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Biology

A Level

How many chromosomes dies each cell of the human body have ?

All human body cells have 23 pairs of chromosomes (46 total), 22 pair of autosomes and 1 pair of sex chromosomes.

However, sperm and egg cells only have one set of chromosomes (23 total).

Answered by Helen K. • Biology tutor

5019 Views

What are three differences between DNA and RNA? ( 3 marks)

RNA is single stranded whereas DNA is double stranded - RNA has the bases A,G,C and U whereas DNA has the bases A,G,C and T - An RNA nucleotide has ribose as its sugar component whereas a DNA nucleo...

Answered by Prahalad N. • Biology tutor

2814 Views

It has been suggested that smoking, an epigenetic factor can lead to tumour growth and cancer. Use your knowledge of the epigenome and its structure to explain how this could occur. [5 marks]

Marking Scheme: MP1: Define epigenome- layers of chemical tags covering the DNA and histone protein complex MP2: Increased Methylation of DNA molecule MP...

Answered by Hannah H. • Biology tutor

2632 Views

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

5734 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

49847 Views