carbon dioxideThe gas, breathed out by animals, that plants need. Its formula is CO2. It enters a leaf through the stomata, and its carbon ends up in the sugar.
chlorophyllA leaf's green dye, which catches the sun's energy. It is kept in the chloroplasts. Its name joins two Greek words, pale green and leaf.
chloroplastThe green speck inside a leaf cell where food is made. Chloroplasts are so small that 400,000 of them fit in one square millimeter of leaf.
glucoseThe plant's food, a kind of sugar. Its formula is C6H12O6. Plants use it for energy, store it, and build it into cellulose for their cell walls.
leafThe thin, wide plant part built to catch light. Most of a leaf's food-making cells lie in a layer near its upper side, where the light falls.
oxygenThe gas left over, let out through the leaf's pores. It is a byproduct, set free when the plant splits water.
photosynthesisHow a leaf turns sunshine into stored food. The word means putting together with light. Plants, algae and some bacteria do it, and it keeps up the oxygen in Earth's air.
Show all 36 terms (29 more)
Photosynthesis, continued
plantAn oak, a daisy or a blade of grass, for example. Nearly all plants make their own food from sunlight. A few have given it up and take their food from other living things.
rootThe hidden half of a plant, below the surface. Most roots grow in soil, where they anchor the plant and take in the water and nutrients it needs.
stomataLittle mouths on a leaf where air goes in and out. The singular is stoma, Greek for mouth. Two guard cells open and close each pore.
sunlightLight from the sun, which powers the whole process. Up to a point, the brighter the light, the faster a plant makes food. Each kind of plant has a brightness beyond which more light makes no difference.
waterA raw material, taken in from the soil. It travels up from the soil to the leaves through tubes called xylem. Without water, photosynthesis stops.
Light and leaves 12
anthocyaninA pigment that turns autumn leaves red or purple. Anthocyanins also color blueberries and raspberries. Their color runs from red and pink through purple to blue and black, depending on acidity.
chlorosisLeaves turning yellow for lack of chlorophyll. A plant in this state can make little or no sugar by photosynthesis.
compensation pointThe light level where sugar made equals sugar used. At this brightness a plant takes in exactly as much carbon dioxide for photosynthesis as it gives off in respiration.
deciduousBare of leaves in winter or in a dry season. Deciduous trees and shrubs usually shed their leaves in the autumn. The opposite is evergreen.
etiolationPale, spindly growth of a plant kept in the dark. The long, weak stem raises the chance that a seedling under soil or leaf litter will reach the light.
evergreenIn leaf through all four seasons. Most conifers, such as pines, are evergreen. So are hollies and live oaks.
greenhouseA see-through shelter where crops stay warm. Its clear walls and roof let sunlight in and hold in the warmth it brings.
grow lightAn electric lamp that stands in for the sun. Many give out mostly red and blue light, which looks pink or purple to the eye.
limiting factorThe scarce input that holds the rate back. Light, water and carbon dioxide can each be one. Carbon dioxide can run short in a tightly sealed greenhouse.
phototropismGrowth that bends a shoot toward a lamp or window. The cells on the shaded side of the stem grow longer, which bends it. A plant hormone called auxin is behind this.
variegationLeaves patched green and white or yellow. The pale patches hold less chlorophyll than the green ones, or none.
xanthophyllA yellow pigment found in leaves. The name is Greek for yellow leaf. Xanthophylls are one of the two main groups of carotenoids; the carotenes are the other.
The two stages 12
antenna complexPigments that gather light and pass its energy on. Also called a light-harvesting complex. Its chlorophylls and carotenoids collect more light than a reaction center could catch alone.
C4 plantA plant that first fixes CO2 into a four-carbon acid. Corn and sugarcane are C4 plants. The extra step cuts down on photorespiration.
Calvin cycleThe second stage, a loop that builds sugar. It runs in the stroma, the fluid of the chloroplast, and uses the ATP and NADPH from the first stage. Other names are the dark reactions and the light-independent reactions.
CAM plantA plant that opens its stomata only at night. It stores the night's carbon dioxide as an acid and uses it by day with its pores shut, which saves water. Nearly all cacti work this way, and so does the pineapple.
carbon fixationLocking carbon from CO2 into an organic compound. Most of it on Earth is done by photosynthesis. Some organisms do it without sunlight, by chemosynthesis.
chemiosmosisIons crossing a membrane down their gradient. Hydrogen ions pass through an enzyme, ATP synthase, and their flow drives the making of ATP.
G3PThe three-carbon sugar the cycle turns out. Short for glyceraldehyde 3-phosphate; another name is triose phosphate. The plant builds glucose and other sugars from it.
light-dependent reactionsThe first stage: light energy is caught and stored. They take place in the thylakoid membranes. Water is split, oxygen is released, and the energy is stored in ATP and NADPH.
photophosphorylationMaking ATP with the energy of light. Light energy pumps hydrogen ions across a membrane. They flow back through ATP synthase, which joins a phosphate to ADP.
photorespirationA wasteful slip: the enzyme grabs oxygen, not CO2. About a quarter of the time, the enzyme rubisco adds oxygen to RuBP, and some of the energy captured by photosynthesis is wasted.
reaction centerWhere captured light first sets an electron moving. It is a complex of proteins and pigments, and one part of a photosystem.
RuBPThe five-carbon sugar that first accepts CO2. Short for ribulose 1,5-bisphosphate. The cycle makes it again at the end of each turn, so it is never used up.
How this list was compiled: Term list chosen for this site on 2026-10-16. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Photosynthesis (its two stages, the thylakoid membranes and the stroma, the four main factors, the oxygen of the atmosphere), Plant, Sunlight, Carbon dioxide, Oxygen, Glucose, Chlorophyll, Chloroplast, Stoma, Leaf, Root, Limiting factor, Compensation point, Variegation, Phototropism, Etiolation, Chlorosis, Deciduous, Evergreen, Anthocyanin, Xanthophyll, Greenhouse, Grow light, Calvin cycle, Biological carbon fixation, Photosynthetic reaction centre, Light-harvesting complex, Chemiosmosis, Photophosphorylation, Ribulose 1,5-bisphosphate, Glyceraldehyde 3-phosphate, Photorespiration (about 25 percent of the enzyme's reactions), C4 carbon fixation (maize and sugarcane) and Crassulacean acid metabolism (the pineapple, and more than 99 percent of the species of cactus). The first set was checked a second time against Plant growth and development, a page of the Oregon State University Extension Service (EM 9901, https://extension.oregonstate.edu/catalog/em-9901-plant-growth-development): the meaning of the word, sunlight, carbon dioxide and water as the three ingredients, the equation, chloroplasts and their 400,000 to a square millimeter, chlorophyll, stomata, water moving up through the xylem, light as a limit, and the sealed greenhouse that runs short of carbon dioxide. That page says the plant splits carbon dioxide into carbon and oxygen; this list follows the Wikipedia article Photosynthesis, which says the oxygen comes from the splitting of water. Also read: What is photosynthesis? of BBC Bitesize (https://www.bbc.co.uk/bitesize/articles/zn4sv9q). The fact after each meaning is from the same pages. Licence: own work
How it works
This photosynthesis worksheet lists twelve words, among them sunlight, water, carbon dioxide, oxygen, glucose, chlorophyll and stomata, beside their meanings in mixed order. Pupils join each word to its meaning with a line. The key prints after the sheet.
Read the full guide
A photosynthesis vocabulary review worksheet in three sets
Set opens on Photosynthesis, the everyday words in plain language. The second set, Light and leaves, has limiting factor, compensation point, variegation, phototropism, etiolation, chlorosis, deciduous, evergreen, anthocyanin, xanthophyll, greenhouse and grow light.
The two stages
The third set has light-dependent reactions, Calvin cycle, carbon fixation, reaction center, antenna complex, chemiosmosis, photophosphorylation, RuBP, G3P, photorespiration, C4 plant and CAM plant.
Xylem, phloem, guard cells and the parts of a flower are words on the photosynthesis word search, not terms here.
Questions and answers
Is there a photosynthesis worksheet for 2nd grade, 3rd grade or 4th grade?
The first set serves all three: twelve everyday words, each with a meaning in plain language. The sheet itself names no grade, and Pairs cuts it to as few as four words.
What is the equation for photosynthesis?
In words: carbon dioxide + water + light energy gives glucose + oxygen. In symbols: 6CO2 + 6H2O + energy gives C6H12O6 + 6O2. Six molecules of each raw material make one molecule of glucose and six of oxygen.
Why are leaves green?
Chlorophyll takes in mainly blue and red light and reflects green, so green is what reaches the eye. In autumn the chlorophyll of many trees breaks down, and the yellow pigments it had masked all summer show through.
Can I save the photosynthesis vocabulary worksheet as a PDF?
Yes. Press Print worksheet and pick Save as PDF in the window that opens. The file has two pages, the sheet and its key.