Q 01/05

The word 'bacterium' comes from an Ancient Greek word meaning what?

A) Staff or cane

B) Seed or grain

C) Small animal

D) Poison drop

Answer · why

A) Staff or cane

The first ones discovered were rod-shaped, hence the walking-stick image; the spherical kind got a separate word meaning 'grain'.

Q 02/05

Bacteria are prokaryotes. Which of these do their cells lack?

A) Ribosomes

B) A cell membrane

C) DNA

D) A nucleus

Answer · why

D) A nucleus

Their single circular chromosome sits in an irregular region of the cytoplasm called the nucleoid.

Q 03/05

Roughly how many bacteria are thought to exist on Earth?

A) About 2 x 10^30

B) About 2 x 10^40

C) About 2 x 10^20

D) About 2 x 10^15

Answer · why

A) About 2 x 10^30

Their combined biomass is exceeded only by that of plants.

Q 04/05

Comma-shaped or slightly curved rod bacteria are known by what name?

A) Coccus

B) Spirillum

C) Bacillus

D) Vibrio

Answer · why

D) Vibrio

The cholera bacterium is the classic vibrio; Robert Koch described it as 'a little bent, like a comma'.

Q 05/05

Staphylococci group together in clusters likened to what?

A) A bunch of grapes

B) A string of pearls

C) A pile of coins

D) A honeycomb

Answer · why

A) A bunch of grapes

The name itself comes from the Greek for 'grape-cluster berry'; streptococci, by contrast, form chains.