Which of the following is an event that occurs in metaphase I of meiosis that causes variation?

The correct answer is C. Psoriasis is a chronic autoimmune skin condition characterized by the rapid buildup of skin cells, and it is considered a noninfectious disease. Chikungunya, dengue, and brucellosis are infectious diseases caused by specific pathogens.

The correct answer is B. Parathyroid hormone (PTH) regulates blood calcium levels by stimulating the release of calcium from bones, reabsorption of calcium in the kidneys, and absorption of calcium in the intestines. Norepinephrine, growth hormone, and melatonin do not play a primary role in calcium regulation.

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 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.

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.

The correct answer is C. A spectrophotometer measures the amount of light absorbed or transmitted by a substance in a liquid. Turbidity, caused by suspended particles, can be assessed by measuring the reduction in light transmission through the sample. The other tools listed are not specifically designed for measuring turbidity.

The correct answer is B. This option involves a control group (water) and an experimental group (energy drink) to compare the effects. By having a group that does not consume the energy drink, researchers can better attribute any observed differences in running speed to the energy drink itself.

The correct answer is B. The phenotypic ratio of 50% green pods and 50% yellow pods indicates that the genotype of the parent with green pods is heterozygous (Gg), and the genotype of the parent with yellow pods is homozygous recessive (gg). The cross would be Gg x gg.

The correct answer is A. Increasing the surface area of a solid reactant by grinding it to a powder exposes more particles to the reactants, enhancing their chances of colliding and increasing the reaction rate. The other options would generally decrease the rate of the reaction.

The correct answer is A. This option describes a chemical reaction known as the reaction of water with sodium, producing hydrogen gas. Chemical reactions involve the breaking and forming of chemical bonds, and in this case, sodium reacts with water to produce hydrogen gas and sodium hydroxide.