Mr Exham IGCSE - Respiration

MAKING SENSE OFRESPIRATION

IGCSE Biology1.1 Life Processes –

Respiration

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Learning Objectives• Can you remember how respiration releases energy?• Can you write out the word equation, and the

balanced symbol equation, for aerobic respiration?• Can you write out the word equation for anaerobic

respiration?• What are the differences between aerobic and

anaerobic respiration?• Can you describe simple experiments to show that

carbon dioxide and heat are produced by respiring seeds or other suitable living organisms?


Respiration• Respiration is a chemical reaction that

happens in all our cells to release energy.• This can be used for

– Contraction of muscle cells, producing movement– Active transport of molecules and ions– Building large molecules, such as proteins– Cell division

• The reaction also releases some heat which is used to maintain steady body temperature.


Respiration• Your cells can carry out two types of

respiration. • One with oxygen which is called aerobic

respiration and one without oxygen called anaerobic respiration.


Aerobic Respiration

Glucose Oxygen Carbon Dioxide+ + Water Energy+


Aerobic Respiration


C6H12O6 + 6O2 6CO2 + 6H20 + Energy


Aerobic Respiration


C6H12O6 + 6O2 6CO2 + 6H20 + Energy


• Respiration using oxygen.• Occurs in the mitochondria of a cell.

Mitochondria

Anaerobic Respiration• Respiration without oxygen.• We shall look at examples in two types of cell.


Anaerobic Respiration• Respiration without oxygen.


YEAST

Anaerobic Respiration• Respiration without oxygen.

YEAST


MUSCLE

Anaerobic respiration in yeast cells

• Also known as FERMENTATION.• Yeast cells are single celled fungi.• Used for commercial purposes such as

brewing.


Anaerobic respiration in yeast cells

• Also known as FERMENTATION.• Yeast cells are single celled fungi.• Used for commercial purposes such as

brewing.


Glucose Ethanol + Carbon Dioxide (+ some energy)

Anaerobic respiration in muscle cells

• Occurs when the blood cannot reach the muscles fast enough to supply them with the required oxygen.


Anaerobic respiration in muscle cells

• Occurs when the blood cannot reach the muscles fast enough to supply them with the required oxygen.


Glucose Lactic Acid (+ some energy)

Oxygen Debt• Anaerobic respiration provides enough energy to

keep the muscles working for a short time.• However lactic acid builds up in the blood which

causes cramps.• The lactic acid has to be broken down using

oxygen.• The volume of oxygen needed to completely

oxidise the lactic acid that builds up in the body during anaerobic respiration is called oxygen debt.


Aerobic or anaerobicAerobic AnaerobicUses oxygen No oxygenOccurs in mitochondria of cell Occurs in cytoplasm of cellReleases lots of energy Releases only a small amount of energyCarbon dioxide and water is produced Lactic acid or ethanol is produced


Respiration experiments• This apparatus can be used to investigate how small

living organisms respire such as woodlice, maggots or germinating seeds.

Hydrogencarbonate indicator – This will change colour from red to yellow when the carbon dioxide level increases due to respiration.

Gauze

Living organisms


Respiration experiments

Boiled seedsGerminating seeds

Cotton wool

Thermometer

The germinating seeds are respiring and therefore releasing heat. The boiled seeds have been killed and are therefore not respiring anymore.

Thermal flask


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Mr Exham IGCSE - Respiration