Question

section 1: freshwater ecosystems
read the passage below and answer the questions that follow.
aquatic organisms are grouped by location and by their adaptations. there are three groups of aquatic organisms. plankton are organisms that cannot swim against currents, so they are drifters. drifting algae, called phytoplankton, are the food base for most aquatic ecosystems. most phytoplankton are microscopic. drifting animals, which may be microscopic or as large as a jellyfish, are called zooplankton. nekton are free - swimming organisms such as fish and whales. benthos are bottom - dwellers, such as mussels, worms, and barnacles. many benthic organisms live attached to hard surfaces or burrow into softer sediments. decomposers, which break down dead organisms, also live in aquatic ecosystems.
identifying main ideas
one reading skill is the ability to identify the main idea of a passage. the main idea is the main focus or key idea. frequently, a main idea is accompanied by supporting information that offers detailed facts about main ideas.
in the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

1. how are organisms in an aquatic ecosystem grouped?

a. by size and shape
b. by the food they eat
c. by how they reproduce
d. by location and adaptations

1. where do many benthic organisms live?

a. attached to hard surfaces
b. in open water
c. near the surface of the water
d. attached to benthos

1. how many groups of aquatic organisms are discussed in this passage?

a. 2
b. 3
c. 5
d. 4

1. which groups of aquatic organisms are discussed?

a. phytoplankton and zooplankton
b. plankton, nekton, and benthos
c. plankton, nekton, benthos, and decomposers
d. plankton, phytoplankton, zooplankton, nekton, and benthos

Explanation:

1. The passage clearly states "Aquatic organisms are grouped by location and by their adaptations."
2. It mentions "Many benthic organisms live attached to hard surfaces or burrow into softer sediments", so attached to hard surfaces is correct.
3. The passage discusses plankton, nekton, benthos, and decomposers - 4 groups.
4. The passage talks about plankton (including phytoplankton and zooplankton), nekton, benthos, and decomposers.

Answer:

1. d. by location and adaptations
2. a. attached to hard surfaces
3. d. 4
4. c. plankton, nekton, benthos, and decomposers