Nokea
What is the process of converting DNA into a protein called?
- A. Transcription
- B. Translation
- C. Replication
- D. Mutation
Correct Answer: B
Rationale: Translation is the correct answer. It is the process of converting the information in mRNA into a sequence of amino acids to form a protein. Transcription (Choice A) is the process of copying a segment of DNA into RNA. Replication (Choice C) is the process of making an identical copy of DNA. Mutation (Choice D) refers to a change in the DNA sequence that can lead to variations in proteins, but it is not the process of converting DNA into a protein.
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What is the formula for calculating molarity?
- A. M = n/V
- B. M = n/L
- C. M = mol/L
- D. M = mol/dm³
Correct Answer: A
Rationale: The correct formula for calculating molarity is M = n/V. In this formula, 'M' represents molarity, 'n' represents the number of moles of solute, and 'V' represents the volume of the solution in liters. Molarity is defined as the number of moles of solute per liter of solution, hence the ratio of moles to volume. Choice B, 'M = n/L', is incorrect because 'L' should represent liters instead of the number of moles. Choice C, 'M = mol/L', is incorrect as it does not include the representation of the number of moles 'n'. Choice D, 'M = mol/dm³', is incorrect because 'dm³' is a volume unit equal to a liter, but the correct representation should be in terms of the volume of the solution in liters. Therefore, the correct answer is M = n/V.
What is the term for the process of exchanging gases (oxygen and carbon dioxide) between the blood and the tissues?
- A. Inhalation
- B. Exhalation
- C. External respiration
- D. Internal respiration
Correct Answer: C
Rationale: External respiration is the correct term for the process of exchanging gases (oxygen and carbon dioxide) between the blood and the tissues. It specifically refers to the exchange of gases that occurs in the lungs, where oxygen is absorbed into the bloodstream and carbon dioxide is released from the bloodstream to be exhaled. Inhalation and exhalation, choices A and B, are phases of the breathing process that involve the intake and expulsion of air into and out of the lungs, respectively. Internal respiration, choice D, is the process of gas exchange that happens at the cellular level between the blood and body tissues, not between the blood and the lungs or tissues as in external respiration. Therefore, external respiration is the most appropriate term for the described gas exchange process in the question.
What term describes the point where parallel rays of light converge or appear to diverge after passing through a lens or reflecting off a mirror?
- A. Aperture
- B. Focal length
- C. Refractive index
- D. Lens thickness
Correct Answer: B
Rationale: The correct answer is 'Focal length.' Focal length is the term used to describe the point where parallel rays of light converge or appear to diverge after passing through a lens or reflecting off a mirror. It is a critical parameter in optics that determines the magnification and image formation in optical systems. Aperture refers to the opening through which light enters a camera or telescope, not the convergence point of light rays. Refractive index is a measure of how much light is bent, not the point where rays converge. Lens thickness is the physical dimension of a lens and does not indicate the convergence point of light rays. Therefore, 'Focal length' is the most appropriate choice in this context.
Which vitamin deficiency can lead to a condition called pernicious anemia, affecting vitamin B12 absorption in the digestive system?
- A. Vitamin A
- B. Vitamin B12 (cobalamin)
- C. Vitamin D
- D. Vitamin E
Correct Answer: B
Rationale: Pernicious anemia is caused by a deficiency in vitamin B12 (cobalamin). Vitamin B12 is essential for the production of red blood cells and for the proper functioning of the nervous system. Pernicious anemia occurs when there is a lack of intrinsic factor, a protein produced in the stomach that is necessary for the absorption of vitamin B12 in the digestive system. Vitamin A, Vitamin D, and Vitamin E deficiencies do not lead to pernicious anemia. Vitamin A deficiency can cause night blindness and skin issues, Vitamin D deficiency can lead to rickets or osteomalacia, and Vitamin E deficiency can result in neurological problems and muscle weakness.
Which of the following statements about prions is TRUE?
- A. They are composed of proteins only
- B. They are easily destroyed by common disinfectants
- C. hey are a type of antibiotic
- D. They are a live organism
Correct Answer: A
Rationale: A) This statement is true. Prions are infectious agents composed entirely of protein, lacking nucleic acids such as DNA or RNA. They are known for causing neurodegenerative diseases in animals and humans.
B) This statement is false. Prions are not easily destroyed by common disinfectants due to their unique structure and resistance to conventional sterilization methods.
C) This statement is false. Prions are not a type of antibiotic. They are a distinct class of infectious agents.
D) This statement is false. Prions are not live organisms but rather misfolded proteins that can induce abnormal folding in normal proteins, leading to disease.