1. Natural Sciences Grade 7
Term 1: Term 1: Life and Living
The biosphere
(PPT 2)

2. The concept of the biosphere (Part 1)
Topic 1 The Biosphere
The concept of the biosphere
(Part 1)
Gr 7 Natural Sciences – Term 1, Topic 1

3. Gr 7 Natural Sciences – Term 1, Topic 1
The Earth
land
Look at the picture of the Earth... What do you see? Is there something else that you cannot see?
water
Tell learners that we can see water and land, but we also know that the earth has an athmosphere around it.
Gr 7 Natural Sciences – Term 1, Topic 1

4. Gr 7 Natural Sciences – Term 1, Topic 1
The biosphere
It is a group of layers where life exists on Earth.
Bio = Life / sphere = shape of the Earth.
Each sphere of the biosphere contains different kinds of living things, including plants, animals and micro-organisms.
Gr 7 Natural Sciences – Term 1, Topic 1

5. The biosphere is made up of the following 3 systems
L = Lithosphere A = Atmosphere H = Hydrosphere
Gr 7 Natural Sciences – Term 1, Topic 1

6. The systems of the Earth
Lithosphere
A thin layer of soil and rocks on the crust and the seabed of the Earth.
Gr 7 Natural Sciences – Term 1, Topic 1

7. The systems of the Earth
Atmosphere
A thin layer of gases that surrounds the Earth and which can sustain life.
Atmosphere: the main gases that make up the atmosphere are nitrogen, oxygen and carbon dioxide.
Gr 7 Natural Sciences – Term 1, Topic 1

8. The systems of the Earth
Hydrosphere
All the water found on Earth.
It includes lakes, rivers, oceans and underground water.
Hydrosphere: hydro=water. This means all the rivers, lakes, oceans and water in the air (water vapour).
Gr 7 Natural Sciences – Term 1, Topic 1

9. Gr 7 Natural Sciences – Term 1, Topic 1
The Biosphere
Gr 7 Natural Sciences – Term 1, Topic 1

10. Gr 7 Natural Sciences – Term 1, Topic 1
The Biosphere
Atmosphere: plants absorb carbon dioxide (the main climate-changing gas) and produce oxygen instead.
Water cycle: Trees and other plants slow down the flow of rainwater to rivers, acting as a natural flood control.
Soil Health: Dead leaves and plants add nutrients to the soil. Insects and animals burrow, helping the soil breathe.
Gr 7 Natural Sciences – Term 1, Topic 1

11. The Biosphere is all about life
Living things that are found in the biosphere:
Lithosphere
Plants
Animals
Micro-organisms in the soil
Micro-organisms are single-celled plant- or animal-like organisms that can be seen with a microscope. For example, protozoa are micro-organisms found in the soil that help to break down organic matter.
Gr 7 Natural Sciences – Term 1, Topic 1

12. Gr 7 Natural Sciences – Term 1, Topic 1
Living things in the Lithosphere... Spot the image that is out of place.
The fish is out of place.
Gr 7 Natural Sciences – Term 1, Topic 1

13. The Biosphere is all about life
Living things that are found in the biosphere:
2) Hydrosphere
Plants
Animals
Micro-organisms
Micro-organisms found in the hydrosphere include amoebae and plankton. Amoebae are microscopic single-celled organisms that live in freshwater (1 = amoeba; many = amoebae)
Gr 7 Natural Sciences – Term 1, Topic 1

14. Gr 7 Natural Sciences – Term 1, Topic 1
Living things in the Hydrosphere... Spot the image that is out of place.
The plant growing on the side of the pond is out of place.
Gr 7 Natural Sciences – Term 1, Topic 1

15. The Biosphere is all about life
Living things that are found in the biosphere:
3) Atmosphere
Animals
Micro-organisms
Animals that spend time in the earth’s atmosphere include birds and flying insects. Bacteria are micro-organisms that can become airborne (for example, when someone coughs, they can spread bacteria)
Natural Sciences - Grade 7
Gr 7 Natural Sciences – Term 1, Topic 1

16. Gr 7 Natural Sciences – Term 1, Topic 1
Living things in the Atmosphere... Spot the image that is out of place.
The earthworm is out of place.
Gr 7 Natural Sciences – Term 1, Topic 1

17. Can you name each system?1) 2)
Atmosphere
Lithosphere
Hydrosphere 3) 4)
Gr 7 Natural Sciences – Term 1, Topic 1

18. The Biosphere also contains dead organic matter
Dead plants and animals that have begun to rot or decay.
Decomposers (such as fungi & bacteria) feed on the organic matter and help break it down.
Nutrients in the dead plants and animals are returned to the ecosystem.
The biosphere consists of all organic matter, and this includes dead organic matter. This matter needs to be broken down, otherwise the Earth will be covered with dead organisms. So very useful micro-organisms called decomposers, break these down into smaller pieces that can be used by the surrounding environment.
Gr 7 Natural Sciences – Term 1, Topic 1

19. Gr 7 Natural Sciences – Term 1, Topic 1
Ecosystems
The biosphere can be divided into smaller units called ecosystems.
Ecosystems can be big or small and include all the living things in a particular place, which interact with the living and non-living environments.
The biosphere is the largest biological system on Earth, but because the Earth has so many different climates, locations such as land, freshwater, seawater, desert etc, this system is further divided into ecosystems
Gr 7 Natural Sciences – Term 1, Topic 1

20. Gr 7 Natural Sciences – Term 1, Topic 1
The biosphere is the largest biological system on Earth, but because the Earth has so many different climates, locations such as land, freshwater, seawater, desert etc, this system is further divided into ecosystems
Gr 7 Natural Sciences – Term 1, Topic 1