Final answer:
Aneuploidy is the condition of having an incorrect number of chromosomes, resulting from either the loss of one chromosome (monosomy) or the gain of one (trisomy), with common outcomes such as Down Syndrome. Polyploidy refers to having more than two complete sets of chromosomes, and is common in plants, leading to increased size and sometimes reproductive isolation. Option number b is correct.
Step-by-step explanation:
The gain or loss of individual chromosomes that is not an exact multiple of a set is known as aneuploidy. Aneuploidy is the condition where an organism has either one extra or one missing chromosome from the normal chromosome set, leading to a numerical chromosomal abnormality. It includes conditions such as monosomy and trisomy. Monosomy refers to the loss of one chromosome and is usually lethal, whereas trisomy signifies the gain of an extraneous chromosome, which can lead to disorders such as Down Syndrome.
Polyploidy, on the other hand, is a condition where a cell or organism has more than two complete sets (usually an even number) of chromosomes. For example, triploidy indicates the presence of three sets of chromosomes, which can occur due to errors during cell division such as meiosis. Polyploid organisms, especially in the plant kingdom, often exhibit increased size and robustness. Reproductive isolation can result from polyploidy due to mismatched chromosome numbers between potential mates, leading to issues with fertility and interbreeding.