Top answers

Explain the Theory of Natural Selection

There are four key points to natural selection: first, that individuals in all species show variation second, that this variation is genetic and therefore heritable third, that certain characteristics give t...
JW
Answered by Josie W. • Biology tutor
4695 Views

Why does a mutation in the genetic code change the structure of a haemoglobin molecule?

The mutation alters the base sequence which therefore changes the sequence of Amino Acids coded for (the primary structure). Now the sequence of Amino Acids has been changed when bonds form and folding occur...
HM
Answered by Harry M. • Biology tutor
4516 Views

What are the differences in the structures of arteries and veins?

Arteries have a much narrower lumen (the middle bit of space) and a much thicker wall. This is due to the fact that arterial walls contain more muscle and elastic fibres, than those of veins. Reason: Arterie...
MC
Answered by Matilda C. • Biology tutor
4510 Views

Describe how water moves from roots to the leaves.

Water moves from the roots to the leaves through tissue called the xylem, in a process called transpiration. As water evaporates out of the leaf, more water is 'pulled upwards' to replace what has been lost.
PS
Answered by Philippa S. • Biology tutor
62079 Views

One form of muscle disease is caused by a mutant myosin allele. It prevents myosin from binding to other myosin molecules, thus preventing contraction. Suggest why.

Sarcomeres are formed of myosin and actin filaments which are interleaved. If myosin cannot bind to each other then thick filaments cannot be formed. Thus, there is nothing to anchor myosin so actin cannot b...
JW
Answered by Jade W. • Biology tutor
11551 Views