Identify the extracellular junction that allows ions and small molecules to pass between two cells.

Correct Answer: B

Rationale: Gap junctions allow direct communication via channels between cells.

Correct Answer: C

Rationale: The primary function of the eye is vision.

Correct Answer: C

Rationale: Lysosomes contain digestive enzymes that break down old or damaged organelles.

Correct Answer: A

Rationale: Blood group O is considered the universal donor because it lacks A and B antigens.

Correct Answer: C

Rationale: The retina is the nervous layer of the eye, containing photoreceptor cells.