Body Systems, Signals & Homeostasis — Chapter quiz · Life Science: Biology, Grade 10

Trace interactions among body systems and explain regulation and defense.

Problem 1

Define negative feedback and give one example from the human body.
Answer and explanation

Negative feedback is a loop in which the response reverses the change that triggered it, restoring the set point. Example: when body temperature rises, sweating and widened blood vessels cool the body back down (or: when blood sugar rises, insulin lowers it again).

Problem 2

Which of these is an example of positive feedback?
  1. Shivering to raise body temperature when cold
  2. Insulin lowering blood glucose after a meal
  3. Sweating to cool down when overheated
  4. Contractions during childbirth intensifying until the baby is born
Answer and explanation

Contractions during childbirth intensifying until the baby is born

Childbirth contractions amplify themselves (positive feedback), while the other three reverse a change (negative feedback).

Problem 3

Which best connects two systems?
  1. Respiratory gas exchange supplies oxygen transported by circulation
  2. The digestive system directly pumps air
  3. Kidneys digest all proteins
  4. The heart performs photosynthesis
Answer and explanation

Respiratory gas exchange supplies oxygen transported by circulation

Systems interact through material transfers.

Problem 4

Explain how structure aids oxygen exchange in the lungs.
Answer and explanation

Thin exchange barriers and large area support diffusion; circulation maintains transport and concentration differences.

Problem 5

Independent chapter check: A record shows increased breathing and pulse during activity, followed by different recovery times. Explain two system links and why one trace cannot identify a unique cause.
Answer and explanation

Respiratory exchange and circulation support changing tissue demand; neural/hormonal regulation can coordinate responses. Different variables have different dynamics, and intensity, conditions and other mechanisms require comparisons before naming one cause.

Respiratory exchange and circulation support changing tissue demand; neural/hormonal regulation can coordinate responses. Different variables have different dynamics, and intensity, conditions and other mechanisms require comparisons before naming one cause.

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.

Problem 6

A person's blood glucose remains above 180 mg/dL for hours after a meal. The failure is best described as a breakdown in
  1. positive feedback amplification
  2. negative feedback regulation of glucose
  3. oxygen transport
  4. the digestive absorption of water
Answer and explanation

negative feedback regulation of glucose

Returning glucose toward its set point after a meal is negative feedback, normally mediated by insulin; a prolonged elevation indicates that loop is not functioning effectively.

Problem 7

Explain why positive feedback is useful in childbirth and blood clotting but dangerous as a way to regulate body temperature.
Answer and explanation

Positive feedback amplifies a change, which suits processes that need to run rapidly to a definite completion: contractions intensify until delivery ends the loop, and clotting accelerates until the vessel is sealed. Each has a built-in endpoint. Temperature has no such endpoint, so amplification would drive the deviation further in the direction it had already moved, pushing the body away from the range in which its enzymes function. Regulation of a variable that must stay within a range requires a response that opposes the change.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Independent chapter check: A regulated variable is below target. An effector raises it toward target but overshoots temporarily after a delay. Classify the intended feedback and explain the overshoot.
Answer and explanation

The intended response is negative feedback because it opposes the deviation. Delayed sensing/response and changing inputs can produce overshoot; a rising value alone does not define positive feedback.

The intended response is negative feedback because it opposes the deviation. Delayed sensing/response and changing inputs can produce overshoot; a rising value alone does not define positive feedback.

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.

Problem 9

A response reduces the original temperature rise. This is…
  1. negative feedback
  2. positive feedback
  3. no possible regulation
  4. a mutation
Answer and explanation

negative feedback

It counteracts the initial change.

Problem 10

Why does a falling glucose value alone not demonstrate the entire insulin mechanism?
Answer and explanation

It is consistent with the model, but additional evidence is needed about hormone release, receptor action, tissue uptake, and other processes.

Problem 11

Independent chapter check: Two tissues reach the same response maximum, but one responds strongly at a lower signal concentration. Explain the difference and why their response does not prove identical receptor abundance.
Answer and explanation

They differ in sensitivity under the stated comparison, not necessarily maximal capacity. Binding, receptor number, downstream amplification and adaptation can differ; further controlled measurements are required.

They differ in sensitivity under the stated comparison, not necessarily maximal capacity. Binding, receptor number, downstream amplification and adaptation can differ; further controlled measurements are required.

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.

Problem 12

Which best describes immune memory?
  1. Persistent responsive cells support a changed later response
  2. All body cells rewrite every gene on purpose
  3. Every microbe is destroyed forever
  4. Skin becomes a nucleus
Answer and explanation

Persistent responsive cells support a changed later response

Memory depends on lasting biological populations and their responses.

Problem 13

Why compare responses to the same antigen under comparable conditions?
Answer and explanation

Different antigens, doses, timing, or hosts could change the response independently of memory.

Problem 14

Independent chapter check: 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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