Q 01/05

What do house dust mites mostly eat?

A) Loose carpet fibres

B) Dropped sugar crumbs

C) Shed pet hair

D) Flakes of human skin

Answer · why

D) Flakes of human skin

A single mite produces about 2,000 droppings in its ten-week life, and those droppings are the allergen, not the mite.

Q 02/05

Detectable dust-mite allergen was found in the beds of roughly what share of surveyed US homes?

A) 24%

B) 54%

C) 84%

D) 99%

Answer · why

C) 84%

Europe fared a little better at 68 percent; the mites simply prefer humid places.

Q 03/05

Demodex mites live in the hair follicles of your face. Roughly what share of elderly people carry them?

A) One in ten

B) One in three

C) Almost none

D) Two-thirds

Answer · why

D) Two-thirds

A small 2014 study found them on every adult tested; they eat skin cells and oil, and mate at the mouth of the follicle.

Q 04/05

What is earwax mostly made of?

A) Dried-up sweat

B) Hardened skin oil

C) Trapped dust

D) Shed skin cells

Answer · why

D) Shed skin cells

On average about 60 percent of it is keratin, the same protein as your hair and nails.

Q 05/05

There are two genetically determined types of human earwax. What are they?

A) Sweet and sour

B) Light and dark

C) Hard and soft

D) Wet and dry

Answer · why

D) Wet and dry

A single letter change in one gene decides it; the dry, flaky type is common in East Asia and among Native Americans.

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