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

Answers to Biological Inquiry Questions – Brooker et al ARIS site
Chapter 21
Figure 21.2
BIOLOGICAL INQUIRY QUESTION: What are two reasons why the groups of species shown in (a)
have variation in their total amount of DNA?
ANSWER: One reason is that more complex species tend to have more genes. A second reason is
that species vary with regard to the amount of repetitive DNA that is found in their genome.
Figure 21.6
BIOLOGICAL INQUIRY QUESTION: Based on their mechanism of movement, which type of TEs do
you think would proliferate more rapidly in a genome, simple TEs (see Figure 21.5b) or
retroelements?
ANSWER: Retroelements. A single element can be transcribed into multiple copies of RNA, which
can be converted to DNA by reverse transcriptase, and inserted into multiple sites in the genome.
Figure 21.8
BIOLOGICAL INQUIRY QUESTION: What is the advantage of a gene family?
ANSWER: The overall advantage is specialization. When multiple copies of a gene are found in the
genome, each copy can become specialized to suit the needs of particular cell types or particular
stages of development.
Figure 21.9
BIOLOGICAL INQUIRY QUESTION: What genetic process explains the differences in protein
abundance in liver cells versus muscle cells?
ANSWER: Gene regulation. Genes that encode metabolic enzymes are highly expressed in liver
cells, while those same genes are expressed in lower amounts in muscle cells. Conversely, genes
that encode cytoskeletal and motor proteins are highly expressed in muscle cells, but less so in liver
cells.