Nokea
Which of the following is an example of a commensal relationship between a microorganism and a human?
- A. Salmonella causing food poisoning
- B. taphylococcus aureus causing skin infections
- C. coli living in the gut
- D. Rabies virus causing neurological disease
Correct Answer: C
Rationale: A commensal relationship is a type of symbiotic relationship in which one organism benefits, while the other is neither harmed nor benefited. In this case, E. coli living in the gut is an example of a commensal relationship because it can benefit from the environment in the gut without causing harm to the human host.
Option A, Salmonella causing food poisoning, is an example of a pathogenic relationship where the microorganism causes harm to the host. Option B, Staphylococcus aureus causing skin infections, is also an example of a pathogenic relationship where the microorganism causes harm to the host. Option D, Rabies virus causing neurological disease, is another example of a pathogenic relationship where the microorganism causes harm to the host.
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What are glands that release hormones directly into the bloodstream without ducts called?
- A. Exocrine glands
- B. Endocrine glands
- C. Apocrine glands
- D. Merocrine glands
Correct Answer: B
Rationale: Endocrine glands release hormones directly into the bloodstream without the use of ducts. This allows the hormones to be distributed throughout the body to target organs or tissues. Exocrine glands, on the contrary, release their secretions through ducts to the external environment or onto a surface, such as sweat glands. Apocrine and merocrine glands are both types of exocrine glands that release their secretions through different mechanisms. Apocrine glands release their secretions along with portions of the cell itself, while merocrine glands release their secretions through exocytosis without loss of cellular material.
What happens to the frequency of a wave when its wavelength is doubled, assuming the speed remains constant?
- A. Frequency remains the same.
- B. Frequency is halved.
- C. Frequency is doubled.
- D. Frequency information is insufficient to determine.
Correct Answer: B
Rationale: When the wavelength of a wave is doubled, and the speed of the wave remains constant, the frequency of the wave is halved. This relationship is governed by the equation speed = frequency x wavelength. Therefore, if the wavelength is doubled while the speed remains constant, the frequency must be halved to maintain a constant speed. Choice A is incorrect because frequency and wavelength are inversely proportional when speed is constant. Choice C is incorrect as doubling the wavelength does not result in a doubled frequency. Choice D is incorrect as the relationship between frequency, wavelength, and speed can be determined using the given information.
What type of energy is stored in food?
- A. Mechanical energy
- B. Kinetic energy
- C. Chemical potential energy
- D. Thermal energy
Correct Answer: C
Rationale: Food stores energy in the form of chemical potential energy. This energy is released during digestion and metabolism to provide the body with the energy it needs to function. It is derived from the bonds within the molecules of food, such as carbohydrates, fats, and proteins. Choice A, mechanical energy, is incorrect as food does not store energy in the form of mechanical energy. Choice B, kinetic energy, is incorrect as kinetic energy is associated with the motion of objects, not stored in food. Choice D, thermal energy, is incorrect as thermal energy relates to heat energy, which is not the primary form of energy stored in food.
What element is responsible for the red color of blood?
- A. Magnesium
- B. Iron
- C. Copper
- D. Zinc
Correct Answer: B
Rationale: The correct answer is B: Iron. Hemoglobin, the protein responsible for carrying oxygen in red blood cells, contains iron in its heme group, contributing to the blood's characteristic red color. Magnesium (choice A), copper (choice C), and zinc (choice D) are not responsible for the red color of blood. Magnesium is an essential mineral involved in various physiological processes, copper is a trace element important for enzyme function, and zinc is a micronutrient essential for multiple cellular functions but not related to the red color of blood.
Which type of RNA carries the genetic code from DNA to ribosomes?
- A. Ribosomal RNA (rRNA)
- B. Transfer RNA (tRNA)
- C. Messenger RNA (mRNA)
- D. Deoxyribonucleic acid (DNA)
Correct Answer: C
Rationale: - Messenger RNA (mRNA) carries the genetic information from DNA in the cell's nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs.
- Ribosomal RNA (rRNA) is a component of the ribosomes where protein synthesis takes place.
- Transfer RNA (tRNA) is responsible for bringing amino acids to the ribosomes during protein synthesis.
- Deoxyribonucleic acid (DNA) is the genetic material that contains the instructions for building and maintaining an organism. DNA is transcribed into mRNA before being translated into proteins.