Organisms And Life Processes


  • Cells
  • Enzyme Theory
  • Enzymes and pH
  • Diffusion and Osmosis
  • Variety 
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  • Created by: Chloe
  • Created on: 22-05-12 08:43


Draw and Label an Animal Cell

Draw and Label a Plant Cell

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Cells 2

Define parts of the cells and its function?:

Cytoplasm: the living membrane that make up the cell, it has a like a solid or liquid texture

Nucleus: it controlls the activites of the cell, contains chromosones which carry genetic material

Cell Membrane: are cells have this skin like subtance on the surface of the cell

Mitochondrion (plural: mitochondria): they carry out some reactions of respiration

Cell Wall: a layer that helps keep the cell in shape

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Enzyme Theory

Enzymes: are made of protein, they speed up chemical reactions (biological catalysts) 

Lock and Key Hypothesis:

  • There is a specific enzyme for a specific substrate, otherwise they won't be broken down
  • If a enzyme becomes DENATURED it means it no longer is able to break down the substance. Most enzymes have a OPTIMUM temperature, a temperature which they work at. For humans its 37 degrees

Lipids turn Fats into GLYCEROL + FATTY ACIDS

Proteases turn Proteins into AMINO ACIDS

Amylase turn Starch into SUGARS

Enzymes, which are biological catalyst, speed up digestion and other reactions in the body, they break down large nutrients into smaller units so they can be absorbed into the blood

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Enzymes and pH

Factors affecting Enzymes:

  • TEMPERATURE: optimum temperature in humans 37 degrees
  • If you increase the temperature the rate of the reaction will speed up, because the higher temperatures give the molecules of enzymes and substrates more energy, so they collide more often
  • If the temperature its above 40 degrees C the heat will destroy the enzyme, since the enzymes are made of proteins and proteins are broken down by heat
  • CONCENTRATION: the rate of the reaction may increase by raising the concentration of the enzyme or substrate 
  • pH: the pH inside cells is around neutral (pH 7) and they work best at this pH (optimum pH) 
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Diffusion and Osmosis

Define these two words?

  • Diffusion: when particles move the an area of high concentration to an area of low concentration (down concentration gradient)
  • Osmosis: diffusion of water across a partially permeable membrane from a area of high water potential to a area of low water potential 

Give Examples of where these two processes occur in humans and plants?


IN HUMANS: in the alveoli (air sacs) in the lungs, which allow gas exchange of oxygen and carbon dioxide between the air and the blood during breathing. Also in the villi of the small intestine. IN PLANTS: diffusion in and out of the stomata, which allows oxygen to be released into the atmosphere due to the process of photosynthesis


IN HUMANS: water is diffused from the kidneys. IN PLANTS: water is diffused into the root hair cells in  the roots of the plant  

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Diffusion and Osmosis 2


  • when particles move from a low concentration to a high concentration

Example of this in humans and plants?

  • IN HUMANS: glucose in the kidneys
  • IN PLANTS: the uptake of minerals by the roots
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Common features in organisms


  • Photoautotrophs; use light to make their own food (photosynthesis, they must have chlorophyll)  6CO2 + 6H2O = C6H12O6 + 6O2
  • Multicellular
  • Cell wall made of cellulose
  • Nucleus
  • Organelles inside membrane e.g mitochondria

Animals: e.g Mammals, reptiles

  • Heterotrophs; they have to eat
  • Multicellular
  • Nucleus 
  • No Cell Wall
  • No Chlorophyll 

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Variety 2

Fungi: e.g yeast, mushrooms

  • Saprotrophics
  • Feeds on dead and decaying matter
  • No need to photosynthesis
  • Hyphae (thread like structures)
  • Can be single or multicellular
  • Pathogenic 

Bacteria: e.g ecoli (in digestive system)

  • No Nucleus, but have DNA found in plasmids or free in the cytoplasm
  • Single celled
  • Pathogenic 
  • Cell Wall
  • Some can carry out photosynthesis
  • Most feed on living or dead material

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Variety 3


  • Single celled
  • Some have more animal features e.g Amoeba, found living in pond water
  • Some more like plants and have chloroplasts e.g Chlorella, a freshwater algae 
  • Some are pathogenic (disease carry organism) e.g Plasmodium, a parasite in blood cells, responsible for causing malaria


  • Single celled
  • No nucleus
  • Smaller than bacteria
  • Pathogenic
  • Can only reproduce in a living host cell
  • Variety of shapes and sizes
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