Explore Learning Gizmos: Cell types

What is the structure labeled with an arrow?

• Cytoplasm

• Flagellum

• Nucleus

• Cell wall

Answer explanation

Explanation: The arrow points to the nucleus of a mouse skin cell. The nucleus is a membrane-bound structure that contains genetic material. Cytoplasm (light purple) is the gel-like substance inside the cell that surrounds the nucleus. Cell walls are found in plant cells, where they provide protection and support. A flagellum is a whip-like appendage that helps some cells move.

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NGSS.MS-LS1-1

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Which statement best describes a cell?

• The smallest structural and functional unit of an organism that can be said to be alive.

• A sac-like membrane that stores water.

• A compartment that contains DNA and regulates when genes are turned on and off.

• A small compartment that includes a cytoplasm, a nucleus, and a cell membrane.

Answer explanation

Cells are the smallest functional units of an organisms that can be considered alive. Choice A describes the nucleus. Choice C describes a vacuole. Choice D could describe a cell, but not all cells contain a nucleus. For example, prokaryotic cells and human red blood cells do not have a nucleus.

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NGSS.MS-LS1-1

NGSS.MS-LS1-2

Which of the samples shown below are eukaryotic?

• A, C, and D

• B and C

• B and D

• A, B, and D

Answer explanation

Sample A contains frog blood cells, sample B contains fungus cells, and sample D contains maple leaf cells. All of these cells contain nuclei and are therefore eukaryotic. Sample C contains E. coli cells. E. coli do not have a distinct nucleus and are therefore prokaryotic cells.

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NGSS.MS-LS1-1

Which of the samples shown below are photosynthetic?

• B, C, and D

• A, B, and C

• A, B, C, and D

• A, C, and D

Answer explanation

Sample A contains Elodea cells, sample C contains maple leaf cells, and sample D contains Euglena cells. All three of these cells contain chloroplasts, which are green organelles that perform photosynthesis. While sample B contains plant cells (root hair cells), these plant cells do not contain chloroplasts so cannot undergo photosynthesis.

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NGSS.MS-LS1-6

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What do the following results from the TEST FOR LIFE tab indicate about the sample?

• A. The sample produces ATP.

• B. The sample is a plant.

• C. The sample is photosynthetic.

• D. Answers A and C.

Answer explanation

The results of the ATP test are positive in both the light and the dark, indicating that the sample produces ATP. The results of the phenol red test are negative in the light and positive in the dark, indicating that the sample undergoes photosynthesis. There is not enough information, however, to determine if the sample is a plant, as other organisms such as Euglena are also able to undergo photosynthesis.

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NGSS.MS-LS1-6