Search our library of Biology A Level questions

Top answers

Biology

A Level

How are impulses propagated along an axon?

The axon is polarised at rest. This means that there is a negative charge within the axon and a positive charge outside. This resting polarisation is caused by a Na/K pump that uses active transport to tr...

Answered by Zia F. • Biology tutor

5236 Views

Describe and explain the process of protein synthesis. (6 marks)

Transcription is the first step of protein synthesis. This involves DNA helicase unwinding the double stranded DNA, and complementary mRNA binding to the DNA bases with the help of the DNA polymerase. DNA...

Answered by Ben S. • Biology tutor

47846 Views

Describe and explain how an action potential is generated (6 marks)

The membrane is at resting potential, -60mV inside compared to outside. It is polarised. 2. Na+ ion channels open and some Na+ ions diffuse into the neurone. 3. The membrane
RE
Answered by Rokshan E. • Biology tutor
9919 Views

What is the difference between gene transcription and gene translation?

Both of these are key steps in gene expression to obtain proteins.

Transcription occurs first. It is the process, happening in the nucleus, where a specific segment of DNA is copied into RNA to for...

Answered by Madeleine G. • Biology tutor

6599 Views

Enzymes known as endopeptidases aid digestion of proteins in the small intestine. why do they only bind to amino acids and not other foods ingested?

Model Answer: this is because enzymes are a protein with a specific tertiary structure which have an active site that is complementary to the substrate (in this case the amino acids of a protein) ultimate...

Answered by Charlotte B. • Biology tutor

2426 Views