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What are the key different types of selection?

Directional selection occurs when a phenotype at the extreme end of a distribution is favoured and so over time the distribution shifts in the direction of the favoured phenotype. An example of this is the d...
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Answered by Abigail C. • Biology tutor
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Describe the synthesis of ATP in oxidative phosphorylation

Oxidative phosphorylation is a critical component of the cell's metabolic pathway, and is responsible for the generation of most of the cell's ATP. Overall, reducing potential in the form of NADH and FADH2, ...
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Answered by Alex G. • Biology tutor
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Describe the structure of the human gas exchange system and explain how we breath in and out.

The human gas exchange system includes the trachea, the bronchioles and the alveoli. During inhalation (breathing in) the diaphragm contracts and the external intercostal muscles contract. This increases the...
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Answered by Hajira I. • Biology tutor
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Explain how increased blood CO2 leads to an increased heart rate

The high CO2 rate is detected by chemoreceptors in the aorta. The chemoreceptors send impulses to the medulla in the brain. The medulla then sends impulses along sympathetic neurons to the sinoatrial node in...
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Answered by Alice V. • Biology tutor
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What is a Pacinian corpuscle and how does it work?

The Pacinian corpuscle is a mechanoreceptor, which means it is a sensory receptor that responds to touch, pressure or vibration. Pacinian corpuscles are found deep in the skin, and respond to both pressure a...
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