Answer:
Carbon dioxide, Oxygen
Explanation:
The circulatory system of our body works following two pathways -
In pulmonary pathway the deoxygenated blood is carried to the lungs while in the second pathway, known as systemic pathway, the oxygenated blood is carried to the various parts and organs of our body. Thus the completed sentence in the question will be -
Blood being pumped by the heart is circulated in two circuits. One circuit carries blood with high levels of carbon dioxide to the lungs, and the other circuit carries blood with high levels of oxygen to the body.
Answer:
The correct answer is D) short-lived plasma cells that secrete antibodies for the antigen
Explanation:
Each B lymphocyte has an antigen receptor (BCR: B cell receptor), a surface immunoglobulin (IgM or IgD), that binds to specific domains of the antigen called antigenic determinants or epitopes. Only B lymphocytes with a high antibody affinity for the antigen, and which are capable of processing and presenting it, will be positively selected. In this contact between the two cells, an exchange of chemical signals takes place that leads to the activation, clonal proliferation and differentiation of B cells into two sister subclones: one of antibody-secreting plasma cells, and the other of memory primed B cells. Therefore, only these last positively selected B lymphocytes will survive, proliferate and differentiate into plasma cells, synthesizing and secreting antibodies of a single isotypic class, with a unique specificity and high affinity, improving the ability to adhere to the antigen and, thus , neutralize and destroy pathogens.
Answer:::::::::::: Meiosis………
Out of the following given choices;
A. DNA accumulates mutations at a regular rate
B. known mutation rate for a gene
C. the number of differences in DNA sequences for a gene in two species
D. the same gene identified in two species
E. All answers are corrects
The answer is E. The molecular clock used rates of mutation to determine the prehistoric time when two species that share a common ancestor diverged. The benchmarks for determining the mutation rate are often fossil or archaeological dates.
