Variations Test

• Differences between living organisms of the same species (and different) are called variations.
• Variation can be due to:

  1. The genes we inherit

  2. The effects of our environment
• Cell membrane conrols the movement of substances in and out of the cell
• The nucleus carries genetic information
• Genetic information is carried on chromosomes
• Chromosomes are made of a chemical called DNA
• A section of DNA is called a gene
• We have 46 chromosomes arranged in 23 pairs in all our body cells

  The only exception to this are eggs and sperm which have 23 chromosomes
• Of each pair of chromosomes, one came from your mum and one for your dad
• As each chromosome in a pair carries genes which code for the same characteristic, you have 2 genes for each characteristic, one from each parent.
• There are 2 types of variation:

  Continuous Variation

  Discontinuous Variation
• When the feature of a living organism fits into one of a number of definite groups(Discontinuous)
• discontinuous variations are due only to genes
• They are represented by a bar graph (Discontinuous)
• Examples: (Discontinuous)

  Blood Groups

  Gender

  Toungue rolling

  Freckles

  DImples

  Un/Attached ear lobes
• S cale

  P lots

  L ine

  A xes

  T itle
• The value for the characteristics can be a whole range of values. (Continuous)
• Characteristics which show continuous variation are due to a combination of the organisms genes and environment.
• Continuous variation is represented by a histogram
• Examples (continuous)

  Height

  Mass

  Intelligence

  Leaf size