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Leaving Cert Biology: Bacteria

How often Bacteria comes up on the Biology papers, every year it was asked, and questions to try.

HL Asked on 6 of the last 10 Higher Level papers, most recently in 2025. most years

OL Asked on 8 of the last 10 Ordinary Level papers, most recently in 2026. most years

June 2027 is the first exam on the new Biology course. These come from the 2016–2026 papers, so read them as a guide.

Bacteria, Higher Level(6 marks)

Quick ones on Bacteria.

(a)How do bacteria reproduce?
  1. Budding
  2. Binary fission
  3. Meiosis
(b)Name for rod-shaped bacteria?
  1. Spirilla
  2. Cocci
  3. Bacilli
(c)Tough resistant structure formed by some bacteria?
  1. Endospore
  2. Sporangium
  3. Zygospore
Show the answers

(a) Binary fission

(b) Bacilli

(c) Endospore

Your turn: Higher Level questions on Bacteria.

Higher Level

Asked on 6 of the last 10 Higher Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2026Not asked
2025Q5
2024Q14
2023Q5
2022Q11
2021Not asked
2019Not asked
2018Q15
2017Q4
2016Not asked

Links open the State Examinations Commission’s paper for that year.

More Bacteria questions

Bacteria, 2 marks

Organism that can respire with or without oxygen?

  1. Obligate anaerobe
  2. Obligate aerobe
  3. Facultative anaerobe
Show the answer

Facultative anaerobe

'Facultative' means optional. E.g. yeast respires aerobically when oxygen is present and ferments when it isn't.

Bacteria, 2 marks

Bacterial structure used for movement?

  1. Plasmid
  2. Flagellum
  3. Capsule
Show the answer

Flagellum

A whip-like tail that rotates to push the bacterium through liquid. Not all bacteria have one.

Bacteria, 2 marks

Why are agar plates incubated upside down?

  1. To stop condensation dripping onto the agar
  2. To let light reach the colonies from below
  3. To let air in underneath the lid of the plate
Show the answer

To stop condensation dripping onto the agar

Drops of water falling on the agar would spread colonies into each other and spoil the results.

Ordinary Level

Asked on 8 of the last 10 Ordinary Level papers, most recently in 2026. most years

Every paper, year by year

YearWhere it came up
2026Q6
2025Q16
2024Q14
2023Q17
2022Q16
2021Q17
2019Q14
2018Not asked
2017Not asked
2016Q12

Links open the State Examinations Commission’s paper for that year.

More Bacteria questions

Bacteria, 2 marks

Which structure do bacterial cells not have?

  1. A cell wall
  2. Cytoplasm
  3. A nucleus
Show the answer

A nucleus

Bacteria are prokaryotic: their DNA lies loose in the cytoplasm. They do have a cell wall and a cell membrane.

Bacteria, 3 marks

What name is given to a round-shaped bacterium?

  1. A spirillum
  2. A coccus
  3. A bacillus
Show the answer

A coccus

Coccus is a ball, bacillus is a rod and spirillum is a spiral. Bacteria are classified by these shapes.

Bacteria, 3 marks

How do bacteria reproduce asexually?

  1. By binary fission
  2. By budding
  3. By producing seeds
Show the answer

By binary fission

Binary fission means splitting in two. In good conditions a bacterium can divide every twenty minutes.

Other Biology topics

All of Leaving Cert Biology