Top answers

Describe the structure of the heart and its function in the human circulatory system.

The heart is a muscular organ composed of 4 chambers ; the left atrium and right atrium (pl. atria ) and the left ventricle and right ventricle (pl. ventricles ). The left and right sides of the heart are se...
AO
Answered by Aine O. • Biology tutor
18432 Views

How are veins and arteries adapted to the transport of blood?

Artery walls are made up of smooth muscle tissue and a thick elastic layer which allows them to expand and contract easily, coping with the changes in blood volume that occur with each heartbeat. The muscle ...
AL
Answered by Amélie L. • Biology tutor
3929 Views

Describe the process of DNA replication

In DNA replication, first the hydrogen bonds between the nitrogenous bases are broken catalysed by the enzyme helicase, causing the DNA double helix to unwind and unzip, leaving the nitrogenous bases exposed...
HN
Answered by Helena N. • Biology tutor
15355 Views

Describe the process of phagocytosis and how antigen presentation leads to antibody production (9 marks)

White cell (macrophage/neutrophil) detects bacteria antigen by binding to cell surface receptorsWhite cell engulfs bacteria (this is endocytosis), bacteria is held in a phagosome Lysosomes enter phagosome an...
CR
Answered by Caine R. • Biology tutor
3503 Views

Tobacco smoke contains carbon monoxide. Explain how carbon monoxide affects a persons ability to exercise.

Carbon monoxide is a poisonous gas. It binds to haemoglobin in red blood cells irreversibly. This means that less oxygen can be carried by red blood cells. As oxygen delivery decreases to muscles and so less...
HP
Answered by Hersh P. • Biology tutor
5200 Views