HESI A2
Biology HESI A2 Practice Exam
1. What is another name for the light-independent reaction in plants?
- A. Photosynthesis
- B. Calvin cycle
- C. Germination
- D. Phosphorus cycle
Correct answer: B
Rationale: The light-independent reaction in plants is also known as the Calvin cycle. This biochemical pathway, named after Melvin Calvin who discovered it, takes place in the stroma of chloroplasts and is responsible for converting carbon dioxide into glucose using ATP and NADPH generated during the light-dependent reactions of photosynthesis. The Calvin cycle does not directly require light to function, hence the alternative name as the light-independent reaction. Choices A, C, and D are incorrect. Photosynthesis is the overall process of converting light energy into chemical energy, which includes both light-dependent and light-independent reactions. Germination is the process where a seed sprouts into a new plant. The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.
2. Where is the site of cellular respiration in eukaryotic cells?
- A. Nucleus
- B. Chloroplasts
- C. Mitochondria
- D. Ribosomes
Correct answer: C
Rationale: The correct answer is C: Mitochondria. Mitochondria are often referred to as the powerhouse of the cell because they are responsible for cellular respiration in eukaryotic cells. During cellular respiration, mitochondria generate energy in the form of ATP. Choices A, B, and D are incorrect. The nucleus is the organelle that houses the cell's genetic material, chloroplasts are responsible for photosynthesis in plant cells, and ribosomes are involved in protein synthesis, not cellular respiration.
3. What provides the cell with the ability to move and propel?
- A. Microfilaments
- B. Microtubules
- C. Flagella
- D. Cilia
Correct answer: B
Rationale: Microtubules are the cellular structures responsible for cell movement and propulsion. Microtubules are part of the cytoskeleton and play a crucial role in various cellular processes, including cell motility and intracellular transport. While microfilaments also contribute to cell movement by enabling muscle contraction and cell shape changes, they are not primarily responsible for propelling the cell. Flagella and cilia are cellular appendages involved in cell movement, but they are composed of microtubules, making them the structures that move due to the actions of microtubules.
4. How many different types of nucleotides are there in DNA?
- A. one
- B. two
- C. four
- D. eight
Correct answer: C
Rationale: The correct answer is 'C: four.' DNA is composed of four different types of nucleotides: adenine, thymine, guanine, and cytosine. These nucleotides pair up in specific combinations to form the genetic code. Choices 'A: one,' 'B: two,' and 'D: eight' are incorrect because DNA consists of a set of four distinct nucleotides, not one, two, or eight.
5. Tundra, savannas, grasslands, deserts, and rainforests are examples of what?
- A. Biomasses
- B. Biospheres
- C. Biodiversity
- D. Biomes
Correct answer: D
Rationale: Tundra, savannas, grasslands, deserts, and rainforests are examples of biomes. A biome is a large geographical area with similar climatic conditions and distinct flora and fauna. Each biome has its unique characteristics, such as temperature, precipitation levels, and types of vegetation, which define the ecosystem within that region. Biomasses refer to the total mass of living organisms in a given area, biospheres are the global ecological system integrating all living beings and their relationships, and biodiversity represents the variety of life forms in a specific habitat.
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