Natural Sciences and Technology Grade 7 Term 1: Live and Living Variation (PPT 1)

Variations within a species Topic 4 Variations within a species Natural Sciences and Technology – Grade 7

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. For example, domestic dogs are from the species Canis Lupus familiaris. People belong to the species Homo sapiens. Natural Sciences and Technology - Grade 7 3

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 4

Natural Sciences and Technology - Grade 7 There is usually a great deal of variation between individuals of a species Just like we find variation between individuals dog species, we find different types of flowers; butterflies; birds, etc. Encourage learners to bring pictures that show these variations. Natural Sciences and Technology - Grade 7 5

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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? Note to teacher: eye colour; hair type; height, etc. Natural Sciences and Technology - Grade 7 7

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 8

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. Inherited characteristics include height, eye colour, nose shape, dimples, hairline, hair appearance, freckles, the shape of earlobes, skin colour, allergies, colour blindness. It also includes the ability to do certain movements with your body, such as rolling your tongue. Ask children to bring photographs of their family members and have them discuss inherited characteristics in their groups. Natural Sciences and Technology - Grade 7 9

Natural Sciences and Technology - Grade 7 Ask: where do you think this tattoo came from? Was the person born with it? Natural Sciences and Technology - Grade 7 10

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. Other characteristics caused by the environment: language we speak; whether you have scars. Intelligence and body weight are the result of both the environment and inheritance. Natural Sciences and Technology - Grade 7 11

Natural Sciences and Technology - Grade 7 Can a horse breed with a donkey? Horses and donkeys belong to different species. If a horse and a donkey breed together, they will produce a mule. The mule will be infertile and not able to reproduce. A lion that breeds with a tiger will reproduce a liger. The liger will be infertile. Natural Sciences and Technology - Grade 7 12

A horse and a donkey will reproduce a mule Natural Sciences and Technology - Grade 7 13

Natural Sciences and Technology - Grade 7 Reproduction Individuals of the same species can reproduce successfully. All people are humans. All the different populations in the world are able to have healthy babies with any other population, because we are all from the same species. For example, a Chinese person and a person from Spain can have a healthy baby together. Natural Sciences and Technology - Grade 7 14

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 It is important to know your family history so that you can make informed decisions about your diet and medical care. Encourage learners to draw a family tree and to make notes of illnesses that are common in the family. Natural Sciences and Technology - Grade 7 15