Answer:
There are prion-like particles in the brain normally, and when these become abnormal they can cause disease. (Ans. A)
Explanation:
Prions are proteins which can trigger normal proteins to fold abnormally, and they are present in the brain. They are causing many types of neurodegenerative diseases in both humans and animals. Which are known as transmissible spongiform encephalopathies.
Prions can enter the brain with the help of infection, also can arise from the gene mutation that encodes the proteins, and sometimes this affects humans by infected meat.
If a person infected from prion disease, it affects central nervous system tissues like brain, eye tissues and spinal cord.
Answer:
A proton gradient is generated by the transport of protons into the thylakoid lumen.
Protons move from the thylakoid lumen to the stroma through ATP synthase, producing ATP.
Explanation:
During photosynthesis, the environment is made acidic inside the lumen i.e. H⁺ are pumped into thylakoid lumen from stroma as a result of which more H⁺ are present in the thylakoid lumen as compared to stroma. It happens during light dependent reaction of photosynthesis. The concentration of H⁺ is already higher in lumen and transfer of more and more H⁺ from stroma increases the concentration of H⁺ even more leading to generation of a potential gradient. These H⁺ subsequently tend to move freely from lumen to stroma via "reverse pumps known as ATP synthase". The reason why these are known as reverse pumps is because pumps usually move particles from lower to higher concentration which is an active movement i.e. not natural so such movement requires energy. Naturally particles move from higher to lower concentration gradient until the concentration becomes equal on both the sides but pumps act opposite of this natural process and move particles from lower to higher concentration and utilize energy to do it. But here H⁺ are moving from higher to lower concentration which occurs naturally so ATP synthase rather than using energy tend to generate energy and this free energy is used to generate ATP from ADP & Pi (inorganic phosphate).
C, it is absorbed by earths surface.
Answer:
The correct answer is - at the G1/S phase and G2/M phase.
Explanation:
The G1/S transition phase or checkpoint is a phase where the cell cycle arrested if during the evaluation of the DNA found damaged or other factors including external factors. Due to this evaluation and inadequate conditions, the cell will not enter the S phase.
The G2/M phase or transition phase is a checkpoint which takes place just before the M phase that ensures that all replicated DNA is not damaged before entering mitosis phase or M phase.
Thus, the correct answer is - at the G1/S phase and G2/M phase.
