1. 7.3 Food Chains and food webs: interactions of life

2. Food chains and food webs: interactions of life  Please write down any notes/questions that are in this colour thanks!  All living things require energy. This energy is used by organisms for growth, repair and reproduction to help the organism survive. What is the source of this energy? The SUN  The Sun is one big nuclear reaction where hydrogen is being made into helium. This releases a LOT of energy (light, heat, gamma radiation, X-rays, microwaves and radiowaves.)

3. Food chains and food webs: interactions of life 7.3 Question 2 ‘The Sun is the source of all life on Earth.’ Do you agree with this statement? Why or why not? (write your answers in your workbook) ‘Yes’, because the Sun provides the initial source of energy for plants to grow.

4. Food chains and food webs: interactions of life  Plants, green algae & a number of microorganisms (i.e the ruffled sea slug), use light from the Sun to provide the energy for life. They convert carbon dioxide and water into food (sugar-called glucose- chemical energy). This is known as photosynthesis.

5. Food chains and food webs: interactions of life  Sunlight is absorbed by chlorophyll (this is what makes the leaf look green) in the leaf, providing energy required to convert the carbon dioxide (taken in through the leaves) and the water (taken in through the roots) into glucose and oxygen.

6. Food chains and food webs: interactions of life Photosynthesis Carbon dioxide + water  glucose + oxygen (in the presence of sunlight and chlorophyll) Producers or Autotrophs- organisms that produce their own food. They are essential because they provide food for all the other organisms in the ecosystem.

7. Food chains and food webs: interactions of life 7.3 Question 3 So you think the term ‘producer’ is an accurate description of a green plant? Explain your reasoning. (please write the answer in your text book) ‘Yes’, because it produces its own food. 7.3 Question 4 Complete the following statement: During photosynthesis, _______ energy from the Sun is converted into _________energy within plants. light chemical

8. The flow of nutrients through an ecosystem Consumers or heterotrophs cannot produce their own food. Animals that eat plants are called primary consumers or herbivores. e.g. Kangaroo Animals that eat herbivores are called secondary consumers or carnivores. e.g. Dingo Consumers that eat both plants and animals are called omnivores. e.g. Humans

9. The flow of nutrients through an ecosystem Complete the following questions quietly in your text book: 7.3 (page 177) Question 1 Question 5 Question 6

10. The flow of nutrients through an ecosystem The nutritional sequence between producers, primary, secondary and tertiary consumers is called a food chain. (each organism links to another.)

11. The flow of nutrients through an ecosystem Food chains rarely have more than six links called trophic levels. The interactions between the food chains and their various food sources are known as a food web.

12. The flow of nutrients through an ecosystem

14. Please complete the following questions in your work book quietly: Question 7 Question 8 Question 9

15. The flow of nutrients through an ecosystem Biodiversity  refers to the number of species present in a community.  Communities with high biodiversity (many species of plants and animals) can survive environmental changes better than those with low biodiversity (only a few different species of plants and animals living together). As there are more options for food if one organism is destroyed. Lets look at the crane/bird in the slides example. (previous slide).  What options does it have to eat? Would it survive if say frogs disappeared?  What would not survive if the plant in the pond disappeared?

16. The flow of nutrients through an ecosystem Biodiversity  In the video when the frogs disappeared what did the grasshoppers do?  By removing the natural vegetation of an area and replacing it with one specific type of plant (wheat) humans have reduced the biodiversity of many ecosystems and some species are now extinct.

17. The flow of nutrients through an ecosystem Please complete the following questions in your work book quietly: Question 12

18. The flow of energy through an ecosystem Read this information together from the text book page 174. Decomposers: the last link in the food chain Organic matter- all matter in the biosphere that comes from living organisms and contain the element carbon. Decomposers- recycle organic material (dead plants/animals) Eg bacteria & fungi Question 10 & 11 (p177)

19. Relationships between organisms Read through “Relationships between organisms” together. (p 175-176) The different types of interaction include: 1.Mutualism (symbiosis) 2.Commensalism 3.Amensalism 4.Competition 5.Exploitation (a- predation b- herbivory c- parasitism) Please complete the remainder of the questions in Your book (Questions 13-19).