Download Answers to Biological Inquiry Questions – Brooker et al ARIS site

Answers to Biological Inquiry Questions – Brooker et al ARIS site
Chapter 15
Figure 15.7
BIOLOGICAL INQUIRY QUESTION: After they have replicated and become compacted in
preparation for cell division, chromosomes are often shaped like an X, as in part (a) of this figure.
Which proteins are primarily responsible for this X shape?
ANSWER: The nuclear matrix proteins form the scaffold on which the chromosomes condense. As
seen in part (b), the scaffold itself is shaped like an X. The other proteins, such as histones, enable
the DNA to condense onto this scaffold.
Figure 15.9
BIOLOGICAL INQUIRY QUESTION: Researchers usually treat cells with drugs that stimulate them
to divide prior to the procedure for making a karyotype. Why would this be useful?
ANSWER: Chromosomes are readily seen when they are compacted in a dividing cell. By adding
such a drug, you increase the percentage of cells that are actively dividing.
Figure 15.18
BIOLOGICAL INQUIRY QUESTION: What is the main reason for meiosis in animals? What is the
reason for mitosis in animals?
ANSWER: The reason for meiosis is to produce gametes. These combine during fertilization to
produce a diploid organism. The purpose of mitosis is to produce a multicellular organism.
Figure 15.22
BIOLOGICAL INQUIRY QUESTION: Could nondisjunction produce a polyploid individual?
ANSWER: Yes, it could. If both sets of chromosomes moved to one pole, this would produce a
diploid gamete. If this gamete united with a haploid gamete, the resulting individual would be a
polyploid (a triploid individual).