Correct Answer: A

Rationale: - Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm for protein synthesis. - Ribosomal RNA (rRNA) is a structural component of ribosomes, which are the cellular machinery responsible for protein synthesis. - Transfer RNA (tRNA) is responsible for bringing amino acids to the ribosome during protein synthesis. Options B, C, and D are incorrect: - Option B lists DNA, RNA, and protein, which are biomolecules but not the three main types of RNA. - Option C lists nitrogenous bases (adenine, guanine, cytosine, and thymine) found in DNA, not types of RNA. - Option D lists components of nucleotides (deoxyribose, ribose, and phosphate), which are building blocks of nucleic

Correct Answer: A

Rationale: The periodic table is a tabular arrangement of the chemical elements, organized based on their atomic number, electron configurations, and recurring chemical properties. Elements are placed in rows (periods) and columns (groups) with similar properties. The elements are listed in order of increasing atomic number, which is the number of protons in the nucleus of an atom. This arrangement reveals a periodic repetition of chemical properties, forming the basis of the periodic law. Choice B, which suggests arranging elements based on increasing atomic mass, is incorrect because the periodic table is primarily organized by atomic number, not atomic mass. Choices C and D are also incorrect as the periodic table is not based on reactivity or color of elements, but rather on atomic number and properties.

Correct Answer: C

Rationale: The correct answer is C, Gliding joint. Gliding joints allow for side-to-side bending movements. These joints are found between the small bones of the wrist and ankle, allowing for flexibility and movement in multiple directions. Hinge joints (A) enable movement in one plane, akin to a door hinge. Ball-and-socket joints (B) allow for a wide range of motion across multiple directions. Saddle joints (D) facilitate movement in two planes.

Correct Answer: B

Rationale: The correct answer is B: Stratum corneum. The stratum corneum is the outermost layer of the epidermis, consisting of dead skin cells that are constantly shed and replaced. It serves as a protective barrier against pathogens and helps to prevent water loss from the body. Choice A, Stratum basale, is the deepest layer of the epidermis where new skin cells are produced. Choice C, Stratum granulosum, is a layer of the epidermis where the cells begin to flatten and lose their nuclei. Choice D, Stratum spinosum, is a layer of the epidermis where cells become irregular in shape and have spiny projections.

Correct Answer: B

Rationale: The correct answer is B: Alveoli. The alveoli are the small air sacs in the lungs where gas exchange occurs. Oxygen from the air we breathe passes into the bloodstream through the alveoli, while carbon dioxide from the bloodstream passes out of the body through the alveoli. Choice A, Bronchi, are the main airways in the lungs and not the site of gas exchange. Choice C, Trachea, refers to the windpipe, which is a different structure than the alveoli. Choice D, Bronchioles, are smaller airways branching off from the bronchi and are not where gas exchange primarily occurs.