ks4 respiration

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KS4 Biology

Respiration


Contents

Respiration

Anaerobic respiration

Summary activities

Releasing energy

Rate of respiration

Aerobic respiration


Energy for life

Every living cell in your body needs energy. The average adult has about 50 million million cells – that’s a lot of energy!

In body cells, the energy needed for life comes from the chemical energy stored in glucose.

energy

Where does all this energy come from?


What is needed for releasing energy?

What other substance is needed for energy to be released from this fuel?

Burning is a chemical reaction in which energy is released in the form of heat.

?fuel oxygen


What does the body need for releasing energy?

The body’s energy-releasing process depends on the digestive system and the breathing system.

How does the body’s energy-releasing process compare with releasing energy from wood?

What are the substances supplied by these systems?

? ??glucose is the fuel

supplied by the digestive system

oxygenoxygen is supplied by

the breathing system


Glucose and oxygen enter the body in different ways,

Where are these substances needed and how do they get there?

Glucose and oxygen are transported around the body by the circulatory system.

Blood flowing in blood vessels takes these important substances to where they are needed – the body’s cells.

Transport around the body

but are needed at the same destinations.


In the body’s cells, the chemical energy stored in glucose is usually released by a chemical reaction with oxygen.

The body’s energy-releasing process

What is this energy-releasing process called?

glucoseoxygen

energy

respiration

Why does every living cell need a constant supply of glucose and oxygen?


Contents

Respiration


Summary activities

Releasing energy

Rate of respiration

Aerobic respiration


Respiration is the process used by the body’s cells to release the chemical energy stored in glucose.

When oxygen is involved in this energy-releasing process, it is called aerobic respiration.

What do you think aerobic means?

Aerobic respiration is an efficient process that generates enough energy to supply the whole body.

Our bodies perform aerobic respiration most of the time, as long as the supply of oxygen remains high enough.

What is aerobic respiration?

aerobic = ‘with oxygen’


Waste products of aerobic respiration

Breathing in obtains the oxygen needed for aerobic respiration. How does the body get rid of the waste products?

Breathing out removes the waste products of aerobic respiration.

How can the waste products of this reaction be identified?

Aerobic respiration releases energy that is useful.

This process is a chemical reaction between glucose and oxygen which also generates waste products.

?glucose oxygen ? energy


Waste products – limewater test

Limewater turns cloudy when carbon dioxide passes through. What does this test tell you about aerobic respiration?

One waste product of aerobic respiration must be…

2. Blow gently through a straw into the limewater.

3. After a short time, the limewater turns cloudy.

limewaterstraw

1. Take a test tube of limewater,

a clear liquid.

…carbon dioxide.


Waste products – see your breath test

Water vapour condenses into a liquid and becomes visible. What does this test tell you about aerobic respiration?

Another waste product of aerobic respiration must be…

What happens when you breathe out onto a cold pane of glass?

What happens when you breathe out on a freezing cold day?

In both cases, you can see some of the air that you have breathed out. Why?

water vapour

…water.


Aerobic respiration: summary

Summarize the process of aerobic respiration in a sentence.

Aerobic respiration is a chemical reaction so it can also be summarized in a word equation.

What is the word equation for this vital chemical reaction?

Aerobic respiration is a chemical reaction that takes place in all living cells,

in which glucose reacts with oxygen to produce carbon dioxide and water

and stored chemical energy is released.


Aerobic respiration: word equation

carbondioxideglucose oxygen water

carbondioxide

wateroxygenglucose

energy

energy


Aerobic respiration: word equation activity


Aerobic respiration: quiz


Contents

Respiration


Summary activities

Releasing energy

Rate of respiration

Aerobic respiration


The rate of respiration

Aerobic respiration is a chemical reaction and so has a rate.

Is the rate of this reaction always the same?

Your body requires different amounts of energy depending on how active you are. So the rate of aerobic respiration changes depending on the amount of energy needed.

During what type of activities, does the rate of aerobic respiration increase so that more energy can be released?

carbondioxideglucose oxygen water energy


When does the body need to release more energy?

How much energy is needed?

During which type of activities is the rate of aerobic respiration higher?

not very active = low energy requirements

very active = high energy requirements


Different energy needs

How does the body respond to these different rates of aerobic respiration?

high energy need

These extremely different activities both need energy from aerobic respiration but is the rate of this reaction the same?

low energy need= low rate of

aerobic respiration= high rate of

aerobic respiration


The body’s response to low energy needs

During sleep, the body’s energy needs are low and so the rate of aerobic respiration is slow but steady.

How does this affect the amount of glucose and oxygen needed?

How does this affect the heart rate and breathing rate?

Under these resting conditions, the body has plenty of time to inhale oxygen and the blood is able to supply enough

low energy need

low rate of aerobic

respiration

low demand for glucose and oxygen

slow heartand breathing

rates

glucose and oxygen to the body’s cells.


The body’s response to high energy needs

During running, the body’s energy needs are high and so the rate of respiration increases to meet this demand.

How does this affect the amount of glucose and oxygen needed?

How does this affect the heart rate and breathing rate?

high energy need

high rate of aerobic

respiration

high demand for glucose and oxygen

fast heartand breathing

rates

Under these tougher conditions, the body has to work hard to supply enough glucose and oxygen to the body’s cellsfor aerobic respiration to produce enough energy.


Contents

Respiration


Summary activities

Releasing energy

Rate of respiration

Aerobic respiration


Not enough oxygen!

Most of the time the body’s cells has a good supply of oxygen and is able to release energy by aerobic respiration.


Sometimes, during strenuous exercise, the breathing rate and blood flow are not able to deliver enough oxygento the body’s cells.

How does this affect the release of energy?


Not enough oxygen!

If the body is not able to supply enough oxygen, aerobic respiration cannot take place and energy is not released!


The body still has a supply of glucose, so how does it continue to get energy?

When there is not enough oxygen, energy can still be released from glucose by another type of respiration called anaerobic respiration.


Respiration without oxygen

During anaerobic respiration, glucose breaks down into a substance called lactic acid and some energy is released.

What do you think anaerobic means?

lacticacid energyglucose

Our bodies can only release energy without oxygen for a short period of time.

anaerobic = ‘without oxygen’

Anaerobic respiration involves the incomplete breakdown of glucose and so releases less energy than aerobic respiration.


Anaerobic respiration: word equation

lacticacidglucose

lacticacidglucose

energy

energy


The problems with anaerobic respiration

Anaerobic respiration is useful to the body when energy is needed in a hurry.

There are two problems with anaerobic respiration:

Anaerobic respiration releases much less energy from glucose compared to aerobic respiration.

Lactic acid is a poisonous waste product.

Why is anaerobic respiration not the best way to get energy from glucose?

lacticacidglucose energy


Why is lactic acid so harmful?

Lactic acid is the product of anaerobic respiration and is harmful because it can stop muscles from doing their job.

If lactic acid builds up in muscle cells, it stops muscles from contracting and relaxing and they become fatigued.

The muscles ache and the body experiences cramp, which forces the body to stop what it is doing and rest.

Why can anaerobic respiration only be carried out for short periods of time?


Recovery and getting rid of lactic acid

After anaerobic respiration, the body is in recovery and must get rid lactic acid.

The body is now at rest but the breathing rate and heart rate remain high. Why does this happen?

carbondioxide

lacticacid oxygen water

Why do the breathing and heart rates return to normal after a few minutes of recovery?

lacticacid energyglucose

Oxygen is needed to get rid of lactic acid by turning it into carbon dioxide and water.


Oxygen debt – build up

During aerobic respiration, muscles get energy from glucose by ‘paying’ for it with oxygen.

During anaerobic respiration, muscles get energy from glucose but do not ‘pay’ for it with oxygen.


lacticacidglucose energy

When and how is this oxygen debt ‘paid off’?

This means that an oxygen debt is created.


It is the oxygen needed to get rid of lactic acid that pays back the oxygen debt.

Oxygen debt – pay off

The oxygen debt caused by anaerobic respiration is paid off during the recovery period after exercise.

carbondioxide

lacticacid oxygen water

oxygen to pay back

‘oxygen debt’

When is the oxygen debt completely paid off?


Anaerobic respiration: word equation activity


Contents

Respiration


Summary activities

Releasing energy

Rate of respiration

Aerobic respiration


Which type of respiration?


Multiple-choice quiz

ks4 respiration

Science