Edexcel GCSE Biology 2BIO1 - Unit B2 Topic 2

Class notes for the 2011 Edexcel GCSE

Biology Unit B2 Topic 2 - Organisms and energy

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  • Created on: 16-10-12 13:25
Preview of Edexcel GCSE Biology 2BIO1 - Unit B2 Topic 2

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B2 Topic 1 Respiration
Topic 2 Photosynthesis
Science B3 Topic 3 Fieldwork
The process by which cells release energy from glucose
Where does respiration take place?
What happens during respiration?
When does respiration happen?
Why do living things need respiration?

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Page 2

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Why do living things need respiration?
Uses of energy:
· temperature control
· muscle movement
· sending nerve impulses
· transport around the body
· growth and repair
· absorbing food
Why is intensive farming a cheaper alternative to
free range farming?
2…read more

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When does respiration happen?
· Occurs all the time
· Some cells respire more than others e.g. muscle cells,
brain cells
· Rate increases when doing physical exercise
What happens during respiration?
Aerobic In the presence of oxygen
glucose + oxygen carbon + water + energy
Anaerobic Respiration The point at which your heart can no
longer supply the muscles fast enough.
glucose lactic acid + energy
· Does not produce much energy (0.8kJ/g compared with
16.…read more

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Unit of
Where does respiration take place?
4…read more

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Gas Exchange
We need to get oxygen from the air into the blood, and we
need to remove waste carbon dioxide from the blood into
the air. Moving gases like this is called gas exchange. The
alveoli are adapted to make gas exchange in lungs happen
easily and efficiently.…read more

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The gases move by diffusion from where they have a high concentration
to where they have a low concentration:
Oxygen diffuses from the air in the alveoli into the blood.
Carbon dioxide diffuses from the blood into the air in the alveoli.
Complete the diagram to show gas exchange in the lungs.…read more

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Investigating Gas Exchange
The purpose of this experiment is to measure the relative
amounts of carbon dioxide in the air we exhale while at rest
and after exercise.
How do you think the amounts of carbon dioxide will compare
between at rest and after exercising?
1. Sit quietly and take a normal breath.
2. Insert the straw into a cup containing 50 ml of water blow
through the straw.
3. Add four drops of universal solution to the flask and stir.
4.…read more

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1. What does the number of drops of ammonia tell us about the
amount of carbon dioxide exhaled?
The greater number of drops of ammonia, the greater amount of
carbon dioxide exhaled.
2. What have you discovered about the effect of exercise on the
amount of carbon dioxide in your exhaled air?
One minute of exercise decreases the amount of carbon dioxide
3. How do your results compare to your predictions?
4.…read more

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Cardiac Output
The amount of blood circulated by the heart. Depends upon heart
rate and stroke volume. - number of
Heart Rate
times the heart beats per
Cardiac Heart minute
= x Stroke Volume - Volume of
Output Rate Volume
blood pumped out of the
heart on each beat
At rest, an athletes heart rate is 60 beats per minute, and stroke
volume is 76 cm3. During exercise these increase to 160 beats per
minute and 105 cm3. Calculate the increase in cardiac output.…read more

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The more active a cell the more energy it needs so respiration
must happen at an increased rate.
Plot the results for Kelly and Rutvi to show how their
breathing and heart rates change during and after exercise
Which person has the fastest recovery time?
Explain your answer
Explain the graph and what it can tell you about the
effect of exercise.…read more



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