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A Level H1 Biology Human Physiology Quiz

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Questions

A-Level Biology H1 Quiz – Human Physiology

Name: ______________________________
Class: _______________________________
Date: ________________________________

Duration: 1 hour 30 minutes
Total Marks: 50

Instructions:

Answer all questions in the spaces provided.
Section A (Multiple Choice): write the letter of the correct answer in the box.
Where a diagram or figure is referenced, use the information provided to support your answers.

Section A: Multiple Choice Questions

5 × 1 mark = 5 marks

1. Which of the following is a feature of specific immunity?
A. Non-specific recognition of pathogens by pattern recognition receptors
B. Production of identical antibodies by the same B cell
C. Physical barriers such as skin and mucous membranes
D. Immediate response without memory

[ ]

2. The primary immune response involves a lag phase because:
A. Antigens are destroyed too quickly
B. Memory cells are immediately produced
C. It takes time for specific lymphocytes to be activated and proliferate
D. Vaccine adjuvants delay the response

[ ]

3. In the human gas exchange system, the main site of diffusion of oxygen into the blood is:
A. Trachea
B. Bronchi
C. Alveoli
D. Bronchioles

[ ]

4. Which of the following statements about the human immunodeficiency virus (HIV) is correct?
A. It destroys red blood cells leading to anaemia
B. It infects helper T cells and weakens the immune system
C. It can be cured with antibiotics
D. It is only transmitted through blood transfusion

[ ]

5. The process by which phagocytes engulf bacteria is known as:
A. Exocytosis
B. Pinocytosis
C. Phagocytosis
D. Receptor-mediated endocytosis

[ ]

Section B: Short Answer Questions

5 × 2 marks = 10 marks

6. Name two types of lymphocytes involved in the specific immune response and state one function of each. [2]

7. Explain why lymph nodes swell during an infection. [2]

8. State two ways in which active immunity differs from passive immunity. [2]

9. During a bacterial infection, a patient’s body temperature may rise. Explain how fever can help the immune response. [2]

10. Identify the role of macrophages in initiating the specific immune response. [2]

Section C: Structured Questions with Diagrams

5 × 3 marks = 15 marks

11. Fig. 1 shows the structure of an antibody molecule.

(i) With reference to Fig. 1, name the parts labelled P and Q. [1]
P: __________________________
Q: __________________________

(ii) Explain how the variable region enables the antibody to bind specifically to one type of antigen. [2]

12. Fig. 2 illustrates the oxygen dissociation curve for adult haemoglobin.

(i) With reference to Fig. 2, describe the shape of the curve and explain its significance in loading oxygen in the lungs. [2]

(ii) At high altitudes, the partial pressure of oxygen is lower. Predict the effect on the % saturation of haemoglobin and explain how this may impact physical performance. [1]

13. Fig. 3 shows a simplified diagram of the inflammatory response.

(i) State the role of histamine in inflammation. [1]

(ii) Explain why increased blood flow and vascular permeability are beneficial during an infection. [2]

14. Fig. 4 is a transmission electron micrograph of a phagocyte engulfing a bacterium.

(i) Name the organelle, visible in large numbers in the phagocyte, responsible for degrading the engulfed bacterium. [1]

(ii) Explain the importance of this organelle containing hydrolytic enzymes. [2]

15. A student prepared three test tubes containing equal amounts of starch solution, amylase enzyme, and different pH buffers. The tubes were incubated at 37 °C. Table 1 shows the time taken for complete starch breakdown.

Tube	pH	Time for starch breakdown (minutes)
1	2	15
2	7	3
3	11	12

(i) With reference to Table 1, state the optimum pH for amylase activity. [1]

(ii) Explain why the time taken at pH 2 and pH 11 is longer than at pH 7. [2]

Section D: Data-Based and Extended Response Questions

5 × 4 marks = 20 marks

16. The graph below shows the concentration of antibodies in the blood of a person after two injections of the same vaccine, given at week 0 and week 8.

Image pending generation for this question.

(i) Explain why there is an increase in antibody concentration after the first injection. [2]

(ii) With reference to the graph, describe two differences between the primary and secondary immune responses. [2]

(iii) Suggest why a booster injection is often given 8 weeks after the initial vaccination. [1]

17. Some strains of the influenza virus mutate rapidly, requiring new vaccines each year.

(i) Explain why the rapid mutation of the virus makes vaccination less effective. [2]

(ii) Describe how memory B and T cells provide long-term immunity to a specific pathogen, but not to a mutated variant. [3]

18. A person with severe combined immunodeficiency (SCID) lacks functional T and B cells. Discuss the consequences for the person’s ability to fight infections. [3]

19. Table 2 shows the percentage of haemoglobin saturated with oxygen at different partial pressures of oxygen for myoglobin and adult haemoglobin.

pO₂ (kPa)	Hb saturation (%)	Mb saturation (%)
1	5	50
2	30	85
4	70	95
6	90	98
8	95	99

(i) With reference to the data, compare the oxygen affinities of myoglobin and haemoglobin. [2]

(ii) Explain the physiological advantage of myoglobin’s oxygen-binding properties in muscle cells. [2]

20. (a) Describe how the human immune system distinguishes between self and non-self antigens. [1]

 _________________________________________________________________________  
 _________________________________________________________________________  

 (b) Discuss the importance of cell-mediated and humoral immunity in protecting the body against viral infections. [2]  

 _________________________________________________________________________  
 _________________________________________________________________________

End of Quiz

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Answers

A-Level Biology H1 Quiz – Human Physiology

Answer Key and Marking Scheme

Section A: Multiple Choice (5 marks)

Question	Answer	Marking Notes
1	B	Specific immunity = clonal selection, antibodies identical for that clone.
2	C	Lag phase due to activation and clonal expansion of lymphocytes.
3	C	Alveoli are the site of gas exchange.
4	B	HIV infects helper T cells (CD4+), impairing immune function.
5	C	Phagocytosis is the engulfment of large particles by phagocytes.

Section B: Short Answer (10 marks)

6. Name two lymphocyte types and one function each. [2]

B‑lymphocytes (B cells) – produce and secrete antibodies.
T‑lymphocytes (T cells) – helper T cells activate other immune cells / cytotoxic T cells kill infected cells.
Any two correctly named and described (1 mark each).

7. Lymph node swelling [2]

Increased blood flow brings more immune cells to the nodes.
Lymphocytes and phagocytes proliferate rapidly within the node to fight infection, causing enlargement.

8. Active vs. passive immunity [2]

Active immunity involves the body’s own production of antibodies and memory cells; passive immunity receives pre-formed antibodies.
Active immunity is long‑lasting (years); passive immunity is temporary (weeks to months).
Accept other valid differences, e.g. active requires exposure to antigen, passive does not.

9. Fever helps by [2]

Higher temperature may inhibit the growth of some pathogens.
Speeds up metabolic reactions of immune cells (e.g. phagocytosis, lymphocyte proliferation), enhancing the response.

10. Macrophage role in initiating specific immunity [2]

Macrophages engulf pathogens and present processed antigen on MHC class II molecules.
This activates helper T cells, triggering cell‑mediated and humoral responses.

Section C: Structured Questions with Diagrams (15 marks)

11. Antibody structure

(i) P = variable region, Q = constant region. [1]
(ii) The variable region has a unique amino acid sequence forming an antigen‑binding site with a shape complementary to a specific antigen (lock‑and‑key). This allows the antibody to bind only to that particular antigen. [2]

12. Oxygen dissociation curve

(i) The curve is sigmoidal (S‑shaped). At the high pO₂ found in the lungs, haemoglobin becomes saturated quickly, allowing efficient loading of oxygen for transport to tissues. [2]
(ii) At lower pO₂, haemoglobin saturation decreases, reducing oxygen delivery to muscles and other tissues. This can cause fatigue and reduced aerobic performance. [1]

13. Inflammatory response

(i) Histamine causes vasodilation and increases capillary permeability. [1]
(ii) Vasodilation increases blood flow, bringing more phagocytes, oxygen and immune components to the site. Increased permeability allows immune cells and antibodies to leave the blood and enter tissues, and delivers nutrients to support defence. [2]

14. Phagocyte organelle

(i) Lysosome. [1]
(ii) Lysosomes contain hydrolytic enzymes (proteases, lipases, etc.). When the phagosome fuses with a lysosome, the enzymes degrade the engulfed bacterium, destroying the pathogen. [2]

15. Enzyme‑pH experiment

(i) pH 7. [1]
(ii) pH 2 and pH 11 are far from the optimum. They cause denaturation of the amylase, altering the shape of its active site so that it can no longer effectively catalyse the breakdown of starch, resulting in longer breakdown times. [2]

Section D: Data‑Based and Extended Response (20 marks)

16. Antibody response graph (5 marks)

(i) After the first injection, the vaccine antigen activates specific B cells. These proliferate and differentiate into plasma cells that produce antibodies, causing the observed rise in antibody concentration after a lag period. [2]
(ii) Any two of: The secondary response has a much larger peak antibody concentration; it occurs more rapidly (shorter lag); it produces a higher proportion of IgG; it is sustained longer. [2]
(iii) The booster re‑exposes memory cells to the antigen, generating a rapid, strong secondary response that provides longer‑lasting protection. [1]

17. Influenza virus mutation (5 marks)

(i) Viral surface antigens (e.g. haemagglutinin, neuraminidase) change their structure. Memory cells and antibodies produced by previous vaccination no longer recognise the mutated epitopes, so the vaccine is less effective. [2]
(ii) Memory B and T cells are specific to the original antigen. Upon re‑exposure to the exact same pathogen, they quickly proliferate and mount a rapid, amplified response (antibody production, cytotoxic T‑cell killing). A mutated variant has different epitopes that are not recognised by the existing memory cells, so no protective memory response is triggered. [3]

18. SCID consequences (3 marks)

Without functional T and B cells, the person lacks both humoral and cell‑mediated immunity.
There is no antibody production, no cytotoxic T‑cell activity, and macrophages cannot be effectively activated.
The individual is extremely susceptible to infections, including opportunistic pathogens that would normally be controlled, leading to severe, recurrent, often life‑threatening illnesses.

19. Myoglobin vs haemoglobin (4 marks)

(i) Myoglobin has a much higher affinity for oxygen than haemoglobin, especially at low pO₂ (e.g. at 1 kPa Mb is 50 % saturated vs. Hb 5 %). Over the range shown, Mb saturates at lower pO₂ while haemoglobin releases oxygen more readily. [2]
(ii) In muscle cells, myoglobin acts as an oxygen store. It binds oxygen firmly when the pO₂ is moderate and releases it only when pO₂ drops very low during intense exercise. This provides a reserve of oxygen that can supply mitochondria for continued aerobic respiration, delaying fatigue. [2]

20. Self/non‑self distinction and viral defence (3 marks)

(a) During lymphocyte maturation, any developing lymphocytes that strongly bind self‑antigens undergo apoptosis (clonal deletion), establishing self‑tolerance. Only lymphocytes that recognise non‑self antigens survive. [1]
(b) Cell‑mediated immunity (e.g. cytotoxic T cells) directly kills virus‑infected host cells, preventing viral replication. Humoral immunity (B cells/antibodies) neutralises free virus particles and marks them for destruction by phagocytes. Together, they provide a comprehensive defence against both extracellular and intracellular stages of viral infection. [2]

End of Answer Key