Top answers

Describe how phagocytosis of a virus leads to presentation of its antigens

Firstly, specialised white blood cells, known as macrophages, detect the virus in the blood stream. This is due to the virus releasing chemicals, and in the process of chemotaxis, the macrophage follows this...
JL
Answered by Jennifer L. • Biology tutor
3648 Views

How is an action potential transmitted across a synapse?

Looking at a cholinergic synapse:The action potential arrives at the presynaptic knob. This causes voltage-gated calcium ion channels to open, and calcium ions to diffuse into the presynaptic knob.The influx...
MM
Answered by Megan M. • Biology tutor
3560 Views

Rat poison is not always an effective rodenticide and will reduce in effectiveness with age. Explain why

Any type of poison is not guaranteed to eradicate rats entirely. This is due to genetic mutations allowing an individual to be immune to certain types of toxins. Whilst the population may be eradicated, if e...
CD
Answered by Charles D. • Biology tutor
2970 Views

Describe the theory of enzyme action.

Enzymes are biological catalysts that speed up the rate of biological reactions. The enzyme active site and the substrate are complimentary in shape. This allows the substrate to bind to the active site of t...
CD
Answered by Catherine D. • Biology tutor
9367 Views

Outline the role of phagocytic white blood cells in defence against pathogens

Phagocytes are part of the innate immune system. They are primarily responsible for clearing extracellular infections e.g. bacteria or fungus, by recognising and ingesting the pathogen. Typically, pathogens ...
AR
Answered by Adeline R. • Biology tutor
2544 Views