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A relationship in which two organisms benefit is referred to as __________.
- A. commensalism
- B. mutualism
- C. parasitism
- D. competition
Correct Answer: B
Rationale: The correct answer is B: mutualism. In mutualism, both organisms benefit from the relationship. This is because they provide each other with resources or services that help both parties. In contrast, commensalism (A) is a relationship where one organism benefits while the other is neither helped nor harmed. Parasitism (C) is a relationship where one organism benefits at the expense of the other. Competition (D) is a relationship where both organisms are negatively affected as they compete for limited resources. Therefore, mutualism is the correct answer as it describes a mutually beneficial relationship between two organisms.
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Which of the following organelles contain oxidative enzymes capable of oxidizing toxic substances?
- A. peroxisomes
- B. lysosomes
- C. lysosomes
- D. peroxisomes
Correct Answer: D
Rationale: The correct answer is D: peroxisomes. Peroxisomes contain oxidative enzymes, such as catalase and peroxidase, that are capable of oxidizing toxic substances. These enzymes help detoxify harmful molecules by breaking them down into harmless products. Lysosomes (choices B and C) contain hydrolytic enzymes for breaking down cellular waste, not oxidative enzymes. Therefore, the correct choice is peroxisomes due to their specific function in detoxification through oxidation reactions.
Which bacterium is known for causing food poisoning due to its production of enterotoxins?
- A. Staphylococcus aureus
- B. Clostridium botulinum
- C. Salmonella enterica
- D. Vibrio cholerae
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus. This bacterium causes food poisoning by producing enterotoxins that lead to symptoms like nausea and vomiting. Staphylococcus aureus can survive in various food items and multiply rapidly, producing toxins that are heat-stable. Clostridium botulinum causes botulism due to neurotoxins, not enterotoxins. Salmonella enterica causes gastrointestinal infections, not primarily food poisoning. Vibrio cholerae causes cholera by producing a toxin that leads to severe watery diarrhea and dehydration, not enterotoxins like Staphylococcus aureus.
Artificial active immunity occurs after a vaccination: injecting or taking antigens by mouth. Takes time for T and B cells to be activated but gives relatively long lasting:
- A. TRUE
- B. FALSE
- C. Both answers can be correct depending on the given situation
- D. None of the above
Correct Answer: A
Rationale: 1. Vaccination introduces antigens to stimulate immune response.
2. T and B cells are activated to produce memory cells for long-lasting protection.
3. Active immunity develops over time post-vaccination.
4. Choice A is correct as it accurately describes the process and outcomes.
5. Choice B is incorrect as it contradicts the process of active immunity.
6. Choice C is incorrect as the process of active immunity is consistent regardless of the situation.
7. Therefore, the correct answer is A as it aligns with the mechanism and characteristics of artificial active immunity.
The United Nations estimates that by the year 2050 more than __________ of the world’s population will live in urban areas.
- A. 35%
- B. 56%
- C. 60%
- D. 69%
Correct Answer: D
Rationale: The correct answer is D (69%). The UN projects that by 2050, around 69% of the world's population will live in urban areas. This is based on current global urbanization trends and population growth rates. Urban areas are experiencing rapid population growth due to factors like rural-to-urban migration and natural population increase. Choices A, B, and C are incorrect because they underestimate the expected urban population growth by 2050. A (35%), B (56%), and C (60%) are too low compared to the projected 69%. Urbanization is a significant global trend, and it is essential to consider the implications of this shift for sustainability, infrastructure development, and resource allocation.
All the statements about Pseudomonas aeruginosa are correct, EXCEPT:
- A. It is a Gram-negative bacterium
- B. It is oxidase-positive
- C. It is non-motile and non-spore forming
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: It is non-motile and non-spore forming. Pseudomonas aeruginosa is motile due to its flagella and is non-spore forming. A is correct because it is a Gram-negative bacterium, and B is correct as it is oxidase-positive. D is incorrect because C is not true.