HESI A2 Practice Test Biology

Correct Answer: C

Rationale: The correct answer is C: ribosome. Ribosomes are the organelles responsible for organizing protein synthesis. They are the site where proteins are assembled based on instructions from the cell's DNA. Ribosomes can be found in the cytoplasm and on the endoplasmic reticulum. Mitochondria (A) are responsible for energy production, the nucleus (B) contains genetic material but does not directly organize protein synthesis, and vacuoles (D) are primarily involved in storage and maintaining cell structure. Therefore, the ribosome is the only organelle directly involved in protein synthesis among the choices provided.

Correct Answer: B

Rationale: The correct answer is B: ATP. ATP (adenosine triphosphate) is the primary molecule responsible for storing and transferring energy in cells through its high-energy phosphate bonds. Glucose (choice A) is a source of energy but not a storage molecule. Fatty acids (choice C) are primarily used for long-term energy storage. Starch (choice D) is a polysaccharide used for energy storage in plants, but ATP is the main energy currency in all cells for immediate use.

Correct Answer: A

Rationale: The second part of an organism's scientific name is the species. In binomial nomenclature, developed by Carl Linnaeus, the scientific name consists of two parts: the genus and the species. The genus is the broader category that encompasses multiple species, while the species is the specific name unique to that particular organism within the genus. Therefore, the correct answer is A: species. Option B: phylum is incorrect as it is a higher taxonomic rank above the genus and species. Option C: population is incorrect as it refers to a group of organisms of the same species in a particular area. Option D: kingdom is incorrect as it is the highest taxonomic rank, encompassing all living organisms categorized into five kingdoms.

Correct Answer: C

Rationale: The correct answer is C: four. DNA is composed of four different types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). Each nucleotide consists of a nitrogenous base, a sugar (deoxyribose), and a phosphate group. These four nucleotides form complementary base pairs, which are essential for DNA replication and protein synthesis. The other choices are incorrect because DNA is made up of multiple nucleotides with specific base pairings, not just one or two types. Therefore, the correct answer is C: four.

Correct Answer: A

Rationale: The correct answer is A: Mitochondrion and chloroplast. Mitochondria are known as the powerhouse of the cell, producing energy in the form of ATP through cellular respiration. Chloroplasts are responsible for photosynthesis in plant cells, converting sunlight into energy. Nucleus is not involved in energy production but contains genetic material. Lysosomes are involved in digestion and waste removal, not energy production. Therefore, A is correct as both mitochondria and chloroplasts play crucial roles in generating cell energy.