Defense, Disease & Homeostasis — Practice · Grade 10 Science

Chapter: Body Systems, Signals & Homeostasis

What this practice covers

By the end of Defense, Disease & Homeostasis you should be able to:

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

Vocabulary used: pathogen, antigen, immune memory.

Problem 1

Which is a barrier defense?
  1. Intact skin
  2. A Punnett square
  3. A chloroplast
  4. A fossil record
Answer and explanation

Intact skin

Skin limits entry rather than identifying one specific antigen.

Problem 2

Why is not every disease contagious?
Answer and explanation

Disease includes noninfectious disruptions, such as inherited or environmental problems.

Problem 3

How can memory change a second response?
Answer and explanation

Persistent antigen-responsive cell populations can expand or act faster.

Problem 4

A bacterial population contains rare resistant variants before treatment. Explain a possible population change after treatment. Explain the reasoning in your own words.
Answer and explanation

Selection can increase resistance frequency; the drug need not intentionally create the useful variant.

Susceptible bacteria are reduced by the treatment.

Resistant survivors can reproduce, increasing the resistant proportion.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 5

Why can inflammation be useful yet cause harm when excessive? Show the reasoning, not just the conclusion.
Hints

Memory is specific; it does not guarantee protection from every pathogen.

Answer and explanation

It recruits protective responses but excessive or misplaced activity can damage tissue.

Problem 6

Why does a changed pathogen antigen sometimes reduce previous protection?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Recognition depends on molecular features; altered antigens can reduce the match to existing immune responses.

Problem 7

A changed control target differs from uncontrolled heatingA changed control target differs from uncontrolled heatingTemperature / target in a supplied model (°C)363738394001234Relative observation timeModel targetMeasured response
Original target/response model, not a diagnostic threshold, fever-management advice or individual record.
Interpret the supplied visual. Why could warming responses occur while the measured temperature is already elevated?
Answer and explanation

The regulated target can be higher still, so the response acts toward it in the stated model.

In a fever model, immune signaling can change thermoregulatory control, producing responses toward a higher target. This differs mechanistically from overheating without an appropriately raised target. Chills or heat-loss responses depend on the relation between current temperature and regulation, not merely whether a reading is above a usual value. Temperature can reflect many processes, and the educational comparison is not enough to classify a real person’s condition. The task is to explain control logic using the supplied target and response curves.

The regulated target can be higher still, so the response acts toward it in the stated model.

Response criteria

  • Read the structures, axes, directions and units correctly.
  • Connect the evidence with the biological mechanism.
  • Respect stated model assumptions and distinguish an observation from a further inference.

Problem 8

A later sample gives more antibody-binding signal than an earlier sample. State one supported conclusion and two things this alone does not establish.
Answer and explanation

It supports increased measured binding under comparable assay conditions. It does not alone establish an exact antibody count, doubled protection, lasting immunity or the full cellular response; additional calibrated/outcome evidence is needed.

It supports increased measured binding under comparable assay conditions. It does not alone establish an exact antibody count, doubled protection, lasting immunity or the full cellular response; additional calibrated/outcome evidence is needed.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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