Quiz 11 Q's Flashcards
Which of the following scientists discovered the Ac and Ds transposable elements in maize?
Barbara McClintock
A corn plant is homozygous for a mutant allele that results in no pigment in the seed (i.e., white). The mutant is caused by Ds insertion that often exits late in seed development, when there is an active Ac element in the genome. The seeds of this plant will be
white with small spots of pigment
Which of the following features do bacterial and corn transposons not have in common?
Both may cause unstable mutations.
Both may carry drug resistance genes in natural populations.
Both may have inverted repeats.
Both may move to new loci.
Both may cause rearrangements.
Both may carry drug resistance genes in natural populations.
An autonomous element
requires no other elements for its mobility.
requires one or more additional elements for its mobility.
is found only in corn (maize).
is found only in plants.
None of the answer options is correct.
requires no other elements for its mobility
Retrotransposons move via an intermediate that is
a double-stranded lollipop.
a retrovirus.
double-stranded RNA.
single-stranded DNA.
single-stranded RNA.
single-stranded RNA
LINEs differ from retrotransposons in that LINEs do NOT
-encode transposase.
-encode reverse transcriptase.
-contain LTRs.
-transpose in a replicative manner.
-contain the transposase gene.
contain LTRs
What percentage of the human genome is derived from transposable elements?
less than 5%
25%
50%
75%
nearly 100%
50%
A particular hybrid species is defined as 3n = 12. It is discovered that at meiosis, pairing is always univalent + bivalent (never trivalent) in this species. How many bivalents will be present in prophase of meiosis I?
2
3
4
8
12
4
For autosomes in diploid organisms, the aneuploid 2n + 1 is
monosomic.
trisomic.
nullisomic.
haploid.
amphidiploid.
trisomic
For autosomes in diploid organisms, the aneuploid 2n – 1 is
monosomic.
trisomic.
nullisomic.
disomic.
amphidiploid.
monosomic
For autosomes in diploid organisms, the aneuploid 2n – 2 is
monosomic.
trisomic.
nullisomic.
disomic.
amphidiploid.
nullisomic
A man is found to be karyotypically 47, XYY. The presence of an extra Y chromosome most likely results from
nondisjunction in a maternal meiocyte at meiosis I.
nondisjunction in a maternal meiocyte at meiosis II.
nondisjunction in a paternal meiocyte at meiosis I.
nondisjunction in a paternal meiocyte at meiosis II.
unequal crossing over.
nondisjunction in a paternal meiocyte at meiosis II
In humans, males have only one X chromosome and females have two, yet housekeeping X chromosome genes are expressed in roughly equal amounts in males and females. How can this be explained?
The X chromosome is hyperactivated in males.
The X chromosomes are hypoactivated in females.
One X chromosome in females is inactivated.
The Y chromosome in males actually contains similar genes as the X chromosome.
One X chromosome in females is inactivated
A hybrid allotetraploid species (2n = 60) was backcrossed to one of the suspected parents (2n = 30). When the F1 underwent meiosis, the prophase chromosome configuration was examined. If the guess about the suspected parent was correct, what would the chromosome configuration look like?
30 pairs
45 singles
60 singles
15 pairs and 15 singles
30 pairs and 15 singles
15 pairs and 15 singles
The red fox has 17 pairs of large, long chromosomes. The arctic fox has 26 pairs of smaller shorter chromosomes. What do you expect to be the chromosome number in somatic tissues of a red fox/arctic fox hybrid?
13
17
26
43
43
