1.1 Food Chains & Webs

Question 1

Consumer

Answer 1

also called heterotrophs, organisms that must consume other organisms for nutrition

Question 2

Decomposer

Answer 2

Decomposers break down dead organisms and waste into nonliving elements. Mushrooms are common decomposers.

Question 3

Ecosystem

Answer 3

the biotic (living) organisms in an environment that includes the abiotic (nonliving) components

Question 4

Food chain

Answer 4

visual display that shows how energy and nutrients flow from one organism to another

Question 5

Food web

Answer 5

a network of interconnected food chains
Organism: an individual animal, plant, or single-celled life form

Question 6

Primary consumer

Answer 6

herbivores that eat producers

Question 7

Producer

Answer 7

also called autotrophs, organisms that produce their own food using inorganic compounds and an energy source like the sun

Question 8

Secondary consumer

Answer 8

carnivores or omnivores that consume primary consumers and/or producers

Question 9

Trophic level

Answer 9

refers to each level in an ecosystem comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy

Question 10

If you had a hamburger for dinner, what would your food chain look like?

Answer 10

Notice that the arrows show the flow of energy through the food chain.

The sun’s energy flows into the grass. When the cow eats the grass, energy from the grass flows into the cow. Finally, when you consume the hamburger, energy from the meat helps fuel your body. Every link in your food chain is connected.

Question 11

How is energy transferred as it flows through the trophic levels in a food chain and a food web?

Answer 11

Energy comes in many different forms. In the case of food chains and food webs, energy is found in all individual organisms at each of the trophic levels. The term trophic relates to the energy a source provides. Producers, various levels of consumers, and decomposers fill each of the trophic levels.

In ecosystems, the transfer of energy starts with the sun, and that same energy fuels every other trophic level.

Question 12

How does the amount of energy available change as you move from one trophic level to the next?

Answer 12

Chemical energy from consuming nutrition is transferred from one trophic level to the next and is measured in units called kilocalories (kcals). One kcal is equal to the amount of heat energy required to raise the temperature of one kilogram of water one degree Celsius. Organisms transform kcals into kinetic energy needed to live, breathe, and move.

Although energy cannot be created or destroyed, the amount of available energy changes from trophic level to trophic level as some of the energy escapes into the environment as heat or is converted to some other form within that trophic level.

Question 13

How can changes in one part of a food web affect another part?

Answer 13

The balance in an ecosystem is delicate. Even small changes that impact the type or number of organisms present can upset the stability of the entire ecosystem. Let’s explore a woodland ecosystem food web to see how adding or removing organisms affects the balance.

Question 14

How may the mallard duck population impact the other types of organisms found in both the northern and southern ecosystems?

Answer 14

Mallard ducks help to keep the populations of producers (grass and weeds) and primary consumers (bugs, small fish, and insects) in both ecosystems balanced. Mallard ducks also serve as a food source to the secondary consumers (wolves, alligators, and hawks).

Question 15

Tertiary consumers

Answer 15

carnivores or omnivores that eat the secondary consumers. Deer are herbivores and wolves are carnivores; they are both consumers.