Exam 2: Mitosis and Meiosis

Living organisms are categorized into two major groups based on the presence or absence of a nucleus. What group is defined by the presence of a nucleus?

What is the outcome of synapsis, a significant event in meiosis?

Regarding the mitotic cell cycle, what is meant by a checkpoint?

In an organism with 52 chromosomes, how many bivalents would be expected to form during meiosis?

The horse (Equus caballus) has 32 pairs of chromosomes, whereas the donkey (Equus asinus) has 31 pairs of chromosomes. How many chromosomes would be expected in the somatic tissue of a mule?

Down syndrome, or trisomy 21, in humans is caused by an extra copy of the relatively small, acrocentric 21. Including only chromosome 21, the X chromosome (medium in size and somewhat metacentric) and the Y chromosome (small and acrocentric), draw one possible array of chromosomes in the four sperm cells produced by the complete meiosis of one primary spermatocyte. For the purposes of this question, assume that males with Down syndrome produce normal ratios of sperm cells. (More than one answer is possible.)

Which type of cell structure is the nucleolus organizer (NOR) responsible for producing?

An interesting group of ants consists of several virtually identical, closely related species, with females having chromosome numbers of 18, 20, 32, 48, 60, 62, and 64. If one crossed a female of species (A) with 32 chromosomes and a male species (B) with 9 chromosomes (males are haploid, and each gamete contains the n complement), how many chromosomes would one expect in the body (somatic) cells of the female offspring?