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Photosynthesisis an important process in plants and the general balance of theenvironment. The word can be broken down into two i.e. “photo”meaning light and “synthesis” meaning putting together. Plantsrequire food but do not necessarily wait to be fed by animals orpeople. The majority of the plants make their own food. This is donewith the assistance of sunlight, and the process is referred to asphotosynthesis. This chapter will outline the definition as appliedin various organisms, importance and the process as a whole. Apartfrom outlining the process in plants, this chapter will discussartificial photosynthesis as well as photosynthesis in bacteria.

Photosynthesisin Plants


  1. Photosynthesis is the process by which organisms such as algae, some kinds of bacteria and green plants make carbohydrates from inorganic salts, waterx and carbon dioxide, with chlorophyll present, utilizing light energy, usually from the sun.

  2. A simpler definition describes photosynthesis as the process by which some organisms and plants make their own food by utilizing water, carbon dioxide and energy from the sun.

Equationfor Oxygenic Photosynthesis

Water+ Carbon Dioxide + Light energy = Glucose + Oxygen + Water

Oxygenicvs. An-oxygenic Photosynthesis

Photoautotrophsrefer to the organisms that synthesize their own foods from nonlivingmatters utilizing energy from the sun. The majority of theseorganisms taken in carbon dioxide and release oxygen. This process iscalled oxygenicphotosynthesis.

Sometypes of bacteria absorb carbon dioxide but do not produce oxygen.This process is called anoxygenicphotosynthesis.

Importanceof photosynthesis

  1. It assists in maintaining the global temperatures. Green plants take in carbon dioxide in the photosynthesis process thereby balancing the global temperatures.

  2. It is responsible for balancing the oxygen levels within the atmosphere. Oxygen which is quite vital to the human beings is a produced due to the photosynthesis process.

  3. It plays a role in the growth and development of animals and plants. Carbohydrates are derived from the process, and they are essential in the growth and development.

  4. It is crucial in maintaining life on earth. It is regarded as the vital energy source for almost all living organisms.

Generally,photosynthesis provide two essential things i.e. food and oxygen.Part of the glucose produced in the process are stores in roots andfruits. It is for this reason that people consume potatoes, carrots,water melons, and apples among others. They are a source of energyfor animals and human beings. Oxygen released due to thephotosynthesis process is what humans and animals breathe and withoutit life cannot exist. Photosynthesis is responsible for the day today survival of human beings as well as animals. It balances theoxygen and carbon dioxide concentrations within the atmosphere.

Requirementsto make food

  • Carbon dioxide

  • Water

  • Sunlight

Howthe plants collect the above necessities

  • The roots absorb water which traverses through the plant vessels to the leaves.

  • Small pores within the leaves absorb carbon dioxide form the atmosphere

  • Chlorophyll which is a green chemical within the leaves absorb light energy

Typicalconstituents of a leaf

  • Stomata – pores within the leaf involved in gaseous exchange between the atmosphere and plant leaves

  • Upper and lower epidermis – lower epidermis comprise guard cells and stomates. Upper epidermis entails outer cell layers that minimizes loss of water through transpiration.

  • Vascular bundles – comprises of phloem and xylem which transport food, dissolved minerals and water to and from the leaves.

  • Mesophyll – photosynthetic cells which are situated between the lower and upper epidermis. They contain the chloroplast.

Thephotosynthesis process

Photosynthesisoccurs within the leaves of plants. Plant leaves consist of very tinycells. Within the cells, tiny structures known as chloroplastsexist. Each of the chloroplasts contain a chlorophyll that makes theleaves look green.

Thechlorophyll takes in energy from the sun. The sun energy is then usedto breakdown water molecules to form oxygen and hydrogen. Oxygen isthen released to the air from the leaves. Carbon dioxide and hydrogenare utilized to make food or glucose for plants. A portion of theglucose is utilized as a source of energy for growth and developmentof the plants and some is stored in the fruits, leaves or roots to beused later by the plants.

Detailedlook at the process

Theprocess of photosynthesis happens in two stages usually called lightindependent reactions and light dependent reactions.

LightDependent Reactions

Lightdependent reactions takes place within the chloroplasts’ thylakoidmembrane in the presence of light. The process involves conversion oflight energy into chemical energy.

  • Chlorophyll absorbs light energy which is moved to the photosystems liable for photosynthesis.

  • Water provides the required electrons and hydrogen ions and also releases oxygen.

  • The hydrogen ions and electrons are then used to develop an energy storage molecule known as ATP, and electron donor/carrier molecule called NADPH. NADPH and ATP are then utilized in the next photosynthesis stage.

LightIndependent Reactions

Thelight independent reactions takes place within the chloroplasts’stroma. The process does not need sunlight. However, both NADPH andATP formed during the previous stage are required in this process.Energy from ATP together with NADPH and carbon dioxide combine toform glucose.


&quotPhotosynthesis Education.&quot n.d. Photosynthesis Education.