A diploid human cell normally has 23 pairs of homologous chromosomes, but as a woman ages, the chances of nondisjunction increase. Imagine that a gamete is produced that received two copies of chromosome 21 due to nondisjunction during meiosis II. If the gamete is fertilized with a normal sperm, the embryo's cells will contain chromosomes.

47 chromosomes instead of 46 because there are 3 chromosomes in pair 21. This is called Down syndrome, described most recently by Lejune in 1958

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.