Natural Sciences and Technology Grade 7 Term 1
- Slides: 15
Natural Sciences and Technology Grade 7 Term 1: Live and Living Variation (PPT 1)
Topic 4 Variations within a species Natural Sciences and Technology – Grade 7
What is a species? • A species is a category within the classification system. • It is the smallest group that an organism belongs to. • A species is a group of living things of the same type that can reproduce with one another. • Humans belong to one species and dogs belong to another species. Natural Sciences and Technology - Grade 7
What are variations? • Variations are the differences between organisms of the same species. • Individuals of the same species can vary quite a bit. • Variations occur in all living things, including people, animals and plants. Natural Sciences and Technology - Grade 7
There is usually a great deal of variation between individuals of a species Natural Sciences and Technology - Grade 7
Natural Sciences and Technology - Grade 7
You already know that there are variations between individuals of the Human species (Homo sapiens). Can you think of some examples of variations? Natural Sciences and Technology - Grade 7
Variations are inherited • Variations are passed down from parents to their children. • This means that they are inherited. • EXAMPLE: height, is an inherited characteristic – Look at the learners in your class when they stand in a line. – Is everyone of the same height? Natural Sciences and Technology - Grade 7
Variations among family members • The chances that families will share characteristics is high. • This is because we inherit features from our parents. Natural Sciences and Technology - Grade 7
Natural Sciences and Technology - Grade 7
Variations caused by the environment • Some characteristics are not inherited. • EXAMPLE: developing muscles, tattoos, hair dye, spending time in the sun which darkens the skin. • These variations do NOT come from your parents. • These characteristics are caused by the environment. Natural Sciences and Technology - Grade 7
Can a horse breed with a donkey? Natural Sciences and Technology - Grade 7
A horse and a donkey will reproduce a mule Natural Sciences and Technology - Grade 7
Reproduction • Individuals of the same species can reproduce successfully. Natural Sciences and Technology - Grade 7
Influence of family history Our family history can put us at a greater risk to develop certain diseases, for example: - heart attacks or heart diseases - diabetes (problems with blood sugar levels) - anaemia (blood disorder) - cancer - cholesterol Natural Sciences and Technology - Grade 7
