5.L.3.1 and 5.L.3.2

The nitrogen cycle is an important cycle found in ecosystems. Nitrogen is used by living organisms to produce a number of complex organic molecules. Most of the nitrogen is found in the atmosphere, where it exists as a gas. Nitrogen is made available in a useful form for animals in the

• plants they eat.

• air they breathe.

• rainwater they drink.

• fertilizers they absorb.

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-3

A salt marsh has a variety of animals and plants. The pyramid represents the amount of energy transferred between organisms in a salt marsh. Which trophic level would lose the MOST useful energy as heat when organisms at that level feed on other organisms?

• 5

• 4

• 3

• 2

Tags

NGSS.MS-LS2-3

Which factor BEST explains why biomass decreases as trophic level increases in a food pyramid?

• Some of the energy is converted to heat.

• The survival rate of organisms gradually decreases

• The availability of space decreases as feeding levels increase.

• Toxic chemicals get concentrated as they move up the food web.

Tags

NGSS.MS-LS2-3

How does the energy in each trophic level of an energy pyramid compare to the energy in the preceding level?

• It has about 5% of the energy from the level below it.

• It has about 10% of the energy from the level below it.

• It has about 15% of the energy from the level below it.

• It has about 20% of the energy from the level below it.

Tags

NGSS.MS-LS2-3

Meadows are grassland areas, usually low-lying with moist soil. Meadows support a rich variety of animal life. A food web for a meadow is shown. The removal of which populations of organisms would have the greatest impact on the food web?

• grasses and shrubs

• seed-eating birds

• rabbits

• snakes

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-4

Food webs are used to identify the feeding relationships between organisms. Which statement can be logically concluded about the food web shown?

• Organism 1 is most likely a type of bacteria.

• Organism 2 is definitely an omnivore.

• Organism 5 is most likely a plant eater.

• Organism 8 is definitely a carnivore.

Tags

NGSS.MS-LS2-2

NGSS.MS-LS2-3

Which organisms contribute MOST to the decomposition of dead organisms?

• snakes

• viruses

• insects

• bacteria

The diagrams show different ways to represent energy flow. Although very different, both diagrams are acceptable because

• different energy diagrams require different organization.

• both diagrams show the information accurately.

• the numbers of animals in the diagrams are different.

• the energy levels change between diagrams.

Tags

NGSS.MS-LS2-3

What is a solvent?

• The substance that does the dissolving in a solution.

• The substance that is being dissolved in a solution.

• The mixing of different substances.

• The process in which neutral molecules lose or gain electrons

In the above picture, a powder is about to be poured into the liquid. Which of the following should be done to make this powder dissolve faster?

• stir the powder in the liquid

• freeze the mixture

• add more powder to the liquid

• store the mixture in a dark place

Tags

NGSS.MS-PS1-2