1. 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.

2. Which hormone, produced by the pineal gland, plays a role in regulating sleep-wake cycles and is often associated with the body's internal circadian rhythm?

A. Melatonin
B. Serotonin
C. Dopamine
D. Endorphin

Correct answer: a

Rationale: The correct answer is A: Melatonin. Melatonin is a hormone produced by the pineal gland that plays a crucial role in regulating sleep-wake cycles and is closely tied to the body's circadian rhythm. It is often referred to as the 'sleep hormone' because it helps signal to the body when it is time to sleep and wake up. Serotonin (option B) is a neurotransmitter that plays a role in mood regulation and happiness. Dopamine (option C) is involved in reward-motivated behavior and movement. Endorphins (option D) are neuropeptides that act as natural painkillers and contribute to feelings of pleasure. Therefore, Melatonin is the hormone associated with the body's internal circadian rhythm and sleep-wake cycles.

3. What is the role of transfer RNA (tRNA) in protein synthesis?

A. Transcribes DNA into mRNA
B. Decodes the genetic code on mRNA
C. Carries specific amino acids to the ribosomes bas(a) Carries amino acids to the ribosomes: This is the function of transfer RNA (tRNA), not ribosomal RNA. (b) Reads the genetic code on mRNA: This is the function of the ribosomes as a whole, not just the ribosomal RNA. (d) Controls the rate of protein synthesis: This is a more complex process involving various factors, not solely ribosomal RNA. ? ed on the mRNA
D. Modifies the structure of proteins

Correct answer: C

Rationale: Rationale: A) Transcribes DNA into mRNA: This is the function of RNA polymerase, not transfer RNA (tRNA). tRNA is involved in protein synthesis, not transcription. B) Decodes the genetic code on mRNA: This is the function of tRNA during translation. tRNA molecules carry specific amino acids and recognize the codons on mRNA, ensuring the correct amino acid is added to the growing polypeptide chain. C) Carries specific amino acids to the ribosomes: This is the primary role of tRNA in protein synthesis. Each tRNA molecule is specific for a particular amino acid and carries it to the ribosome, where it is added to the growing protein chain. D) Modifies the structure of proteins: This is not a function of tRNA. Protein modification can occur after translation is complete and involves other cellular processes and molecules.

4. The author's tone towards UBI can be described as

A. Strongly supportive, advocating for its immediate implementation without reservations.
B. Strongly critical, highlighting only the potential drawbacks and dismissing its benefits.
C. Neutral and objective, presenting both sides of the argument without taking a stance.
D. Cautiously optimistic, acknowledging both the potential and challenges while calling for further discussion.

Correct answer: D

Rationale: The passage acknowledges both positive and negative aspects of UBI, suggesting a cautious and balanced perspective, aligning with D.

5. What is the main function of vacuoles in plant cells?

A. To provide structural support for the cell
B. To transport substances in and out of the cell
C. To synthesize proteins and lipids
D. To store water, enzymes, and waste products

Correct answer: D

Rationale: Rationale: Vacuoles in plant cells primarily function as storage organelles. They store water, enzymes, pigments, and waste products. Vacuoles help maintain turgor pressure within the cell, which provides structural support for the plant cell. While vacuoles can also be involved in transporting substances within the cell, their main function is storage. Synthesizing proteins and lipids is primarily carried out by other organelles such as the endoplasmic reticulum and Golgi apparatus.

6. What is the term for a solution that contains the maximum amount of solute that can dissolve at a specific temperature and pressure?

A. Saturated solution
B. Unsaturated solution
C. Dilute solution
D. Concentrated solution

Correct answer: A

Rationale: A saturated solution is one in which the maximum amount of solute has dissolved under specific conditions. The other choices do not accurately describe a saturated solution.