lecture - genetics Flashcards
(25 cards)
If both alleles of a particular gene are identical, the person is said to be
homozygous.
heterozygous.
homologous.
polygenic.
homozygous.
Flower color in a plant species is controlled by a single gene with alleles that display incomplete dominance. If a plant with red flowers that is homozygous dominant is crossed to a plant with white flowers that is homozygous recessive, the color of the offspring flowers will be expected to be
all pink.
all red.
all white.
red and white
all pink.
The trend toward increased height and weight due to improved nutrition in certain human populations is an example of the effect of ________ on phenotypes.
the environment
codominance
polygenic inheritance
gene linkage
the environment
A pregnant woman elects to undergo an amniocentesis and it is found that her fetus contains trisomy 21. What is the diagnosis?
Correct answer:
Down syndrome.
Turner syndrome
Trisomy X
Cri-du-chat syndrome
down sydrome
If the two alleles of a particular gene pair are the same, the individual is ________ for that gene.
homozygous
heterozygous
homologous
haploid
homozygous
true or false: Alleles are alternative versions of chromosomes.
false
true or false:A Punnett square can be used to determine possible phenotypic ratios of offspring given a particular combination of parental alleles.
true
A composite display of an individual’s chromosomes is known as a(n) ________.
karyotype
genotype
pedigree
phenotype
karyotype
In a cross between one homozygous recessive male and one homozygous dominant female, all of the offspring will be
heterozygous.
homozygous.
male.
Cannot determine with the information given.
heterozygous.
An example of a genotype is
homozygous dominant.
green eyes.
brown hair.
attached earlobes.
homozygous dominant.
What is the difference between genotype and phenotype?
Genotype is the genetic makeup; phenotype is the observable characteristic.
Define “Dominant Allele”
An allele that masks the expression of a recessive allele in a heterozygote.
Define “Recessive Allele”
An allele that is masked by a dominant allele in a heterozygote.
What is “Incomplete Dominance”?
The heterozygote phenotype is intermediate between the two homozygous phenotypes.
What is “Codominance”?
Both alleles are fully expressed in the heterozygote.
What is “Polygenic Inheritance”?
A trait controlled by multiple genes.
How can the environment affect phenotype?
Environmental factors can influence gene expression.
What is a karyotype used for?
To visualize chromosomes and detect abnormalities.
What is Trisomy? Give an example.
Having an extra copy of a chromosome. Example: Down syndrome (Trisomy 21)
What is Monosomy? Give an example.
Missing a copy of a chromosome. Example: Turner syndrome (XO).
Define “Locus”
The specific location of a gene on a chromosome.
In a monohybrid cross of two heterozygotes (Aa x Aa), what is the expected phenotypic ratio if A is dominant?
3:1 (3 dominant phenotype : 1 recessive phenotype)
State the Law of Segregation
Allele pairs separate during gamete formation
State the Law of Independent Assortment
Genes for different traits assort independently during gamete formation
