Interactions within a ecosystem

1. Interactions within a ecosystem

2. 2.1 Ecosystems have interactions • All ecosystems have interactions with the following three : • Producers • Consumers • Decomposers • Question: What are examples of the above three?

3. The Trophic level of an organism is the position it occupies in a food chain, Trophic refers to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. • The number of steps an organism is from the start of the chain is a measure of its Trophic level. Food chains start at: • Level 1: Plants and algae make their own food and are called primary producers. • Level 2: Herbivores eat plants and are called primary consumers. • Level 3: Carnivores which eat herbivores are called secondary consumers. • Level 4: Carnivores which eat other carnivores are called tertiary consumers. • .

4. Discussion: Mouse and Plant in a jar • Questions: • What will happen to the mouse and the plant in this jar? • What would happen to the mouse if the plant we removed? • What would to the plant if the mouse were removed?

5. Questions: • What will happen to the mouse and the plant in this jar? • Both will continue to live • What would happen to the mouse if the plant we removed? • The mouse would die from the lack of oxygen produced by the plant (think of trees) • What would to the plant if the mouse were removed? • The plant would stop to grow due to not enough carbon dioxide

6. Cellular respiration • Cellular respiration is the metabolic process that occurs whereby cells obtain energy from organic molecules. The process requires oxygen, and releases carbon dioxide which are transported between the lungs and cells by the blood. • Certain organic molecules, such as carbohydrates and fats, are formed to store chemical potential energy. Cellular respiration is the reaction where a cell breaks down these molecules to obtain the energy required.

7. Definitions • Consumers: is any organism that has to seek out and eat, or consume other living things for food. (Humans are an example) • Carnivores: Animals that consume other animals for food • Herbivores: Animals that consume plants and plant-like food • Omnivores: Animals that will consume both animals and plants to survive

8. What are They?

9. 2.2 Food Chains and Flow of Energy • The process of Photosynthesis: The cycle of plants and how they make energy! The sun(light energy), water, minerals and carbon dioxide are all absorbed by the plant. The plant then uses them to make glucose/sugar, which is the energy/food for the plant. Oxygen is also produced by the plant in this cycle, which is then let off into the air! Have you noticed how clean and pure the air feels when there are plants around? They are filling the air with oxygen! • Plants need two raw materials to make their food. (Raw materials are materials in their nature state) • Water comes from the soil (think of house plants) • Carbon Dioxide comes from the air • What another material is missing?

10. 2.3 Food web • A food chain shows how each living thing gets its food. Some animals eat plants and some animals eat other animals. For example, a simple food chain links the trees & shrubs, the giraffes (that eat trees & shrubs), and the lions (that eat the giraffes). Each link in this chain is food for the next link. A food chain always starts with plant life and ends with an animal. • Plants are called producers because they are able to use light energy from the Sun to produce food (sugar) from carbon dioxide and water. The process by which plants make food is called photosynthesis. • Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers. There are three groups of consumers.

11. Food Web Con’t. • Animals that eat ONLY PLANTS are called herbivores (or primary consumers). • Animals that eat OTHER ANIMALS are called carnivores. • carnivores that eat herbivores are called secondary consumers • carnivores that eat other carnivores are called tertiaryconsumers e.g., killer whales in an ocean food web ... phytoplankton → small fishes → seals → killer whales

12. Food web con’t. • Animals and people who eat BOTH animals and plants are called omnivores. • Then there are decomposers(bacteria and fungi) which feed on decaying matter. These decomposers speed up the decaying process that releases mineral salts back into the food chain for absorption by plants as nutrients.

13. Activity: Disappearing organisms • What type of food do you eat? • Do you only eat one type of food? • Do other consumers only eat one type of food? (think in other countries) • Questions: Suppose that one type of living thing were to disappear from an ecosystem • Which type do you think would have the greatest impact on the other living things? • Which would have the least? • How would the ecosystem be affected

14. Section 2 assessment