When is o2 produced in photosynthesis

During the light, provided the rate of photosynthesis is sufficiently high, plants, give out oxygen. The overall reaction for photosynthesis as given above is a simplification. Photosynthesis involves several different chemical reactions, but these can be summarised in two main stages.

In the first reaction, energy is used to split water molecules into hydrogen and oxygen. The hydrogen is needed for the second stage of reactions and the oxygen is released by the plant as a waste product. In the reactions of the second stage, the hydrogen is combined with carbon dioxide to make glucose.

Some of the glucose produced by photosynthesis is used for respiration. Glucose is the starting point for the biosynthesis of materials that plants need to live. The glucose not used for respiration is used in the following ways:. Ultimately, oxygen is produced along with carbohydrates. Oxygenic photosynthesis functions as a counterbalance to respiration by taking in the carbon dioxide produced by all breathing organisms and reintroducing oxygen to the atmosphere.

On the other hand, anoxygenic photosynthesis uses electron donors other than water. The process typically occurs in bacteria such as purple bacteria and green sulfur bacteria , which are primarily found in various aquatic habitats. For example, many bacteria use the bad-eggs-smelling gas hydrogen sulfide, producing solid sulfur as a byproduct. Though both types of photosynthesis are complex, multistep affairs, the overall process can be neatly summarized as a chemical equation.

Here, six molecules of carbon dioxide CO 2 combine with 12 molecules of water H 2 O using light energy. The end result is the formation of a single carbohydrate molecule C 6 H 12 O 6 , or glucose along with six molecules each of breathable oxygen and water. Similarly, the various anoxygenic photosynthesis reactions can be represented as a single generalized formula:.

The letter A in the equation is a variable and H 2 A represents the potential electron donor. Pigments are molecules that bestow color on plants , algae and bacteria, but they are also responsible for effectively trapping sunlight.

Pigments of different colors absorb different wavelengths of light. Below are the three main groups. Photosynthetic eukaryotic organisms contain organelles called plastids in their cytoplasm. The double-membraned plastids in plants and algae are referred to as primary plastids, while the multiple-membraned variety found in plankton are called secondary plastids, according to an articlein the journal Nature Education by Cheong Xin Chan and Debashish Bhattacharya, researchers at Rutgers University in New Jersey.

Plastids generally contain pigments or can store nutrients. Colorless and nonpigmented leucoplasts store fats and starch, while chromoplasts contain carotenoids and chloroplasts contain chlorophyll, as explained in Geoffrey Cooper's book, " The Cell: A Molecular Approach " Sinauer Associates, Photosynthesis occurs in the chloroplasts; specifically, in the grana and stroma regions. The grana is the innermost portion of the organelle; a collection of disc-shaped membranes, stacked into columns like plates.

The individual discs are called thylakoids. Consequently, they provide an abundance of energy for other organisms. Plants exist in a wide variety of shapes and sizes.

A Coleochaete orbicularis Charophyceae gametophyte; magnification x 75 photograph courtesy of L. B Chara Charophyceae gametophyte; magnification x 1. C Riccia liverwort gametophyte showing sporangia black embedded in the thallus; magnification x 5 photograph courtesy of A. D Anthoceros hornwort gametophyte showing unbranched sporophytes; magnification x 2. E Mnium moss gametophyte showing unbranched sporophytes with terminal sporangia capsule ; magnification x 4. F Huperzia clubmoss sporophyte with leaves showing sessile yellow sporangia; magnification x 0.

G Dicranopteris fern sporophyte showing leaves with circinate vernation; magnification x 0. H Psilotum whisk fern sporophyte with reduced leaves and spherical synangia three fused sporangia ; magnification x 0. I Equisetum horsetail sporophyte with whorled branches, reduced leaves, and a terminal cone; magnification x 0.

J Cycas seed plant sporophyte showing leaves and terminal cone with seeds; magnification x 0. Origin of land plants. New York: J. Wiley and Sons, All rights reserved. Part B: courtesy of M. Feist, University of Montpellier. Coleochaete orbicularis. Both the gametophyte and the background are bright green. The gametophyte has an irregular circular shape and a scalloped edge.

It is divided into many box-like segments cells , each with a visible, round nucleus inside. Panel b shows a Chara gametophyte. The organism has branching, tendril-like leaves reaching from a primary stalk.

The green leaves are punctuated with small, round, yellow structures. A green liverwort gametophyte, In panel c, is protruding from the soil. Its four primary stems each diverge into two halves and then branch again at their termini, so that each has a forked end.

Panel d shows a hornwort gametophyte. Each green stem resembles a single blade of grass. Panel e shows moss gametophytes with sporophytes protruding from the ground. The gametophytes have small green leaves, and the sporophytes are thin, unbranched, brown stalks. Each sporophyte has a fluorescent orange, oviform capsule called a sporangia perched on top of its stalk. Panel f shows six clubmoss sporophytes emanating from the ground. Some stand vertically out of the soil, and some curve or have fallen horizontally.

They have many stiff, protruding, spine-like, green leaves. The sporangia are small yellow balls at the base of the leaves. Panel g shows fern sporophytes with many stems covered with small, elongated, symmetrical green leaves.

Panel h shows a whisk fern sporophyte with long, straight, green stems beaded with yellow, round synangia along their lengths. In panel i, a horsetail sporophyte is shown. It has a single long stem, which is surrounded by a skirt of green leaves at its base and an elongated, yellow cone at the top. In Panel j, a large Cycas seed plant sporophyte is shown. Long fronds emanate upwards from the plant's trunk, and in the center of them there is a large mass called the cone. Panel a is a photomicrograph of a gametophyte of a microscopic green alga called Coleochaete orbicularis.

Most living things depend on photosynthetic cells to manufacture the complex organic molecules they require as a source of energy. Photosynthetic cells are quite diverse and include cells found in green plants, phytoplankton, and cyanobacteria. During the process of photosynthesis, cells use carbon dioxide and energy from the Sun to make sugar molecules and oxygen.

These sugar molecules are the basis for more complex molecules made by the photosynthetic cell, such as glucose. Then, via respiration processes, cells use oxygen and glucose to synthesize energy-rich carrier molecules, such as ATP, and carbon dioxide is produced as a waste product.

Therefore, the synthesis of glucose and its breakdown by cells are opposing processes. Figure 2 2 in the sky represents the process of photosynthesis.