The Calvin cycle is a part of photosynthesis, the process plants and other autotrophs use to create nutrients from sunlight and carbon dioxide. The process was first identified by American biochemist Dr. Melvin Calvin in 1957.

Illustration by Tim Gunther

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  • The Calvin cycle is a process that plants and algae use to turn carbon dioxide from the air into sugar, the food autotrophs need to grow.

    Every living thing on Earth depends on the Calvin cycle. Plants depend on the Calvin cycle for energy and food. Other organisms, including herbivores, also depend on it indirectly because they depend on plants for food. Even organisms that eat other organisms, such as carnivores, depend on the Calvin cycle. Without it, they wouldn't have the food, energy, and nutrients they need to survive.

    The Calvin cycle has four main steps: carbon fixation, reduction phase, carbohydrate formation, and regeneration phase. Energy to fuel chemical reactions in this sugar-generating process is provided by ATP and NADPH, chemical compounds which contain the energy plants have captured from sunlight.

  • Term Part of Speech Definition Encyclopedic Entry
    air Noun

    layer of gases surrounding Earth.

    Encyclopedic Entry: air
    algae Plural Noun

    (singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

    ATP Noun

    (adenosine triphosphate) chemical found in most living cells and used for energy.

    autotroph Noun

    organism that can produce its own food and nutrients from chemicals in the atmosphere, usually through photosynthesis or chemosynthesis.

    Encyclopedic Entry: autotroph
    biochemist Noun

    person who studies the properties and reactions of chemicals in living or once-living material.

    Calvin cycle Noun

    series of reactions that take place during photosynthesis, where carbon dioxide and water from the atmosphere are converted into sugar.

    carbohydrate Noun

    type of sugar that is an important nutrient for most organisms.

    carbon dioxide Noun

    greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.

    carbon fixation Noun

    method plants use to attach carbon dioxide from the atmosphere to a chemical (RuBP) in order to start the process of photosynthesis.

    carnivore Noun

    organism that eats meat.

    Encyclopedic Entry: carnivore
    chemical reaction Noun

    process that involves a change in atoms, ions, or molecules of the substances (reagents) involved.

    energy Noun

    capacity to do work.

    food Noun

    material, usually of plant or animal origin, that living organisms use to obtain nutrients.

    Encyclopedic Entry: food
    herbivore Noun

    organism that eats mainly plants and other producers.

    Encyclopedic Entry: herbivore
    NADPH Noun

    (nicotinamide adenine dinucleotide phosphate) chemical found in most living cells and used for energy.

    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    plant Noun

    organism that produces its own food through photosynthesis and whose cells have walls.

    reduction phase Noun

    second step in the Calvin cycle of photosynthesis, where energy reacts with chemicals to create the simple sugar G3P.

    regeneration phase Noun

    fourth and final step in the Calvin cycle of photosynthesis, where energy and sugar interact to form the molecule RuBP, allowing the cycle to start again.

    sugar Noun

    type of chemical compound that is sweet-tasting and in some form essential to life.