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Biology

A Level

Describe how a new phenotype may arise in the population and increase in frequency using the theory of natural selection.

A mutation arises in an individual that confers a selective advantage. The phenotype the mutation produces is selected for by natural selection and so the individual survives to reproductive age. This m...

Answered by Katy A. • Biology tutor

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What is the Krebs cycle?

Photosynthesis has four stages:

Glycolysis.
The Link Reaction.

3. The Krebs Cycle.

Oxidative Phosphorylation...

Answered by Megan S. • Biology tutor

6342 Views

Name the first stage of respiration. How many net ATP molecules are produced?

Glycolysis - 2 ATPs (net) are produced. 2 are input into the reaction and 4 are produced as a result.

Answered by Lydia W. • Biology tutor

2672 Views

How does the body's response to a second infection by a bacterial pathogen differ from the first? (3 marks)

faster response due to the presence of memory cells

there are many more cells specific for this pathogen therefore clonal selection and expansion of B cells is quicker

BT
Answered by Beth T. • Biology tutor
2652 Views

Explain the role of inorganic ions in the body.

The resting membrane potential of cells is maintained by the actions of Na+ and K+. A resting cell is impermeable to Na+ so the concentration of Na+ is greater outside the cell than in it. However the cel...

Answered by Callum D. • Biology tutor

7185 Views