Tooth decay is caused by sugars.
What feeds on sugars in the mouth to cause tooth decay?
Answer: B
Correct answer: Bacteria
Streptococcus mutans and related bacteria in dental plaque ferment sugars from food and produce acid, and it is the acid that dissolves the enamel. Sugar alone would do nothing without them, which is why brushing - removing the plaque - matters as much as avoiding sweets.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
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.
Please log in or register to report this question.
