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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: __________________________
Score: ________ / 40
Duration: 45 minutes
Total Marks: 40
Instructions:
- Answer all questions.
- Write your answers in the spaces provided.
- The number of marks for each question or part question is given in brackets [ ].
- Use clear scientific terminology and refer to specific biological structures/processes where appropriate.
Section A: Multiple Choice Questions (Questions 1–10)
Select the most appropriate answer for each question. Each question carries 1 mark.
1. Which of the following best describes the role of antibodies in the immune response?
A. They engulf pathogens via phagocytosis.
B. They bind to specific antigens to agglutinate pathogens.
C. They release histamine to increase blood vessel permeability.
D. They differentiate into memory cells upon first exposure.
[1]
2. A patient receives a vaccine containing inactivated polio virus. What is the primary immunological benefit of this vaccination?
A. Immediate production of high levels of IgM antibodies.
B. Activation of cytotoxic T-cells to destroy infected host cells immediately.
C. Formation of memory B-cells for a rapid secondary response upon future exposure.
D. Passive immunity transferred from the vaccine to the patient’s bloodstream.
[1]
3. Which statement correctly distinguishes between innate and adaptive immunity?
A. Innate immunity is specific; adaptive immunity is non-specific.
B. Innate immunity has a lag time; adaptive immunity is immediate.
C. Innate immunity involves memory cells; adaptive immunity does not.
D. Innate immunity is present at birth; adaptive immunity develops after exposure.
[1]
4. In the context of HIV infection, why does the virus specifically target helper T-cells?
A. Helper T-cells produce antibodies directly.
B. Helper T-cells are required to activate both B-cells and cytotoxic T-cells.
C. Helper T-cells line the respiratory tract, the primary entry point for HIV.
D. Helper T-cells have the highest rate of division in the body.
[1]
5. Which of the following is a characteristic of active immunity but NOT passive immunity?
A. Protection is immediate.
B. Antibodies are obtained from another organism.
C. Memory cells are produced.
D. Protection is short-term.
[1]
6. During an inflammatory response, histamine causes vasodilation. What is the physiological advantage of this process?
A. It reduces blood flow to prevent pathogen spread.
B. It increases the delivery of phagocytes and plasma proteins to the site of infection.
C. It lowers the temperature of the tissue to inhibit bacterial growth.
D. It constricts capillaries to prevent swelling.
[1]
7. Which cell type is responsible for the secondary immune response?
A. Plasma cells
B. Memory B-cells
C. Macrophages
D. Helper T-cells
[1]
8. Why are antibiotics ineffective against viral infections such as influenza?
A. Viruses mutate too quickly for antibiotics to target.
B. Viruses lack the metabolic pathways and cell structures targeted by antibiotics.
C. Antibodies neutralize antibiotics before they can act on viruses.
D. Viruses replicate inside the nucleus, where antibiotics cannot penetrate.
[1]
9. Which of the following best explains the concept of herd immunity?
A. When a large proportion of the population is vaccinated, the spread of the pathogen is reduced, protecting unvaccinated individuals.
B. When animals are vaccinated, humans are protected from zoonotic diseases.
C. When individuals take antibiotics, they prevent the spread of viruses to others.
D. When the immune system of one person protects another through physical contact.
[1]
10. What is the role of antigen-presenting cells (APCs) in the adaptive immune response?
A. To produce antibodies specific to the antigen.
B. To engulf pathogens and display antigen fragments on their surface to activate helper T-cells.
C. To directly kill infected host cells.
D. To release cytokines that cause fever.
[1]
Section B: Structured Questions (Questions 11–15)
Answer the questions in the spaces provided.
11. Fig. 11.1 shows the structure of an antibody molecule.
(Note: Imagine a Y-shaped molecule with two heavy chains and two light chains, with variable regions at the tips and constant regions forming the stem.)
(a) Identify the region of the antibody that binds to the antigen.
[1]
(b) Explain why an antibody is specific to a particular antigen.
[2]
(c) Describe how the binding of antibodies to pathogens can lead to their destruction by phagocytes.
[2]
12. Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis.
(a) State the mode of transmission for TB.
[1]
(b) Explain why TB is more prevalent in overcrowded living conditions.
[2]
(c) Suggest one reason why the development of a fully effective vaccine for TB has been challenging.
[1]
13. The human immune system responds to pathogens in a coordinated manner.
(a) Distinguish between the terms antigen and antibody.
[2]
(b) Describe the role of helper T-cells in activating B-cells.
[2]
14. Vaccination is a key strategy in controlling infectious diseases.
(a) Define the term vaccination.
[1]
(b) Explain why booster doses are sometimes required for certain vaccines.
[2]
15. HIV (Human Immunodeficiency Virus) attacks the immune system.
(a) State the type of nucleic acid found in HIV.
[1]
(b) Explain how HIV infection leads to the condition known as AIDS (Acquired Immunodeficiency Syndrome).
[2]
Section C: Data Response and Extended Answer (Questions 16–20)
Answer the questions based on the information provided and your biological knowledge.
16. Fig. 16.1 shows the change in antibody concentration in the blood of a patient over time. The patient was exposed to Antigen X on Day 0 and again on Day 20.
(Graph Description: Curve A rises slowly from Day 0, peaks at Day 14, and declines. Curve B rises rapidly from Day 20, peaks higher than Curve A at Day 24, and declines slowly.)
(a) Identify which curve (A or B) represents the secondary immune response.
[1]
(b) Explain the difference in the lag phase between the primary and secondary responses.
[2]
(c) Explain why the concentration of antibodies in the secondary response is higher than in the primary response.
[2]
17. Malaria is caused by the protoctist Plasmodium, which is transmitted by the female Anopheles mosquito.
(a) Explain why malaria is classified as an infectious disease but not a contagious disease.
[2]
(b) Suggest two methods to control the spread of malaria, referring to the life cycle of the vector or pathogen.
[2]
18. Antibiotics are often prescribed for bacterial infections. However, the overuse of antibiotics has led to the emergence of antibiotic-resistant bacteria.
(a) Explain how natural selection leads to the evolution of antibiotic-resistant bacterial populations.
[3]
(b) Suggest one strategy hospitals can use to reduce the spread of antibiotic-resistant bacteria.
[1]
19. The skin acts as a primary barrier against infection.
(a) Describe two ways in which intact skin prevents pathogen entry.
[2]
(b) When the skin is broken, blood clotting occurs. Explain the importance of blood clotting in preventing infection.
[2]
20. Essay Question.
"Discuss the importance of memory cells in providing long-term immunity against specific pathogens. In your answer, compare the primary and secondary immune responses."
[6]
End of Quiz
Answers
A-Level Biology H1 Quiz - Human Physiology (Answer Key)
Total Marks: 40
Section A: Multiple Choice Answers
1. B
Reasoning: Antibodies bind to antigens, causing agglutination (clumping) which facilitates phagocytosis. They do not engulf pathogens (phagocytes do), release histamine (mast cells do), or differentiate into memory cells (B-cells do).
2. C
Reasoning: Vaccines stimulate the primary immune response, leading to the formation of memory B-cells and T-cells. This ensures a rapid and robust secondary response upon actual infection.
3. D
Reasoning: Innate immunity is non-specific and present at birth. Adaptive immunity is specific, has a lag time, involves memory, and develops after exposure.
4. B
Reasoning: Helper T-cells release cytokines that are essential for activating B-cells (for antibody production) and cytotoxic T-cells (for killing infected cells). Their depletion cripples the entire adaptive immune response.
5. C
Reasoning: Active immunity involves the host’s immune system producing its own antibodies and memory cells. Passive immunity involves receiving pre-formed antibodies without memory cell production.
6. B
Reasoning: Vasodilation increases blood flow and permeability, allowing more phagocytes and plasma proteins (like antibodies and clotting factors) to reach the infected tissue.
7. B
Reasoning: Memory B-cells (and Memory T-cells) persist after the primary response and are responsible for the rapid secondary response. Plasma cells are effector cells that produce antibodies but are short-lived.
8. B
Reasoning: Antibiotics target specific bacterial structures (e.g., cell walls, ribosomes) or metabolic pathways. Viruses lack these structures and rely on host cell machinery, making them unaffected by antibiotics.
9. A
Reasoning: Herd immunity occurs when a high percentage of the population is immune, breaking the chain of transmission and protecting those who are not immune (e.g., immunocompromised individuals).
10. B
Reasoning: APCs (like macrophages and dendritic cells) ingest pathogens, process them, and display antigen fragments on MHC molecules to activate helper T-cells, initiating the adaptive response.
Section B: Structured Questions Answers
11.
(a) Variable region / Hypervariable region / Tip of the Y-shape. [1]
(b) The variable region has a specific tertiary structure (shape) [1] that is complementary to a specific antigen’s epitope [1].
(c) Antibodies bind to antigens on the pathogen surface [1]. This causes agglutination (clumping), making it easier for phagocytes to engulf and destroy many pathogens at once [1]. (Alternatively: Opsonization marks pathogens for phagocytosis).
12.
(a) Airborne droplets / Inhalation of droplets from coughing/sneezing. [1]
(b) Overcrowding facilitates close contact between individuals [1], increasing the likelihood of inhaling infectious droplets expelled by an infected person [1].
(c) Plasmodium has a complex life cycle / Antigenic variation / The bacterium hides inside host cells (macrophages) making it hard for antibodies to reach it. [1] (Any valid biological reason).
13.
(a) Antigen: A molecule (usually protein) on the surface of a pathogen that triggers an immune response [1]. Antibody: A protein produced by plasma cells (B-cells) that specifically binds to an antigen [1].
(b) Helper T-cells bind to antigen-presenting cells [1]. They release cytokines [1] which stimulate B-cells to divide by mitosis and differentiate into plasma cells and memory cells [1]. (Max 2 marks: need link between T-cell activation and B-cell response).
14.
(a) The introduction of a harmless form of a pathogen (or its antigens) into the body to stimulate an immune response and produce memory cells [1].
(b) Memory cells may decline in number over time [1]. Booster doses restimulate the immune system, increasing the number of memory cells and antibody levels to ensure long-term protection [1].
15.
(a) RNA. [1]
(b) HIV infects and destroys helper T-cells [1]. As the number of helper T-cells drops, the immune system cannot activate B-cells or cytotoxic T-cells effectively [1], leaving the body vulnerable to opportunistic infections (AIDS).
Section C: Data Response and Extended Answer
16.
(a) Curve B. [1]
(b) The secondary response has a shorter lag phase because memory B-cells are already present [1]. These cells recognize the antigen immediately and differentiate rapidly into plasma cells, unlike naive B-cells which require activation and clonal selection in the primary response [1].
(c) There are more memory B-cells available to respond than naive B-cells in the primary response [1]. This leads to a faster rate of division and differentiation into plasma cells, producing a higher concentration of antibodies more quickly [1].
17.
(a) Infectious diseases are caused by pathogens entering the body [1]. Contagious diseases are transmitted directly from person to person. Malaria requires a vector (mosquito) for transmission and cannot be passed directly from human to human [1].
(b) 1. Use of insecticide-treated nets to prevent mosquito bites (blocks transmission). [1]
2. Drainage of stagnant water to remove mosquito breeding sites (reduces vector population). [1]
(Other valid answers: Indoor residual spraying, biological control of larvae).
18.
(a) Variation exists in bacterial populations due to mutation [1]. Some bacteria possess genes for antibiotic resistance. When antibiotics are used, non-resistant bacteria die, while resistant bacteria survive [1]. Resistant bacteria reproduce and pass the resistance gene to offspring [1]. Over time, the population becomes dominated by resistant strains [1]. (Max 3 marks for clear logical sequence).
(b) Strict hygiene practices (hand washing) / Isolation of infected patients / Rotating antibiotics / Reducing unnecessary prescription. [1]
19.
(a) 1. Physical barrier: Keratinized layer of dead cells prevents pathogen entry. [1]
2. Chemical barrier: Sebaceous glands secrete sebum/oils with low pH that inhibits bacterial growth. [1]
(b) Clotting seals the wound [1], preventing pathogens from entering the bloodstream and underlying tissues [1]. It also traps any pathogens that may have entered at the site of injury.
20. Essay Marking Guide (6 Marks)
Level 3 (5-6 marks): Comprehensive answer. Clearly distinguishes primary and secondary responses. Explains the mechanism of memory cell formation and function. Uses correct terminology (clonal selection, differentiation, lag phase, antibody titre).
Level 2 (3-4 marks): Good answer. Describes primary and secondary responses but may lack detail on the mechanism of memory cells. Some terminology errors.
Level 1 (1-2 marks): Basic answer. Mentions memory cells but fails to compare responses effectively. Limited biological detail.
Key Points to Include:
- Primary Response:
- First exposure to antigen.
- Lag phase is long (days/weeks) as naive B-cells must be activated.
- Clonal selection and expansion occur.
- Differentiation into plasma cells (short-lived, produce antibodies) and memory B-cells.
- Antibody concentration rises slowly and peaks at a lower level.
- Role of Memory Cells:
- Memory B-cells persist in the blood/lymph for years/decades.
- They are specific to the antigen.
- They do not produce antibodies immediately but are "primed" for rapid response.
- Secondary Response:
- Upon re-exposure to the same antigen.
- Memory cells recognize the antigen immediately.
- Rapid division and differentiation into plasma cells.
- Lag phase is very short.
- Antibody concentration rises rapidly to a much higher peak.
- Antibodies remain in circulation longer.
- Significance:
- Prevents disease symptoms by neutralizing pathogens before they can cause significant harm.
- Basis of vaccination and long-term immunity.