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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 MP3: enzymes attracted to complex/ acetyl groups removed...
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Answered by Hannah H. • Biology tutor
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The Polar Bear is the largest species of bear in the world. With regards to adaptation, suggest a reason for this.

The habitat of the Polar Bears is the arctic. This is a much colder climate than the other species of bear found in the wild. Therefore the Polar Bear has adapted to live in this colder climate. One adaptati...
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Answered by Zia F. • Biology tutor
6708 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 trans...
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Answered by Zia F. • Biology tutor
6875 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 li...
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Answered by Ben S. • Biology tutor
52530 Views

Describe and explain what is meant by ‘natural selection’. (4 marks)

Natural selection is a theory devised by Charles Dickens. Due to the existent of alleles and genetic variation, some organisms will be better adapted for survival in their given habitat. As a result of this ...
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Answered by Charlotte G. • Biology tutor
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