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Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs. Details of breathing are not required. (AQA Biol. 2016)

Oxygen diffuses from the air where it is present at a higher concentration and pressure, to the lungs where it is at a lower concentration and pressure - we say it moves 'down' these gradients; high to low. ...
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Answered by David M. • Biology tutor
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Explain how you may test a plant specimen for starch?

This can be done via the iodine test- you would use an iodine solution and pipette this unto the plant cutting. For a positive test, the specimen would turn into a blue/ black colour in the presence of iodine.
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Answered by Isabella M. • Biology tutor
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Draw a punnet square between two carriers of cystic fibrosis and from this, work out the odds of their child being affected with CF.

I will draw the punnet square on the whiteboard. After drawing it, the ratio of CC:Cc:cc will be 1:2:1 As a recessive gene, only people with the homozygous recessive genotype (cc) will have cystic fibrosis s...
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Answered by Maddie B. • Biology tutor
4687 Views

Describe what is meant by the double circulation system of the heart.

The double circulatory system refers to the heart having two, connected, closed circuits. The first goes from the right ventricle of the heart to the lungs and back to heart via the left atrium. The second p...
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Answered by Ibrahim M. • Biology tutor
9656 Views

Describe the process of semi-conservative replication.

DNA is a double-stranded molecule with a base unit on each side held together by hydrogen bonds. A binds to T and C binds to G. DNA polymerase facilitates the localised breaking of these hydrogen bonds. Free...
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Answered by Nick S. • Biology tutor
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