Correct Answer: A

Rationale: The correct answer is A: Stapes (Middle ear bone). The stapes, located in the middle ear, is indeed the smallest bone in the human body. Despite its small size, the stapes is vital for hearing as it transmits and amplifies sound vibrations, contributing significantly to auditory perception. Choices B, C, and D are incorrect. The patella (kneecap) is the largest sesamoid bone in the human body, not the smallest bone. Phalanges are the bones in fingers and toes, not the smallest bone overall. Ribs are long bones that protect the chest cavity, not the smallest bone in the body.

Correct Answer: D

Rationale: The correct answer is D, 'Both transcription and translation.' Genetic information flows from DNA to RNA through transcription and from RNA to protein through translation. Replication is the process of copying DNA to produce an identical DNA molecule. Choice A, 'Replication,' is incorrect because replication is not directly involved in the flow of genetic information from DNA to protein. Choice B, 'Transcription,' is incorrect as it represents the process of synthesizing RNA from a DNA template, which is the initial step in the flow of genetic information. Choice C, 'Translation,' is also incorrect as it refers to the process of translating the information in mRNA into a sequence of amino acids during protein synthesis, which is the second step in the flow of genetic information.

Correct Answer: C

Rationale: Destructive interference is the term used to describe the phenomenon when two waves meet and their amplitudes are such that they cancel each other out, resulting in a wave with a smaller amplitude or no wave at all. This cancellation effect occurs due to the waves being out of phase. This is in contrast to constructive interference, where two waves combine to produce a wave with a larger amplitude. Refraction is the bending of waves as they pass through different mediums, such as light passing through glass, while diffraction is the bending of waves around obstacles or through openings. In this case, the concept described in the question specifically aligns with destructive interference, making it the correct answer.

Correct Answer: C

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.

Correct Answer: B

Rationale: The correct answer is B: Alveoli. The alveoli in the lungs are responsible for gas exchange. They have a thin membrane that allows for the exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the capillaries surrounding them. This process is essential for respiration, providing oxygen to the body's tissues and removing carbon dioxide, a waste product of cellular metabolism. Choices A, C, and D are incorrect. The trachea is a passageway that carries air to and from the lungs but is not directly involved in gas exchange. Bronchi are airway passages that further divide into smaller bronchioles leading to the alveoli but do not perform gas exchange themselves. The diaphragm is a muscle involved in the breathing process by aiding in inhalation and exhalation, but it is not the structure responsible for gas exchange in the respiratory system.