Characteristics of Life & Biological Diversity — Practice · Grade 7 Science

Chapter: Scientific Inquiry & Diversity of Life

What this practice covers

By the end of Characteristics of Life & Biological Diversity you should be able to:

8 questions, written answer and multiple choice, each with a worked explanation.

Vocabulary used: organism, homeostasis, prokaryotic, eukaryotic, classification.

Problem 1

Why does movement alone not establish life?
Answer and explanation

Nonliving objects can move through motors, wind, or gravity. Cellular organization and interacting life processes provide stronger evidence.

Problem 2

Why is “all living things eat other organisms” incorrect?
Answer and explanation

Photosynthetic organisms can build sugars using inorganic inputs and light. Organisms differ in how they obtain food and energy.

Problem 3

Can a living cell lack a nucleus?
Answer and explanation

Yes. Bacteria and other prokaryotes lack a membrane-enclosed nucleus but carry genetic material and perform cellular processes.

Problem 4

Does a classification key by itself show ancestry?
Answer and explanation

Not necessarily. It identifies using chosen features; an ancestry claim requires evidence supporting inherited relationships.

Problem 5

Illustrative records: A is a seed with cells that later germinates; B is a battery toy that moves; C is a bacterium with a membrane and DNA but no enclosed nucleus. Use several characteristics to classify living status and explain why movement and a nucleus are not sufficient tests.
Answer and explanation

A and C are living under the supplied records. A’s cellular organization and germination support that conclusion despite its earlier dormancy. C can function without an enclosed nucleus because it is prokaryotic. B’s movement alone does not establish cellular life. The comparison relies on the supplied biological observations, not a rule that every moving object is alive.

Identify cellular organization in A and C.

Use germination as evidence of a seed’s life process.

Separate powered toy motion from cellular activity.

Recognize C as a prokaryotic 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 6

A fungus has walls but no chloroplasts. Must it be an animal or a plant?
Answer and explanation

No. Those two categories do not exhaust biological diversity. Fungi have their own characteristics; combine cell features, nutrition, and relationship evidence rather than forcing a two-category choice.

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

Which record supports a prokaryotic cell?
  1. No DNA at all
  2. DNA and ribosomes but no membrane-enclosed nucleus
  3. A nucleus and no membrane
  4. Only a plastic motor
Answer and explanation

DNA and ribosomes but no membrane-enclosed nucleus

Prokaryotes contain genetic material and ribosomes without a membrane-enclosed nucleus.

Problem 8

Why can an individual unable to reproduce still be living?
Answer and explanation

Living status involves functioning cellular organization and interacting life processes. Reproduction characterizes life cycles and populations; it is not required from every individual at every time.

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