Photosynthesis

It is a type of condensation reaction, in which, monomers join together into polymers, while losing water molecules. This process is carried out, by losing from one of the monomers and (H) from another monomer. The two unstable monomers join together, and they combine forming water. When small organic sugar molecules are chemically joined, a water molecule must be removed.

Chromatiaceae is a family of purple sulphur bacteria. e.g. Chromatium. These are short, Gram-negative rods, ~1 µm in diameter and 3-4 µm long. They are able to use sulphur and sulphide, as the sole photosynthetic electron donor and sulphur can be oxidized to sulphate. These bacteria use an inorganic sulphur compound, such as, hydrogen sulfide, as an electron donor.

Only the light reactions of photosystem I and II are light dependent.

The amount of water available will affect the rate of photosynthesis because if the plants do not have enough water, stomata will be shut and plants will be deprived of carbon dioxide.

Only the autotrophs can perform photophosphorylation. It means electrons once emitted from photsystem 1(P 700) returns back to it after passing through a series of electron carriers, in an electron transport system. A P700 molecule is a pigment, which can absorb the sunlight of wavelength, around 700 nanometer.

Frederick Frost Blackman proposed the law of limiting factors. A process is contingent on a variety of factors, like the rate is limited by the speed of the slowest factors. This minimum value is the optimum value, which indicates the highest rate and a maximum value above which no photosynthesis can occur.

Cyclic photophosphorylation was the term,  named by the scientist Arnon. The synthesis of ATP from ADP during light reaction of photosynthesis,  is called photophosphorylation.

A granum (plural grana) is a stack of thylakoid discs. Chloroplasts can have from 10 to 100 grana. Grana are connected by stroma thylakoids, also called intergrana thylakoids or lamellae.

Chlorophyll is the molecule that traps this 'most elusive of all powers' - and is called a photoreceptor. It is found in the chloroplasts of green plants, and this is what makes,  green plants, green. The basic structure of a chlorophyll molecule is a porphyrin ring, co-ordinated to a central atom, Mg. This is very similar in structure to the heme group found in hemoglobin, except that in heme, the central atom is iron, whereas in chlorophyll,  it is magnesium.

Meristematic cells give rise to all three fundamental mature cell types. Their major function is cell division, and so their cell cycle indeed cycles. The walls are thin, the vacuole is largely missing, the plastids are immature, etc.

These cells are hard and brittle. The cells develop an extensive secondary cell wall (laid down on the inside of the primary wall). This wall is invested with lignin, making it extremely hard. Lignin, plus suberin and/or cutin, make the wall waterproof as well.

Functions for sclerenchyma cells,  include discouraging herbivory and conduction.  Sclerenchyma includes the fibers used for making thread and fabric, particularly the fibers from flax,  that are spun and woven into linen.

This is a single layer of cells containing few or no chloroplasts. The cells are quite transparent and permit most of the light that strikes them,  to pass through, to the underlying cells. The upper surface is covered with a waxy, waterproof cuticle, which serves to reduce water loss,  from the leaf.

An organic compound is any member of a large class of chemical compounds, whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic and CO₂ acts as an inorganic source of carbon, for organic compounds.

The absorbed energy is used in splitting the water molecule, into the two components (Hydrogen and Oxygen) and releasing electrons. The free molecular oxygen is given out as a by-product and the energy of electrons, is used to add one inorganic phosphate to ADP to form ATP whereas, the H⁺ ions are picked by NADP⁺ which is reduced to NADPH.

Chlorophyll, the green pigment common to all photosynthetic cells, absorbs all wavelengths of visible light, except green, which it reflects, to be detected by our eyes.

The hydrogen ions also called protons, are made available by splitting up of water. Non-cyclic photophosphorylation needs a constant supply of water molecules. The net result of non-cyclic phosphorylation is the formation of oxygen, NADPH and ATP molecules. Oxygen is produced, as a waste product of photosynthesis.

Carbon dioxide, either in the atmosphere or in solution in surface waters, is the major source of carbon for living organisms. It is converted to organic form, by the autotrophs, which use it as sole carbon source. The most important in this conversion, are the photosynthetic autotrophs (seed plants on land and algae in water) that carry out oxygen producing type of photosynthesis.

Photosynthetic phosphorylation or photophosphorylation is the process of phosphate group transfer into ADP to synthesize energy rich ATP molecule making use of light, as external energy source. Down flow of protons from high to low concentration along H⁺ conc. gradient through ATPase complex, provides the energy that allows an ATP synthase enzyme, to produce ATP from ADP + Pi

The material within the chloroplast, is called the stroma. It contains one or more molecules of small circular DNA. It also contains ribosomes, however most of its proteins, are encoded by genes contained in the host cell nucleus, with the protein products, transported to the chloroplast. The enzymes necessary for carbon fixation, occur in the stroma of the chloroplast.

Green light is the least useful to photosynthesis. The best evidence for this, is that most plants appear green under white light. The green light is either reflected from the plant or passes through, allowing us, to see it. The other colours present in the white light, are absorbed.

Photosynthetic phosphorylation or photophosphorylation is the process of phosphate group transfer into ADP to synthesize energy rich ATP molecule making use of light, as external energy source. Down flow of protons from high to low concentration along H⁺ conc. gradient through ATPase complex provides the energy, that allows an ATP synthase enzyme, to produce ATP from ADP + Pi

The energy released in chemical reactions is known as chemical energy. Energy can also be stored in matter as chemical energy which depends on how the particles of matter are arranged. Therefore, chemical energy depends on the positions of objects and is a form of potential energy.

Ingen-Housz was a Dutch physiologist, biologist and chemist. He is best known for showing that light is essential to photosynthesis and thus having discovered photosynthesis. He also discovered that plants, like animals have cellular respiration.

Oxygen and carbon dioxide enter and leave the cell via simple diffusion. Water enters and leaves via osmosis. During the day the leaf takes in carbon dioxide and releases oxygen and water vapour. Since it is also using energy, it will also give off small amounts of carbon dioxide. At night, it is not carrying on photosynthesis, so the oxygen and water vapour, are not being given off. The carbon dioxide that is being produced by respiration, is used in the dark reactions making sugar. Living cells need ATP to carry on active transport. Using energy, ions and small molecules may be pumped into or out of a cell, even against a concentration gradient.