Nokea
Which of the following nucleic acids carries the genetic information copied from DNA to the ribosomes?
- A. DNA
- B. mRNA
- C. rRNA
- D. tRNA
Correct Answer: B
Rationale: The correct answer is B: mRNA. Messenger RNA (mRNA) is responsible for carrying the genetic information copied from DNA to the ribosomes for protein synthesis. mRNA serves as a temporary copy of the genetic instructions stored in DNA and acts as a messenger between the nucleus and ribosomes in the cytoplasm where protein synthesis occurs. While rRNA (ribosomal RNA) and tRNA (transfer RNA) play essential roles in the process of translation at the ribosomes, mRNA is the nucleic acid directly involved in carrying the genetic code for protein synthesis. Therefore, choices A, C, and D are incorrect as DNA is the original genetic material, rRNA is a component of the ribosomes, and tRNA carries amino acids during protein synthesis, respectively.
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What is the role of hemoglobin in red blood cells?
- A. To carry carbon dioxide to the lungs
- B. To carry oxygen from the lungs to the body
- C. To regulate blood pressure
- D. To produce white blood cells
Correct Answer: B
Rationale: Hemoglobin in red blood cells functions to carry oxygen from the lungs to tissues in the body. It binds to oxygen in the lungs and releases it to the body's cells, ensuring they have an adequate oxygen supply for metabolic processes. Choice A is incorrect because hemoglobin primarily carries oxygen, not carbon dioxide. Choice C is incorrect because hemoglobin's role is not related to blood pressure regulation. Choice D is incorrect because hemoglobin is not involved in the production of white blood cells.
Which system's primary function is protection, sensory reception, thermoregulation, osmoregulation, insulation, and vitamin D absorption?
- A. Nervous system
- B. Integumentary system
- C. Endocrine system
- D. Digestive system
Correct Answer: B
Rationale: The correct answer is the Integumentary system (Option B). The integumentary system, which includes the skin, hair, nails, and glands, serves various functions such as providing protection against external factors, sensory reception, regulating body temperature (thermoregulation), maintaining water balance (osmoregulation), insulating the body, and absorbing vitamin D from sunlight. The nervous system (Option A) is responsible for transmitting signals throughout the body. The endocrine system (Option C) produces and secretes hormones to regulate bodily functions. The digestive system (Option D) is involved in breaking down food for nutrient absorption. Therefore, the primary functions described in the question align with those of the integumentary system, making it the correct choice.
Find the lowest coefficients that will balance the following combustion equation: __C H + __O2 → __CO2 + __H2O
- A. 1:5:5:2
- B. 4:10:20:8
- C. 2:9:10:4
- D. 2:5:10:4
Correct Answer: C
Rationale: To balance the combustion equation CxHy + O2 → xCO2 + y/2 H2O, we need to balance the carbon and hydrogen atoms. The balanced equation for the given combustion is: 2C H4 + 9O2 → 2CO2 + 4H2O. This means that the correct coefficients are 2:9:10:4, which corresponds to choice C. Choice A (1:5:5:2) does not balance the equation correctly, choice B (4:10:20:8) has excessive oxygen and does not balance the equation, and choice D (2:5:10:4) does not provide the correct ratio of oxygen to balance the equation.
Which feedback loops are less common and sometimes harmful because they enhance stimuli rather than inhibit them?
- A. Negative feedback loop
- B. Positive feedback loop
- C. Inhibitory feedback loop
- D. Stimulating feedback loop
Correct Answer: B
Rationale: Correct. Positive feedback loops enhance or amplify changes, which can sometimes be harmful as they drive processes further from equilibrium. In contrast, negative feedback loops work to counteract deviations from a set point, promoting stability. Choice A, 'Negative feedback loop,' is incorrect because negative feedback loops inhibit or reduce changes, promoting stability. Choice C, 'Inhibitory feedback loop,' is incorrect as it is synonymous with negative feedback loops. Choice D, 'Stimulating feedback loop,' is incorrect as it inaccurately describes the nature of positive feedback loops.
Which of the following describes a typical gas?
- A. Indefinite shape and indefinite volume
- B. Indefinite shape and definite volume
- C. Definite shape and definite volume
- D. Definite shape and indefinite volume
Correct Answer: B
Rationale: The correct answer is B: 'Indefinite shape and definite volume.' A gas does not have a definite shape as it takes the shape of its container, conforming to its surroundings. However, a gas does have a definite volume because it fills the entire volume of the container it occupies. This characteristic allows gases to expand to fill the available space provided by the container, while their volume remains constant within that container. Choice A is incorrect because gases do not have an indefinite volume but rather a definite volume. Choice C is incorrect as gases do not have a definite shape but take the shape of their container. Choice D is incorrect as gases do not have a definite shape and their volume is definite, not indefinite.