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(Level 2 Unit 4 Lesson 2) Exercise 3: Scanning

Scan through the text for the following words. Click once on the first occurrence of the word in the text.


Energy flows from the sun to the plants to the plant eaters to the meat eaters.

Green plants and certain types of bacteria and algae are the primary producers because they are the ones that produce usable energy for the rest of the living organisms on earth. They use energy from the sun to make sucrose, glucose, and other compounds that other life forms can eat and "burn" for energy. In each one of those sugar molecules a little bit of the sun's energy is stored in a form that we can call chemical energy. But it might better be called "potential energy" since it is a sort of "doing-nothing-for-now-waiting-to-happen" kind of energy.

Herbivores are the plant eaters. They have the ability to digest the plants they eat and release the energy stored in the plant cells for their own use. Some examples of animals in this group are deer, cows, elephants, rabbits, elks, zebras, most insects, and birds that eat fruit and seeds. Sometimes scientists call this level of the food chain the Primary Consumers.

These are the meat eaters. Predators and scavengers are in this group. Sometimes this level in the food chain is referred to as the Secondary Consumers. They eat the animals that eat the plants and sometimes they eat each other. Most of these animals can't eat plants at all. They would starve to death if it weren't for the Herbivores digesting the plants first. They've got the top job but they're really quite helpless without all the boring plants and herbivores. Cats and dogs, killer whales, sharks, spiders, snakes, wolves, vultures, hawks, eagles, crocodiles, and many other fierce predators that for some reason we are especially fascinated with, are in this group.

They are the organisms that eat up dead bodies, both plant and animal. And aren't we happy they do. This group of useful creatures are mostly bacteria and fungus, but also, according to our sources, includes maggots, dung beetles, earth worms and many other eaters of dead organic matter. Without them there would be a lot of dead bodies lying around. They're like carnivores and herbivores, because they also have to get their energy from the cells of animals or plants. The difference is they prefer their food dead - very dead.

What do you think? Are maggots decomposers or carnivores (or just horrible little things we'd rather not think about)?

Omnivores are the last type and eat both plants (acting a primary consumers) and meat (acting as secondary or tertiary consumers). Examples of omnivores are:

Bears: They eat insects, fish, moose, elk, deer, sheep as well as honey, grass, and leaves.
Turtles: They eat snails, crayfish, crickets, earthworms, but also lettuce, small plants, and algae.
Monkeys: They eat frogs and lizards as well as fruits, flowers, and leaves.
Squirrels: They eat insects, butterflies, bird eggs and nesting birds and also seeds, fruits and nuts.

Some animals can eat plants and other animals. So you could say they are both a herbivore and a carnivore. That's the way humans are. We can eat plants and we can eat meat. It must have been too difficult for biologists to say herbicarnivore or carniherbivore (donít try to find these words in your dictionary), so they decided to call humans, and others like us, omnivores. It means we'll eat just about anything we can get our hands on. I can't think of anything better than being an omnivore. We can be either primary or secondary consumers. It makes shopping so easy!

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