Energy from the Sun

In this lesson, students compare the interactions among organisms within two different biomes: the Sahara desert and the Amazon rainforest. They trace the flow of energy from the sun to producers and then consumers and decomposers, and analyze how although different biomes have different kinds of organisms, the need for energy is the same for all living things.

• Plants and animals have specific structures that allow them to survive in their particular environment.
• There are many different biomes around the world with their own types of living things. A biome is a specific geographic area with a particular climate that supports different kinds of organisms, The Sahara is one biome. The Amazon rainforest is another biome.
• All living things have similar requirements, including the need for energy to grow, move, and reproduce. Without energy, living things cannot survive.
• When organisms eat one another, energy flows from one to the other.
• There are different kinds of consumers, depending on what they eat.
  
  

• How are animals and plants that live in the Sahara able to survive for long periods of time without water?
• How is life in the Amazon different from life in the Sahara?
• Why would the organisms of the Sahara have trouble surviving in a biome such as the Amazon rainforest?
• Why are plants important in all biomes?
• How are plants able to make food from sunlight?
• Why do the arrows in a food chain (the path that energy travels as one organism eats another) go from the producers to the consumers, even though the consumers are eating the producers?
• How is a food web different from a food chain?
• How do herbivores get energy when they eat plants? How do carnivores get energy since they don’t eat plants?
  
  

Misconception: Ecosystems do not change much over time.

Fact: Ecosystems change for a variety of reasons, including environmental changes and human activity.

Misconception: The organisms in an ecosystem are not part of a larger whole, but instead are just a collection of living things surviving independently of one another and their environment.

Fact: Ecosystems are systems, made up of smaller interacting parts. Both the living and nonliving parts of an ecosystem influence the overall ecosystem.

Biome : a specific geographic area with a particular climate that supports different kinds of organisms

Consumer : an organism that eats other organisms

Decomposer : an organism that breaks down organic material and feeds on the nutrients

Ecosystem : a community of different organisms that depend on interacting with each other and their physical environment for survival

Energy : the ability to do work (move an object, heat up an object, charge an object, etc.)

Food Chain: the path that energy travels as one organism eats another

Food Web: a visual that shows the network of food chains in an ecosystem

Forest : an area of land covered by trees

Photosynthesis : the process of turning sunlight, carbon dioxide, and water into glucose and oxygen

Producer : an organism that captures energy from sunlight through a process called photosynthesis

Capturing the Sun’s Energy

All living things need water. An organism is a complete living thing. Organisms in the Sahara have different ways of finding water. Date palms are plants that have long roots to survive in a dry climate. Their roots reach water deep underground. Date palms then store the water in their roots.

Organisms also need energy. Energy is the ability to do work. Moving an object is work. Heating up an object and charging an object are also work. Organisms need energy to survive, grow, and reproduce. All energy on Earth begins with the sun. As the sun shines, it produces light energy. When the light energy reaches the date palms in the Sahara, the trees capture the energy and turn it into food.

Trees capture sunlight because they are producers. Producers are organisms that capture energy from sunlight. They do this through a process called photosynthesis [foh- toh-sin-thuh-sis]. All plants are producers.

Producing Energy

Date palms and other plants have leaves. These leaves have internal structures that collect the sun’s energy. These internal structures are called chloroplasts [klawr-uh-plasts].

Chloroplasts use the sun’s energy, along with water and carbon dioxide, to create a sugar called glucose. Glucose is food for the plant. It gives the plant energy to grow. Plants store extra glucose in their leaves and other parts. Chloroplasts also make oxygen. Oxygen is a gas. A plant that receives no light cannot make food. Plants also get nutrients from the soil. A plant will not grow if there are not enough nutrients in the soil or a regular supply of water.

Consuming Energy

The Sahara is also home to the jerboa. The jerboa is a tiny rodent. It has its own ways of dealing with the heat and dryness of the desert. It has short forearms and powerful back legs. It uses its arms and legs to dig into the sand. It digs until it reaches the underground roots of plants. These roots store water. Jerboas eat the roots. The roots give them energy as well as water. Some jerboas also eat insects for energy.

Jerboas and foxes are consumers. Consumers are organisms that eat other organisms. All animals are consumers. Consumers eat other living things for energy and nutrients. Just like fennec foxes, jerboas are most active at night. Fennec foxes often hunt jerboas for food. When a fennec fox eats a jerboa, it gets some of the jerboa’s energy. The fennec fox is a carnivore because it only eats other animals. The jerboa is an omnivore because it eats both plants and animals. Camels are herbivores because they only eat plants.

For the hands-on activity in this lesson, students construct two different food webs to answer the question of how energy and matter move through tropical and desert biomes. Students use their food web models to explain why all food webs have producers, consumers, and decomposers. Students present their food web models, arguing about how the model provides evidence of the flow of energy from the sun to different living things.