1. Myelin sheath is a fatty substance that insulates and protects the long extensions of some nerve cells. It is produced by:

A. Schwann cells
B. Astrocytes
C. Neurons
D. Oligodendrocytes

Correct answer: A

Rationale: The correct answer is A: Schwann cells. Schwann cells are a type of glial cell in the peripheral nervous system that produce the myelin sheath around axons. Myelin sheath is essential for the rapid conduction of nerve impulses and provides insulation and protection to nerve fibers. Astrocytes are glial cells that provide support and maintain homeostasis in the central nervous system, but they do not produce myelin. Neurons are the main functional units of the nervous system responsible for transmitting nerve impulses. Oligodendrocytes are another type of glial cell in the central nervous system that produce myelin sheath around axons in that region, not in the peripheral nervous system where Schwann cells are responsible for myelination.

2. What is the process of converting light energy into chemical energy called?

A. Respiration
B. Fermentation
C. Photosynthesis
D. Hydrolysis

Correct answer: C

Rationale: Rationale: - Respiration (Option A) is the process by which cells break down glucose to release energy. - Fermentation (Option B) is an anaerobic process that also involves the breakdown of glucose to release energy. - Hydrolysis (Option D) is a chemical process that involves the breakdown of molecules by adding water. Photosynthesis (Option C) is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. During photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose and oxygen. This process is essential for the survival of plants and ultimately sustains life on Earth by providing oxygen for other organisms to breathe and serving as a source of energy in the food chain.

3. Which biome is characterized by cold temperatures, permafrost, and coniferous trees?

A. Tundra
B. Desert
C. Rainforest
D. Savanna

Correct answer: A

Rationale: Rationale: A) Tundra: This biome is characterized by cold temperatures, permafrost (permanently frozen subsoil), and vegetation such as mosses, lichens, and coniferous trees like spruce and fir. The tundra is found in high latitudes near the Arctic Circle and high altitudes in mountainous regions. B) Desert: Deserts are characterized by low precipitation levels and high temperatures, with sparse vegetation adapted to arid conditions. C) Rainforest: Rainforests are characterized by high levels of rainfall, warm temperatures, and dense vegetation with a variety of plant and animal species. D) Savanna: Savannas are tropical grasslands with scattered trees and shrubs, characterized by a distinct wet and dry season. In this case, the description of cold temperatures, permafrost, and coniferous trees aligns most closely with the characteristics of the tundra biome, making option A

4. What part of speech is the underlined word in the sentence: "He felt a growing sense of unease"?

A. Verb
B. Noun
C. Adjective
D. Adverb

Correct answer: B

Rationale: "Sense" represents a concept or feeling, making it a noun here.

5. During which phase of the cell cycle does cytokinesis typically occur?

A. Interphase
B. Mitosis
C. Meiosis
D. G2 phase

Correct answer: B

Rationale: Rationale: Cytokinesis is the process of dividing the cytoplasm of a cell into two daughter cells after the nucleus has divided during mitosis. In the cell cycle, cytokinesis typically occurs at the end of the mitotic phase, following the separation of the duplicated chromosomes into two identical sets in the daughter nuclei. Interphase (option A) is the phase where the cell grows, carries out its normal functions, and prepares for cell division. Meiosis (option C) is a specialized type of cell division that occurs in sexually reproducing organisms to produce gametes. G2 phase (option D) is the phase of the cell cycle following DNA replication in S phase and preceding mitosis, where the cell prepares for cell division.

6. What scientific term encompasses a permanent alteration in the DNA sequence?

A. Trait
B. Mutation
C. Allele
D. Variation

Correct answer: B

Rationale: Rationale: A) Trait: A trait is a characteristic or feature of an organism that is determined by its genes. B) Mutation: A mutation is a permanent alteration in the DNA sequence that can result from errors during DNA replication, exposure to mutagens, or other factors. C) Allele: An allele is a variant form of a gene that can result in different traits or characteristics. D) Variation: Variation refers to the differences in traits or characteristics among individuals of the same species, which can be influenced by genetic and environmental factors. In this context, the term that specifically refers to a permanent alteration in the DNA sequence is "mutation."