Which bacterium helps in the setting of curd?
Answer: B
Correct answer: Lactobacillus
Lactobacillus ferments the lactose in milk to lactic acid. The acid lowers the pH until the milk protein casein coagulates, which is what sets the curd - and the acid also preserves it, by excluding other organisms.
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Penicillium, from which an antibiotic is obtained, is a type of -
Answer: D
Correct answer: Fungus
Penicillium is a mould, that is a filamentous fungus. Fleming noticed in 1928 that a colony of it contaminating a plate had killed the bacteria around it, and penicillin was the result.
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Which of the following diseases is caused by a bacteria?
Answer: B
Correct answer: Tuberculosis
Tuberculosis is caused by Mycobacterium tuberculosis. Chicken pox and polio are viral, and dengue is a virus carried by Aedes mosquitoes.
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The disease caused by fungi is
Answer: D
Correct answer: ringworm
Ringworm is a fungal infection of the skin - despite the name, no worm is involved; the ring is the advancing edge of the fungus. Measles, chicken pox and polio are all viral.
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The largest type of microorganism is a
Answer: D
Correct answer: fungus
Fungi are the largest of the microorganisms - many are multicellular, and their mycelia can extend for metres, though the individual structures need a microscope. Bacteria are a few micrometres across and viruses smaller still, measured in nanometres.
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The Baltimore system is used to classify
Answer: A
Correct answer: Viruses
The Baltimore system classifies viruses into seven groups by the nature of their genome - DNA or RNA, single or double stranded, and the sense of it - because that determines how each must produce its mRNA. David Baltimore devised it in 1971, and it cuts across the older classification by host and shape.
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The pores in bread are due to gas bubbles of
Answer: D
Correct answer: Carbon dioxide
Yeast ferments the sugars in the dough and releases carbon dioxide, which is trapped as bubbles by the gluten. Baking sets the structure around them, leaving the pores - and driving off the alcohol produced alongside.
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Which of the following does not have the capacity to reproduce outside the host cell?
Answer: D
Correct answer: Virus
A virus has no ribosomes and no metabolism, so it can only replicate inside a living host cell, using the host’s machinery. Bacteria, fungi and algae are complete cells and multiply on their own.
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Tetanus, pneumonia and tooth decay are examples of
Answer: C
Correct answer: bacterial diseases
All three are caused by bacteria: tetanus by Clostridium tetani, pneumonia commonly by Streptococcus pneumoniae, and tooth decay by Streptococcus mutans acting on sugars. Being bacterial, all three can be treated with antibiotics - and tetanus and pneumonia can be vaccinated against.
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Viruses are not considered living because they do not have all of the seven characteristics of living things. Which one of these characteristics do viruses have?
Answer: D
Correct answer: Reproduction
Of the seven characteristics of life, a virus shows only reproduction - and even that only inside a host cell, using the host’s machinery. It does not grow, move, feed, respire, excrete or respond to stimuli, which is why viruses sit on the border of the living and the non-living.
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