Cellular Control Systems Test

Year 12 Science | Homeostasis, Feedback Mechanisms & the Cell Cycle

Name:

Date:

🔬 Part 1: Multiple Choice

Circle the best answer for each question.

1. Which type of feedback mechanism is most commonly used by the body to maintain homeostasis?

A) Positive feedback

B) Negative feedback

C) Neutral feedback

D) Amplifying feedback

2. Which of the following is an example of a positive feedback loop?

A) Blood glucose regulation by insulin

B) Body temperature regulation through sweating

C) Uterine contractions intensifying during childbirth

D) Thyroid hormone regulation via the pituitary gland

3. In the central dogma of molecular biology, which correctly describes the flow of genetic information?

A) RNA → DNA → Protein

B) Protein → DNA → RNA

C) DNA → RNA → Protein

D) DNA → Protein → RNA

4. During which phase of the cell cycle does DNA replication occur?

A) G1 phase

B) S phase

C) G2 phase

D) M phase (Mitosis)

5. The sinoatrial (SA) node is often called the "pacemaker" of the heart because it:

A) Pumps blood to the lungs

B) Initiates the electrical impulse that triggers each heartbeat

C) Controls the opening and closing of heart valves

D) Regulates blood oxygen levels

6. Select all components that are part of a feedback loop:

A) Stimulus

B) Receptor / sensor

C) Control center (integrator)

D) Effector

E) Mitochondria

✏️ Part 2: Short Answer

Answer each question using complete sentences.

7. Explain the difference between negative feedback and positive feedback. Give one real-life body example of each.

8. Describe what happens to the cell cycle when checkpoint controls fail. How can this lead to cancer?

9. Explain how DNA structure determines protein function. Why is the sequence of nucleotide bases so important?

📊 Part 3: Diagram Labeling

Use the word bank below to label the diagram of the feedback loop and complete the cell cycle diagram.

10. Label the stages of the cell cycle in the correct order by filling in the blanks below:

Start → Interphase: __________ → __________ → __________ then → __________ (M phase) → Cell Division Complete

11. In the space below, draw and label a simple negative feedback loop for body temperature regulation. Include: stimulus, receptor, control center, effector, and response.

12. Bonus: Trace the path of an electrical signal through the cardiac conduction system by filling in the blanks:

The impulse begins at the __________________ node, travels to the __________________ node, then moves through the Bundle of His and Purkinje fibers, causing the ventricles to __________________.