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Biology
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Describe how water moves from roots to the leaves.

Water moves from the roots to the leaves through tissue called the xylem, in a process called transpiration. As water evaporates out of the leaf, more water is 'pulled upwards' to replace what has been lo...

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Answered by Philippa S. Biology tutor
61397 Views

Maltose is hydrolysed by the enzyme maltase. Explain why maltase catalyses only this reaction.

The enzyme maltose will always fold into in a tertiary structure, which results in the active site being in a specific shape that only the substrate maltase can bind to. This is often illustrated using th...

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Answered by Philippa S. Biology tutor
27015 Views

Describe how the rhythmicity of the heart is established and maintained with respect to the different stages in the cardiac cycle (6 marks)

The Sinoatrial Node (SAN) generates the wave of excitation/ Action potential (AP).

The AP spreads across the atrial walls, stimulating the myocardial cells to contract This initiates the atrial sys...

HM
Answered by Haider M. Biology tutor
6669 Views

Explain how the structure of RNA differs from that of DNA? (3 marks)

RNA is single-stranded, DNA is double-stranded.

RNA contains the base Uracil, DNA contains thymine instead.

RNA contains the sugar Ribose, DNA has Deoxyribose instead.

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Answered by Haider M. Biology tutor
21680 Views

What are the events in synaptic transmission?

  1. The presynaptic action potential reaches the synaptic knob. 2) The terminal is depolarised. 3) Voltage gated calcium channels in the presynaptic knob open. 4) Calcium enters through the calcium chan...
TD
30914 Views

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