Nokea
What is the basic unit of communication in the nervous system?
- A. Neuron
- B. Astrocyte
- C. Neurotransmitter
- D. Synapse
Correct Answer: A
Rationale: A neuron is the basic unit of communication in the nervous system. Neurons are specialized cells responsible for transmitting information through electrical and chemical signals. Astrocytes are a type of glial cell that provide support and nourishment to neurons but do not participate in signal transmission. Neurotransmitters are chemicals that facilitate signal transmission between neurons, and synapses are the specific junctions where these signals are transmitted. Therefore, the correct answer is 'A: Neuron' as it is the primary cell involved in transmitting information in the nervous system.
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The resolution of an optical instrument, like a microscope, refers to its ability to distinguish between:
- A. Different colors of light
- B. The presence or absence of light
- C. Variations in intensity
- D. Very close, nearly identical objects
Correct Answer: D
Rationale: The resolution of an optical instrument, such as a microscope, refers to its ability to distinguish between very close, nearly identical objects. This is crucial in microscopy to clearly visualize and differentiate fine details and structures. Resolving power plays a significant role in determining the quality and effectiveness of an optical instrument. Choices A, B, and C are incorrect because the resolution of an optical instrument does not primarily deal with different colors of light, presence or absence of light, or variations in intensity. Instead, it specifically focuses on the instrument's ability to differentiate between objects that are very close and nearly identical in nature.
What scientific term encompasses a permanent alteration in the DNA sequence?
- A. Trait
- B. Mutation
- C. Allele
- D. Variation
Correct Answer: B
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."
Which part of the brainstem controls heart rate and breathing?
- A. Medulla oblongata
- B. Pons
- C. Midbrain
- D. Thalamus
Correct Answer: A
Rationale: The medulla oblongata is a critical part of the brainstem responsible for regulating essential functions such as heart rate, breathing, and blood pressure. It houses centers that oversee these involuntary processes, making it the correct answer. The pons, midbrain, and thalamus do not primarily control heart rate and breathing, thus making them incorrect choices for this question.
Which of the following colligative properties refers to the elevation of the boiling point of a solution?
- A. Freezing point depression
- B. Vapor pressure lowering
- C. Osmotic pressure
- D. Boiling point elevation
Correct Answer: D
Rationale: The correct answer is D, 'Boiling point elevation.' Boiling point elevation is a colligative property that describes the increase in the boiling point of a solvent when a non-volatile solute is added to it. This occurs because the presence of solute particles in the solvent lowers the vapor pressure of the solution, requiring a higher temperature to reach the same vapor pressure as the pure solvent. Choices A, B, and C are incorrect. Freezing point depression refers to the lowering of the freezing point of a solution, vapor pressure lowering is the reduction in vapor pressure due to the presence of solute particles, and osmotic pressure is the pressure required to prevent the flow of solvent molecules across a semipermeable membrane in osmosis.
What is the name of the white blood cells that attack foreign invaders?
- A. Phagocytes
- B. Lymphocytes
- C. Platelets
- D. Red blood cells
Correct Answer: A
Rationale: Phagocytes are a type of white blood cell that plays a crucial role in the immune system by engulfing and digesting foreign invaders such as bacteria, viruses, and other harmful substances. They are part of the body's innate immune response and are essential for protecting the body against infections. Lymphocytes, on the other hand, are another type of white blood cell involved in the adaptive immune response, producing antibodies, and coordinating immune responses. Platelets are cell fragments involved in blood clotting, while red blood cells are responsible for carrying oxygen to tissues. Therefore, the correct answer is Phagocytes (Choice A) because they are specifically tasked with attacking and destroying foreign invaders in the body, distinguishing them from the other choices which have different functions within the immune system.