Biology Study Guide- Food Chains and Food Webs

What is a food chain?

A linear sequence of organisms through which nutrients and energy pass as one organism eats another. For example, grass photosynthesizes, mice eat the grass, and owls eat the mice.

What is parasitism?

A non-mutual relationship between species, where one species, the parasite, benefits at the expense of the other, the host.

What is predation?

A relationship between two organisms of unlike species in which one of them acts as predator that captures and feeds on the other organism that serves as the prey.

What is commensalism?

A relationship between two organisms where one receives a benefit or benefits from the other and the other is not affected by it. In other words, one is benefited and the other is neither benefited nor harmed.

What is an ecosystem?

A system that includes all living organisms in an area as well as its physical environment functioning together as a unit.

What is an example of parasitism?

A tick feeding off the blood of a mammal.

What is a carnivore?

An animal that eats a diet consisting mainly of meat, whether it comes from live animals or dead ones (scavenging).

What is an herbivore?

An animal that gets its energy solely from eating plants.

What is an omnivore?

An animal that includes both plants and animals in its normal diet.

What is competition?

An interaction between organisms or species in which both the organisms or species are harmed. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.

What is a chemotroph?

An organism that uses energy from chemicals to build organic compounds out of carbon dioxide or similar molecules.

What is a photoautothoph?

An organism that uses energy from sunlight to make sugars out of carbon dioxide in photosynthesis.

These are the organisms at the top of a food chain.

Apex consumer.

What is an example of commensalism?

Atlantic puffins use burrows for nesting that were made by rabbits.

[AUTOTROPHS/HETEROTROPHS] form the base of food chains and food webs.

Autotrophs

[AUTOTROPHS/HETEROTROPHS] make their own food. An example would be plants, which use sunlight to synthesize sugars.

Autotrophs

What is an example of mutualism?

Bees get the nectar they need to make honey by traveling between flowers. The bee brings pollen from one plant to another, resulting in pollination.

Heterotrophs are considered [PRODUCERS/CONSUMERS] in the food web.

Consumers

What are four examples of multicellular animals that act as decomposers?

Earthworms, slugs, crabs, and vultures.

The autotrophic organisms that form the base of the food web are known as _____________.

Primary producers

Autotrophs are considered [PRODUCERS/CONSUMERS] in the food web.

Producers

How is energy transferred in a food web?

Energy is transferred between trophic levels when one organism eats another and gets the energy-rich molecules from its prey's body.

What are the two key types of decomposers?

Fungi and bacteria.

Organize these organisms into a food web-- beginning with primary producers and ending with tertiary consumers: Owl, snake, grass, fox, mouse

Grass, mouse,snake, owl, fox.

If only 10% of energy is transferred from one trophic level to the next, where does the rest go?

It is lost during transfer, broken down in respiration, or lost to incomplete digestion by higher trophic level.

What is an example of predation?

Lynx hunting, killing, and eating rabbits.

What is a decomposer?

Organisms that break down dead organic material and wastes. They are often not mentioned in food chains or food webs, though they play a key role in the health of an ecosystem.

Determine the trophic level each of these organisms would occupy as part of a coherent food chain: Owl, snake, grass, fox, mouse

Owl- tertiary consumer; snake- secondary consumer; grass- primary producer; fox- apex consumer; mouse- primary consumer

What are three examples of photoautotrophs?

Plants, algae, cyanobacteria.

These organisms consume primary producers.

Primary consumers

What are three examples of omnivores?

Racoons, orangutans, skunks.

These organisms consume primary consumers.

Secondary consumers

What is an example of competition?

Squirrels require oak trees and their acorns for food, compete with chipmunks and deer and acorn weevils for the acorns, must avoid predators like hawks, and so on.

These organisms consume secondary consumers.

Tertiary consumers

What is a trophic level?

The position that an organism occupies in a food chain - what it eats, and what eats it

What is mutualism?

The way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other.

What is a food web?

These consist of many interconnected food chains and are more realistic representation of consumption relationships in ecosystems.

Explain the 10% rule of energy transfer.

When energy enters a trophic level, some of it is stored as biomass, as part of organisms' bodies. This is the energy that's available to the next trophic level since only energy storied as biomass can get eaten. As a rule of thumb, only about 10% of the energy that's stored as biomass in one trophic level—per unit time—ends up stored as biomass in the next trophic level—per the same unit time. This is the 10% rule of energy transfer.

What is the difference between a food chain and a food web?

Where the food chain gives you a snapshot of what organisms may be eating each other, the food web goes much deeper-- showing the many interconnected food chains that an ecosystem is comprised of.