Nokea
If a portion of a strand of DNA bases reads 5' AGCTAGCGT 3', what would the sequence of bases on the complementary strand read?
- A. 3' AGCTAGCGT 5'
- B. 5' UCGAUCGCA 3'
- C. 3' TCGATCGCA 5'
- D. 5' TCGUTCGCU 3'
Correct Answer: C
Rationale: To determine the sequence of bases on the complementary DNA strand, you must apply the base pairing rules: adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). The given original sequence is 5' AGCTAGCGT 3'. Consequently, the complementary strand will read 3' TCGATCGCA 5'. Each base on one strand corresponds with its complementary base on the other strand, forming a sequence that complements the original one.
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Which of the following blood vessels is affected by a myocardial infarction?
- A. coronary
- B. vena cava
- C. pulmonary
- D. aorta
Correct Answer: A
Rationale: A myocardial infarction affects the coronary arteries, not the vena cava, pulmonary, or aorta. The coronary arteries supply blood to the heart muscle, and blockages in these arteries can result in a heart attack. The vena cava is a large vein that carries deoxygenated blood back to the heart, the pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation, and the aorta is the main artery that carries oxygenated blood from the heart to the rest of the body. These vessels are not typically associated with myocardial infarctions as they perform different functions within the circulatory system.
Blockage and inflammation of which of the following structures most often leads to facial acne?
- A. Lacrimal glands
- B. Sebaceous glands
- C. Ceruminous glands
- D. Sudoriferous glands
Correct Answer: B
Rationale: Sebaceous glands are responsible for producing sebum, an oily substance that can clog pores when overproduced or combined with dead skin cells. This blockage promotes the growth of acne-causing bacteria and leads to inflammation. The other glands listed in the choices do not play a significant role in the development of facial acne. Ceruminous glands produce earwax (cerumen) to protect the ear canal, sudoriferous glands produce sweat to regulate body temperature, and lacrimal glands produce tears to lubricate and protect the eyes.
Why do chloride ions have a negative charge?
- A. It lost a proton.
- B. It gained a proton.
- C. It gained an electron.
- D. It lost an electron.
Correct Answer: C
Rationale: Chloride ions (Cl-) have a negative charge because they gained an electron. When an atom gains an electron, it increases the number of negative charges relative to positive charges, resulting in a net negative charge, as seen in chloride ions. In the case of chloride ions, a chlorine atom gains an extra electron to achieve a stable electron configuration, turning it into a chloride ion with a negative charge.
What process causes most of the carbon dioxide from the blood to move into alveoli?
- A. Active transport
- B. Diffusion down a concentration gradient
- C. Passive transport using carrier proteins
- D. Conversion to carbon monoxide
Correct Answer: B
Rationale: The correct answer is B: Diffusion down a concentration gradient. In the alveoli, there is a higher concentration of carbon dioxide in the blood compared to the air, leading to the movement of carbon dioxide from the blood into the alveoli through diffusion. This natural movement occurs due to the concentration gradient, ensuring the elimination of carbon dioxide during respiration. Active transport, a process requiring energy, is not involved in this movement. Passive transport using carrier proteins is not the primary mechanism for carbon dioxide movement in the lungs. Conversion to carbon monoxide is incorrect as it does not explain the physiological process of carbon dioxide exchange in the alveoli.
What is the term given to the sequence of nucleotides that contains the information to make a specific protein molecule?
- A. Gene
- B. Locus
- C. Promoter
- D. Operator
Correct Answer: A
Rationale: The correct answer is A: Gene. A gene is the term used to describe the sequence of nucleotides that contains the information necessary to synthesize a specific protein molecule. Genes act as the fundamental units of heredity and provide the instructions for building proteins, which play crucial roles in various biological processes within an organism. In contrast, a locus refers to the specific position or location of a gene on a chromosome. Promoter is a regulatory region of DNA that initiates the transcription process for a particular gene, while an operator is a DNA segment that interacts with a repressor protein to modulate the expression of neighboring genes.