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Explain the sequence of events that occur in the control of the cardiac cycle.

The sino-atrial node depolarises which causes a wave of excitation to pass through the atria (right prior to left) before reaching the atrio-ventricular node. The wave of excitation causes systole of the ...

Answered by Hannah G. • Biology tutor

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What is the difference between haploid and diploid cells? (2 Marks)

Diploid cells contain 2 sets of chromosomes (23 pairs of chromosomes) e.g. body cells. Haploid cells contain half the amount of chromosomes as diploid cells (only

Answered by Katie D. • Biology tutor

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Describe how a sperm cell is adapted to its role (4 marks).

The role of a sperm cell is to fertilise an egg cell and pass on genetic material. The nucleus of the sperm cell contains the male genetic material/DNA. The head of the sperm cell contains many mitochondr...

Answered by Katie D. • Biology tutor

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Describe the stages of the mitotic cell cycle, explaining the appearance of cells at each stage.

The cell cycle can be broken into two. When the cell is replicating its DNA and preparing for division, it is in interphase. Interphase cells have a nucleus with chromosomes arranged as c...

Answered by Hannah M. • Biology tutor

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Outline the role and organisation of the autonomic nervous system in mammals

The are two main areas of the autonomic nervous system are the sympathetic and the parasympathetic nervous systems. These are contrasting pathways and their main function is to regulate internal organ f...

Answered by Christopher T. • Biology tutor

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