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Biology

A Level

Briefly describe the main differences between fast and slow twitch muscles and how does this relate to their specific functions.

First of all, slow-twitch (type I) muscle fibres have a large number of mitochondria allowing them to carry out aerobic respiration at a high rate by providing a site for the Kreb's cycle (taking ...

Answered by Sebastian G. • Biology tutor

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Describe the process by which an action potential is propagated across a cholinergic synapse

A cholinergic synapse is one which uses acetycholine (ACh) as it's neurotransmitter. When the action potential reaches the synaptic knob at the presynaptic cell it leads to voltage gated Ca²⁺ch...

Answered by David M. • Biology tutor

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The epithelial cells in the lungs are arranged into alveoli. Explain how the alveoli create a surface for efficient gaseous exchange.

Alveoli are made of two main types of cells. The alveoli walls are made of a single layer of squamous alveolar cells (aka Type I cells), which are flat and thin, further ...

Answered by Yasamin M. • Biology tutor

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Glucose is filtered out of the blood, but is not found in urine. Explain why glucose is not present in urine

Glucose is filtered out of the blood in the glomerulus of the kidneys. All of the glucose is then is actively transported back into the capillaries in the area of the nephron called the proximal convolute...

Answered by Alex C. • Biology tutor

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Describe how mRNA is produced in the nucleus of a cell

Production of mRNA is called Transcription, which can be divided into 3 stages: Initiation, Elongation and Termination.Initiation: DNA Helicase (Enzyme) binds to a promoter region of DNA (a short section ...

Answered by George K. • Biology tutor

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