Cells, Transport & Cellular Energy — Chapter quiz · Life Science & Scientific Inquiry, Grade 7

Five focused units, a three-session investigation, chapter review, and chapter quiz.

Problem 1

What other information is needed to infer mass from cell count?
Answer and explanation

Cell sizes and composition matter. More cells do not supply a complete mass measurement by themselves.

Problem 2

A newly observed unicellular organism has no tissue. Does that contradict cell theory?
Answer and explanation

No. Unicellular organisms consist of one cell that carries out life processes. Tissues are not required in every organism.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 3

Why is “mitochondria create energy” misleading?
Answer and explanation

They help transfer energy from food into usable forms; energy is not created.

Problem 4

A bacterium has DNA and ribosomes but no nucleus. Can it still make proteins?
Answer and explanation

Yes. Ribosomes can use cellular instructions without an enclosed nucleus; the arrangement differs from the typical eukaryotic-cell model.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 5

Does absence of chloroplasts prove a root cell is an animal cell?
Answer and explanation

No. Many plant cells are not photosynthetic; other structures and tissue context help identify them.

Problem 6

A bulb cell has a wall and nucleus but no visible chloroplasts. Must the observation be wrong?
Answer and explanation

No. Many plant tissues lack chloroplasts, and visible detail also depends on the instrument. Use tissue context and additional features.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 7

What must be known before predicting osmosis?
Answer and explanation

Which materials can cross, their concentrations, and relevant pressure or other conditions; a membrane is not universally permeable.

Problem 8

A membrane is freely permeable to the solute in a second model. Can the previous nonpenetrating-solute prediction be copied unchanged?
Answer and explanation

No. Solute redistribution changes the relevant conditions. Determine permeability and concentrations before predicting water movement.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 9

Does falling carbon dioxide around a lit plant prove it stopped respiring?
Answer and explanation

No. Photosynthetic uptake can exceed respiration while both continue; the measurement is a net change.

Problem 10

A student says plants use respiration only at night. Correct the claim.
Answer and explanation

Plants respire in light and darkness. Photosynthesis can occur in suitable light at the same time, so a net gas change must account for both processes.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

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