How does a single cell sustain life?

What is the smallest unit that can be said to be alive?

• an atom

• an organelle

• a nucleus

• a cell

Answer explanation

Cells are the basic units of living things. Single-celled organisms contain all the functions necessary for life within one cell. Paramecia are one type of single-celled microscopic organisms that live in ponds.

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Which of the following is an example of an organelle?

• a heart

• a nucleus

• a molecule

• a lung

Answer explanation

Organelles carry out special functions. Just as the body has organs that carry out different functions, each cell in the body has special structures that carry out particular functions. These structures are called organelles.

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Organelles carry out special functions in eukaryotes.Just as the body has organs that carry out different functions, each cell in the body has special structures that carry out particular functions. These structures are called organelles. Each organelle is surrounded by a membrane. The membrane keeps it separate from other cell components. An organelle performs a specific function to help meet the basic needs of the cell. Together, the sum of these contributions ensures the survival of the cell. Based on this text, what do you think would happen if the organelles were missing or not working?

• Eukaryotes are not alive so it would not matter.

• Without the organelles, the cell would not function and may not survive.

• Organelles can help a cell but they are not really necessary.

• The organelles are shaped differently but they all do they same thing.

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This is a poll (not a graded question)

Which organelle would you be?

• The mighty mitochondria

• The nucleus that runs the show

• The cell membrane that controls who and what goes in and out

• The chloroplast that makes food for everyone

• The cell wall that holds everything together and protects everyone

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What function does the cell membrane do for the cell?

• It makes food

• It directs the other organelles

• It creates energy for the cell

• It controls what enters and leave the cell

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The cell wall is a tough, protective barrier that surrounds the outer membrane of plant cells. There is another organelle that is found only in plants that is green and produces chlorophyll. Which is it?

• Mitochondrion

• Nucleus

• Cell membrane

• Chloroplast

Answer explanation

A chloroplast is a membrane-bound organelle in plants that is the site of photosynthesis. Chloroplasts are organelles that produce chlorophyll. This chemical traps the sun's energy. The chlorophyll then transforms this energy into sugar that is used as food by plant.

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Scientists divide organisms into two main groups based on their cell structure. Cells that have DNA that is not inside a nucleus and that do not have any membrane-bound organelles are called prokaryotes (bacteria). Cells that do enclose the DNA inside a nucleus and have other membrane-bound organelles are called eukaryotes. The photo shows a drawing of a Paramecium which is a single-celled microscopic organism that lives in ponds. Is it a prokaryote or a eukaryote?

• Eukaryote

• Prokaryote

• all of the above

• none of the above

Answer explanation

Paramecium are eukaryotes. In contrast to prokaryotic organisms, such as bacteria and archaea, eukaryotes have well-organized cells that contain organelles.

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In eukaryotes, there is an organelle found near the center of the cell that acts as a control center for the cell. What is it?

• the nucleus

• the cell membrane

• the cell wall

• the prokaryote

Answer explanation

DNA, is located inside the nucleus. The genetic information in DNA directs the main functions of the cell.

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