Chains of Life

1. Chains of Life Today’s Objectives: describe how energy passes out of food chains calculate the efficiency of energy transfer in food chains Starter: What do all food chains start with? Why?

2. What is the producer in this food web?

3. Keywords: • animal, aquatic life, bird, carnivore, crustacean, eating, ecology, fish, food, food chain, herbivore, human, mammal, man, marine life, marine mammal, ocean, phytoplankton, plankton, predator, prey, sea, seabird, zooplankton

4. What is photosynthesis? • Arrange the following words to form the equation for photosynthesis: water, glucose, carbon dioxide, energy from the sun, oxygen.

5. Photosynthesis - reminder • Vidoe clip (saved) Now copy and complete the following passage: • The light from the Sun provides the energy for a very important process called ……………………………. • In this process, ………………… dioxide and ………………… , together with the energy from sunlight, react to form ……………………… and oxygen. • Plants can store ………………… in the form of starch in their cells and tissues. Other organisms can get this energy by ………………… the plants.

6. Answers energy from Sun carbon dioxide + water  glucose + oxygen Gaps in the passage: Photosynthesis, carbon, water, glucose, glucose, eating

7. How efficient is an ecosystem? • What is meant by an ecosystem? • Living and non-living components of an environment. • How is energy lost in the ecosystem? • Inedible parts of plants and animals • Faeces, urine, gas • Respiration • Heat • Movement

8. Calculating efficiency energy in tissues Percentage efficiency = ---------------------------- X 100% energy in food eaten Calculate the efficiency of energy transfer for a salmon that has ingested 80kJ of food and has 10kJ of energy in its tissues.

9. Task • Now complete activity 1 and 2 from the worksheet. • Write the answers into your book. • Extension: • Cold-blooded animals such as fish have a higher efficiency of energy transfer than warm-blooded animals. Explain why. • Explain how organisms are broken down after they have died.

10. Answers Activity 1 Q1 a) 10%; b) 4%; c) 25% Q2 The snail is cold-blooded so no energy is transferred to heat to keep the snail warm. The cow has to keep itself warm and move about, and also many parts of the cow such as the hair, horns and hooves are indigestible and not available to the next level of the food chain; this reduces percentage efficiency. The maize plant is low down the food chain and most parts of the plant are edible; thus the percentage efficiency is higher. Activity 2 Q1 Honey fungus breaks down dead wood; a tree with honey fungus is likely to have a proportion of dead wood in it; this can be dangerous because it can cause branches to fall or the tree to tilt or fall over; this could cause injury to someone in a public place. Q2 After detritivores have broken the dead matter into smaller pieces, there is a larger surface area for the decomposers to act on; this means they will be able to break down the dead matter more quickly.

11. Plenary • Define the words: decomposers and detritivores. • Describe the role of decomposers and detritivores in a habitat.