Top answers

An extract of DNA contains 4000 base pairs. The extract is identified to contain 300 guanine bases. How many adenine bases can be found in the DNA extract?.

3700
KS
2516 Views

Explain how the physical properties of water enable organisms to survive over a range of temperatures.

Water has a very high specific heat capacity due to the collective forces of the many hydrogen bonds. A lot of energy goes into breaking these bonds rather than raising the temperature of the water, hence pr...
AB
Answered by Arunima B. • Biology tutor
24202 Views

Tetrodotoxin (TTX) is a chemical found in pufferfish which binds to voltage-gated sodium channels causing inactivation via a conformational change. Poisoning can result in paralysis leading to death. How might this occur? (4 marks)

This question asks about nerve action potential generation. There are a couple of clues - these include 'voltage-gated sodium channels' and 'paralysis' which suggests the idea of failure of impulse transmiss...
RA
Answered by Rafee A. • Biology tutor
5547 Views

Describe methods of solute transport across a cell membrane.

For non-polar small molecules simple diffusion down a concentration gradient through the phospholipid bilayer is possible as it is soluble in the hydrophobic fatty acid tails of the membrane. An example of t...
AF
Answered by Ayano F. • Biology tutor
3809 Views

Describe the process of natural selection

Within a population of a species there will be variation between individuals. These variations arise because of mutations causing differences in alleles and phenotypes. Some individuals will have an allele w...
HR
Answered by Harry R. • Biology tutor
2864 Views