Download Food Webs Nov.7-11

Science Vocabulary and Notes:
Chapter 3, Lesson 2: Food Webs
Vocabulary.
1. Food Web- is a network of food chains that have some links in common
2. Competition- is the struggle between organisms for the same resource
3. Exotic species- are non-native plant and animals that have been introduced
into an environment
4. Energy pyramid- is a model that shows how much energy flows through a food
web
Notes:
What are food webs?
1. In most food chains, each type of organism is eaten by more than one type of
consumer.
2. This can make organism a part of more than one food chain. These food
chains can be combined to form a food web.
3. A food web is a network of food chains that have some links in common.
4. Life in an ecosystem is a constant struggle. In addition to food, organisms also
compete for water, sunlight, and space.
5. Competition is the struggle between organisms for the same resource.
How can food webs change?
6. When one population in a food web changes, all the other populations in the
food web can be affected.
7. When top carnivores are removed from a food web, prey populations are no
longer controlled.
8. Prey organisms can now reproduce without limits.
9. When prey populations increase in number, they need more producers to
supply them with food.
10. Soon there would be less grass and other producers to support these
organisms. ‘
How do new organisms change food webs?
11. Humans can change ecosystems by introducing new species.
12. Exotic species are non-native plant and animals that have been introduced
into an environment.
13. These plans and animals can threaten native species.
14. One example of an exotic species would be Zebra mussels.
15. Zebra mussels were introduced into freshwater ecosystems in the United
States by humans.
16. In a food web, organisms compete with each other for food and other
resources.
17. When an exotic species, such as Zebra mussles, is introduced into an
ecosystem, it also competes with native species for these resources.
18. Some native species cannot compete well with exotic species.
19. As a result, the native species may decline in number or may completely
disappear and become extinct after some time.
What is an energy pyramid?
20. An energy pyramid is a model that shows how much energy flows through a
food web.
21. Producers are at the bottom level of the pyramid.
22. Only about 10 percent of the Sun’s energy that a producer receives is turned
into food energy.
23. They use the other 90 percent to live and grow.
24. Consumers make up the next levels of the pyramid.
25. The bottom of the pyramid represents the largest level because it contains the
most organisms, and therefore contains the most energy.
26. In any ecosystem, the number of producers is greater than the number of
herbivores.
27. There are many more herbivores than carnivores.
28. There are fewer numbers of organisms and less available energy at each
higher level of the pyramid.