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Leaving Cert Biology: Photosynthesis

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

HL Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

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

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

Photosynthesis, Higher Level(6 marks)

Quick ones on Photosynthesis.

(a)Splitting of water by light?
  1. Hydrolysis
  2. Photolysis
  3. Glycolysis
(b)Source of the oxygen released in photosynthesis?
  1. Glucose
  2. Carbon dioxide
  3. Water
(c)Colour of light least absorbed by chlorophyll?
  1. Green
  2. Blue
  3. Red
Show the answers

(a) Photolysis

(b) Water

(c) Green

Your turn: Higher Level questions on Photosynthesis.

Higher Level

Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q11
2025Q13
2024Q13
2023Q7
2022Q9, Q14
2021Q13
2019Q12
2018Q8
2017Q13
2016Q11

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

More Photosynthesis questions

Photosynthesis, 2 marks

Where in the chloroplast do the light-dependent reactions happen?

  1. The stroma (chloroplast fluid)
  2. Outer chloroplast membrane
  3. Thylakoid membranes (grana)
Show the answer

Thylakoid membranes (grana)

Chlorophyll and the electron transport chain sit in the thylakoid membranes, stacked into grana. The light-independent reactions happen in the stroma around them.

Photosynthesis, 2 marks

Where in the chloroplast do the light-independent reactions happen?

  1. Cristae
  2. Stroma
  3. Grana
Show the answer

Stroma

The stroma holds the enzymes that use ATP and NADPH to turn CO2 into glucose. Cristae belong to mitochondria, not chloroplasts.

Photosynthesis, 2 marks

Electron carrier made in the light-dependent reactions?

  1. NADPH
  2. NADH
  3. ATP
Show the answer

NADPH

NADP+ picks up electrons and a proton to become NADPH. NADPH carries them to the light-independent reactions to reduce CO2. NADH is the carrier in respiration.

Ordinary Level

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

Every paper, year by year

YearWhere it came up
2026Q13
2025Q13
2024Q12
2023Q13
2022Q14
2021Q17
2019Q7
2018Q13
2017Q14
2016Q13

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

More Photosynthesis questions

Photosynthesis, 2 marks

What are the raw materials for photosynthesis?

  1. Glucose and oxygen
  2. Glucose and water
  3. Carbon dioxide and water
Show the answer

Carbon dioxide and water

Word equation: carbon dioxide plus water, using light energy, gives glucose plus oxygen. Glucose and oxygen are the products, not the raw materials.

Photosynthesis, 2 marks

What are the products of photosynthesis?

  1. Starch and nitrogen
  2. Glucose and oxygen
  3. Carbon dioxide and water
Show the answer

Glucose and oxygen

The plant keeps the glucose as food and releases the oxygen as a waste gas through the stomata.

Photosynthesis, 2 marks

What supplies the energy for photosynthesis?

  1. Light energy from the sun
  2. Heat from the soil
  3. Energy from minerals
Show the answer

Light energy from the sun

Light energy is trapped by chlorophyll and converted into the chemical energy stored in glucose.

Other Biology topics

All of Leaving Cert Biology