An amniocentesis is a medical procedure that is used to detect many genetic disorders in humans before birth. The karyotype below shows the number and
structure of homologous pairs of chromosomes in a body cell of a human fetus taken
from this medical procedure.
What caused the chromosomal alteration in number 21?

A) a part of a chromosome was lost (deletion)
B) a duplicated chromosome failed to separate (nondisjunction)
C) part of the chromosome attached to another chromosome (translocation)
D) some of the genes on a chromosome were reversed (inversion)

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

the alkaline earth metals (beryllium (be), magnesium (mg), calcium (ca), strontium (sr), barium (ba), and radium (ra)) are a group of chemical elements in the s-block of the periodic table with very similar properties: shiny. silvery-white. hopefully this ? i didn't fully understand the question