A simple <em><u>refracting</u></em> telescope uses two convex lenses to gather and focus light from a distant object.
Answer and Explanation:
Nondisjunction occurs when homologous chromosomes fail to segregate during anaphase I or sister chromatids fail to segregate during anaphase II. The result is an addition or loss of one or more chromosomes. Nondisjunction is associated with disorders like Down's syndrome due to an extra chromosome, Klinefelter's syndrome or Turner's syndrome. These phenomenon where one has three members of homologous chromosome is called trisomy.
This is because the GP120 protein
of the HIV virus that forms the ‘knob’ is
essential for the infection of CD4 cells
of the immune system by the virus. The glycoprotein is, therefore, a good
target for vaccines especially since the
molecule is highly conserved because most mutations in the region could be highly deleterious to the virus.
Genetic variation enables bacteria to adapt to changes in their environment. Since, bacteria reproduce asexually (binary fission), they can share genes (genetic transfer) via other mechanisms such as conjugation (exchange of genetic material through direct contact between two bacteria), transformation, and transduction(exchange of genetic material via bacteriophages).
Transformation is a process by which bacteria takes in DNA from its environment through the cell membrane.