B. Is the correct answer.
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:
chemotaxis
Explanation:
Chemotaxis is movement of the organism in the response to the chemical stimulus.
Bacteria, somatic cells and single-cell as well as multicellular organisms direct movements of their body according to some chemicals in the environment. This is very important for the bacteria to find the food by swimming toward highest concentration of the food molecules or also to flee from the poisons.
<u>Thus, it is a process by which various cells are drawn to the target area by a microbe invader.</u>
