Chapter 14: Genetics Flashcards
What is a character?
The heritable feature that varies among individuals
What is a trait?
Each variant for a character such as a color
What is hydridization?
Two contrasting varieties that breed
What is the p generation?
The true breeding parents
What is the f1 generation?
The hybrid offspring of the p generation
What are alleles?
The alternative versions of a gene
How many alleles does an organism inherit?
2 from each parent
What is the dominant allele?
Determines the organisms appearance
What is the recessive allele?
The allele that has no noticeable appearance on organism
What is the law of segregation?
The two alleles for a heritable character separate during gamete formation and end up in different gametes
What are monohybrids?
Heterozygous for one character
What is a mono hybrid cross?
A cross between heterozygous
What is the law of independent assortment?
each pair of alleles segregates independently of each other pair of alleles during gamete formation
What is complete dominance?
When phenotypes of the heterozygous and dominant homozygote are identical
What is incomplete dominance?
When the phenotype of f1 hybrids is somewhere between the phenotypes of two parental varieties
What is codominance?
Two dominant alleles affect the phenotype in separate ways
What are carriers?
Heterozygous individuals who carry recessive alleles but are phenotypically normal
What do we mean when we use the terms monohybrid cross and dihybrid cross?
A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
Traits are inherited in discrete units and are not the results of “blending.”
How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
8
The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?
different possible assortment of chromosomes into gametes
Mendel continued some of his experiments into the F2 or F3 generation to _____.
observe whether or not a recessive trait would reappear
Which of the following statements about independent assortment and segregation is correct?
The law of independent assortment requires describing two or more genes relative to one another.
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
HT
Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that
traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1
The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following?
All of the genes controlling the traits behaved as if they were on different chromosomes.
Mendel’s observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?
anaphase I of meiosis
Mendel’s second law of independent assortment has its basis in which of the following events of meiosis I?
alignment of tetrads at the equator
Why did the F1 offspring of Mendel’s classic pea cross always look like one of the two parental varieties?
One allele was dominant
