Nokea
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.
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What type of covalent bonds are present between the monomers of an enzyme macromolecule?
- A. Phosphodiester bonds
- B. Glycosidic bonds
- C. Ester bonds
- D. Peptide bonds
Correct Answer: D
Rationale: Enzymes are a type of biological macromolecules known as proteins. Proteins are composed of amino acid monomers that are linked together by peptide bonds. These peptide bonds form through a condensation reaction between the amino group of one amino acid and the carboxyl group of another amino acid. The specific covalent bonds present between the monomers of an enzyme macromolecule are peptide bonds. Therefore, the correct answer is D: Peptide bonds.
Which laboratory method is most useful to separate genomic DNA fragments by size?
- A. Titration
- B. Spectrophotometry
- C. Electrophoresis
- D. Filtration
Correct Answer: C
Rationale: Electrophoresis is the most suitable laboratory method for separating genomic DNA fragments by size. It works by subjecting DNA fragments to an electric field, causing them to migrate through a gel matrix based on size differences. Smaller fragments move faster and travel farther than larger ones, allowing for separation and analysis based on size. Titration is a technique used to determine the concentration of a solution, not to separate DNA fragments by size. Spectrophotometry is used to measure the amount of light absorbed by a substance at different wavelengths, not for DNA fragment size separation. Filtration is a method used to separate solid particles from a liquid or gas by passing it through a filter medium, not for separating DNA fragments by size.
Which of the following are the major parts of the nervous system?
- A. PNS and Somatic Nervous System
- B. Autonomic Nervous System and CNS
- C. PNS and CNS
- D. Autonomic Nervous System and Somatic Nervous System
Correct Answer: C
Rationale: The nervous system comprises two major parts: the peripheral nervous system (PNS) and the central nervous system (CNS). The PNS includes nerves outside the brain and spinal cord, while the CNS consists of the brain and spinal cord. Choice C (PNS and CNS) correctly identifies the primary divisions of the nervous system, encompassing both the peripheral and central components. Therefore, the correct answer is C.
How many times stronger is the hydrogen-ion concentration of a pH 4 solution compared with a pH 9 solution?
- A. 50
- B. 100,000
- C. 0.000001
- D. 5
Correct Answer: B
Rationale: The pH scale measures the concentration of hydrogen ions in a solution, where each pH unit change represents a tenfold difference in concentration. In this case, the pH 4 solution is 5 units lower than the pH 9 solution. Therefore, the difference of 5 pH units translates to a 10^5 times (or 100,000 times) increase in hydrogen-ion concentration in the pH 4 solution compared to the pH 9 solution. The pH scale is logarithmic, with each unit representing a tenfold change, so a 5-unit difference results in a 100,000-fold difference in hydrogen-ion concentration. Hence, option B, 100,000, is the correct answer.
Testosterone is classified as which of the following types of hormones?
- A. Androgen
- B. Progestin
- C. Estrogen
- D. Aldosterone
Correct Answer: A
Rationale: Testosterone is classified as an androgen, which is a type of steroid hormone responsible for the development of male characteristics such as facial hair, deepening of the voice, and muscle growth. Androgens are primarily produced in the testes in males and in smaller amounts in the ovaries and adrenal glands in females. Progestins, estrogens, and aldosterone are different types of hormones with distinct functions and are not categorized under androgens.