biology 3 Genetics

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genes located close together on the same chromosome are refereed to as _________genes and generally _______

linked.....do not sort independently during meiosis

in tomatoes, cut-leaf shape (C) is dominant over potato-leaf shape (c), and purple stem (P) is dominant over green stem (p). In the table below, the result of mating producing an F1 is given:
Purple-cut:1790 purple-potato:620
Green-cut:623 Green-potato:22

PpCc X PpCc

in humans, the _____________ determines the sex of the offspring because __________

male....the male can contribute either an X or Y chromosome

the expression of both alleles for a trait in the heterozygous individual is

codominance

one gene is found to code for a ceratain structural protein. In homozygous recessive individuals, a defective allele results in poor development of cartilage between bones (and thus sore joints), droopy skin (due to insufficient collagen formation), and a weak underdeveloped nose (lack of cartilage). This phenomenon would be best clasified as

pleiotropy

GgTt pea plants can produce ___________type(s) of gametes, but a ggtt can produce __________type(s) of gametes

two....one

which of the following is not true?

Incomplete dominance supports the blending hypothesis

a carrier of a genetic disorder who does not show symptoms is most likely to be ______ to transmit it to offspring

heterozygous for the trait and able

in humans, skin color ranges from almost white to very dark brown along a very gradual continuum. this is primarily due to genetics and is linked to several independent genes. what types of pattern of inheritance describes this?

polygenic inheritance

Mendel's principle of independent assortment states that

each pair of alleles segregates independently during gamete formation

in sheep, eye color is controlled by a single gene with two alleles. when a homozygous brown eyed sheep is crossed with a homozygous yellow-eyed sheep, tan-eyed offspring are produced. if the tan-eyed sheep are mated with each other, what percent of their offspring will most likely have brown eyes?

25%

which of the following is not true?

the hybrid offspring of a cross are the P1 generation

which of the following terms refer to the situation where a single phenotypic characteristic is determined by the additive effects of two or more genes

polygenic inheritance

jane knows she is a carrier for Tay Sachs disease ( a recessive autosomal disorder), but has no idea whether her husband is. they want to know what the odds of having a chile with the disease will be. given that the incidence of carriers for Tay Sachs is 1/30, and it is homozygous recessive genetic disorder, what are the odds that her chill will have Tay Sachs Disease.

1/120

which of the following is not true of pedigree

it uses molecular genetics techniques to determine genetic relationships

assuming that the probability of having a female child is 50% and the probability of having a male child is also 50%, what is the probability that the couple's first born child is female and second-born child a male.

25%

which one of the following is an example of incomplete dominance in humans

hypercholesterolemia

the vast majority of people afflicted with recessive disorders are born to parents who were

not affected at all by the disease

the chromosome theory of inheritance states that

the behavior of chromosomes during meiosis and fertilization accounts for patterns of inheritance

in general, the frequency that crossing over occurs between two linked genes depends on

how far apart they are on the chromosome

in peas, the trait for tall plants is dominant (T) and short is recessive (t). The trait for yellow seed color is dominant (Y) and green is recessive (y). A cross between the two plants resulted in 296 tall yellow plants and 104 tall green plants. Which of the following are most likely the genotypes of the parents

TtYy X TTYy

both aminocentesis and chorionic villus sampling allow for __________ and ________of the fetus so that it can be tested for abnormalities

karyotyping.....biochemical testing

which of the following kinds of data could be used to map the relative position of three genes on a chromosome

the frequencies with which the corresponding traits occur together in offspring

how might a lethal dominant allele avoid elimination from a population of people

1) by being non-lethal in a heterozygous form
2) by arising later in life

many genetic disorders of humans are caused by

recessive alleles

imagine that beak color in a finch species is controlled by a single gene. you mate a finch homozygous for orange (pigmented) beak with a finch homozygous for ivory (unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of

incomplete dominance

recessive sex-linked human conditions include which of the following

red-green color blindness, muscular dystrophy, and hemophilia

using a six-sided die, what is the probability of rolling either a 5 or 6

1/6 +1/6=1?3

what is the normal complement of a sex chromosome in human males

on X chromosome and on Y chromosome

why are sex-linked condition more common in men than in women

men need inherit only one copy of the recessive allele for the condition to be fully expressed

Dr.Smiths parents have normal hearing. however dr.smith has an inherited form of deafness. deafness is a recessive trait that is associated with the abnormal allele d. the normal allele at this locus, associated with normal hearing, is D. smiths parents could have which of the following genotypes

Dd and Dd

which of the following is not true

an allele that is always expressed is referred to as recessive

Huntington's disease is due to an autosomal dominant allele. if a heterozygous male marries a normal female, what percentage of offspring will have huntingtons

50%

which of the following best explains why dominant alleles that cause lethal disorders are less common than recessive alleles that cause lethal disorders

most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce

what is meant by the statement that "male bees are fahterless"

male bees develop from unfertilized eggs

alleles of a gene are found at ________

chromosomes

how many sex chromosomes are in a human gamete

one

what is a testcross

a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest

in a cross of a purple-flowered, short-stemmed plant with a yellow-flowered, long-stemmed plant, the expected phenotypic ration is 1 purple-short:1 purple long: 1 yellow short:1 yellow long. when you do the actual cross you observe a 5 purple short:1 purple long:1 yellow short:5 yellow long phenotypic ratio which of the following explains these results.

the genes are linked

which set of parents could NOT be the parents of a child with type O blood

father type AB, mother type O

a couple had five children, all sons. if the woman gives birth to a sixth child, what is the probability that the sixth child will be a son

1/2

several inherited disorders are much more common in close-knit religious communities, such as the Amish, than in the general population. this is at lest party due to the fact that _______

people in such communities are more likely to marry relatives

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