A woman gave birth to a stillborn baby with numerous malformations. What protozoan disease could cause intrauterine death?
- A. Toxoplasmosis
- B. Leishmaniasis
- C. Malaria
- D. Amebiasis
Correct Answer: A
Rationale: The correct answer is A: Toxoplasmosis. Toxoplasmosis is caused by the protozoan Toxoplasma gondii, which can be transmitted from mother to fetus during pregnancy leading to stillbirth and malformations. This parasite can cross the placenta and infect the fetus, causing severe complications. Leishmaniasis (B), Malaria (C), and Amebiasis (D) are not known to cause intrauterine death or malformations in the same way as Toxoplasmosis. Leishmaniasis is transmitted by sandflies, Malaria by mosquitoes, and Amebiasis by contaminated food or water.
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Which of the following methods is the simplest heat-related method to sterilize metal?
- A. Incineration
- B. Autoclaving
- C. Direct flaming
- D. Indirect heating
Correct Answer: C
Rationale: The correct answer is C: Direct flaming. Direct flaming is the simplest heat-related method to sterilize metal because it involves passing the metal through a flame to kill microorganisms. The high temperature of the flame effectively destroys any bacteria or spores present on the metal surface. Incineration (A) is not practical for sterilizing metal as it involves burning at extremely high temperatures. Autoclaving (B) uses steam under pressure to sterilize, which is effective but more complex than direct flaming. Indirect heating (D) is not an effective method for sterilizing metal as it does not directly expose the metal to high temperatures required for sterilization.
Which bacteria is commonly associated with urinary tract infections (UTIs)?
- A. Escherichia coli
- B. Clostridium botulinum
- C. Staphylococcus aureus
- D. Bacillus cereus
Correct Answer: A
Rationale: The correct answer is A: Escherichia coli. E. coli is commonly associated with UTIs due to its ability to colonize the urinary tract. It possesses adhesins that allow it to attach to the bladder wall, causing infection. E. coli is also a common inhabitant of the intestinal tract, making it easily able to migrate to the urinary system.
Explanation of incorrect choices:
B: Clostridium botulinum - This bacterium causes botulism, a rare foodborne illness, not UTIs.
C: Staphylococcus aureus - Often associated with skin infections and abscesses, not UTIs.
D: Bacillus cereus - Known for causing food poisoning, not UTIs.
Bacterial ribosomes consist mainly of:
- A. Carbohydrates
- B. Lipids
- C. DNA
- D. rRNA
Correct Answer: D
Rationale: The correct answer is D: rRNA. Bacterial ribosomes consist mainly of ribosomal RNA (rRNA), which plays a crucial role in protein synthesis. Ribosomes are composed of rRNA and proteins, with rRNA being the major component. rRNA serves as the structural and catalytic component of the ribosome, aiding in the binding of mRNA and tRNA during translation. Carbohydrates (A) and lipids (B) are not primary components of ribosomes, and DNA (C) is not found in ribosomes as they are involved in storing genetic information, not in protein synthesis.
Which scientist is most responsible for ending the controversy about spontaneous generation?
- A. John Needham
- B. Joseph Lister
- C. Louis Pasteur
- D. Robert Koch
Correct Answer: C
Rationale: The correct answer is C: Louis Pasteur. He conducted experiments that definitively disproved the theory of spontaneous generation through his famous swan-neck flask experiment. By showing that microorganisms only appeared in the broth when exposed to air, Pasteur demonstrated that they did not arise spontaneously. John Needham's experiments were inconclusive, Joseph Lister is known for his contributions to antiseptic surgery, and Robert Koch is credited with developing Koch's postulates for identifying the causative agents of diseases, but neither of them directly contributed to ending the controversy about spontaneous generation.
The papillary layer of the skin is part of the:
- A. epidermis
- B. dermis
- C. hypodermis
- D. subcutaneous layer
Correct Answer: B
Rationale: The correct answer is B: dermis. The papillary layer is located in the dermis, specifically at the junction with the epidermis. It contains capillaries, lymphatics, and sensory receptors, contributing to the skin's strength and elasticity. The epidermis (choice A) is the outermost layer of the skin, while the hypodermis (choice C) and subcutaneous layer (choice D) are deeper layers beneath the dermis, primarily composed of fat cells and connective tissue. Therefore, the papillary layer is part of the dermis, making choice B the correct answer.