In the Northern Hemisphere, winter generally begins on December 21 or 22. This is the winter solstice, the day of the year with the shortest period of daylight. Summer begins on June 20 or 21, the summer solstice, which has the most daylight of any day in the year. Spring and fall, or autumn, begin on equinoxes, days that have equal amounts of daylight and darkness. The vernal, or spring, equinox falls on March 20 or 21, and the autumnal equinox is on September 22 or 23.
Explanation:
After repeated stimulation by antigen, B cells can make antibodies that bind their antigen with much higher affinity a process called affinity maturation. ... Thus, antigen stimulation greatly increases the antibody arsenal. Antibodies are proteins, and proteins are encoded by genes.
Answer:
c. A chromosomal mutation can change the total number of chromosomes in the cell.
Explanation:
A gene mutation affects a single gene, and replication error is the main cause of gene mutation. A chromosomal mutation affects one part of chromosome or full chromosome. error in meiosis is the main cause of chromosomal mutation. Both mutations are responsible for a change in DNA. A chromosomal mutation leads to the change in total number of chromosomes in the cell.
Stable elements are those which have atleast one isotope with no tendency to "decay", i.e., change into anotherelement.