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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
2750 Views

How do I know which verbs take 'etre' and which verbs take 'avoir' in the past tense?

The best to learn which verbs take 'etre' is through MS VANDERTRAMP. (Then I would explain what each letter stands for). After this I would remind the student of compound verbs. For example, entrer is a verb...
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Answered by Gemma M. • French 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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