B3 Life on Earth

  • Created by: Falisha
  • Created on: 24-06-13 09:00

What is adaptation?

A species is a group of organisms that breed together to produce fertile offspring. They have features that help them survive in their environment. These are adaptations. Adaptation increases the chance of survival.

How do species interact?

Within a place where the organism lives – its habitat. There is competition. Animals – food, shelter and mating Plants- space and light Species rely on each other and their environment. Species are independent A food web shows what eats what in a habitat. Changes in the food web can affect other animals. This could result in extinction of a species.

How plants do use energy from the sun?

Plants absorb 1-3% of light from the sun that fall on their leaves. Photosynthesis uses this energy. This produces a chemical reaction that makes plant cells and store energy. Plants are producers. Animals, bacteria and fungi rely of plants for food. All life is dependent on energy from the sun.

How is energy transferred?

Energy is transferred by... When consumers eat other organisms When decomposers and detritions eat dead organism Only small amounts of energy are passed on the food web. The rest is lost through Using the life processes Escapes as heat Is excreted as waste Cannot be eaten and is passed on to decomposers Because so much energy is lost, food chains do not have more than 4 species. 32/160 x 100 = 20%

How is carbon recycled?

It is recycled by the environment. Take out co2: photosynthesis, dissolved in water, animals respiration by breaking down glucose. Return co2: decomposition, combustion, volcanic activity.

How is nitrogen recycled?

Microorganisms are vital to the nitrogen cycle. Decomposer bacteria break down dead organisms Nitrogen fixing bacteria…




These revision notes neatly summarise the key facts in the OCR B3 unit which covers energy flow, evolution and biodiversity. Making a glossary or set of flashcards of the key terms in the notes would be a useful exercise.




Untiring Bacon





I didn't know life began just 3500 years ago, thx for the info