CMA 1 Flashcards
In a testcross between a female Drosophila that is heterozygous for two unlinked autosomal genes and a male that is homozygous recessive for both, what is the probability of finding a female fly amongst the offspring with the same genotype as her mother? (Enter your answer in decimal format eg 0.35)
NB Autosomal genes are inherited independent of sex
0.125
Corn has a colour gene ‘C’ and a height gene ‘T’ with the following phenotypes: CC and Cc = purple; cc = white; TT = tall; Tt = medium; tt = dwarf. What phenotypic ratio would you expect in the progeny of the dihybrid cross CcTt x CcTt?
3:6:3:1:2:1
Andy is blood group O, his mother and father are blood group A and B respectively. What is the probability that Andy’s new-born sister will be blood group A?
1/4
Drosophila, homozygous for a null allele of the ebony gene have black bodies and the ebony allele is recessive to its wild type partner. Drosophila heterozygous for a mutant allele of the Curly gene have curly wings and Curly homozygotes die. Which of the following phenotypic ratios would you expect to see in the living progeny of flies which were heterozygous (mutant/wild type) for both genes?
6:3:2:1
The phenotypic ratio expected in the F2 generation of a standard dihybrid cross is 9:3:3:1. If there are 24,000 F2 progeny, how many individuals would you expect to have the least frequent phenotype?
1500
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. What will be the phenotype(s) of the offspring?
All yellow with full pods
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. What will be the phenotype(s) of the offspring?
All yellow with full pods
Let W = purple flowers, w = white flowers, D = tall plants and d = dwarf plants. What combination of gametes could be produced by an individual that is heterozygous for both traits?
WD, Wd, wD, wd
Let W = purple flowers, w = white flowers, D = tall plants and d = dwarf plants. What combination of gametes could be produced by an individual that is heterozygous for both traits?
WD, Wd, wD, wd
Which of the following scientists provided the explanation for the stability of the 50:50 sex ratio in disexual species
Fisher
The cross AaBb x AaBb is called a
dihybrid cross
The cross AaBb x AaBb is called a
dihybrid cross
If a pure-breeding ebony-bodied female Drosophila is crossed with a pure-breeding wild type male and their offspring are allowed to interbreed, how many ebony-bodied flies would you expect to find amongst 8400 F2 progeny?
2100
If a pure-breeding ebony-bodied female Drosophila is crossed with a pure-breeding wild type male and their offspring are allowed to interbreed, how many ebony-bodied flies would you expect to find amongst 8400 F2 progeny?
2100
A set of genes located on the same chromosome is known as a linkage group. Members of a linkage group can assort independently if…
crossing over occurs between their locations
A set of genes located on the same chromosome is known as a linkage group. Members of a linkage group can assort independently if…
crossing over occurs between their locations
A pure-breeding wild type female Drosophila was crossed to a pure breeding male with ebony body, brown eyes and vestigial wings. All of the F1 progeny were wild type. If these F1 flies are allowed to interbreed, how many different phenotypes would you expect to see amongst their offspring?
8
Which of the following statements about coelacanths is false?
they have lungs but no gills
Which of the following statements about coelacanths is false?
they have lungs but no gills
In the human ABO blood groups, IA and IB are dominant over IO, but not over one another. IA and IB are said to be ………..
codominant
In the human ABO blood groups, IA and IB are dominant over IO, but not over one another. IA and IB are said to be ………..
codominant
When a pure-breeding wildtype female fly (genotype bw+bw+, e+e+) is crossed to a pure-breeding brown-eyed, ebony-bodied male (genotype bw bw, e e), the F1 progeny are all wildtype. If the F1 flies interbreed, what is the probability of finding a brown-eyed fly with wildtype body colour amongst their offspring?
3/16
When a pure-breeding wildtype female fly (genotype bw+bw+, e+e+) is crossed to a pure-breeding brown-eyed, ebony-bodied male (genotype bw bw, e e), the F1 progeny are all wildtype. If the F1 flies interbreed, what is the probability of finding a brown-eyed fly with wildtype body colour amongst their offspring?
3/16
Full Pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. Which TWO of the following genotypes could apply to a yellow plant with constricted pods? (Note that choosing more than two options will result in a score of 0)
YYff, Yyff
Alternative versions of a gene are called…
alleles
Alternative versions of a gene are called…
alleles
If a dihybrid individual BbCc is testcrossed, what is the probability of finding an individual that is homozygous for one gene and heterozygous for the other in the resulting generation?
1/2
If a dihybrid individual BbCc is testcrossed, what is the probability of finding an individual that is homozygous for one gene and heterozygous for the other in the resulting generation?
1/2
If a dihybrid individual BbCc is testcrossed, what is the probability of finding a double homozygous recessive in the resulting generation?
1/4
If a dihybrid individual BbCc is testcrossed, what is the probability of finding a double homozygous recessive in the resulting generation?
1/4
A diploid individual whose two copies of a given gene are the same is said to be __________ for the gene
homozygous
A diploid individual whose two copies of a given gene are the same is said to be __________ for the gene
homozygous
The extant species Latimeria chalumnae belongs to a group that is an important link in evolution because it was the first group of?
jointed fins
The extant species Latimeria chalumnae belongs to a group that is an important link in evolution because it was the first group of?
jointed fins
Which one of the following terms best describes an organism with two homologous sets of chromosomes?
diploid
Which one of the following terms best describes an organism with two homologous sets of chromosomes?
diploid
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. The offspring are then testcrossed. Presuming independent assortment, what is the expected phenotypic ratio of resulting progeny?
9:3:3:1
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. The offspring are then testcrossed. Presuming independent assortment, what is the expected phenotypic ratio of resulting progeny?
9:3:3:1
Which of the following geological periods is the most recent (closest to the present)?
Cretaceous
How may different genotypes would you expect to find amongst the wild type offspring of a cross between Drosophila that are heterozygous for both ebony and vestigial wing (ie they are both e+e, vg+vg)?
9
The diagram below illustrates a human pedigree for an inherited disease. Females and males are represented by circles and squares respectively. Red symbols indicate persons affected by the disease. What form of inheritance does the disease show?
The disease is present in each generation, both men and women are affected, each affected individual has an affected parent.
autosomal dominant
The diagram below illustrates a human pedigree for an inherited disease. Females and males are represented by circles and squares respectively. Red symbols indicate persons affected by the disease. What form of inheritance does the disease show?
The disease is present in each generation, both men and women are affected, each affected individual has an affected parent.
autosomal dominant
Which one of the following explains why men tend to suffer from sex-linked genetic disorders more frequently than women?
Men have only one X chromosome therefore have only a single allele of most X-linked genes.
Genes A, B and C are unlinked and encode enzymes which act sequentially in a metabolic pathway that normally synthesises black pigment via colourless intermediates.
If two individuals that are heterozygous (wild type and null alleles) at all 3 gene loci are mated, what proportion of their progeny will be colourless?
37/64
Genes A, B and C are unlinked and encode enzymes which act sequentially in a metabolic pathway that normally synthesises black pigment via colourless intermediates.
If two individuals that are heterozygous (wild type and null alleles) at all 3 gene loci are mated, what proportion of their progeny will be colourless?
37/64
A diploid individual who only has one copy of a given gene is said to be __________ for that gene.
hemizygous
A diploid individual who only has one copy of a given gene is said to be __________ for that gene.
hemizygous
If genes A, B and C each control a different visible characteristic, and each gene has two alternative alleles that exhibit contrasting phenotypes with one showing complete dominance over the other, how many different phenotypic combinations will be found amongst the progeny of an Aa,Bb,Cc x Aa,Bb,Cc cross?
8
If genes A, B and C each control a different visible characteristic, and each gene has two alternative alleles that exhibit contrasting phenotypes with one showing complete dominance over the other, how many different phenotypic combinations will be found amongst the progeny of an Aa,Bb,Cc x Aa,Bb,Cc cross?
8
If the alleles of both of the genes involved in a dihybrid cross exhibit incomplete dominance and independent assortment, what proportion of the F2 progeny would you expect to show the most frequent phenotype?
1/4
If the alleles of both of the genes involved in a dihybrid cross exhibit incomplete dominance and independent assortment, what proportion of the F2 progeny would you expect to show the most frequent phenotype?
1/4
Under normal circumstances, what phenotypic ratio would you expect to see in the offspring of a cross between Drosophila that are both heterozygous for a single gene that controls a visible phenoype such as eye colour? (presume wild type is dominant to mutant)
3 wild type to 1 mutant
Under normal circumstances, what phenotypic ratio would you expect to see in the offspring of a cross between Drosophila that are both heterozygous for a single gene that controls a visible phenoype such as eye colour? (presume wild type is dominant to mutant)
3 wild type to 1 mutant
A diploid individual whose two copies of a given gene are different is said to be __________ for the gene
heterozygous
Presuming that none of the following phenomena cause lethality, which of them is most likely to affect the genotypic ratios observed in the progeny of a dihybrid cross?
close linkage of the two genes
Presuming that none of the following phenomena cause lethality, which of them is most likely to affect the genotypic ratios observed in the progeny of a dihybrid cross?
close linkage of the two genes
The cross AaBb x aabb is called a
testcross
The cross AaBb x aabb is called a
testcross
Sometimes an allele of one gene will interact so as to modify the expression of the alleles of a second gene in an interaction called…
epistasis
Environmental temperature influences the body temperature of many animals, especially those that live in _______ environments.
aquatic
Environmental temperature influences the body temperature of many animals, especially those that live in _______ environments.
aquatic
If two individuals, both heterozygous for a particular gene, are crossed and the phenotypic ratio amongst their numerous progeny is 2 : 1 (dominant : recessive). The simplest explanation is that…
the dominant allele is also lethal in homozygotes
If two individuals, both heterozygous for a particular gene, are crossed and the phenotypic ratio amongst their numerous progeny is 2 : 1 (dominant : recessive). The simplest explanation is that…
the dominant allele is also lethal in homozygotes
Corn has a colour gene ‘C’ and a height gene ‘T’ with the following phenotypes: CC and Cc = purple; cc = white; TT = tall; Tt = medium; tt = dwarf. What phenotypic ratio would you expect in the progeny of the dihybrid cross CcTt x CcTt?
3:6:3:1:2:1
Corn has a colour gene ‘C’ and a height gene ‘T’ with the following phenotypes: CC and Cc = purple; cc = white; TT = tall; Tt = medium; tt = dwarf. What phenotypic ratio would you expect in the progeny of the dihybrid cross CcTt x CcTt?
3:6:3:1:2:1
If two genes are at opposite ends of a large chromosome, they will usually behave as if…
they are on different chromosomes
Abnormally high concentrations of ______ have been found in rocks dating from the end of the Cretaceous.
iridium
Abnormally high concentrations of ______ have been found in rocks dating from the end of the Cretaceous.
iridium
In the fungus Aspergillus nidulans, wild type (+) conidial colour is green and is controlled by two genes: y which gives yellow conidia when mutant (-), and w which gives white conidia when mutant. The w gene is epistatic to y.
An auxotrophic strain of the fungus has yellow conidia and requires biotin and proline for growth. Which one of the following genotypes could it have?
?
Most physiological processes…
occur more rapidly as temperature increases
Gene A and gene B both lie on the same chromosome approximately 12 centimorgans appart. If one of the F1 progeny of the cross AABB x aabb were mated to an individual with the genotype aabb, how many individuals with the genotype AaBb would you expect amongst 1000 progeny?
?
In the haploid fungus Neurospora the amino acid arginine is synthesised from its precursor in a sequential 4 step reaction via the intermediates of ornithine, citrulline and arginosuccinine.
If an auxotrophic mutation in one strain blocks the pathway at step 3, and an unlinked auxotrophic mutation in a second strain blocks the pathway at step 2, what would be the result of crossing these two mutant strains?
all progeny will be able to synthesize arginine
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. The offspring are then testcrossed. How many different phenotypes do you expect in the offspring?
4
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. The offspring are then testcrossed. How many different phenotypes do you expect in the offspring?
4
Suppose the sporophyte generation of a moss is heterozygous for a gene (Ll) which affects leaf shape in the haploid gametophyte. The allele L causes elongate leaves and the allele l causes short leaves.
What will be the expected proportions of elongate-leaves and short-leaved gametophytes produced from the sporophyte?
half short-leaved and half-long leaved
In the fungus Aspergillus nidulans, wild type (+) conidial colour is green and is controlled by two genes: y which gives yellow conidia when mutant (-), and w which gives white conidia when mutant. The w gene is epistatic to y.
An auxotrophic strain of the fungus has yellow conidia and requires biotin and proline for growth. Which one of the following genotypes could it have?
w+y-bi-pro-
Gene A and gene B both lie on the same chromosome approximately 12 centimorgans appart. If one of the F1 progeny of the cross AABB x aabb were mated to an individual with the genotype aabb, how many individuals with the genotype AaBb would you expect amongst 1000 progeny?
440
Full pod shape (F) is dominant to constricted pod shape (f) and yellow pod colour (Y) is dominant to green pod colour (y) in pea plants. A pure-breeding green plant with full pods is crossed with a pure-breeding yellow plant with constricted pods. The offspring are then testcrossed. Presuming independent assortment, what is the expected phenotypic ratio of resulting progeny?
1:1:1:1
How may different genotypes would you expect to find amongst the wild type offspring of a cross between Drosophila that are heterozygous for both ebony and vestigial wing (ie they are both e+e, vg+vg)?
4
Gene A and gene B both lie on the same chromosome approximately 12 centimorgans appart. If one of the F1 progeny of the cross AABB x aabb were mated to an individual with the genotype aabb, how many individuals with the genotype AaBb would you expect amongst 1000 progeny?
440
In the haploid fungus Neurospora the amino acid arginine is synthesised from its precursor in a sequential 4 step reaction via the intermediates of ornithine, citrulline and arginosuccinine.
If an auxotrophic mutation in one strain blocks the pathway at step 3, and an unlinked auxotrophic mutation in a second strain blocks the pathway at step 2, what would be the result of crossing these two mutant strains?
some progeny will be able to synthesize arginine and some will not
