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How is the process by which plants turn towards a light source called and what is the role of auxin (IAA) in it?

The process is called phototropism (‘photo’-light, ‘tropism’ – ‘tendency of an animal or plant to turn or move in response to a stimulus’). IAA (Indole Acetic Acid) is a plant hormone belonging to a class ca...
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Answered by Emiliya T. • Biology tutor
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Name a substance that can be transported across a membrane by simple diffusion and explain why it is able to be transported by this method.

Oxygen is an example of a molecule that is able to move across a membrane via simple diffusion. It is able to do so as it is a non-polar, uncharged molecule. Thus, it is a lipophillic molecule which means th...
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Answered by Tamarind R. • Biology tutor
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How do I write a good introduction for essays?

A good introduction is very important for an essay. It conceptualises the essay and shows the examiner you understand not only the words in the question, but what the question is asking of you. A good introd...
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Answered by Stephanie K. • History tutor
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Describe the electrical conduction system of the heart and how it initiates the heart beat

The sinoatrial node (SAN) is the pacemaker of the heart and initiates a wave of excitation (impulse) at a regular interval. This wave of excitation sweeps across the walls of the atria and in doing so causes...
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Answered by James M. • Biology tutor
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How do I know which nouns are feminine and masculine?

Firstly, nearly all nouns ending in "a" are feminine, so if you are not sure it's a safe bet that it's feminine. There a few exceptions (mapa, systema, programa, etc.), which you will just have to ...
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Answered by Bryn E. • Spanish tutor
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