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Electroencephalography (EEG) measures electrical activity in the brain, primarily reflecting the activity of:
- A. Neurons
- B. Astrocytes
- C. Oligodendrocytes
- D. Microglia
Correct Answer: A
Rationale: EEG measures electrical activity in the brain, primarily reflecting the activity of neurons. Neurons are the primary cells responsible for generating electrical impulses and transmitting information in the brain. Astrocytes, oligodendrocytes, and microglia are other types of cells in the brain that have different functions and are not primarily involved in generating the electrical activity measured by EEG. Astrocytes support neuronal function, oligodendrocytes produce myelin to insulate axons, and microglia are involved in immune responses and maintaining brain health, but they do not generate the electrical impulses detected by EEG.
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What is the common name for the compound CH₃COOH?
- A. Acetic acid
- B. Formic acid
- C. Butyric acid
- D. Propionic acid
Correct Answer: A
Rationale: The compound CH₃COOH is commonly known as acetic acid. Acetic acid is a clear, colorless liquid with a sour taste and a pungent smell. It is a weak acid found in vinegar and is used in the production of various chemicals. Formic acid, butyric acid, and propionic acid are different organic acids with distinct chemical structures and properties, but they are not the common name for the compound CH₃COOH.
What is the primary function of hair on the human body?
- A. Insulation
- B. Sensory perception
- C. Protection
- D. Vitamin D synthesis
Correct Answer: C
Rationale: The primary function of hair on the human body is protection. Hair acts as a barrier to protect the skin from external factors such as sunlight, dust, and other environmental elements. While hair can also provide some insulation by trapping heat near the body and contribute to sensory perception by detecting touch or movements, its main role is to safeguard the skin from potential harm, making protection the most essential function. Vitamin D synthesis is primarily related to the skin's exposure to sunlight and is not a direct function of hair.
What is the function of the pituitary gland?
- A. Produces hormones that regulate growth and metabolism
- B. Filters blood and removes waste products
- C. Stores and releases bile
- D. Produces red blood cells
Correct Answer: A
Rationale: The correct answer is A: Produces hormones that regulate growth and metabolism. The pituitary gland is often referred to as the 'master gland' because it produces and releases hormones that regulate various bodily functions, including growth, metabolism, reproduction, and stress response. It does not filter blood or remove waste products (option B), store and release bile (option C), or produce red blood cells (option D). The pituitary gland's primary role is in hormone production and regulation, influencing many essential functions in the body.
What structure in plant cells provides rigidity and support?
- A. Cell membrane
- B. Golgi apparatus
- C. Plastid
- D. Cell wall
Correct Answer: D
Rationale: The correct answer is D, the cell wall. The cell wall is the structure in plant cells that provides rigidity and support. It is a tough, rigid structure located outside the cell membrane. Composed primarily of cellulose, the cell wall offers structural support to the cell, helping it maintain its shape and protect it from damage. The other choices, such as the cell membrane (choice A), Golgi apparatus (choice B), and plastid (choice C) do not provide rigidity and support to plant cells. The cell membrane is a selectively permeable barrier, the Golgi apparatus is involved in processing and packaging proteins, and plastids are organelles responsible for functions like photosynthesis and storage, but they do not provide the structural support that the cell wall does.
Which type of mutation involves a change in the number of chromosomes?
- A. Point mutation
- B. Frameshift mutation
- C. Missense mutation
- D. Aneuploidy
Correct Answer: D
Rationale: A) Point mutation involves a change in a single nucleotide base pair within the DNA sequence.
B) Frameshift mutation involves the insertion or deletion of nucleotides, causing a shift in the reading frame of the genetic code.
C) Missense mutation involves a single nucleotide change that results in a codon that codes for a different amino acid.
D) Aneuploidy involves a change in the number of chromosomes, where an individual may have an extra chromosome (trisomy) or a missing chromosome (monosomy). Aneuploidy can lead to genetic disorders such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X). Changing the number of chromosomes is a characteristic feature of aneuploidy, making it the correct answer. Point mutation, frameshift mutation, and missense mutation do not involve a change in the number of chromosomes and are focused on alterations at the nucleotide level within the DNA sequence.