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The source of electrons for photosynthesis in green plants and cyanobacteria is water. Two water molecules are oxidized by the energy of four successive charge-separation reactions of photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions.
Sieve elements are very rich in sugars and various organic molecules. Plants don't want to lose these sugars when the sieve elements get damaged, as the molecules are a very large energy investment. The plants have both short-term and long-term mechanisms to prevent sieve element sap loss. [2]
Freezing temperatures induce dehydrative stress on plants, as water absorption in the root and water transport in the plant decreases. [2] Water in and between cells in the plant freezes and expands, causing tissue damage. Cold hardening is a process in which a plant undergoes physiological changes to avoid, or mitigate cellular injuries caused ...
Photosystem II (of cyanobacteria and green plants) is composed of around 20 subunits (depending on the organism) as well as other accessory, light-harvesting proteins. Each photosystem II contains at least 99 cofactors: 35 chlorophyll a, 12 beta-carotene , two pheophytin , two plastoquinone , two heme , one bicarbonate, 20 lipids, the Mn
Cyanobacteria (blue-green algae) bloom on Lake Erie (United States) in 2009. These kinds of algae can cause harmful algal bloom. A harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, water deoxygenation, mechanical damage to other organisms, or by other means.
The rhizosphere is the thin area of soil immediately surrounding the root system. It is a densely populated area in which the roots compete with invading root systems of neighboring plant species for space, water, and mineral nutrients as well as form positive and negative relationships with soil-borne microorganisms such as bacteria, fungi and insects.
However, the reason for CAM in aquatic plants is not due to a lack of available water, but a limited supply of CO 2. [15] CO 2 is limited due to slow diffusion in water, 10000x slower than in air. The problem is especially acute under acid pH, where the only inorganic carbon species present is CO 2 , with no available bicarbonate or carbonate ...
In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in a maximum overall photosynthetic efficiency of 3 to 6% of total solar radiation. [1]