An alien visiting Earth for the first time would see many differences between humans. While all members of a species are similar, there is also variation between individuals in features like height, number of petals on a flower, or heart rate. Variation can be either discontinuous, where traits fall into distinct groups, or continuous, where traits show a range of differences. Examples of discontinuous human variations include blood type and ability to roll one's tongue, while continuous variations include height and heart rate.

1. Variation

2. How might he describe this classroom of humans to his people? Imagine an alien is visiting Earth for the first time. What differences might he see between all of us?

3. How do we divide up all the living things on Planet Earth? Animalia Chordata Mammalia Carnivora Canidae Canis C. lupis

4. How do we decide if living things are the same or a different species? A mule is a sterile offspring: can’t produce offspring of it’s own Donkey X Donkey Donkey X Horse Mule Horse X Horse

5. Lion x tiger Sterile Horse x zebra Sterile L i g e r Z e b r o r s e

6. Fertile : able to produce offspring L a b r a d o o d l e Labrador x Poodle

7. A species is a group of living organisms which share the same general physical characteristics and can mate to produce fertile young. Can we define a species now?

8. A Species -Define a species. -Give examples of animals of the same species reproducing to produce offspring. -Give examples of animals that are not the same species reproducing to produce offspring. -State the key difference between these offspring. Notes

9. Variation Although all members of a species are very similar, there are differences in their features – variation Activity In your groups pick any species of mammal and list variations in their features.

11. Examples of discontinuous variation: Other species: -Smooth or wrinkled pea coat -White or red eyes in fruit flies -flower colour in sweet peas Ear lobes attached unattached Blood Groups O B A AB Tongue rolling Roller Non-roller

12. 1) Continuous variation: - Characteristics which do not show clear cut differences (show a range of differences). What features might show a range of variation? Number of petals on a daisy Heart rate Height

13. Discontinuous data Continuous data Distinct data can be presented as a bar graph. Ranges of data can be presented as a histogram or line graph. No. of pupils Tongue rolling ability Roller Non-roller Pea seed shoot lengths (mm) No. of seeds 1-5 6-10 11-15 16-20 21-25