Browse all practice questions for the Leaving Certificate Photosynthesis Practice Test. Search by topic, open any question and review its full explanation, then test yourself in the practice quiz.

Leaving Certificate Photosynthesis Practice Test 2026 - Free Photosynthesis Practice Questions and Study Guide course image
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  • What happens to the oxygen released from splitting water?
  • What term describes the nutrition of plants?
  • Which leaf layer contains more organelles for photosynthesis?
  • Which gas produced in photosynthesis is released by leaves and used by other organisms?
  • Which complex is responsible for splitting water to release oxygen in photosynthesis?
  • Why is temperature important for photosynthesis, and what happens at high temperature?
  • Which stage uses light energy to synthesize ATP and NADPH?
  • What happens to the hydrogen released when water is split?
  • Which pigment class helps protect photosystems by dissipating excess light energy as heat?
  • Why is the dark stage given the alternative name of the light-independent stage?
  • Which gas is released as a byproduct of photosynthesis?
  • What is the electron donor for PSII and the key process at PSII?
  • Where do ADP and NADP+ go after the dark stage?
  • True or False: Photosynthesis occurs in both prokaryotic and eukaryotic organisms.
  • How many CO2 molecules are required to synthesize one molecule of glucose in photosynthesis?
  • Which are the three main phases of the Calvin cycle?
  • In which pathway of the light stage is oxygen produced?
  • Why is a suitable temperature necessary for the dark stage of photosynthesis?
  • Which set of products results from the photolysis of water during photosynthesis?
  • Which organisms perform oxygenic photosynthesis?
  • What happens when stomata are opened during photosynthesis?
  • Which is a fate of the oxygen produced during photosynthesis?
  • What do the letters ATP stand for?
  • Photosynthesis occurs in which types of organisms?
  • Where does carbon dioxide enter the leaf?
  • What are the overall products of the light-dependent reactions?
  • Which statement describes a process that releases carbon dioxide into the air?
  • Which gas is essential for photosynthesis?
  • Suggest a reason why life on earth might not continue without photosynthesis.
  • Which cell organelle is primarily involved in photosynthesis?
  • Name the cell structures, present in large numbers in the upper part of the leaf that are needed for photosynthesis.
  • During photosynthesis light energy is converted into which form of energy?
  • Which provides the energy carrier for the dark stage to proceed?
  • Name a gas essential for the dark stage of photosynthesis.
  • Which pigment-containing organelle captures light energy for photosynthesis?
  • In photosynthesis, what is the role of NADP-?
  • What is photophosphorylation and how many ATP are produced per NADPH in non-cyclic flow?
  • Name the cells that control the opening of the stomata.
  • What is the role of ATP in photosynthesis?
  • Describe cyclic photophosphorylation and when it occurs.
  • In the Calvin cycle, what is the purpose of RuBP regeneration?
  • Name the group of biological catalysts which control photosynthesis.
  • What is the fate of the carbon in the carbon dioxide used in the dark stage of photosynthesis?
  • In C4 plants, what is the sequence of CO2 fixation and release?
  • Which enzyme fixes CO2 in C3 photosynthesis in the mesophyll cells?
  • Which two pathways are cited as plants’ strategies to mitigate RuBisCO inefficiency?
  • How is the proton gradient across the thylakoid membrane established for ATP synthesis?
  • Name two environmental factors on which the rate of photosynthesis depends.
  • What are the main reactants and products of the Calvin cycle?
  • What is the role of water in photosynthesis according to the material?
  • What is a key difference between the light-dependent and light-independent reactions of photosynthesis?
  • Which molecule produced in the light-dependent stage carries reducing power to the dark reactions?
  • What is the role of ATP synthase in chloroplasts?
  • What occurs when stomata close during photosynthesis?
  • Where does the Calvin cycle take place in chloroplasts?
  • Describe non-cyclic electron flow and its outputs.
  • How does light intensity affect the rate of photosynthesis?
  • What is the main source of carbon dioxide used by plants in the dark stage of photosynthesis?
  • Name the element at the centre of a chlorophyll molecule.
  • The cells in the palisade layer of a leaf contain many organelles that carry out photosynthesis. Suggest why the cells here contain more of these organelles than the cells in the mesophyll.
  • Which stage of photosynthesis captures light energy to synthesize ATP and NADPH?
  • In a leaf, where would you expect to find the greatest concentration of chlorophyll?
  • Which statement best contrasts C3 and C4 photosynthesis regarding CO2 concentration and typical habitats?
  • What is the role of ferredoxin in photosynthesis?
  • Which leaf tissue is known for having many chloroplasts to maximize light capture?
  • Which gas is produced as a byproduct of photosynthesis?
  • What gas is released during photosynthesis?
  • From which substance is oxygen produced during photosynthesis?
  • Which plant type is particularly efficient in hot and dry conditions due to CO2 concentration mechanisms?
  • What is the net product of the Calvin cycle after fixing three CO2 molecules?
  • In which cell organelle is chlorophyll found?
  • Which organelle is the site of photosynthesis?
  • What supplies energy to the dark stage of photosynthesis?
  • Which statement describes the fate of the oxygen produced during photosynthesis?
  • Which pigments contribute to photosynthesis and why is pigment diversity important?
  • To what group of biomolecules do the main products of the dark stage belong?
  • Describe CAM photosynthesis and its adaptation.
  • What is the role of NADP in photosynthesis?
  • How does CAM photosynthesis differ from C4 in terms of stomatal behavior and timing?
  • Two products of the light stage vital for the dark stage are NADPH and ATP. Which are they?
  • The Calvin cycle takes place in which part of the chloroplast?
  • What is the stoichiometry of ATP and NADPH required per CO2 fixed in the Calvin cycle?
  • Where do the light-dependent reactions occur?
  • During the reduction phase of the Calvin cycle, which statement correctly describes the fate of 3-PGA?
  • What is the relationship between the rate of photosynthesis and either the light intensity or the carbon dioxide concentration?
  • What is the chemical formula for glucose?
  • In which stage of photosynthesis is oxygen produced?
  • Why are ATP and NADPH production during the light reactions essential for the Calvin cycle?
  • What is the primary function of RuBisCO in the Calvin cycle?
  • Carbon dioxide is released from plants via which two processes?
  • Which is a fate of oxygen after production in photosynthesis?
  • What is the difference between oxygenic and anoxygenic photosynthesis?
  • Which colour of light is not absorbed by plants?
  • What is RuBP and what is its role in photosynthesis?
  • Name a structure found on stems which allow gas exchange.
  • Which observation indicates photosynthesis is occurring in aquatic plants?
  • Which statement best describes a potential benefit of having more than one chlorophyll pigment?
  • In leaf cells, which pigment traps light energy for photosynthesis?
  • How does water availability affect photosynthesis in leaves?
  • Is energy released or absorbed during photosynthesis?
  • Which factors can limit the rate of photosynthesis and how is the limiting factor determined?
  • What is the main source of energy for photosynthesis?
  • What is the primary product of the Calvin cycle used for sugar synthesis?
  • Where does the water needed for photosynthesis enter the plant?
  • Which enzyme catalyzes the initial CO2 fixation in C4 plants?
  • What supplies energy for carbohydrate synthesis in the dark stage?
  • Where is NADPH formed in the light-dependent reactions?
  • What is the main purpose of the dark stage?
  • In the Calvin cycle, which molecule is regenerated to allow continued CO2 fixation?
  • Which gas is fixed into organic molecules during photosynthesis?
  • Light energy is converted into what form during photosynthesis?
  • Which molecule leaves the Calvin cycle to be used in biosynthesis for the plant?
  • What is meant by the term photosynthesis?
  • Which molecule donates electrons and protons to CO2 during the dark stage?
  • What is photorespiration and under what conditions does it occur?
  • How does chlorophyll function in light absorption and energy transfer?
  • What is a possible product formed from carbon dioxide during photosynthesis?
  • Which organelle carries out photosynthesis in plants?
  • The dark stage is also known as which of the following?
  • The energy for photosynthesis is captured from which source?
  • What is the net chemical equation for photosynthesis using common shorthand?
  • In which stage of photosynthesis does carbon dioxide provide carbon for carbohydrate formation?
  • How many NADPH and ATP are required to fix three CO2 in the Calvin cycle?
  • Which statement best describes why light-dependent reactions are essential for photosynthesis?
  • What does ADP stand for?
  • Why must the first stage occur before the second stage in photosynthesis?
  • How many molecules of CO2 are needed to make one glucose molecule?
  • In a leaf, the region containing the most chlorophyll is the?
  • What does NAD stand for?
  • What happens to ADP and NADP+ at the end of the dark stage of photosynthesis?
  • Which equation correctly represents photosynthesis?
  • Where is NADPH formed during the light-dependent reactions?
  • Which of the following is the product formed from carbon dioxide during the dark stage of photosynthesis?
  • In which stage does ATP form?
  • In C4 photosynthesis, CO2 is fixed in mesophyll cells by which enzyme and transported to bundle-sheath cells?
  • Which statement best describes the energy change in photosynthesis?
  • Which gas from the air do plants primarily use for photosynthesis?
  • Describe the significance of RuBP regeneration in the Calvin cycle?
  • Where does the electron released from splitting water go?
  • Explain the role of carotenoids in photosynthesis beyond light absorption.
  • The oxygen produced in photosynthesis originates from which molecule?
  • Where do the light-dependent reactions occur in the chloroplast?
  • What is the role of PEP carboxylase in C4 photosynthesis?
  • How is NADPH formed in the light-dependent reactions of photosynthesis?
  • During the Calvin cycle, which step involves the reduction of 3-phosphoglycerate to glyceraldehyde-3-phosphate?
  • Besides carbon dioxide, which small molecule is needed for photosynthesis?
  • The energy used in photosynthesis is captured from which form of energy?
  • What is the source of the oxygen released during photosynthesis?
  • To boost photosynthesis in a greenhouse, which change would be effective?
  • What does the thylakoid membrane house during photosynthesis?
  • During oxygenic photosynthesis, which molecule is released as a byproduct?
  • Which enzyme catalyses the first CO2 fixation in the Calvin cycle and why is its activity significant?
  • What can cause a decrease in chlorophyll content and how does this affect photosynthesis?
  • Which component of the chloroplast is most directly involved in carbon fixation?
  • What is Hill's reaction and its purpose?
  • Which statement is true about the overall outcome of photosynthesis?
  • Which tissue transports water from roots to leaves?
  • In the second stage compounds of the general formula Cx(H2O)y are formed. What name is given to this group of compounds?
  • What substance is split into electrons, oxygen and protons during photosynthesis?
  • Which of the following would most effectively increase the rate of photosynthesis in a greenhouse?
  • Where does the Calvin cycle take place within the chloroplast?
  • What is the role of the chloroplast envelope?
  • Identify the two photosystems and their primary pigments.
  • For a pondweed experiment, how would you quantify the rate of photosynthesis?
  • What does the Hill reaction demonstrate about photosynthesis?
  • Which pigment primarily absorbs light for photosynthesis?
  • Which is true about CO2 usage for glucose synthesis?
  • Why is RuBisCO considered inefficient, and how do plants mitigate this?
  • Why are aquatic plants such as Elodea suitable for investigating photosynthesis?
  • What is the main carbohydrate produced during photosynthesis?
  • Where are chloroplasts predominantly located in the leaf to maximize photosynthesis?
  • How do leaves adapt to high light intensity to prevent photodamage?
  • Which energy carriers are produced by the light-dependent reactions and supplied to the Calvin cycle?
  • Name the two types of particle transferred from NADPH to CO2 in the dark stage of photosynthesis.
  • In what main part of a plant does most photosynthesis take place?
  • What is the energy cost to fix one CO2 into a sugar precursor in the Calvin cycle?
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