Nokea
During which phase of meiosis do chiasmata structures form?
- A. Prophase I
- B. Prophase II
- C. Metaphase I
- D. Metaphase II
Correct Answer: A
Rationale: Chiasmata structures, where crossing over occurs, form during Prophase I of meiosis. This phase is characterized by homologous chromosomes pairing up and crossing over, leading to the exchange of genetic material between non-sister chromatids. Chiasmata are visible points of contact where genetic material has been exchanged, and they play a critical role in genetic diversity. Prophase II is the phase where chromosomes condense again in the second meiotic division, but chiasmata formation occurs in Prophase I. Metaphase I is the phase where homologous chromosomes align at the metaphase plate, not where chiasmata form. Metaphase II is the phase where replicated chromosomes align at the metaphase plate in the second meiotic division, but chiasmata formation occurs earlier in Prophase I.
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Which deadly disease was eliminated through an intensive vaccination program?
- A. AIDS
- B. Smallpox
- C. Diabetes type 1
- D. Rheumatoid arthritis
Correct Answer: B
Rationale: Smallpox was eradicated globally through an intensive vaccination program. The World Health Organization (WHO) led a successful global campaign to vaccinate people against smallpox, ultimately leading to its eradication in 1980. AIDS, diabetes type 1, and rheumatoid arthritis are serious conditions, but they were not eliminated through vaccination programs like smallpox. Therefore, the correct answer is B, Smallpox. AIDS is caused by the human immunodeficiency virus (HIV) and remains a significant global health issue. Diabetes type 1 is an autoimmune condition where the body attacks insulin-producing cells, leading to high blood sugar levels. Rheumatoid arthritis is an autoimmune condition that primarily affects the joints, causing inflammation and pain.
What is a major structure of the limbic system?
- A. Brainstem
- B. Spinal cord
- C. Hypothalamus
- D. Cerebral cortex
Correct Answer: C
Rationale: The correct answer is C: Hypothalamus. The hypothalamus is a significant structure of the limbic system responsible for regulating various functions such as emotions, autonomic functions, and hormone production. It plays a crucial role in maintaining homeostasis and orchestrating responses to stress and emotional stimuli. Choices A, B, and D are incorrect. The brainstem, although a vital part of the brain, is not a major structure of the limbic system. The spinal cord is not part of the limbic system; it is primarily involved in transmitting sensory and motor information between the brain and the rest of the body. The cerebral cortex is responsible for higher cognitive functions but is not a major structure within the limbic system.
What two factors enable some intercellular chemical signals to diffuse across cell membranes and bind to intracellular receptors?
- A. They are small and soluble.
- B. They are large and soluble.
- C. They are small and insoluble.
- D. They are large and insoluble.
Correct Answer: A
Rationale: The correct answer is A: 'They are small and soluble.' Small and soluble molecules can easily pass through cell membranes and bind to intracellular receptors. Being small allows them to pass through the membrane, while being soluble enables them to dissolve in the aqueous environment inside the cell. Choice B is incorrect because large molecules typically cannot pass through the cell membrane easily. Choices C and D are incorrect because insoluble molecules would not dissolve in the aqueous environment inside the cell, hindering their ability to bind to intracellular receptors.
In which position allows access to the stomach?
- A. Medial
- B. Prone
- C. Superficial
- D. Supine
Correct Answer: B
Rationale: The question now specifies the need for a position that allows access to the stomach. The correct answer is 'B: Prone.' In the prone position, the patient lies face down, which facilitates access to the stomach for various procedures or examinations. Choice A, 'Medial,' refers to a direction rather than a patient position. Choice C, 'Superficial,' describes a superficial depth rather than a patient position. Choice D, 'Supine,' is a position where the patient lies face up, which does not provide easy access to the stomach.
Which muscle causes a joint to bend?
- A. Cardiac
- B. Extension
- C. Flexor
- D. Smooth
Correct Answer: C
Rationale: The correct answer is C: Flexor. A flexor muscle contracts to bend a joint, such as bending the elbow or knee. Flexor muscles are responsible for flexing or bending a joint, while extensor muscles are responsible for extending or straightening a joint. Choice A, Cardiac, is incorrect as cardiac muscle is found in the heart and is responsible for pumping blood. Choice B, Extension, is incorrect as extension refers to the straightening or extending movement of a joint, which is opposite to bending. Choice D, Smooth, is incorrect as smooth muscles are involuntary muscles found in organs like the intestines and blood vessels, not directly responsible for bending joints.