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    I understand that plants are the basis of all food chains, but I don't understand really why humans depend on plants.

    Sorry if this is confusing.

    So - plants manufacture a range of biological molecules, and the animals that eat these make use of these molecules.

    But I don't understand how this works, and what is really going on.

    I guess the problem I have understanding this is with the food chains.

    Can anyone help?

    Thank you very much! ^.^
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    You do understand how a food chain works, right? Not every species is capable of killing other species for food

    In our case (human beings), there are those who refuse to eat meat. And things like fibre, vitamins and some minerals which we need in our diet won't come from meat.
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    I am referring to the OCR specification - yeah, I am struggling with food chains. I am confused about energy transfer. I understand that not all humans eat meat.
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    (Original post by Shostakovish)
    I am referring to the OCR specification - yeah, I am struggling with food chains. I am confused about energy transfer. I understand that not all humans eat meat.
    Your body needs to consume energy rich food to live and energy cannot be created or destroyed, only converted, e.g. chemical energy from food is converted to kinetic energy when you move. You and other animals excrete digested waste from which you have extracted some of the chemical energy. There's no way of getting the energy you converted to kinetic energy by running for the bus back into the food chain, there needs to be an input of energy at the base of the food chain to keep the chain going.

    Plants get energy from the sun through photosynthesis - they convert light energy into chemical energy which can then be consumed by animals.

    I think this is sufficient for GCSE.
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    In very, very simple terms:

    Humans have to get energy from somewhere.

    We cannot get energy directly from the sun.

    The sun provides energy for plants.

    We eat plants to get this energy from them.
 
 
 
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