Nokea
What is the waxy or oily substance produced by sebaceous glands that helps lubricate the skin and hair?
- A. Keratin
- B. Melanin
- C. Sebum
- D. Sweat
Correct Answer: C
Rationale: Sebum is the waxy or oily substance produced by sebaceous glands. It helps lubricate the skin and hair, keeping them moisturized and protected. Keratin is a protein that makes up hair, skin, and nails, providing structure and strength. Melanin is a pigment that gives color to the skin, hair, and eyes, providing protection against UV radiation. Sweat is a watery fluid produced by sweat glands to help regulate body temperature by cooling the body through evaporation.
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Which type of waves require a medium (solid, liquid, or gas) to propagate?
- A. Transverse waves
- B. Longitudinal waves
- C. Electromagnetic waves
- D. Surface waves
Correct Answer: B
Rationale: Longitudinal waves require a medium (solid, liquid, or gas) to propagate because the particles in the medium move parallel to the direction of the wave. As a result, they rely on the medium for transmission. Transverse waves, on the contrary, do not need a medium and can travel through a vacuum, making choice A incorrect. Electromagnetic waves, represented by choice C, do not require a medium as they consist of oscillating electric and magnetic fields that can propagate through a vacuum. Surface waves, the option in D, involve a combination of both longitudinal and transverse motion and do require a medium to travel, but longitudinal waves are the ones that strictly depend on a medium for propagation.
In the cardiovascular system, what does the term 'double circulation' refer to?
- A. The separation of oxygenated and deoxygenated blood flow within the heart.
- B. The regulation of blood pressure through vasoconstriction and vasodilation.
- C. The cyclic contraction and relaxation of the heart muscle.
- D. The existence of two separate circulatory pathways, one for the lungs and one for the body.
Correct Answer: D
Rationale: The term 'double circulation' in the cardiovascular system refers to the existence of two separate circulatory pathways, one for the lungs (pulmonary circulation) and one for the body (systemic circulation). Oxygen-poor blood is pumped from the heart to the lungs for oxygenation, and then oxygen-rich blood is pumped from the lungs back to the heart to be circulated to the rest of the body. Choices A, B, and C are incorrect as they do not accurately describe the concept of 'double circulation.' Choice A refers to the separation of oxygenated and deoxygenated blood within the heart, choice B relates to blood pressure regulation mechanisms, and choice C describes the cardiac muscle's contraction and relaxation, none of which define 'double circulation' in the context of the cardiovascular system.
Which type of cartilage allows for smooth movement at joints and absorbs shock?
- A. Hyaline cartilage
- B. Fibrocartilage
- C. Elastic cartilage
- D. None of the above
Correct Answer: B
Rationale: Fibrocartilage is the correct answer. It is found in areas requiring both support and resilience, such as the intervertebral discs and knee joints. Fibrocartilage contains collagen fibers for strength and proteoglycans for resilience, making it suitable for functions that involve smooth movement at joints and shock absorption. Hyaline cartilage, while providing structural support, is not primarily responsible for smooth movement and shock absorption. Elastic cartilage is more flexible and is found in locations like the ear and epiglottis, but it is not known for its shock-absorbing properties. Choosing 'None of the above' disregards the correct option of fibrocartilage, which is specifically designed for the functions described in the question.
During antibiotic use, bacteria can evolve resistance. This is an example of:
- A. Coevolution (two species influencing each other's evolution)
- B. Convergent evolution (unrelated organisms evolving similar traits)
- C. Macroevolution (large-scale evolutionary change)
- D. Artificial selection acting on a natural process
Correct Answer: D
Rationale: The process of bacteria evolving resistance to antibiotics due to the selective pressure exerted by the antibiotics is an example of artificial selection (human intervention selecting for certain traits) acting on a natural process (bacterial evolution). Antibiotic use creates a selective pressure that favors the survival and reproduction of bacteria with resistance traits, leading to the evolution of antibiotic-resistant strains.
- Coevolution (option A) refers to the influence of two species on each other's evolution, which is not the case in the scenario described in the question.
- Convergent evolution (option B) involves unrelated organisms evolving similar traits due to similar environmental pressures, which is not directly applicable to the situation of bacteria evolving resistance to antibiotics.
- Macroevolution (option C) refers to large-scale evolutionary changes over long periods, which is not specifically demonstrated in the context of bacteria evolving resistance during antibiotic use.
What is the relationship between the Pauli exclusion principle and the structure of the atom?
- A. It defines the maximum number of electrons allowed in each energy level.
- B. It explains why oppositely charged particles attract each other.
- C. It describes the wave-particle duality of electrons.
- D. It determines the arrangement of protons and neutrons in the nucleus.
Correct Answer: A
Rationale: The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers. This principle defines the maximum number of electrons allowed in each energy level, influencing the structure of the atom. Choice B is incorrect as it refers to the concept of electrostatic attraction, not directly related to the Pauli exclusion principle. Choice C is incorrect as it pertains to the wave-particle duality, a different aspect of quantum mechanics. Choice D is incorrect as it relates to the arrangement of protons and neutrons in the nucleus, not governed by the Pauli exclusion principle.