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Explain how bacteria can become resistant to antibiotics.

Sometimes, a chance mutation in bacterial DNA allows certain bacteria to become resistant to certain types of antibiotic. When an antibiotic is given, only the non-resistant strains of bacteria will be kille...
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Answered by Rachel A. • Biology tutor
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If fetal haemoglobin is so good at binding oxygen, why aren't we adapted to keep it until adulthood?

Firstly, although fetal haemoglobin is better at binding oxygen, it is also worse at giving up oxygen to the tissues which need it. Secondly, if adults had haemoglobin with the same affinity for oxygen as fe...
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Answered by Amber B. • Biology tutor
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Describe the stages in viral replication

The first stage in viral replication occurs when a virus attaches to the surface of a host cell. The viral nucleic acid (VNA) then enters the cell. The VNA then takes over the cell, altering the metabolism o...
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Answered by Tara F. • Biology tutor
15769 Views

I often understand the question and think I have answered it correctly, but I don't get all the marks for my answer. What am I doing wrong?

One of the things that you need to remember about Biology A Level is that you have to memorise the key points of the mark scheme. Something that I consistently struggled with when I was doing past papers is ...
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Answered by Shannon M. • Biology tutor
7030 Views

Describe the pathway of electrical activity in the heart during contraction.

The sino-atrial node (SAN) is located within the wall of the right atrium, and acts like a pacemaker (it instigates the rhythms of the heart). The SAN sends out regular waves of electrical activity along the...
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Answered by Jack R. • Biology tutor
7102 Views