Ch 20 Practice Flashcards
A diagram that uses sperms genotypes on one side and egg genotypes on the other side to predict the genotypes of offspring is called a ______ ______.
Punnett square
If a male exhibits a sex-linked trait, the allele for the trait came from the mother and resides on the ______.
X chromosome
Phenotype
The physical appearance of a trait (e.g., blue eyes)
Genotype
The specific combination of alleles an individual is born with
Alternate forms of a gene are called ______.
Allele
______ alleles require two copies to be present in order to exert their effect.
Recessive
An organism with a ______ genotype carries two identical alleles for a given gene.
Homozygous
For each gene, an individual inherits ______ allele(s) with ______ being contained in the sperm and ______ being contained in the egg.
2, 1, 1
If neither parent is affected by an autosomal dominant disorder, what percentage of their children will be affected?
0; Both parents possess the recessive traits.
What are the characteristics of polygenic phenotype?
- Alleles have additive effects on phenotype
- Phenotype variation appears continuous
- The phenotype can be influenced by the environment
How many copies of a damaged allele must be present for a recessive genetic disease to be expressed?
2
The specific genes or combination of alleles for a trait is called an individual’s ______.
Genotype
A person who is heterozygous for an autosomal recessive disorder and shows the dominant phenotype is called a(n) ______.
Carrier
All combinations of alleles are possible in the gametes because the ______ align independently during meiosis.
Chromosomes
How many traits are being considered in a dihybrid cross?
2
The position of a gene on a chromosome is called its ______.
Locus
______ occurs when one gene affects multiple, seemingly unrelated traits.
Pleiotropy
An individual with one recessive allele and one ______ allele has a heterozygous genotype.
Dominant
An individual hat inherits two copies of the same form of a gene from his or her two parents has a ______ genotype.
Homozygous
A genetic system in which alleles are equally expressed in a heterozygote is called ______.
Codominance
Sickle-cell disease is an example of which type of condition?
Autosomal recessive disorder
A genetic system in which a heterozygous individual displays a phenotype intermediate between that of an individual homozygotic for either allele is called ______ ______.
Incomplete dominance
In simple one-trait crosses, one gene affects one trait. In ______ inheritance, multiple genes govern a trait, and in ______, one gene affects many traits.
Polygenic, pleiotropy
The ______ allele of a gene is represented with an uppercase letter.
Dominant
An Ff x Ff cross is an example of:
A monohybrid cross
