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The pacemaker cells of the sino-atrial node in the right atrium generate an impulse.This impulse travels through the atria, causing depolarisation of cardiac muscle cells and atrial contraction.The impuls...

Excess nitrates and phosphates are water soluble and enter rivers/lakes/waterway due to leaching.Algae in the water use the increased level of ions for growth. This is called Algal bloom.Build up of algae...

Changes in blood water levels are detected by the hypothalamus through the negative feedback mechanism in homeostasis (2 marks). The pituitary gland releases anti-diuretic hormone into the bloodstream as ...

The steps are as follows:The desired gene is isolated by 'cutting' it out using a restriction enzyme. The same restriction enzyme is then used to 'cut' a vector (plasmid or virus). These can either be lef...

Red blood cells transport oxygen around the body via the circulatory system and are the most common cell in the blood. They carry a special protein called hemoglobin which binds to oxygen, allowing it to ...