Photosynthesis has two main parts (light-independent and light dependent). Which descriptions can BEST be used to explain photos
ystem I and photosystem II? I. Light-independent reaction II. Light-dependent reaction III. Products are ATP and NADPH. IV. Occurs in the thylakoid membranes V. Occurs in the stroma VI. Photolysis of water occurs during this stage.
The light-dependent reactions use light energy to make two molecules needed for the next stage of photosynthesis: the energy storage molecule ATP and the reduced electron carrier NADPH. In plants, the light reactions take place in the thylakoid membranes of organelles called chloroplasts. Photosystems, large complexes of proteins and pigments (light-absorbing molecules) that are optimized to harvest light, play a key role in the light reactions. There are two types of photosystems: photosystem I (PSI) and photosystem II (PSII). Both photosystems contain many pigments that help collect light energy, as well as a special pair of chlorophyll molecules found at the core (reaction center) of the photosystem. The special pair of photosystem I is called P700, while the special pair of photosystem II is called P680. In a process called non-cyclic photophosphorylation (the "standard" form of the light-dependent reactions), electrons are removed from water and passed through PSII and PSI before ending up in NADPH. This process requires light to be absorbed twice, once in each photosystem, and it makes ATP . In fact, it's called photophosphorylation because it involves using light energy (photo) to make ATP from ADP (phosphorylation). Here are the basic steps: Light absorption in PSII. When light is absorbed by one of the many pigments in photosystem II, energy is passed inward from pigment to pigment until it reaches the reaction center. There, energy is transferred to P680, boosting an electron to a high energy level. The high-energy electron is passed to an acceptor molecule and replaced with an electron from water. This splitting of water releases the O 2 O 2 start text, O, end text, start subscript, 2, end subscript we breathe. ATP synthesis. The high-energy electron travels down an electron transport chain, losing energy as it goes. Some of the released energy drives pumping of H + H + start text, H, end text, start superscript, plus, end superscript ions from the stroma into the thylakoid interior, building a gradient. ( H + H + start text, H, end text, start superscript, plus, end superscript ions from the splitting of water also add to the gradient.) As H + H + start text, H, end text, start superscript, plus, end superscript ions flow down their gradient and into the stroma, they pass through ATP synthase, driving ATP production in a process known as chemiosmosis. Light absorption in PSI. The electron arrives at photosystem I and joins the P700 special pair of chlorophylls in the reaction center. When light energy is absorbed by pigments and passed inward to the reaction center, the electron in P700 is boosted to a very high energy level and transferred to an acceptor molecule. The special pair's missing electron is replaced by a new electron from PSII (arriving via the electron transport chain). NADPH formation. The high-energy electron travels down a short second leg of the electron transport chain. At the end of the chain, the electron is passed to NADP + + start superscript, plus, end superscript (along with a second electron from the same pathway) to make NADPH. The net effect of these steps is to convert light energy into chemical energy in the form of ATP and NADPH. The ATP and NADPH from the light-dependent reactions are used to make sugars in the next stage of photosynthesis, the Calvin cycle. In another form of the light reactions, called cyclic photophosphorylation, electrons follow a different, circular path and only ATP (no NADPH) is produced.
D. The statement is inaccurate because humans would not be able to distribute the product of nitrogen fixation from industrial processes in the same way that bacteria are able to distribute it globally now.
Explanation:
Nitrogen fixing bacteria has the responsibility in nature to trap and fix atmospheric nitrogen in ecosystems. They are very important components of the nitrogen cycle and play an important role in maintaining the balance of nutrients in nature.
If humans discover industrial processes to fix nitrogen, the process will be unsustainable in the long run if nitrogen-fixing bacteria ever go extinct because humans would not be able to distribute the product of nitrogen fixation from industrial processes in the same way that bacteria are able to distribute it globally now across several ecosystems all over the world.
I believe it results to a conformation change that moves the Na+ binding site to the inside of the cell. ATP hydrolysis involves the release of chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate.For example in muscles. The process of moving sodium and potassium ions across the cell membrane is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+ ATPase.
Extensive damage to oligodendrocytes in the cns could result in l<u>oss of sensation and motor control.</u>
Explanation:
Oligodendrocytes are presnt in glial cells of Central nervous System which comprises of Brain and spinal cord.They are related to the nerve cells. It provides support by production of glial cell line derived neutrophic factor (GDNF) and brain derived neurotrophic factor (BDNF) or insulin growth factor IGF-1 they reduce ion leakage and decrease the capacitance of the cell membrane. Due to intensive damage of the Oligodendrocytes the motor nerves and other nerves of CNS damages looses it activity.
These are mainly occurred due to peripheral injury or demylinated diseases like multiple sclerosis, leukodystrophies,cerebral plasy and other congential disorders.Some chemicals like fluorouracil causes damage to the oligodendrocytes.
