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Which of the following is LEAST likely to be found in a human cell's genes?
- A. Sequences of amino acids to be transcribed into mRNA
- B. Lethal recessive traits like sickle cell anemia
- C. Mutated DNA
- D. DNA that codes for proteins the cell doesn't use
Correct Answer: D
Rationale: Human cells typically contain genes that code for proteins necessary for the cell's functions. DNA that codes for proteins the cell doesn't use would be an inefficient use of the cell's resources. Therefore, it is less likely to be found in a human cell's genes. Options A, B, and C are more commonly associated with genes found in human cells. Choice A refers to the genetic information needed for protein synthesis, while choice B involves traits that can be present in the gene pool. Mutated DNA (choice C) can also be found in human cells as a result of genetic alterations. However, DNA that codes for proteins not utilized by the cell would be redundant and not typically retained in the genome.
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Which type of capillary is the most permeable?
- A. Continuous capillaries
- B. Sinusoidal capillaries
- C. Fenestrated capillaries
- D. Vascular capillaries
Correct Answer: B
Rationale: Sinusoidal capillaries are indeed the most permeable type. They are characterized by large gaps between endothelial cells, allowing for the passage of large molecules and cells. These capillaries are commonly found in organs like the liver, bone marrow, and spleen where high permeability is required for specialized functions such as filtration and exchange of substances.
Continuous capillaries have tight junctions and are the least permeable, found in muscles, lungs, and the central nervous system where strict control over permeability is needed. Fenestrated capillaries, on the other hand, have small pores or fenestrations and are intermediate in permeability, found in organs like the kidneys, endocrine glands, and intestines where selective permeability is necessary. Vascular capillaries is not a specific type of capillary and is not a valid choice.
How many mL of a 0 M stock solution of HCl should be added to water to create 250 mL of a 50 M solution of HCl?
- A. 31.25 mL
- B. 32 mL
- C. 30 mL
- D. 31.3 mL
Correct Answer: B
Rationale: To prepare 250 mL of a 50 M solution of HCl, the formula V1 x C1 = V2 x C2 is used, where V1 is the volume of the stock solution, C1 is the concentration of the stock solution, V2 is the final volume of the desired solution, and C2 is the final concentration of the desired solution. Given V1 x 0 M = 250 mL x 50 M, solving for V1 results in V1 = (250 mL x 50 M) / 0 M = 32 mL. Therefore, 32 mL of the 0 M stock solution of HCl needs to be added to water to create a 250 mL solution of 50 M HCl. Choices A, C, and D are incorrect because they do not represent the accurate volume required for the dilution calculation based on the given concentrations and volumes in the problem.
Which type of reaction builds larger and more complex molecules from smaller ones, requiring energy?
- A. Catabolic reaction
- B. Anabolic reaction
- C. Exothermic reaction
- D. Hydrolytic reaction
Correct Answer: B
Rationale: The correct answer is 'Anabolic reaction.' Anabolic reactions involve the synthesis of larger and more complex molecules from smaller ones, requiring an input of energy, often in the form of ATP. These reactions are essential for processes like growth, repair, and the building of cellular structures. Catabolic reactions, on the other hand, break down larger molecules into smaller ones, releasing energy. Exothermic reactions release heat, while hydrolytic reactions involve the breakdown of molecules with the addition of water. Therefore, choices A, C, and D are incorrect as they do not describe the process of building larger and more complex molecules from smaller ones with the requirement of energy.
The Human Genome Project is a worldwide research project launched in 1990 to map the entire human genome. Although the Project was faced with the monumental challenge of analyzing tons of data, its objective was completed in 2003, two years ahead of its deadline. Which of the following inventions likely had the greatest impact on this project?
- A. The sonogram
- B. X-ray diffraction
- C. The microprocessor
- D. Magnetic Resonance Imaging (MRI)
Correct Answer: C
Rationale: The microprocessor, a key component of modern computers, played a crucial role in the success of the Human Genome Project. The ability of microprocessors to process vast amounts of data quickly and efficiently allowed scientists to analyze the massive amounts of genetic information generated by the project. This technological advancement significantly accelerated the pace of genome sequencing and data analysis, ultimately leading to the completion of the project ahead of schedule. Choices A, B, and D are incorrect. The sonogram is used for imaging in medical diagnostics, X-ray diffraction is a technique for studying the structure of materials at the atomic level, and Magnetic Resonance Imaging (MRI) is a medical imaging technique that uses magnetic fields and radio waves to produce detailed images of the body. While these inventions have their own importance in various fields, they did not have the same impact on the Human Genome Project as the microprocessor did.
What are the three types of capillaries?
- A. Continuous, fenestrated, sinusoidal
- B. Continuous, discontinuous, fenestrated
- C. Sinusoidal, alveolar, continuous
- D. Continuous, fenestrated, vascular
Correct Answer: A
Rationale: The correct answer is A: Continuous, fenestrated, sinusoidal. Capillaries are classified into three types based on their permeability: continuous (least permeable), fenestrated (moderately permeable), and sinusoidal (most permeable). Choices B, C, and D are incorrect because they do not represent the three main types of capillaries. Choice B includes 'discontinuous' which is not a recognized type. Choice C includes 'alveolar' which is not a type of capillary, and Choice D includes 'vascular' which is too broad and not specific to capillary classification.