1. Objective 2
(7.12) Science concepts. The student knows that there is a relationship between organisms and the environment. The student is expected to
(B) observe and describe how organisms including producers, consumers, and decomposers live together in an environment and use existing resources;

2. HIGHLIGHT 1
Food Webs are part of student expectation (7.12) and may include examples from Texas or the southwestern United States in addition to global examples.

3. All of the external conditions that affect an organism
ENVIRONMENT
All of the external conditions that affect an organism
Biotic factors are the living parts of the environment
Abiotic factors are the nonliving parts of the environment

4. What are the biotic and abiotic factors in this picture?

5. BIOTIC ABIOTIC Cows Grass Trees Shrubs Others unseen Air Water
Soil, rocks
Light
Temperature

6. ENERGY FLOW AMONG ORGANISMS
Everything you do requires energy. How do you get the energy that you need?

7. All living things get energy from their food to carry out life processes.
Plants make their food.
Animals eat their food.

8. A food chain shows how each living thing gets its food
A food chain shows how each living thing gets its food. Plants make food using energy from the sun. Some animals eat plants and some animals eat other animals. Each link in a chain is food for the next link. Arrows indicate the direction of energy flow.

9. sagebrush pronghorn coyote
pronghorn
coyote

10. Plants are called producers because they are able to use the energy from the sun to produce the food they need using carbon dioxide and water.

11. Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers.
There are three groups of consumers.

12. HERBIVORES Animals that eat ONLY PLANTS are called herbivores.

13. CARNIVORES Animals that eat OTHER ANIMALS are called carnivores.

14. OMNIVORES Animals that eat BOTH animals and plants are called omnivores.
American bear
Raccoon

15. OMNIVORES
Copyright © Tim McCabe, NRCS

16. Some animals eat dead animals or carrion. They are called scavengers
Some animals eat dead animals or carrion. They are called scavengers. They help break down or reduce organic material into smaller pieces.
roach
vulture
hyeina

17. DECOMPOSERS Organisms (bacteria and fungi) which feed on decaying matter.
Decomposers and scavengers break down dead plants and animals. They also break down the waste (feces) of other organisms. Decomposers are very important for any ecosystem. If they weren't in the ecosystem, the plants would not get essential nutrients, and dead matter and waste would pile up.

18. DECOMPOSERS Fungi Bacteria

20. THINK ABOUT IT!
What would happen to a forest ecosystem if the bacteria and fungi on the forest ground all died of disease?

21. A herbivore is called a primary, or first order consumer because it eats the producers.
A carnivore that eats herbivores is a secondary, or second order consumer.
Some predators are called tertiary, or third order consumers. These animals usually have no predators.

22. Photosynthesis
Producer
Primary Consumer
Secondary consumer
Tertiary consumer
Decomposer

23. Why are there more herbivores than carnivores?
In a food chain, energy is passed from one link to the next. When a herbivore eats, only a fraction of the energy that it gets from the plant food becomes new body mass; the rest of the energy is lost as waste or converted to heat (by the herbivore).

24. Likewise, when a carnivore eats another animal, only a portion of the energy from the animal food is stored in its tissues. In other words, organisms along a food chain pass on much less energy (in the form of body mass) than they receive.

25. ENERGY PYRAMID
Because a large amount of energy is lost at each link, the further along the food chain you go, the less energy is available.
We use the energy pyramid as a model to show decreasing available energy at each level in the pyramid.

26. 0.1% energy
1% energy
10% energy
100% energy

27. FOOD WEBS
Most organisms are part of more than one food chain. Many animals eat more than one kind of food in order to meet their food and energy requirements. These interconnected food chains form a food web.

29. MARINE FOOD WEB

30. INTERACTIONS AMONG ORGANISMS
Predator-prey
An animal that hunts or kills other animals for food is called a predator.
An animal that is eaten by another is called prey.

31. Can you match some predator-prey relationships?

32. Predator Prey

33. YOUR TURN! 1. In this food web, the bacteria probably function as
A producers
B herbivores
C decomposers
D carnivores

34. The correct answer is “C”, decomposers
The correct answer is “C”, decomposers. Bacteria are decomposers that break down the remains of dead plant and animal material.
A. Incorrect. Bacteria in this food web are not producers.
B. Incorrect. Bacteria are decomposers of both plant and animal material.
D. Incorrect. Bacteria are decomposers of both plant and animal material.

35. 2. Energy used by producers
in this grassland food web
is provided by
A. sunlight
B. water C. oxygen D. carbon dioxide

36. Correct. Producers use energy from the sun to produce food in the form of sugar.
Incorrect. Water is a raw material (reactant) necessary for producing food, it is NOT energy.
Incorrect. Oxygen is a product of photosynthesis, it is NOT energy.
Incorrect. Carbon Dioxide is also a reactant necessary for photosynthesis, it is NOT energy.

37. 3. Which of the following is the correct flow of energy through an ecosystem?
Producers sun decomposers consumers
Sun consumers decomposers producers
Sun producers consumers decomposers
Producers consumers decomposers sun

38. The correct answer is “C”.
The sun provides energy that producers use to make food.
Consumers eat plants or other consumers to get energy.
Plants and animals die.
Decomposers get energy by feeding on decaying plant and animal matter.

39. A suburban community has a colony of bats that feeds mainly on the mosquitoes that live in the ecosystem. Because of the danger of West Nile Virus being spread by mosquitoes, the community launched a spraying program to kill the mosquitoes. What effect will this most likely have on the bat population?
A. The bat population will not be affected.
B. The bat population will decrease because its food supply will decrease.
C. The bat population will increase because it will find other things to eat.
D. The bat population will be killed off by the mosquito spray.

40. The correct answer is “B”
The correct answer is “B”. The bat population is likely to decrease because of a decrease in the food supply.
A Incorrect. The competition for food will be too great for the population to not be affected.
C Incorrect. The bat population is unlikely to find another food source to cause its population to increase.
D Incorrect. The mosquito spray is unlikely to kill off the bats.