HESI A2 Biology 2024

Correct Answer: C

Rationale: The correct answer is C (50%). In this scenario, the male offspring will inherit the X chromosome with the hemophilia gene from the mother, making him a hemophiliac. The female offspring will inherit one X chromosome with the hemophilia gene, making her a carrier. Therefore, 50% of the offspring are predicted to be carriers only. Option A (0%) is incorrect as carriers will be present. Option B (25%) is incorrect because only male offspring will have hemophilia. Option D (100%) is incorrect as not all offspring will be carriers.

Correct Answer: A

Rationale: The correct answer is A. When messenger RNA reaches the cytoplasm, it attaches to a ribosome for protein synthesis. Ribosomes are the cellular machinery responsible for translating the genetic code carried by mRNA into proteins. Option B is incorrect as mRNA does not "unzip" in the cytoplasm. Option C is incorrect because mRNA does not pair with DNA bases in the cytoplasm; it pairs with ribosomes. Option D is incorrect as mRNA does not "pull free" of the DNA strand in the cytoplasm; it has already been transcribed from DNA in the nucleus.

Correct Answer: D

Rationale: The correct answer is D: Fragmentation. Fragmentation is the form of asexual reproduction where an organism breaks into fragments, and each fragment can develop into a new individual. In this scenario, ocean waves tearing sponges into pieces allows each piece to grow into a new sponge, demonstrating fragmentation. A: Budding involves the formation of a new organism from a small outgrowth on the parent organism. This process does not involve breaking the parent organism into pieces. B: Vegetative propagation is a method of asexual reproduction in plants where new individuals are formed from vegetative parts like stems or roots. This does not apply to sponges. C: Binary fission is a form of reproduction seen in single-celled organisms where the cell divides into two identical cells. This process is not applicable to sponges, which are multicellular organisms.

Correct Answer: C

Rationale: The correct answer is C: Osmosis. Osmosis is the process of water moving across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration. In this scenario, the strong salt solution outside the bacteria creates a hypertonic environment, causing water to move out of the bacteria, leading to its shrinkage. Dehydration synthesis (A) is a process where molecules combine to form a larger molecule with the loss of water. Hydrolysis (B) is the opposite process where a larger molecule is broken down into smaller molecules by the addition of water. Isotonic transport (D) refers to the movement of molecules across a membrane to maintain equilibrium, not the specific process described in the question.

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.