Recall: a species is a group of living organisms with similar features Members of the same species...
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VARIATIONMonday, June 13, 2011 – Lesson 4
Outcomes:Level E: I can identify what variation is
Level D: I can describe how variation occurs in living organisms
Level C: I can explain how variation occurs and why it is important for species
Aim:How does variation occur in species?
Species
• Recall: a species is a group of living organisms with similar features
• Members of the same species can breed together
• Example: All dogs are members of the same species by they don’t all look the same
• List 5 characteristics of dogs that are similar.• List 5 characteristics that are different.
Variation• Differences between members of the same
species are called variation
• Can I get 10 volunteers... 2 from each table
• How many different ways could you classify these 10 people?
What Causes Variation
• Variation is cause by either environmental factors or inherited factors
This type of variation is passed on in genes from parent to offspring
This type of variation is influenced by living conditions and surroundings
• What are some of the inherited characteristics of humans?– Eye colour, hair colour, height, blood type
• Any other inherited characteristics?
• Environmental variation is cause by differences in living conditions and surroundings
• What do you think causes environmental variation?– Food supply, temperature, water supply, humidity,
disease• How would these affect variation?– Influence the way you look, speak, and how you
do things
• Some inherited characteristics can be affected by environmental factors
Which are inherited, environmental or both?Inherited Environmental Both
Blood Group
Wears glasses
Tongue Rolling
Freckles
Speaks Italian
Dyed Pink Hair
Neutral Eye Colour
Height
Welsh Accent
Continuous vs. Discontinuous Variation
Examples of Variation in Humans
• Discontinuous: Blood Type, hair colour
• Continuous: Height, eye colour
What about plants?
• Plants and organisms from other kingdoms are also affected by inherited and environmental factors
Plenary: True or False
1. Members of the same species all look the same
FALSE!
Members of the same species have similar features but do not look the same
2. Only living things that are members of the same species can breed together to produce fertile offspring
TRUE!Some species can be interbred – but their
offspring are infertile
3. Variation only occurs in animals
FALSE!Variation occurs in all living things, including
plants and bacteria
4. Variation caused by environmental factors can be passed from parent to offspring
FALSE!
Only inherited characteristics are passed from parent to offspring
5. Identical twins are more alike than most but even they are not exactly the same
TRUE!Identical twins inherit the same features but
they have different fingerprints
6. The ability to roll your tongue is an inherited characteristic.
TRUE!
Have you inherited this type of variation?