Micro Organisms Questions and Answers

Answer: A

Correct answer: bacteria and fungi in the soil.

Decomposition is the work of both bacteria and fungi. Fungi are particularly good at breaking down tough materials such as cellulose and lignin, and bacteria complete the process - between them turning dead matter into humus and releasing the nutrients it contains. Viruses play no part.

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.

Answer: C

Correct answer: They are used to make yoghurt.

Yoghurt is made with bacteria - Lactobacillus and Streptococcus - not with fungi. The other three are genuine benefits: fungi produce antibiotics such as penicillin, they act as decomposers, and they are essential to cheese making.

Answer: B

Correct answer: Bacteria

Bacteria are unicellular: one cell is the whole organism. Bread mould and most fungi are multicellular, and a virus is not a cell at all.

Answer: C

Correct answer: Chickenpox

Chickenpox is caused by a virus, varicella-zoster. Bread mould, potato blight and mushrooms are all fungi or fungus-like organisms.

Answer: A

Correct answer: bacteria

Yoghurt is made with bacteria - Lactobacillus bulgaricus and Streptococcus thermophilus - which ferment lactose to lactic acid. The acid coagulates the milk protein and gives yoghurt its texture and its sharp taste.

Answer: B

Correct answer: Virus

Viruses are the smallest, typically 20-300 nanometres - far below the resolution of a light microscope, which is why they were unknown until the electron microscope. Bacteria are measured in micrometres, a thousand times larger, and fungi larger still.

Answer: C

Correct answer: Viruses cause milk to go sour faster.

Milk sours because bacteria ferment its lactose to lactic acid - viruses have nothing to do with it. The other three statements are true: warmth speeds bacterial growth, bacteria are the cause, and the souring is the acid produced.

Answer: A

Correct answer: Fungi contain chlorophyll.

Fungi have no chlorophyll and cannot photosynthesise - which is why they must absorb organic nutrients, as saprotrophs or as parasites. The absence of chlorophyll is the main reason they are no longer classed as plants at all, but placed in a kingdom of their own.

Answer: B

Correct answer: antibiotics

Antibiotics are substances produced by microorganisms - moulds and soil bacteria - that kill or inhibit other microorganisms. Penicillin from Penicillium is the type case. They act on bacterial structures such as the cell wall and the 70S ribosome, which is why they are useless against viruses.