Answer:
Helper T cells stimulate B-cells to produce antibodies and killer T cells to destroy the non-self cells. Cytotoxic T cells on the other hand are direct attack cells. They can kill the micro organisms by creating pores on the invader's cell.
Explanation:
T lymphocyte mediated immunity of cell mediated immunity do not secrete antibodies but they help stimulate the B cells to produce them. Immature T cells are produced in bone marrow from where they migrate to thymus via blood. In the thymus maturation of T cells occur and then they migrate to lymphoid tissue and get differentiated into three types:
a. Helper T cells: As the name suggests, they help in activating other immune cells, in other terms they are the regulator of virtually all functions of immune system. Protein mediator called lymphokines are produced by these helper T cells in order to regulate the immune functions. Some examples of these lymphokines are: Interleukin-2 interleukin-3, interferon gamma. T helper cells stimulate the B-cells to produce antibodies.
b. Cytotoxic cells or killer T cells: The lymphokine interleukin-2 is responsible for the growth and proliferation of both cytotoxic T cells and suppressor T cells. With the help of receptor proteins on the surface of killer T cells, they bind to the specific antigen. After binding, they secrete a pore forming protein called perforins which create pores on the invaders cell membrane for water to enter into it thereby cell swells and finally lyse.
c. Suppressor T cells: They suppress the function of above two T cells.
Answer:
Restriction enzyme, also called restriction endonuclease, a protein produced by bacteria that cleaves DNA at specific sites along the molecule
Explanation:
Hope it helps
If the producer were to disappear then all the other organisms will either go extinct, survival of the fittest, or have to adapt to the change.
Answer:
a. establishment of left-right asymmetry
Explanation:
- Cardiac looping is the process in which the heart transforms itself from a straight embryonic heart into a loop that is wounded helically.
- The looping of the heart takes place on the 23rd day of development.
- As a result of this looping, there is bending of the cranial portion of the heart to the towards the right end and the caudal portion of the heart towards the left end.
- At the end of this looping the atrium takes up a dorsal and cranial position and the ventricle is displaced towards left.
- Thus, the outcome of looping is the establishment of left-right asymmetry.
Answer: A decrease in a number of trees—plant new ones and protect existing trees
The loss of a bird habitat—provide nesting boxes
An endangered aquatic species— regulate recreational activities such as boating and fishing
A increase in air pollution— encourage public transportation
I hope this helps!
