genetics ch. 6

A lethal gene is a gene that

• is dominant

• is sex linked

• is incompletely dominant

• causes the death of the offspring

An organism that develops as a result of parthenogenesis is

• haploid

• diploid

• triploid

• monosomic

an example of a haploid cell would be a

• gamete

• corn cell

• cell from a person with Down syndrome

• a human liver cell

Triploids are sterile because

• the three homologous chromosomes do not line up in pairs during meiosis

• they were not formed from gametes and thus do not have the ability to make gametes

• the chromosomes that are trying to line up during meiosis are not from the same organism and thus cannot pair

• they lack sufficient sex chromosomes to form gametes

The absence of a chromosome or the presence of an extra chromosome in an organism is called

• trisomy

• monosomy

• aneuploidy

• gene syndrome

Which equation indicates a tetraploid condition

• 2n=16

• n + n = 16

• 4n = 16

• 3n =16

down syndrome usually results from

• nondisjunction

• parthenogenesis

• sex-limited traits

• somatic mutation

an advantage of growing triploid fruits is that they are often

• larger

• seedless

• stronger

• all of these

Which of the following is not true of an inversion chromosome mutation

• the segment breaks off and reattaches at the same position

• the segment rotates 180 degrees

• the segment attaches to a nonhomologous chromosome

• results are usually not as serious as other changes within the chromosome

Proto-oncogenes code for proteins that do all of these except

• increase cell division

• prevent uncontrolled cell division

• affect the synthesis of certain growth factors

• work with tumor supressor genes to regulate the cell cycle