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:
Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.
Explanation:
The most accurate statement that supports the researcher's claim is that atmospheric carbon dioxide is the raw material for photosynthesis.
Photosynthesis is the process by which green plants manufactures their food in the presence of carbon dioxide and water using sunlight.
The product is usually glucose and oxygen.
The chemical equation is shown below;
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
This raw material is a by-product of cellular respiration in human beings. Other process also releases carbon dioxide. Green plants uses this organic material to manufacture its food through photosynthesis.
We can attribute the increased growth rate in plants to the proliferation of the gases in the atmosphere.
Answer:
D) Must be reproduced in living cells
Answer:
D.Sexual reproduction requires that the amount of DNA in a cell be doubled.
Explanation:
Answer:
A tiger cub begins to grow.
Explanation:
Makes the most sense.
