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Biology

A Level

A patient is infected by a pathogen. Explain the process of the imitation of the immune response (5 marks) The paitent was prescribed antibiotics yet their symptoms did not improve. What can you infer from this? (1 mark)?

5 of the following...
Pathogen has antigens on its surface that are recognised as foreign by the immune system
T helper cells stimulate cytotoxic T cells, B cells and phagocytes (or lysosomes)

Answered by Harriett F. • Biology tutor

2707 Views

Explain the steps of action potential across an axon membrane?

Resting Potential-3 Na+ out, 2 K+ in.Action potential- A stimulus is detected causing Sodium voltage gated channels to open, leading to Na+ to flow into the axon and therefor making the inside less negati...

Answered by Isabelle J. • Biology tutor

3300 Views

Why is DNA replication semi-conservative?

DNA is in a double helix structure, meaning there are two strands. When we need DNA to replicate, for example when a cell divides during growth, the strands undergo unwinding. This process is done by an e...

Answered by Emma C. • Biology tutor

5477 Views

What is the difference between mitosis and meiosis?

Mitosis is the process used by normal body cells for everyday replication to maintain a healthy body, for example tissue regeneration. On the other hand, meiosis is the process whereby the gametes, sperm ...

Answered by Clare G. • Biology tutor

3903 Views

What are reflexes and how do they produce movement quickly?

A reflex occurs when movement is produced without conscious thought. They can therefore be described as autonomic and produce movement faster than voluntary movements (which do require conscious thought)....

Answered by Samuel W. • Biology tutor

3264 Views