BIO313 EXAM(2) Practice Questions Name:___________________________ 1) Regarding
ID: 61654 • Letter: B
Question
BIO313 EXAM(2) Practice Questions Name:___________________________
1) Regarding familial Down syndrome, which of the following statements is most likely true?
a) The affected individuals (with Down) have 47 chromosomes.
b) The carriers have 46 chromsomes.
c) The affected individuals have 46 chromosomes. d) The carriers have nondisjunction during meiosis.
2) Which mode of chromosomal rearrangement with crossover would generate dicentric chromosome in cells?
a) paracentic inversion
b) duplication
c) non-reciprocal translocation d) preicentric inversion
e) reciprocal translocation
3) Which of the following statements about Down syndrome is false?
a) Individuals with Down syndrome are triploid.
b) Down syndrome occurs due to nondisjunction in either meiotic division in the mother.
c) Most Down syndrome births happen to women over age 35.
d) Familial Down syndrome is due to nondisjunction.
e) All of the above are false
4) Autotriploids _____.
a) can result from the fertilization of a haploid gamete with an abnormal diploid gamete
b) can result from the fertilization of an egg by two haploid sperm
c) can result from the crossing of a diploid with a tetraploid
d) have three chromosome sets that are identical in terms of number and content
e) all of the above
5) Chromosome duplication often result in abnormal phenotypes because
a) developmental processes depend on the relative amounts of proteins encoded by different
genes
b) extra copies of the genes within the duplicated region do not pair in meiosis c) the chromosome is more likely to break when it loops in meiosis
d) extra DNA must be replicated which slows down cell division.
6) A chromosome with genetic markers A, B, C, D, E, and F is shown below:
A B C D centromere E F
-------------------------------------------0------------------------ Another chromosome is found to contain
A B D C centromere E F -------------------------------------------0------------------------
Useappropriateterminologytodescribethedifferencebetweenthesetwo chromosomes.
If the two chromosomes are paired during meiosis, use diagram to explain the genetic consequence if a single crossover takes place between C and D (3 points).
7) Red-green color blindness is a human X-linked recessive disorder. Betty has normal color vision, but her father is color-blind. Betty marries Jim, who also has normal color vision. Betty and Jim have a daughter who has Turner syndrome and is color-blind.
a) In which parent did the non-disjunction take place?
b) Did the daughter inherit her X chromosome from Betty or from Jim?
10) (3.5 Pts) Species I has 2n=14 and species II has 2n=20. Give all possible chromosome numbers that may be found in the following individuals
a. An autotriploid of species I –
b. An autotetraploid of species II –
c. An allotriploid formed from species I and species II –
d. An allotetraploid formed from species I and species II – e. Trisomy in species I –
f. Monosomy in species II –
g. Tetrasomy in species I –
11) The color of sunflower pollen can be orange, yellow, or white-cream. Crosses reveal that true- breeding orange is dominant to both yellow and white-cream. However, a cross between true-breeding white-cream and yellow plants produced F1 plants with orange pollen. The F2 populations of this cross resulted in a ratio of nine orange: four white-cream: three yellow. What type of inheritance do these results suggest?
12) What blood types are possible among the children of a cross between a man who is blood- type A and a woman of blood type B?
13) A number of all white cats are crossed and they produce the following types of progeny: 12/16 all-white; 3/16 black; and 1/16 gray.
a) Give the genotypes of the progeny b) Which gene is epistatic?
14) In rabbits, a series of multiple alleles
controls coat color in the following way:
C is dominant to all other alleles and
causes full color. The chinchilla
phenotype is due to the Cck allele, which
is dominant to all alleles other than C.
The Ch allele, dominant only to Ca
(albino), results in the Himalayan coat
color. Thus, the order of dominance is
C> Cck > Ch > Ca. For each of the
following three cases, the phenotypes of the P1 generations of two crosses are shown, as well as the phenotype of one member of the F1 generation.
For each case, determine the genotypes of the P1 generation and the F1 offspring, and predict the results of making each indicated cross between F1 individuals.
15) Cross between true breeding brown dog and true breeding white dog, producing all white F1 offspring. F1 X F1 cross produced the following F2 offspring:
White 118 Black 32 Brown 10
a) How many genes are involved?
b) What class of dogs are the double recessive homozygotes and what is their genotype? c) What is the genotype of the black dogs?
d) What are the genotypes of the white dogs?
e) What kind of gene interaction example is this case of question (2)?
16)
17) In Drosophila melanogaster, forked bristles are caused by an allele (Xf) that is X linked and recessive to an allele for normal bristles (X+). Brown eyes are caused by an allele (b) that is autosomal and recessive to an allele for red eyes (b+). A female fly that is homozygous for normal bristles and red eyes mates with a male fly that has forked bristles and brown eyes. The F1 are intercrossed to produce the F2. What will the phenotypes and proportions of the F2 flies be from the cross?
18) Miniature wings in Drosophila melanogaster result from an X-linked gene (Xm) that is recessive to al allele for long wings (X+). Sepia eyes are produced by an autosomal gene (s) that is recessive to an allele for red eyes (s+).
(1 Pt) A female fly that has miniature wings and sepia eyes is crossed with a male that has normal wings and is homozygous for red eyes. The F1 are intercrossed to produce the F2. Give the phenotypes and their proportions expected in the F1 and F2 flies form this cross.
(1 Pt) A female fly that is homozygous for normal wings and has sepia eyes is crossed with a male that has miniature wings and is homozygous for red eyes.
19)
The F1 are intercrossed to produce the F2. Give the phenotypes and their proportions expected.
20) A summer-squash plant that produces disc-shaped fruit is crossed with a summer-squash plant that produces long fruit. All F1 have disc-shaped fruit. When the F1 are intercrossed, F2 progeny are produced in the following ratio:
Disc-shaped fruit: 9/16
Spherical fruit: 6/16
Long fruit: 1/16
Give the genotypes of the F2 progeny.
Explanation / Answer
1. Familial Down Syndrome:
Statement 1 is correct for Down syndrome. Down syndrome involves Trisomy 21 which is caused by unsucessful seperation of chromosome number 21 during ova or sperm developement. So the resulting sperm or egg consists an extra copy of chromosome number 21 which makes 24 chromosomes in this cell. On combinig with normal cell for other parent, the baby has 47 chrmosomes.
Familial down syndrome is caused by the fusion of chrmosome 21 with other chromosome (chromosome 14) and thus known as translocation down syndrome.
2. Paracentric inversion
3. The correct answer is e.
All the statements are false for Down Syndrome.
4. The correct answer is e.
All the statements are true for autotriploids.
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