Population density is the amount of people in one place. Population distribution is the spread of people around the world.
The true statements about he T cell receptors are 1, 2 and 4.
T cell receptors are the molecules found on the surface of the T lymphocytes. V(D)J recombination is the unique mechanism of genetic recombination that occurs only in the lymphocytes during the early stages of T and B cell maturation resulting in the T cell receptors. They recognize antigen fragments bound to MHC molecules. Majority of the T cell receptors consists of an alpha chain and a beta chain and a few with gamma and delta chains. Each chain is composed of a variable and a constant region. Within these chains are the complementary determining regions (CDRs) which determine the antigen to which the T cell receptor will bind.
Answer:
Option (a).
Explanation:
Phylogentic tree may be defined as the the diagrammatic representation of the evolutionary relationship of the organism. The phylogenetic trees are made on the hypothesis and do not explain any fact.
The branching in the phylogenetic tree determines the evolution of the species from the common ancestor. The common ancestor is located at the base of the phylogenetic tress. Since, Ardipithecus ramidus is located at the base it shows that Ardipithecus ramidus is a common ancestor.
Thus, the correct answer is option (a).
What elements are always present in protein?
A. radium, boron, fluorine, and chlorine
B. mercury, iron, lead, and aluminum
C. carbon, hydrogen, oxygen, and nitrogen ( ✔ )
D. neon, argon, krypton, and copper
<h2><u>Explanation</u> : </h2>
Proteins are one of the primary constituents of living matter. They consist of long chains of amino acids, which are bonded together by peptide linkages and thus called polypeptides. There are about 20 amino acids, and the atoms most prevalent in these are carbon, hydrogen, oxygen, nitrogen, and sulphur.
C) drying your clothes on an outdoor clothing line. This way of drying your clothes doesn’t use any power. And is environmentally friendly.