B7 OCR Topic 1 introduction

introduction to topic 1 B7

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  • Created by: Misha Mau
  • Created on: 09-04-10 19:43
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1A: Harvesting the Sun
Plants use energy from the sunlight through photosynthesis to make carbon dioxide and water into
compounds like glucose.
Energy from sunlight is converted into chemical energy which is stored and then either used as:
a) Food: uses it as a slow release of energy or
b) Raw materials: to help the plant cells grow.
Autotrophs make their own food and most of them are plants but they can be some bacteria. The
bacteria don't use light to drive their food making process but they gain energy from chemical reactions
using raw material from their environment.
Heterotrophs rely on other organisms for their food like animals eating other animals and plants.
Energy stored in a plant may be transferred into another animal if they eat it because the energy stored
in the plant cells is eaten.
When this energy is transferred some is lost at every stage of the food chain as movement or
respiration. The energy is dissipated to the surroundings and it warms the air and it eventually radiated
back to space.
Photosynthesis: The process in green plants which uses energy from sunlight to convert carbon dioxide
and water into the sugar glucose.
Autotroph: An organism which produces its own organic compounds.
Heterotroph: An organism which must eat other organisms for its source of organic compounds.


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