Question

What is true about T-lymphocytes in mammals?
A. There are four types of T cells, Cytotoxic T-cells, helper T cells and suppressor T cells, memory T cells.
B. These originate in lymphoid tissues
C. They scavenge damage cells and cellular debris
D. These are produced in thyroid

Answer 1

lymphocytes are part of the immune system of the body. Immunity describes the defense mechanism of our body or human beings. It is present in almost all animals or organisms. Every organism is born with some kind of immunity and some immunity adapts as organisms grow up. Human baby is born with two types of immunity- innate and adaptive.

Complete answer:
Option A: There are four types of Cytotoxic T-cells, helper T cells and suppressor T cells, memory T cells- T cells are manufactured and formed in the thymus gland. T cells have different types of classifications which are mentioned in the option.
Hence, option A is correct.
Option B: These originate in lymphoid tissues- T cells are originated and matured in the thymus gland. Lymphoid tissues include MALT, GALT and progenitor cells.
Option B is not correct.
Option C: They scavenge damage cells and cellular debris- The T cells primary function is to provide immunity alongside the B cells. They do not scavenge damage cells; they kill the invader cells.
Option C is not correct.
Option D: These are produced in thyroid- T cells are developed in thymus gland not in thyroid gland, thyroid gland is a part of the endocrine system as it produces growth hormone, not a part of the immunity system.
Option D is not correct.

Hence, Option A is the correct answer.

Note:
When an outer component such as- dust particle, pollen or microbes which are invisible to the eyes enters the body the body develops an immediate action like- coughing or sneezing as the first line of defense act here. While it is a microbe which can prevent the first line and enters the internal organs of the body the blood components act here and kill the invader as soon as possible.