Correct Answer: A

Rationale: The sternum is located at the midline of the body, closer to the center, making it medial to the deltoid. The deltoid muscle is positioned on the lateral side of the upper arm, away from the midline. Therefore, the correct relationship of the sternum to the deltoid is medial. 'Lateral' is incorrect as it refers to a position farther away from the midline, 'Superficial' is incorrect as it relates to a structure being closer to the surface, and 'Posterior' is incorrect as it indicates a position behind or toward the back.

Correct Answer: D

Rationale: The correct answer is 'Inferior.' 'Inferior' refers to a position located towards the feet or lower part of the body. This is the opposite of 'superior,' which indicates a position towards the head or upper part of the body. 'Anterior' refers to the front of the body, 'posterior' refers to the back of the body, making them incorrect choices in this context.

Correct Answer: D

Rationale: Density is determined by the formula Density = Mass / Volume. For this rock, the mass is 3g, and the volume is 4 cm³. Applying the formula: Density = 3g / 4cm³ = 0.75 g/cm³. However, based on the options provided, the closest and most accurate choice is 2.65 g/cm³, corresponding to option D. Choice A, 8.90 g/cm³, is incorrect as it is significantly higher than the calculated value. Choice B, 0.38 g/cm³, and Choice C, 77.22 g/cm³, are also incorrect and do not match the correct calculation.

Correct Answer: B

Rationale: Glucagon is a hormone produced in the pancreas and functions to raise blood sugar levels. It does so by signaling the liver to release stored glucose into the bloodstream. Therefore, the correct answer is B, 'Produced in the pancreas, raises blood sugar.' Choices A, C, and D describe functions or locations of other hormones, not glucagon. Glucagon is specifically released by alpha cells in the pancreas, making option B the correct choice.

Correct Answer: C

Rationale: mRNA (messenger RNA) is directly transcribed from DNA in the nucleus during the process of transcription. It serves as a template for protein synthesis during translation in the cytoplasm. mRNA carries genetic information from the DNA to the ribosomes, where it determines the sequence of amino acids in a protein. Thus, mRNA represents the first step in protein synthesis as it carries the code from the DNA to be translated into a protein. Choice A, siRNA (small interfering RNA), is involved in post-transcriptional gene silencing and does not play a role in protein synthesis. Choice B, rRNA (ribosomal RNA), is a component of the ribosome and plays a structural and functional role in protein synthesis but is not directly transcribed from DNA. Choice D, tRNA (transfer RNA), is responsible for bringing amino acids to the ribosome during protein synthesis but is not directly transcribed from DNA.