve cells) packed together.

Can you state what makes up the CNS and label these parts. (Grade E)

Can you match senseswith their sense organs and what they detect changes in. (Grade D)


Can you modify the pathway to represent what happens in a different situation.(Grade B)

Can you justify whyChristopher Reeve can move his eyes but not his legs.(Grade A)

2.21 Describe how stimulation of receptors in the sense organs sends electrical impulses along neurones

When our receptors in our senses detect a stimuli (a change such as the school bell) it starts an electrical impulse that follows a certain pathway. This is the nerve pathway.

Stimulus is the change in the environment. Eg a bellReceptors detect this change (eg in the ear) and starts an electrical

impulse. Sensory neurone - takes electrical impulse to brain in CNS.Brain (relay neurone) decides which neurone to send impulse to

through the relay neurone. Relay neurone passes the impulse to a motor neurone. Relay neurones are in the spinal cord and brain.

Motor neurone takes the electrical impulse to effector (muscle or gland).

Effector or muscle contracts.Response – you respond eg put your coat on to leave lesson.

ExampleStimulus is the change in the environment. You step barefoot

on a sharp stone.Receptors in the skin detect this change and starts an

electrical impulse. Sensory neurone takes impulse from the receptors, up

through the spinal cord to brain in CNS.Brain (relay neurone) decides which neurone to send impulse

to through the relay neurone. Relay neurone passes the impulse to a motor neurone.

Motor neurone takes the impulse from the brain, down the spinal cord to effector.

Effector or muscle contracts.Response – you respond by lifting your foot up.

2.20 Explain the structure and function of dendrons and axons in the nervous system

This is the structure of a sensory neurone – they take messages to the CNS.

What the structure do – their functions.

Cell bodyDendrites

Axon endings

Axon

2.23 Describe the structure and function of sensory, relay and motor neurones and synapses including: a the role of the myelin sheath

ALL: List some equipment and explain what you will use the equipment for. (Grade D)MOST: Establish the risks in the experiment and explain how you will prevent the risks from causing harm (Grade

C)SOME: Discuss the variables you will control, how you will control them and discuss why each needs to be

controlled (Grade B)FEW: Construct a logically ordered plan, explaining how the plan will test the hypothesis and why you have

chosen your range (Grade A)

Dendrites

Cell bodyMyelin sheath

Axon

Effector (muscle cells)

Axon endings

Sensory Nerve Motor NerveEnds in the receptor cell Ends in a muscle cell

Small cell body Large cell body

Small axon long dendron

Longer axon, no dendron

Dendrites collect impulses from receptor cells

Dendrites collect impulses from other neurones

Axon ending pass impulses to other neurones

Axon ending pass impulses to effector cells

How are sensory and motor neurones different?

Receptors detect a stimulus, start an electrical impulse which travels down a sensory neurone. When it needs to go to a relay neurone there is a gap between the two neurones called a synapse. Synapse = a gap between 2 neurones.Synapses slow electrical impulse down slightly but they are useful as the neurotransmitter is only released at one end (the axon endings ) and so the impulse can only travel in one direction.

This is what happens at synapses so that the impulse continues. (next slide)

2.10 Explain how a coordinated response to a stimulus is achieved, including the roles of the synapse and neurotransmitters

This is a close up of one of the places where one neurone (the axon ending) meets the dendrite on the next neurone.

ALL: Outline what a ‘synapse’ is. Define what a neurotransmitter is and give an example.(Grade D)MOST: Establish the meaning of neurotransmission and establish how electrical impulses get from one

neurone to the next. (Grade C)FEW: Explain why electrical impulses only travel in one direction . (Grade B)FEWER: Determine how Botox works. (Grade A-A*)

ALL: Outline what a ‘synapse’ is. Define what a neurotransmitter is and give an example.(Grade D)MOST: Establish the meaning of neurotransmission and establish how electrical impulses get from one

neurone to the next. (Grade C)FEW: Explain why electrical impulses only travel in one direction . (Grade B)FEWER: Determine how Botox works. (Grade A-A*)

KEYWORDSNeurotransmitter: A chemical that

diffuses across a synapse to start an electrical impulse in the next neurone.

Neurotransmission: The transmission of impulses from neurone to neurone.

• Where the axon endings of one neurone meet the next neurone (or effector), there is a tiny gap called a synapse.

1. An electrical impulse arrives at the end of the axon ending of neurone 1. (This is happening at number one on the diagram).

2. Neurotransmitter is released into the synapse (the gap) (this is happening at number 2 on the diagram).

3. The neurotransmitter diffuses across the synapse. (this is happening at number 3 on the diagram)

4. The neurotransmitter binds to receptors on the next neurone and makes an electrical impulse start up in the next neurone.

b the roles of neutotransmitters

Reflex arcs

• A reflex arc is the connection of a sensory neurone, then relay neurone, then a motor neurone that allows a reflex action to occur (automatic and involuntary response).

• The impulse does not go to the brain.

• Reflexes are important as they are quick, actions that you don’t think about doing. The body does them automatically to protect you.

c the reflex arc

1) Drinking a glass of water2) Sweating in hot weather3) Making saliva when you smell food4) Blinking when dust gets in your eye5) Pulling your hand from a hot object6) Watching television7) Coughing if food goes down your windpipe8) Kicking when your knee is tapped9) Ducking when a ball goes near your head10) Sneezing in a dusty room11) Reading a book12) Shivering in the cold

Examples of reflexes are in yellow.

Called reflexes - are fast, automatic reactions.

They do not involve the thinking part of the brain.

Responses you don’t have to think about them – they are involuntary.

There are two types of responses

Responses that you think about are

You choose to do them.

They involve the brain and you thinking about them.

voluntary

Differences between reflex responses and normal responses. Reflexes are highlighted in yellow again.

A rapid (very fast) automatic response.(Reflex)

A slower response that is not automatic. (Normal response)

Involuntary response –done without the brain. (Reflex)

Voluntary response – involves the brain. (Normal response)

Done without thinking about it. (Reflex)

Response you can choose to do or not. (Normal response)

Responses that protect the body (Reflex)

Usually involves a number of different neurones making the response slower. (Normal response)

Usually involves just 2-3 neurones - a sensory neurone linked directly to a motor neurone (or with a relay neurone in the middle). (Reflex)

Homeostasis and Thermoregulation

What is homeostasis?2.1 Define homeostasis as the maintenance of a stable internal environment.Homeostasis is the maintenance of a stable internal environment.

Basically, it is keeping certain things constant in your body.

For example temperature – the regulation or control of body temperature is called Thermoregulation. Human body temperature should be 37°C.

Water levels in blood – the regulation or control of blood water levels is called Osmoregulation.

Glucose levels in blood – the regulation or control of blood glucose levels is carried out by the hormones insulin and glucagon.

2.2 Demonstrate an understanding of the homeostatic mechanisms of: a thermoregulation and the effect of temperature on enzymes.Thermoregulation is the regulation or control of body temperature, which should be at 37°C for a human.

If body temperature rises too high or too low it can lead to organ failure or death.

Things called enzymes in your body work best at 37°C. Enzymes are things that help chemical reactions needed for survival happen quickly. For instance, enzymes help to break down your food into smaller bit so they can absorbed into the blood.

If your body temperature goes too high or too low then the enzymes cant work as well and so either slow down or if they become too hot will denature (stop working altogether).

Your body does certain things then to keep you at 37°C if you get too hot or too cold. These are the homeostatic mechanisms. They are: SweatingHairs flatten or raiseVasodilation and vasoconstrictionShivering

Homeostatic Mechanisms.

The hypothalamus in the brain controls thermoregulation. It is the hypothalmus that will decide what course of action to take.

What detects the change in temperature? It is receptors or nerve endings in the SKIN! See next slide.

Structures in the skin.

What they all do:Sensory nerve endings: Detect the change in temperature, start an electrical impulse which it send along a sensory neurone to the hypothalamus in the brain. Sebaceous gland: Releases oil to keep skin healthy and soft. Blood vessels: Can get narrower or wider to allow less or more blood to flow. This can conserve heat or allow the loss of extra heat.Sweat gland: Releases sweat onto skin surface. Erector muscle: Contracts to lift the hair up when cold. Relaxes to flatten the hair when hot. Hair: If stood up traps a layer of air against the skin that acts as insulation.If flat, allow air to circulate so heat is more easily transferred from the skin to the surroundings.

A part of the brain controls our responses when we are hot / cold

The hypothalamus gets information from nerve endings in the skin and also from the blood.

If the bodys temp goes below 37 degrees it causes:

ShiveringSweatingVasoconstrictionVasodilationHairs to stand up / down

• All: Define homeostasis and thermoregulation (Grade E)• Most: Establish what happens when your body gets too hot or too cold (Grade D)• SOME: Discuss the mechanisms that regulate your body temperature (Grade C)• FEW: As above but your explanation needs to include vasodilation and vasoconstriction.

(Grade B)

b the roles of the hypothalamus – regulating body temperature

2.3 Explain how thermoregulation takes place, with reference to the function of the skin, including:

a the role of the dermis – sweat glands, blood vessels, nerve endings, hair, erector muscles and sebaceous glands

In the dermis are the sweat glands. When you are hot the sweat gland releases sweat onto the skin surface. It contains water which evaporates. This transfers heat from the skin to the surroundings –this cools the skin.

In the dermis are nerve endings: Detect the change in temperature, start an electrical impulse which it send along a sensory neurone to the hypothalamus in the brain. The hypothalamus will decide what actions need to take place.

Erector muscles and hairs: Attached to the hair. Contracts to lift the hair up when cold. Relaxes to flatten the hair when hot.

When hairs are raised (when you are cold) this traps a layer of air against the skin which provides insulation.

When hairs are flat (when you are warm) this allows air to move and circulate away from the skin. This makes it easier for heat to be transferred from the skin to the surroundings.



Sebaceous gland: Releases oil to keep skin healthy and soft.

Blood vessels: These allow vasoconstriction when you are cold and vasodilation when you are hot. Vasoconstriction: When we are cold the hypothalamus makes blood vessels closest to the skin surface constrict (get narrower). This makes more blood flow in deeper blood vessels that are further away from the skin. This keeps warm blood deeper in so that heat loss to the air is reduced. Vasodilation: When we are hot the hypothalamus makes blood vessels closest to the skin surface dilate (get wider). This makes more blood flow in blood vessels that are closer to the skin surface. That’s why we look pink. This makes it easier for the blood to lose heat to the air by radiation so we cool down.



HIGHER ONLY 2.4 Explain how thermoregulation takes place, with reference to: a vasoconstriction

and b vasodilation c negative feedback

Keywords and definitions

Endocrine system – all the glands in the body Endocrine gland – makes and releases hormones

Hormone – a chemical messenger that travels in the blood to cause a response

Target organ – the organ that the hormone travels to in order for it to respond.

2.5 Recall that hormones are produced in endocrine glands and are transported by the blood to their target organ

The bodies glands, the

hormones they release and

their functions.

Osmoregulation is the regulation of water levels.

b osmoregulation

The pituitary gland releases the hormone ADH (anti diuretic hormone) which travels to the kidneys. The following slide gives you a flow diagram of what happens.

Normal water levels in blood

Normal water levels in blood

Water levels increase (after drinking)

Water levels decrease (after sweating)

Pituitary gland produces less ADH

Kidney produces little concentrated urine produced

Pituitary gland produces more ADH

Kidney produces lots of dilute urine

c blood glucose regulation

After exercising the blood glucose levels decrease.

After eating, glucose levels in the blood increase.

The pancreas releases the hormone glucagon.

The pancreas releases the hormone insulin.

This travels in the blood to the liver which responds by converting glycogen to glucose and putting it back in the blood.

This travels in the blood to the liver which responds by taking out the excess glucose and storing it as glycogen.

Blood glucose levels back to normal.

Blood glucose levels are normal.

See previous slide.

2.6 Explain how blood glucose levels are regulated by insulin and excess blood glucose is converted to glycogen in the liver

H 2.7 Explain how blood glucose levels are regulated by glucagon and glycogen causing the conversion of glycogen to glucose

Type 1 Diabetes

2.8 Recall that Type 1 diabetes is caused by a lack of insulin

2.9 Explain how Type 1 diabetes can be controlled, including the roles of diet and injection of insulin usually into the subcutaneous fat

2.10 Explain how, in Type 1 diabetes, the level of physical activity and diet affectthe amount of insulin required

Information on next slide

• People who have diabetes cannot control …their blood glucose / sugar levels.

• Low blood glucose levels can cause …unconsciousness. • High blood glucose levels can cause …tiredness, damage to

organs such as eyes. • If there is too much blood glucose the kidneys …get rid of it in

the urine. • Type 1 diabetes is caused by the pancreas not producing

insulin. • Type 1 diabetes can be controlled by …injecting insulin into

the subcutaneous fat layer beneath the skin. • This works by…absorbing the insulin quickly and easily then

spreading into blood vessels and travelling in the blood. • Type 1 diabetics can also try to control their own blood

glucose levels by not eating too many carbohydrates (starchy or sugary foods) and also exercising.

Type 2 Diabetes2.11 Recall that Type 2 diabetes is caused by a person becoming resistant to insulin

2.12 Explain how Type 2 diabetes can be controlled by diet and physical activity

2.13 Evaluate the correlation between obesity (including calculations of BMI) and Type2 diabetes

Type 2 diabetes is caused by …the liver cells not responding (resistant) to insulin. The risk factors for Type 2 diabetes are …age (getting older), not taking exercise, being obese and eating a high fat diet. Type 2 diabetes can be controlled by … a doctor may prescribe medication. Regular exercise and eating a healthy balanced diet low in fat or carbohydrates. This works by…exercise increases respiration which uses glucose from the blood so blood glucose decreases. If a diet is low in fat then the person may begin to lose weight. A diet low in carbohydrates will contain less glucose so less glucose goes into the blood.

Doctors class someone as being obese if they …have a BMI of over 30.

This is calculated by using the equation:

Plant Hormones2.14 Explain how plant growth substances (hormones) bring about:

a positivism phototropism in shootsb positive gravitropism (geotropism) in roots

Tropism – growing towards or away from a stimulus. Phototropism - growing towards or away from light. (positive phototropism is growing towards light, negative phototropism is growing away from light. Gravitropism (or geotropism) – growing towards or away from gravity. Auxin – a plant hormone that affects the elongation of cells in plants. Negative tropism – Growing away from a stimulus.Negative phototropism - Growing away from light.Positive tropism- Growing towards a stimulus. Positive phototropism- Growing towards light. Negative gravitropism- Growing away from gravity. Positive gravitropism- Growing towards gravity.

What is it to be positive phototropic and negative phototropic?

Are shoots positively gravitropic and negative gravitropic? Are they positively phototropic and negative phototropic

Shoots are …positively phototropic and negatively gravitrophic.Why? because …they grow towards light and away from

gravity.

What are roots? Roots are …positively geotrophic. And negatively phototropic.

Why because …they grow towards gravity and away from light.

ALL: Define the words tropism, phototropism and gravitropism”. (Grade D)MOST: Establish how auxins work in shoot tips and roots to cause positive phototropism (Grade

C)SOME: Explain fully, including the role of auxin in positive gravitropism and giberellins in plant

growth, how plant hormones work to help the plant grow more successfully (Grade B)

So what happens? And why is this useful?1. Auxin produced in

shoot tip. 2. Travels to shaded part

of the shoot.3. Causes cells to

elongate.4. Shoot bends towards

the light.

This enables more light to be captured for photosynthesis.

2.15 Explain how auxins bring about shoot curvature using cell elongation

Roots grow down – this is caused by plant hormones called auxins.




1. Auxin produced in root tip. 2. Travels to underside of the

root.3. Inhibits (stops or slows)

cell elongation here.4. Root bends towards

gravity. This enables roots to grow down to collect more water and nutrients for grow.Also anchors the plant into the ground.

Gibberellins – another plant hormone• Some seeds need a period of dark or cold before they

germinate (start to grow).• What happens after this dark / cold period?

• After the dark / cold period gibberellins (plant hormones) are released. They cause the starch in the seed to be turned into sugars that the seed uses for energy to grow.

• Gibberellins also stimulates flower and fruit production.




Auxin experiment

Explain why the shoots in the experiments shown in Figure D have or have not bent towards the light source.

A : A No bending because auxins, which cause bending, are produced in the tip of the shoot and this has been removed.

B No bending because tip of shoot needs to be exposed to light in order to get the auxins to move. The cap stops the light.

C Bending because tip of shoot needs to be exposed to light in order to get the auxinsto move. The cap still allows light to reach the shoot tip.

D Bending because tip of root needs to be exposed to light in order to get the auxins to move. The base of the shoot is not affected by light and has no effect on what happens in the root tip. E Bending because the auxins need to move down from the tip to have their effect, and they can diffuse through the jelly block. F No bending because the auxins need to move down from the tip to have their effect, and their movement is blocked by the impermeable plasticG Auxins move out of the jelly block and into the shoot, causing cell elongation and so bending on that side. negative phototropism.

Higher only 2.18 Demonstrate an understanding of the uses of plant hormones, including:

a selective weedkillers

b rooting powder

c seedless fruit

d fruit ripening

B1 Topic 2 Core GCSE - Holgate Ac Papers/B1 Topic 2 Revisio… · B1 Topic 2 Core GCSE The bare...

Documents

Transcript of B1 Topic 2 Core GCSE - Holgate Ac Papers/B1 Topic 2 Revisio… · B1 Topic 2 Core GCSE The bare...