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How do vaccines prevent certain diseases?

Vaccines introduce a dead, inactive or altered form of a pathogen (a microbe that causes an infectious disease) into the body. These pathogens have antigens, which have a shape specific to that pathogen. The...
AM
Answered by Alice M. • Biology tutor
3124 Views

Describe the structure of proteins (5)

The primary structure of proteins consist of the sequence of amino acids that are joined by peptide bonds. These amino acids are joined together via a condensation reaction. The secondary structure is formed...
SK
Answered by Saiful K. • Biology tutor
21936 Views

What are the differences between directional and stabilising selection? Give an example of each.

In directional (a.k.a. adaptive) selection, one extreme of a population has a selective advantage i.e. is fitter than other individuals of the population. This causes a directional shift towards this extreme...
BS
Answered by Ben S. • Biology tutor
5516 Views

What’s the difference between mitosis and meiosis?

Mitosis is a type of cell division in which a cell divides to form two cells that are genetically identical to the original cell and each other. During the cell cycle, the cell’s amount of genetic material i...
RD
Answered by Rebecca D. • Biology tutor
3897 Views

A student wants to study red blood cells beneath a microscope. She is not sure which solution she should use to observe such cells. In solution A, she sees figure A (plasmolysis) and in solution B she sees nothing. Can you explain her observations?

Solution A - plasmolysis. The red blood cells were in an hypertonic solution (solution had a lower water potential than the red blood cells due to increased concentration of solute) thus water molecules move...
RF
Answered by Roxy F. • Biology tutor
3549 Views