HESI A2 Biology 2024

Correct Answer: D

Rationale: The correct answer is D: Citric acid. Citric acid is not a component of DNA nucleotides. A DNA nucleotide consists of a simple sugar (deoxyribose), a nitrogen base (adenine, thymine, cytosine, or guanine), and a phosphate group. Citric acid is not part of the structure of DNA; it is a component of the citric acid cycle in cellular respiration. Therefore, it is not found in the nucleotide of DNA. The other choices (A, B, and C) are all components that make up a DNA nucleotide, making them incorrect options.

Correct Answer: A

Rationale: The correct answer is A: Mitochondrion. Mitochondria are known as the powerhouse of the cell due to their role in energy production through cellular respiration. They generate ATP, the main energy currency of the cell, through the citric acid cycle and oxidative phosphorylation. Vacuole (B) stores materials, cell membrane (C) regulates what enters and exits the cell, and ribosome (D) is responsible for protein synthesis. Mitochondria uniquely carry out the process of energy production, making them the correct choice.

Correct Answer: B

Rationale: During glycolysis, glucose is broken down into molecules of pyruvic acid through a series of enzymatic reactions. This process occurs in the cytoplasm of cells and is the first step in cellular respiration. Pyruvic acid can then enter the citric acid cycle (Kreb's cycle) to further generate ATP. Choice A is incorrect because glucose's energy is not entirely lost but rather partially captured in the form of ATP. Choice C is incorrect as glucose is not stored in NADH but rather NADH is generated during glycolysis. Choice D is incorrect as glucose does not join with molecules of citric acid during glycolysis but rather pyruvic acid is the end product.

Correct Answer: A

Rationale: The correct answer is A: Cow. Cows are ruminant animals, meaning they have a complex digestive system that requires a lot of energy to break down cellulose from grass. This process is less energy-efficient compared to the digestive systems of other animals like caterpillars, coyotes, and crickets. Caterpillars have efficient digestion due to their specialized enzymes, coyotes are carnivores with more efficient nutrient absorption, and crickets have simpler digestive systems. Therefore, the cow would have the least energy efficiency in nutrient consumption among the options provided.

Correct Answer: D

Rationale: The correct answer is D: Mitosis. In the tip of a plant's root, cells undergo mitosis to increase in number. In mitosis, a parent cell divides into two identical daughter cells, ensuring the growth and repair of tissues. Meiosis, choice A, is a process of cell division that produces gametes with half the genetic material. Cytokinesis, choice B, is the process of cytoplasmic division following cell division. Fractioning, choice C, is not a biological process related to cell division. Mitosis is the only process mentioned that specifically describes cell division for growth and repair in plants.