Variationsin Organisms Presented By: Ms. SaweraFarrukh
Contents • Spotting Variation • Different species • Same species • What is Variation? • What causes Variation? • Inherited Variation • Environmental Variation • What about other features?
Spot the differences There are lots of differences between these organisms. For example: some have leaves; some lay eggs; some eat plants. These organisms are different because they are all from different species.
Spot the differences – same species There are also differences between organisms of the same species. For example, these people are all from the same species but how many differences between them can you spot?
What is variation? Even though people are all from the same species, there are many ways in which they are different from each other. Some of them are male, some are female, some are tall, some are short. The differences that occur both between different species and within the same species are called variation.
What causes variation? • Variation is caused by two factors: • Some features are cause by inherited factors. • These are features that are passed on from parents. • For example, natural hair colour is an inherited feature. • Some features are caused by environmental factors. • These are features that are affected by the surroundings. • For example, someone can be born with brown hair which then gets lighter in the Sun or might be dyed a different colour.
Environmental or Inherited? Sometimes it is not easy to determine whether a feature is inherited or environmental. Scientists have now decided that only four characteristics are truly inherited and not affected by the environment at all. Can you guess what they are? • body weight • hair length • blood group • some inherited diseases • freckles • gender
What about other features? Some features are caused by a mixture of inheritance and the environment, for example, nose shape. Someone might have a nose that looks just like their mum’s. But if they were in an accident, they might break their nose and put a kink in it. So their initial nose shape was probably inherited but over time it is likely to have been affected by the environment. How can the environment affect skin colour?