The right answer is D (less responsive to antigens)
It is proven that, after puberty, thymus activity (an organ that is included in the lymphatic system, producing T cells that pick up antigens) decreases and that in adult and aged people the thymus has no role. Work done in humans indicate that in fact the cellularity begins to decline from birth in favor of lymphocyte perivascular spaces and connective and adipose tissue, which leads to a decrease in the capture of antigens.
Answer:
B. DR, Dr, Rd, dr
Explanation:
This question involves two genes. Alleles D and R are dominant over alleles d and r. These two genes obey the law of independent assortment as proposed by Gregor Mendel.
Based on the question, a genotype RrDd will produce the following combination of gametes following the process of meiosis:
DR, Dr, dR, dr
Hello, I figured your question was missing its options so I went online to find them. Here they are:
The process of phagocytosis involves all of the following EXCEPT
:
a. adhesion.
b. secretion of cytotoxins.
c. elimination.
d. vesicle fusion.
e. chemotaxis.
Answer:
The correct answer is: b) secretion of cytotoxins.
Explanation:
Phagocytosis is a mechanism performed by cells in which the plasma membrane engulfs a large particle. Phagocytosis is used by cells in the immune system to ingest pathogens like viruses and bacteria.
Phagocytosis consists of many steps:
- activation
- the phagocytes that were resting are activated in the inflammatory response when a pathogen enters the body.
- chemotaxis - this refers to the process in which the phagocyte moves to the pathogen by following the chemical factors released by these germs.
- adhesion - the phagocyte attaches to the pathogen.
- ingestion
/vesicle fusion - the phagocyte sends pseudopods to engulf the pathogen, and places it in a phagosome, which is an endocytic vesicle. The phagosome and the phagocyte will fuse so the pathogen gets inside.
- elimination - the pathogen is destroyed in the phagocyte by the lysosomes present in it.
<u>The</u><u> secretion of cytotoxins</u><u> is not a part of the phagocytosis, and is a process exclusive to </u><u>T cells</u><u> (leukocytes that lack the ability to phagocyte).</u>
Answer:
The sugar and phosphate group make up the backbone of the DNA double helix, while the bases are located in the middle.
Explanation:
