How does the human eye focus light?

Correct Answer: C

Rationale: The human eye focuses light by adjusting the shape of its lens. The lens changes shape to allow the eye to focus on objects at different distances, a process known as accommodation. The cornea is the transparent outer covering of the eye that helps to focus light but does not change shape like the lens. The iris controls the size of the pupil to regulate the amount of light entering the eye. The retina is the light-sensitive layer at the back of the eye that receives and processes images but does not adjust the focus of light.

Correct Answer: B

Rationale: The correct answer is stratified squamous epithelium. This type of epithelium is found in areas subjected to mechanical and chemical stresses, such as the lining of the esophagus. The multiple layers of cells provide protection against abrasion from the passage of food. Simple squamous epithelium (choice A) is a single layer of flat cells and is not well-suited for protection against abrasion as it lacks the multiple layers. Simple cuboidal epithelium (choice C) is found in areas where secretion and absorption occur, such as kidney tubules, and is not typically found in the esophagus where protection against abrasion is necessary. Stratified cuboidal epithelium (choice D) is rare in the body and is not a characteristic tissue type of the esophagus, which requires stratified squamous epithelium for its protective function.

Correct Answer: C

Rationale: Lysosomes are membrane-bound organelles containing digestive enzymes that break down macromolecules, such as proteins, carbohydrates, and lipids, into their smaller building blocks. These enzymes help in the process of intracellular digestion and recycling of cellular components. The Golgi apparatus is involved in processing and packaging proteins for secretion or for use within the cell. Mitochondria are responsible for producing energy in the form of ATP through cellular respiration. The endoplasmic reticulum is involved in protein synthesis and lipid metabolism. Therefore, the correct answer is 'C: Lysosomes' as they specifically function in the breakdown of macromolecules into smaller components, distinguishing them from the other organelles mentioned.

Correct Answer: B

Rationale: An unsaturated solution is a solution that contains less solute than the maximum amount it could dissolve at a specific temperature and pressure. In an unsaturated solution, more solute can still be added and dissolved in the solvent. Choice A, a saturated solution, refers to a solution in which the maximum amount of solute has been dissolved at a specific temperature and pressure, leading to equilibrium. Choice C, a supersaturated solution, contains more solute than it can normally hold at a specific temperature and pressure, achieved through special conditions followed by rapid cooling or evaporation. Choice D, a concentrated solution, refers to a solution with a high amount of solute compared to the amount of solvent, regardless of reaching the saturation point.

Correct Answer: D

Rationale: The correct answer is D, a concentrated solution. A concentrated solution contains a higher concentration of solute compared to another solution. This means there is a large amount of solute dissolved in the solvent, making it more concentrated than other solutions. Choices A, B, and C are incorrect. A saturated solution is one in which no more solute can be dissolved at a given temperature, an unsaturated solution can dissolve more solute at the given conditions, and a dilute solution has a low concentration of solute relative to the solvent.