Topic 3 Day 1 - Food Chains and Webs

The diagram above shows a partial food web. Based on the food web, which of the organisms acts as both a primary consumer and a secondary consumer?

• Fox

• Mouse

• Rabbit

• Toad

Answer explanation

The mouse is acting as both a primary and secondary consumer in the food web. Primary consumers are animals that eat plants, and secondary consumers are animals that eat primary consumers. In this food web, the mouse may consume plant matter as well as other organisms, like insects, making it a primary and secondary consumer.

Tags

SC.912.L17.9

The flowchart shows the unidirectional flow of energy through a food chain and the cycling of matter in nature.

How would the absence of decomposers most significantly affect the flowchart?

• The flow of energy would be affected.

• The dissipation of energy would be less.

• It would stop the cycling of matter in nature.

• The supply of nutrients for the producers would be less.

Answer explanation

The absence of decomposers would stop the cycling of matter in nature. Decomposers play a vital role in breaking down dead organic material and recycling its nutrients back into the ecosystem. Without them, this process would be halted, disrupting the natural cycle of matter.

Tags

SC.912.L17.9

Which of the following represents a food chain in the food web above?

• copepods → snapper → seal → orca

• diatoms → copepods → killifish → snapper → seal

• orca → herring → snapper → killifish → copepod → diatom

• squid → bluefish → herring → mackerel

Answer explanation

The correct choice is 'diatoms → copepods → killifish → snapper → seal'. This represents a food chain where each organism is a source of food for the next. This is the onyl food chain that starts with a producer. Starting with diatoms, which are consumed by copepods, that in turn are eaten by killifish, which are then prey for snappers, which are finally consumed by seals. This sequence accurately represents a food chain in the food web from the question.

Tags

SC.912.L17.9

Examine the food web above. Which pair of consumers in this food web has the greatest amount of energy available for consumption?

• hawk and mountain lion

• rabbit and grasshopper

• snake and songbird

• trees and grass

Answer explanation

The amount of energy available decreases as you move up the food chain. Grasshoppers and rabbits are primary consumers, feeding directly on producers like grass and plants, hence, they have more energy available for consumption compared to higher trophic level consumers like hawks, mountain lions, snakes and songbirds.

Tags

SC.912.L17.9

Look at the food web shown above. Which organisms are producers?

• Deer and mice

• Grass and shrubs

• Snakes and hawks

• Grasshoppers and frogs

Answer explanation

In a food web, producers are the organisms that make their own food through the process of photosynthesis. They form the base of the food web as they provide food for primary consumers. In the given question, grass and shrubs are the producers as they can produce food, while deer and mice, snakes and hawks, and grasshoppers and frogs are consumers who depend on producers for their food.

Tags

SC.912.L17.9

The diagram above shows a partial food web. Food webs, such as the one shown, were first used in 1927 by the animal ecologist Charles Elton.

Which of the following transfers is the most energy efficient?

• Plant → Grasshopper → Toad → Snake

• Plant → Mouse → Fox

• Plant → Grasshopper → Mouse → Fox

• Fox → Plant → Mouse

Answer explanation

The efficiency of energy transfer in a food web is typically highest when there are fewer trophic levels, or steps, in the food chain. The option 'Plant → Mouse → Fox' has fewer steps than the other options, making it the most energy efficient transfer. Each step in a food chain results in energy loss, so fewer steps mean more energy is retained.

Tags

SC.912.L17.9