A student conducts an experiment where they dissolve 1 g each of several substances in 50 mL of water. They have 12 identical plastic cups of water and places 1 g of salt into three of the cups, 1 of sugar into three of the cups, and 1 g of baking soda into three of the cups. The three remaining cups contain only water. All the cups are put in a freezer and the temperature of the solution in each cup is recorded every 15 minutes for 4 hours.

Which of the following questions is the student most likely investigating?

The pharynx is primarily composed of muscle tissue. It plays a role in swallowing and is part of both the respiratory and digestive systems, which requires coordinated muscular activity.

The correct answer is C. The digestive system is responsible for breaking down complex food molecules, including proteins, into simpler components such as amino acids that can be absorbed and utilized by the body.

The correct answer is A. Chromatin is a complex of DNA and proteins, including histones, found in the nucleus of eukaryotic cells. It carries the hereditary information in the form of genes. ATP, plasmids, and histones are involved in cellular processes but do not carry hereditary information.

The correct answer is C. Helper T-cells play a crucial role in the immune system by coordinating and stimulating other immune cells, including cytotoxic T-cells, to attack and destroy foreign agents.

The correct answer is C. The renal vein is responsible for draining oxygen-depleted blood from the kidneys. After the kidneys filter waste and excess substances from the blood, the deoxygenated blood is carried away from the kidneys by the renal vein

The correct answer is B. Emphysema is a disease that primarily affects the alveoli, which are tiny air sacs in the lungs responsible for gas exchange. The destruction of alveoli walls in emphysema reduces the surface area available for oxygen and carbon dioxide exchange.

The correct answer is B. Atoms become cations by losing electrons. Potassium has one electron in its outermost shell, and it is more likely to lose that electron to achieve a stable, cationic state. Fluorine, helium, and oxygen are more likely to gain electrons and form anions.

The correct answer is C. Chlorine molecule (Cl2) has only one covalent bond between the two chlorine atoms, which share one pair of electrons. The other molecules have more covalent bonds: water has two, methane has four, and ammonia has three.

The correct answer is D. The typical pathway of blood flow involves arteries branching into arterioles, which further branch into capillaries, facilitating the exchange of nutrients and gases with the organ's tissues.

Independent assortment occurs during metaphase I when homologous chromosome pairs line up randomly at the cell’s equator. This randomness contributes to genetic variation because the distribution of maternal and paternal chromosomes into gametes is different each time meiosis occurs.