Biology chapters 12 and 13
Albinism is a recessive genetic disorder. Consider that an albino and an individual that is homozygous for normal pigmentation have a child. What is the probability that the child will be an albino?
0
In humans. eye shape is controlled by a single gene. Almond-shaped eyes are dominant over rounded eyes. The length of eyelashes is also controlled by a single gene, and long eyelashes are dominant over short eyelashes. Consider a man that is heterozygous for almond eyes and long eyelashes and a woman with rounded eyes and short eyelashes. If they have 2 children, what is the probability that the first child looks like dad and the second child looks like mom?
1/16 1/8
In pea plants, the gene for round seed (R) is dominant, and wrinkled seeds (r) are recessive. The endosperm of the pea is also either starchy, a dominant gene (E), or waxy (e). Suppose a cross is made between a parent that is heterozygous for round seeds that are waxy and a parent that is homozygous for both wrinkled seeds that are starchy. What percentage of the offspring do you expect to have round starchy seeds?
1/2 The genotypes of the parents would be Rree x rrEE. The possible gametes from the first parent (Re, re) and from the second parent (all rE) would create a punnett square that is just 2 total boxes in size. Of those, one of the two boxes will be round and starchy
Dimples is an inherited dominant trait in humans. Suppose that one parent is heterozygous for dimples and the other parent does not have dimples. What is the probability that their child will be a girl and have dimples?
1/4
Tay-Sachs disease is one of the most prevalent genetic disorders among individuals of the Ashkenazi Jewish community. This disorder is inherited in a recessive manner. If two individuals are carriers of this disease, what is the likelihood that they will have a child afflicted with Tay-Sachs?
1/4
If two people who are both heterozygous for Huntington's disease (an autosomal dominant trait) marry, what is the probability that they will have three children, all of which are normal?
1/64
A female is homozygous for the recessive X-linked gene for Lesch-Nyhan syndrome. What percent of her daughters would be expected to be unaffected carriers assuming that their father does not have Lesch-Nyhan syndrome?
100%
A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color-blind marries a color-blind male. What is the probability that this couple's son will be color-blind?
100%
How many unique gametes could be produced from an individual with the genotype AABbCcDdeeFf?
16
Consider this cross: DdEe x DdEe If this cross produces 320 individuals, how many of them are expected to display the dominant phenotype for both of the genes?
180
The following data were collected on 2000 progeny from a testcross of a dihybrid: Uf 795 UF 192 uf 188 uF 825 From this data, what is the genetic map distance between loci U and F?
19.0 map units
The following data were obtained from testcrossing a trihybrid plant (1000 total progeny): eFg 310 EFG 94 Efg 90 EFg 11 efg 87 EfG 315 eFG 83 efG 10 What is the distance from locus E to locus G?
19.4 map units
Assuming complete dominance, what is the phenotypic ratio of the offspring of the cross AaBb x aabb?
1:1:1:1
Which of the following phenotypic F2 ratios suggests incomplete dominance?
1:2:1
In a mammal, how many inactivated X chromosomes (Barr bodies) would be present in the somatic cells of individuals who were XXX?
2
In a diploid species where N=10, how many chromosomes would a trisomic individual have?
21 (2n+1)
Three brothers have blood types A, B, and 0. What are the chances that the parents of these three will produce a fourth child whose blood type is AB?
25%
A testcross of an F1 dihybrid in petunia gave the following results: round leaf, pink flower 75 round leaf, white flower 25 lanceolate leaf, pink flower 25 lanceolate leaf, white flower 75 What is the distance (in map units) between the locus for leaf shape and the locus for flower color?
25.0
Sickle cell anemia is the most common inherited disorder of individuals of African descent. It is a recessive autosomal disorder. Consider that two individuals are both carriers of this disorder. If they have four children, what is the probability that one child is affected and the other three are not affected?
27/64 This question is not specifying an order, so all the various orders/ways this could happen do have to be considered. There are four different orders if you write them all out: affected, normal, normal, normal normal, affected, normal, normal normal, normal, affected, normal normal, normal, normal, affected Calculate the probability of each order. For the first one, this would be 1/4 x 3/4 x 3/4 x 3/4 = 27/256 If you find the probability of each one, all will individually be 27/256. Then you will need to add all of those together. So, 27/256 + 27/256 + 27/256 + 27/256 =108/256 which reduces down to 27/64
Consider a diploid species where N = 22. How many chromosomes would be present in a monosomic individual?
43 2N-1
If two genes are located on different chromosomes, what would you expect their recombination frequency to be? ___ %
50
What is the maximum recombination frequency between any two genes? ___% Enter only a number/numeral in the provided box.
50
Flower color in carnations displays incomplete dominance. There are two alleles involved in determining whether the flowers are red, pink or white. Plants that display red flowers and plants that display white flowers are both homozygous. Plants that display pink flowers are heterozygous. If two plants with pink flowers are crossed, what percentage of the offspring are expected to have pink flowers?
50%
The maximum recombination frequency between two genes is
50%
The offspring of two parents that are heterozygous for a given trait have a ______ chance of being homozygous for that trait.
50%
What would be the recombination frequency between two genes located 65 map units apart?
65%
Consider this cross: AaBBCcDdEeff x aaBbCcDdeeFf What is the probability of an offspring having the dominant phenotype for all 6 genes?
9/128
Cystic fibrosis is the most common inherited disorder of individuals of European descent. It is a recessive autosomal disorder. Consider that two individuals already had one child afflicted with cystic fibrosis. What is the probability that their next 2 children will not have this disorder?
9/16
Four genes (A, B, C, D) are known to be located on the same chromosome. A series of crosses was completed to determine the recombination frequencies: A-B 46% A-C 16% A-D 38% B-C 30% B-D 8% C-D 22% Based on these numbers, what is the correct order of the genes on the chromosome?
ACDB/BDCA
Gregor Mendel is credited with the Law of Segregation. Select all of the statements that are part of this law:
An individual's two factors/alleles will separate from each other during gamete formation. Correct! Each individual contains two factors/alleles for each trait. Correct! If there are two different factors/alleles present, then one factor will be dominant and one factor will be recessive.
Consider an individual with the genotype DdEE. Select all of the following gametes that are possible from this individual.
DE dE
Which of the following events explains why the two genes in a dihybrid cross assort independently?
Each tetrad lines up along the meiosis metaphase I plate separately from the other tetrads.
A 9:3:3:1 phenotypic ratio is characteristic of the
F2 generation of a dihybrid cross.
In a certain plant, blue flowers are dominant to yellow flowers, and short-stalked plants are dominant to long-stalked plants. Consider that a blue-flowered plant with a short stalk is crossed with a yellow-flowered plant that has a long stalk. The results of this cross are as follows: Offspring appearance: Number of offspring: Blue flowers, short stalk 85 Blue flowers, long stalk 376 Yellow flowers, short stalk 392 Yellow flowers, long stalk 77
How many recombinant offspring were produced? 162 What is the recombination frequency between the flower color gene and the stalk length gene? 17.4 Are these genes linked? yes
In humans, males are XY and females are XX. The abnormal combinations of XXY and XYY are also male, while the combinations of X and XXX are female. Based on this information, which of the following statements about human sex determination must be true?
If even one Y is present, the organism will always be male.
Which statements are true concerning linked genes? Select all that apply.
Linked genes always reside on the same chromosome. The greater the physical distance between genes, the greater the recombination frequency between them will be.
What is the difference between polyploidy and aneuploidy?
Polyploids have extra copies of every single chromosome, while aneuploids may have an extra copy of just one chromosome.
In humans, hemophilia A is inherited as an X-linked recessive trait. If a man and a woman produce a daughter who is afflicted with this disorder, which of the following must be true? Select all that apply.
The daughter inherited a recessive gene from each parent. The mother must be heterozygous. The father is also afflicted with hemophilia. The mother is a carrier of hemophilia.
Suppose that flower color is controlled by a single gene designated with the letter F/f. The yellow color is dominant to white. What would be the genotype and phenotype of a heterozygous plant?
The genotype would be Ff and the phenotype would be yellow.
In humans, hemophilia A is inherited as an X-linked recessive trait. If a man and a woman produce a son who is afflicted with this disorder, which of the following must be true?
The mother carries the allele for hemophilia A. If the son inherited the allele for hemophilia A, he must have inherited it from his mother. This is because sons inherited their Y chromosome from their father. Fathers do not pass their X chromosome on to their sons.
The following data were collected on 1000 progeny (i.e. offspring) from a testcross of a dihybrid: De 382 DE 111 de 106 dE 401 From this data, what is the genetic map distance between loci D and E?
The recombinant offspring would be the ones with the lower numbers: DE 111 de 106 If you add these together (217) and then divide by the total (1000), you get 21.7%. Each % is equal to 1 m.u., so 21.7% = 21.7 m.u.
Each gene may have a variety of alleles. What makes these alleles different from each other?
The specific nucleotide sequence.
In humans, free/unattached earlobes are dominant to attached earlobes. Suppose that a man and woman both have free earlobes, but both of them had one parent with attached earlobes. Based on the expected inheritance patterns, what would the couple's four children look like?
Three children will have free earlobes and one will have attached earlobes.
The sex of a child is dictated by the inheritance of:
a single Y or X chromosome from the father
A man who carries an X-linked allele will pass it on to
all of his daughters.
Errors during what phases of meiosis are responsible for the production of aneuploids? Select all that apply.
anaphase II anaphase I
When an organism gains or loses one or more chromosomes but not a complete haploid set, the condition is known as
aneuploidy
What type of inheritance refers to genes that are located on a chromosome other than a sex chromosome?
autosomal
Which represents the genotype of a homozygous condition?
bb
A human male carrying an allele for a trait on the X chromosome is:
hemizygous
The presence or absence of a widow's peak (pointed hairline) is controlled by a single gene in humans. If two individuals that both have widow's peaks have ten children that all have widow's peaks, what would be the logical genotype of the parents?
homozygous dominant
Genes for two different traits that are located next to each other on the same chromosome would most likely be
inherited together
Homologous chromosomes contain the same ___.
loci.
Consider that a couple of mixed ancestry have several children, and all of the children vary widely in their skin coloration. Some children are much lighter and some children are much darker in coloration. What is the simplest explanation for this observation?
polygenic inheritance
Dimples in one or both cheeks are due to a dominant gene (D). What are the possible phenotypes of offspring from parents who both have dimples?
some offspring could have dimples and others no dimples.
The basic diploid chromosome number in pumpkins is 16. A new species of pumpkin is found that has four complete sets of the chromosomes found in the 16 chromosome species. This species is said to be
tetraploid
In a paternity suit, a woman with type O blood claims that a man is the father of her child. The child has type O blood. If the suspected father has type A blood, you conclude that:
the defendant may be the father, but so could another male
Two genes could not exhibit linkage in genetic crosses if:
they are near the opposite ends of the chromosome. the rate of recombination between them is 50%. they are on different chromosomes. they are 150 map units apart on the same chromosome.
