1. Which of the following is a MAJOR consequence of a stroke?

A. Irregular heart rhythm.
B. Rapid weight gain or loss.
C. Brain damage due to interrupted blood flow.
D. Chronic fatigue and muscle weakness.

Correct answer: C

Rationale: The correct answer is C: 'Brain damage due to interrupted blood flow.' A stroke occurs when there is a sudden interruption in the blood supply to the brain, leading to brain damage. This interruption can result in various consequences such as paralysis, speech and vision problems, cognitive impairments, and in severe cases, even death. Other options like 'Irregular heart rhythm' (A) and 'Chronic fatigue and muscle weakness' (D) can be associated with health conditions but are not direct consequences of a stroke. 'Rapid weight gain or loss' (B) is typically not a major consequence of a stroke compared to the significant impact of brain damage.

2. What phenomenon occurs when light passes through a medium but does not change direction, such as when passing through a window?

A. Diffraction
B. Reflection
C. Dispersion
D. Transmission

Correct answer: d

Rationale: Transmission occurs when light passes through a medium without changing direction, as observed when light passes through a window.

3. The study of the geographical distribution of organisms and the factors that influence it is known as:

A. Paleontology (the study of fossils)
B. Taxonomy (the classification of organisms)
C. Biogeography
D. Population genetics

Correct answer: C

Rationale: Rationale: Biogeography is the study of the geographical distribution of organisms and the factors that influence their distribution patterns. This field of study examines how and why species are distributed where they are, considering factors such as historical events, ecological interactions, and physical geography. Paleontology (option A) is the study of fossils and the history of life on Earth, focusing on extinct organisms. Taxonomy (option B) is the science of classifying and naming organisms based on their characteristics. Population genetics (option D) is the study of genetic variation and evolutionary processes within populations of organisms. In this context, biogeography is the most appropriate choice as it specifically deals with the distribution of organisms in space and time.

4. Which sexually transmitted infection (STI) can potentially cause infertility in both men and women if left untreated?

A. Human papillomavirus (HPV)
B. Chlamydia
C. Gonorrhea
D. Syphilis

Correct answer: D

Rationale: The correct answer is D: Syphilis. Syphilis is a sexually transmitted infection that can potentially cause infertility in both men and women if left untreated. In men, untreated syphilis can lead to damage to the testicles and epididymis, affecting sperm production. In women, syphilis can result in pelvic inflammatory disease (PID) which can lead to scarring and blockages in the fallopian tubes, causing infertility. While other STIs like chlamydia and gonorrhea can also lead to infertility if left untreated, syphilis is particularly known for its severe impact on reproductive health in both genders.

5. Vaccines work by stimulating the immune system to develop:

A. A physical barrier against pathogens
B. An inflammatory response
C. Immunological memory to a specific pathogen
D. Phagocytes to engulf pathogens

Correct answer: C

Rationale: The correct answer is C: 'Immunological memory to a specific pathogen.' Vaccines work by introducing a harmless form of a pathogen or a piece of it to stimulate the immune system. This exposure triggers the production of antibodies and memory cells specific to that pathogen. These memory cells 'remember' the pathogen, allowing the immune system to respond more effectively and rapidly if exposed to the actual pathogen in the future. Options A, B, and D are incorrect because vaccines do not create a physical barrier, induce a general inflammatory response, or directly cause phagocytes to engulf pathogens; instead, vaccines enhance the immune system's ability to recognize and combat specific pathogens.