Conditions inside the body must be controlled within narrow limits


water content

ion content

body temperature

blood glucose concentration.

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Natural Selection

The theory of evolution states that evolution happens by natural selection.

  • Individuals in a species show a wide range of variation.
  • This is because of differences in genes.
  • Individuals most suited to the environment are more likely to survive and reproduce.
  • The genes that allowed the individuals to be successful are passed to the offspring in the next generation.
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Key Terms (A)

Active Transport: movement of molecules through partially permeable cell membranes

Adaptation: The process of getting used to the environment.

Aerobic respiration: Respiration using oxygen from the atmosphere 

Anaerobic Respiration: The process of respiration without using oxygen from the air.

Antibody: A protein molecule that protects the body from invading cells

Asexual Reproduction: without producing gametes. An example of this is cloning.

Artery- A blood vessel which transports oxygenated blood.

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Key Terms (B)

Bacteria: A type of single-celled organism without a nucleus. Bile: An alkaline fluid produced in the liver to aid digestion and the breaking down of food molecules. Biomass: The mass of living organisms in a certain area. Biodegradable: A substance that will be broken by natural processes. Bladder: A muscular sac that contains and ejects urine. Brain: The organ that coordinates the actions and responses of the body. Bronchiole: A small branch of bronchus which connects a bonchus to the alveoli. Bronchus: A tube that connects the trachea to the lungs.

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Key Terms (C)

Capillary: The smallest blood vessel, through which substances are exchanged to and from the blood.

Carbohydrates: A groups of foods which provide energy

Catalyst: A substance that speeds up a chemical reaction

Chlorophyll: The green pigment in leaves which absorbs light for photosynthesis

Chloroplasts: Structures in a plant cell which contain chlorophyll

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Diffusion Definition

Diffusion: The movement of molecules from an area of high concentration to an area of low concentration

Image result for Diffusion

       Before Diffusion                           During Diffusion                               After Diffusion 

     (High concentration)                   (Movement//Diffusion)                             (diffused)

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Key Terms (E)

Enzymes: Biological catalysts found in the body

                              Image result for enzyme

Evolution: The change overtime in the genes of species

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Image result for enzyme

enzymes accelerate, or catalyse, chemical reactions 

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Osmosis: Diffusion of water molecules through a partly permeable surface

Image result for osmosis diagram gcse

For osmosis to happen you need:

* two solutions with different concentrations

* a partially permeable membrane to separate them

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