HESI A2 Biology 2024

Correct Answer: C

Rationale: Rationale: 1. The Krebs cycle produces ATP (A), CO2 (B), and NADH (D) as products. 2. Glucose (C) is not directly produced by the Krebs cycle; glucose is the starting molecule that enters glycolysis before the Krebs cycle. Summary: A, B, and D are products of the Krebs cycle, while glucose (C) is not directly produced by the Krebs cycle but is a substrate for glycolysis.

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: B

Rationale: The correct answer is B: Vacuole. Vacuoles are organelles that provide storage space for the cell, storing water, nutrients, and waste products. They help maintain the cell's internal pressure and shape. Mitochondria (A) are responsible for energy production, not storage. The cell membrane (C) is a protective barrier, and ribosomes (D) are involved in protein synthesis, not storage. Therefore, only the vacuole fits the role of providing storage space for the cell.

Correct Answer: A

Rationale: The correct answer is A: Hydrogen atoms. Saturated fats have all of their carbon atoms bonded to hydrogen atoms, with no double bonds between carbon atoms. This results in a "saturated" molecule with as many hydrogen atoms as possible. Choices B, C, and D are incorrect because saturated fats are not saturated with carbon, oxygen, or nitrogen atoms. These choices do not accurately reflect the chemical structure of saturated fats, which are primarily composed of carbon and hydrogen atoms.

Correct Answer: D

Rationale: The correct answer is D (46). Humans have 23 pairs of homologous chromosomes, totaling 46 chromosomes. Each pair consists of one chromosome from each parent. Choices A (13), B (23), and C (26) are incorrect as they do not represent the total number of pairs of homologous chromosomes in humans. A and C do not reflect the correct total number of chromosomes, while B only specifies the number of individual chromosomes, not pairs. Therefore, option D is the correct choice because it accurately represents the total number of homologous chromosome pairs in humans.