Energy and living things
This Topic is About...
- I will learn why living things need energy.
- I will find out where living things get their energy from.
- I will describe food chains.
- I will make drawings of food chains to show how energy moves between living things.
You’re going to be a science explorer!
Key Words
- carnivore
- consumer
- food chain
- herbivore
- omnivore
- predator
- prey
- producer
Tap to Learn the Meanings!
- carnivore: An animal that eats only other animals.
- consumer: A living thing that gets energy by eating plants or animals.
- food chain: A path showing how energy passes from one living thing to another.
- herbivore: An animal that eats only plants.
- omnivore: An animal that eats both plants and animals.
- predator: An animal that hunts and eats other animals.
- prey: An animal that is hunted and eaten by another.
- producer: A plant that makes its own food using sunlight.
Fantastic! You now know key words about how living things get their energy.
Living things need energy
All living things need energy. They need energy to move, to grow, to reproduce and to carry out other life processes. Plants and animals will not be healthy if they don’t have enough energy.
We get our energy from the food we eat. The energy moves from the food into our bodies. We use that energy to live and be healthy.
Plants do not eat food to get their energy. Plants use light energy from the Sun to make or produce their food. We call plants producers. Plants are the only living things that can make their own food.
Animals need plants for energy
Animals including humans cannot make their food. They must eat, or consume, plants or other animals to get their food and energy. Animals including humans are called consumers.
Some animals eat plants only. We call animals that eat only plants herbivores. Zebras and snails are examples of herbivores.
Some animals eat other animals that eat plants. We call these animals carnivores. Carnivores eat herbivores. They also sometimes eat other carnivores. Tigers and owls are examples of carnivores.
Sometimes carnivores are called predators. The animals that carnivores kill and eat are called prey. For example, an owl that kills and eats a mouse is a predator. The mouse is the prey.
Animals that eat both plants and animals are called omnivores. For example, monkeys mostly eat plant leaves, fruits and seeds, but they also eat insects and other small animals.
FUN QUESTIONS
1. Why are plants called producers?
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2. Why are animals called consumers?
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3a. What is the difference between predators and prey? Give an example in your answer.
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3b. In what way are predators and prey similar?
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3c. Can a herbivore be a predator? Say why or why not.
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Food chains
Afood chain shows the order in which animals eat plants and other animals to get energy. Food chains always contain a producer and at least one consumer. Energy is always transferred from the producer to the consumer because the consumer eats the producer. Look at the examples.
In food chain 1, the corn is the producer and the hen is the consumer.
Identify the producer and the consumer in food chain 2.
We can show a food chain as a drawing. When we draw a food chain, we show the order in which food, and the energy it contains, are transferred from one living thing to the next. The order of living things in a food chain is always:
producer → consumer
The arrows in the food chain show the direction in which the energy in the food is transferred.
This is the drawing of food chain 1:
corn → hen
If a boy eats the hen in food chain 1, he is another consumer. So now the food chain is:
corn → hen → boy
Let’s Investigate!
Question: How can we draw and describe simple food chains?
Activity:
- Put the living things in the correct order to make food chains. Then draw each food chain.
- a) tomato → bird → cat
- b) rice plant → grasshopper → frog → snake
- Draw a food chain of your own that includes a person as the second consumer.
- Describe the energy transfers that happen in your food chain.
Tap to See Answers
- 1a: Tomato → Bird → Cat. The tomato is the producer, the bird is the primary consumer, and the cat is the secondary consumer.
- 1b: Rice plant → Grasshopper → Frog → Snake. Each step transfers energy from one organism to the next.
- 2: Example: Lettuce → Rabbit → Human → Lion. Here, the human is the second consumer.
- 3: Energy from the Sun is passed to the plant (producer), then to the herbivore (primary consumer), and finally to the carnivore (secondary consumer). Some energy is lost as heat at each stage.
Well done! You’ve built and explained real food chains like an ecologist.