EXAM 4- AGR3303 True/False
Assuming normal distribution, the mean +/- 2 standard deviations should include approximately how much of the total measurements?
95%
At a locus of two alleles A and a, the genotypic frequencies in teh Hardy-WEinberf population, after random mating, are expected to be p2, pq, q2
False
The components of phenotypic variance include only genetic variance and environmental variance
False, also have G value?
An X-linked recessive trait is never seen in females.
False, can have both copies
Affected people with an autosomal dominant trait have 100% chance to pass the trait to their kids
False, depends on if theyre AA or Aa
Heritability indicates the degree to which a characteristic is genetically determined
False, does not indicate degree, but it is a variation proportion ratio
If we know the recombination frequency of two linked genes, we can predict the outcomes of crosses with the two linked genes
False, for you to make the outcome, you need to know whether its coupling or repulsion and the recombination frequency
Odd number of crossover evens between two genes can't be detected in the test cross
False, its an even number
Some linked genes can exhibit recombination frequencies of more than 50%
False, maximum 50%, never above this
X-linked recessive traits can be passed from father to son
False, needs mother also
When heritability is high, environmental factor will not influence character
False, no matter how high environment could influence
The cellular reason for X-inactivation is to reduce the amount of nondisjunction during meiosis
False, not really related to x-inactivation
Three-point test crosses are only informative when both parents are true-breeding
False, on is heterozygote and one is homo recessive
The higher the coefficient of coincidence, the higher the crossover interference
False, opposite relationship always
One centriMorgan (cM) is one map unit and 100% recombination frequency
False, should be 1% recombination frequency
At Hardy-Weinberg equilibrium, the allele frequencies do not change from generation to generation, while genotypic frequencies can increase or decrease from generation to generation
False, the genotypic frequency will stabilize and not change
Height in all organisms is always a continuous trait
False, the height is qualitative not quantitative
Recombination of different alleles of different genes can only occur through crossing over
False, the recombination can also happen through independent assortment!!
Linked genes are allelic
False, they are not allelic
The X and Y chromosomes are named after their characteristic shape
False, they are not named after that
X and Y chromosomes can't pair and segregate into different cells in meiosis
False, they can pair 5%
Completely linked genes on the same chromosome can show independent assortment
False, they do not show independent assortment
Linked genes segregate independently
False, they don't
The condition XXXY is always lethal in humans
False, this can be a condition
Absence of Y chromosome in humans is lethal and results in embryo abortion
False, this is Turner Syndrome
Recombination frequencies can be predicted by a chi-square test
False, this is calculated by the amount of recombinants, chi square has to do with independent assortment
For the X-linked recessive traits, normally there are more females than males affected
False, this is males
As the number of loci affecting a character increases, the number of phenotypic classes in the F2 decreases
False, this is opposite
A Y-linked trait is always passed from a father to a son
True
A chromosome map shows the linear order of gene loci present on a chromosome and the relative distances between them.
True
A normal human female heterozygous for two X-linked alleles usually express only one of those alleles in any given cell in her body
True
A testcross includes one parent that is homozygous recessive for all gene loci being examined
True
A woman with normal color vision must be a carrier (heterozygote) if she has a father who is color blind
True
Autosomal recessive traits often appear to "skip" generation
True
Barr body is an inactivated X-chromosome visible in the nucleus of a cell in female mammals
True
Both autosomal recessive and dominant traits appear equally in males or females
True
Coupling and repulsion phases can result in the same phenotypes of the offspring but in very different numbers
True
Crossovers on chromosomes are frequently not independent events. The interference occurs when one crossover inhibits another
True
For the X-linked dominant trait, affected fathers normally pass the trait to daughters, but will not pass the trait to sons
True
Genotypic and allelic frequencies of samples from a population are used to represent the gene pool of the population
True
Heritability is used to estimate what proportion of a traits variance in a population is genetic variance
True
In a cross between a white-eyed female fruit fly and red-eyed male, will produce all red-eyed females and white eyed-males
True
In humans SRY is the male determining gene
True
In humans, there are about 5% pseudoautosomal regions at both tips of the X and Y chromosomes
True
Linked genes with a low recombination frequency are closer than genes with higher recombination frequency
True
Most continuously varying characteristics are both polygenic and influenced by environmental factors
True
Random mating is an important assumption in Hardy-Weinberg law
True
Standard deviation is calculated in the same units as the original measurements while variants is calculated in units squared
True
Temperature during embryonic development determines sex in reptiles like turtles and alligators.
True
The heritability of an individual cannot be estimated
True
When both parents are heterozygous for an autosomal recessive trait, 1/4 of their children will inherit the trait
True
When narrow-sense heritability is high for a particular trait, offspring tend to resemble their parents for that trait
True
Which statement is true for quantitative traits? a. Quantitative traits are normally influenced by multiple genes b. Quantitative traits are normally influenced by environmental factors. c. Quantitative traits are those for which multiple genes contribute in an equal and additive way to the phenotype. d. All of the above are true. e. a and b are true
a and b are true
Suppose that researchers estimate that broad-sense heritability of IQ in Sweden is 0.8. Which of the following conclusions is (are) valid, assuming that the estimate is accurate? a. Most variance for IQ in Sweden is due to total genetic variance. b. In Sweden, the environment does not play a role in determining the IQ of individuals. c. Enriching the environment of poor children in Sweden would not lead to improvement on IQ tests. d. Broad-sense heritability of IQ in the United States probably is close to 0.8.
a. Most variance for IQ in Sweden is due to total genetic variance.
If broad-sense heritability for a trait is very high and narrow-sense heritability is very low, which of the following must be true? a. Additive variance must be high relative to total phenotypic variance. b. Dominance variance must be high relative to total phenotypic variance. c. Environmental variance must be high relative to total phenotypic variance. d. Genotypic-environmental covariance must be high relative to total phenotypic variance.
b. Dominance variance must be high relative to total phenotypic variance
The estimated broad-sense heritability for milk production in a herd of dairy cattle is high. Which is a valid inference? a. Most of the variation in milk production in the herd is due to additive genetic variance within the herd. b. Most of the variation in milk production in the herd is due to dominant genetic variance. c. Little of the variation in milk production is due to environmental variation within the herd. d. Broad-sense heritability for milk production will be high in most other herds of dairy cattle.
c. Little of the variation in milk production is due to environmental variation within the herd.
Knowing the __________ of a trait has great practical importance because it allows statistical predictions regarding the phenotypes of offspring to be made on the basis of the parents' phenotypes. a. variance b. inbreeding coefficient c. heritability d. genotype
c. heritability
Heritability: a. is universal for a given trait. b. is the degree to which a specific trait is genetically determined. c. is specific for a given population in a specific environment. d. can be used as a quantitative measure of genetic differences between two populations.
c. is specific for a given population in a specific environment.
Suppose that pumpkin weight is controlled by five unlinked loci, each with two segregating alleles (A/a, B/b, C/c, D/d, E/e) that have additive effects. What fraction of the F2 offspring from a cross of AABBCCDDEE and aabbccddee parents are expected to have the same weight phenotype as the aabbccddee parent? a. 1/4 b. 1/10 c. (1/2)^5 d. (1/4)^5
d. (1/4)^5
______________ can cause a single genotype to produce a range of potential phenotypes. a. Epistasis b. The inbreeding coefficient c. Hybrid vigor d. Environmental effects e. Heritability
d. Environmental effects
Two highly inbred tobacco plants are crossed. One has dark green leaves. The other has yellow leaves. The F1 have light green leaves. Six hundred progeny from F1 ´ F1 crosses are analyzed. Their leaves show continuous variation in color, but none has dark green or yellow leaves. What do these data suggest about the number of genes determining this trait? a. There are 2 genes that determine this trait. b. There are 3 genes that determine this trait. c. There are 4 genes that determine this trait. d. There are more than 4 genes that determine this trait.
d. There are more than 4 genes that determine this trait.
A series of experiments shows that oil content in a diploid grain is influenced by five genes (a through e) with additive alleles. The highest producing strain is 20% oil content; the lowest has close to 0%. A plant of unknown genotype has an oil content of 12%. What is a possible genotype for this plant? (+ = additive alleles) a. a+a+b+b+c+c+d+de+e b. a+a+b+b ccddee c. a+a+b+bccddee d. aab+bc+cd+d+e+e+
d. aab+bc+cd+d+e+e+
