Gentics Quiz 1, 2, 3

Genetics is defines as the branch of biology associated with

heredity and variation

The observation feature of an organism is referred to as a

phenotype

A primary discovery to generate recombinant DNA molecules was the use of

restriction enzymes

Organism that are well understood from a scientific standpoint and are often used in basic biological research are often called 

model organisms 

Which of the following is incorrect?

homologous chromosomes contain identical genetic information

Which of the following is not a source of genetic variation in meiosis?

polar body formation

The event referred to as disjunction occurs during

anaphase

During meiosis, chromosome number reduction takes place in

anaphase I

Assuming a typical monohybrid cross in which one allele is completely dominant to the other, what phenotypic ratio is expefcted if the F1s are

3:1

Mendel crossed two pear plants with round seeds. All seeds of the offspring were round. He then crossed a plant with round seeds to a plant with wrinkled seeds, and all offspring had wrinkled seeds. Which of the following is true? 

wrinkled is dominant 

The process that leads to the development of haploid games is best described as 

segregation 

A cross between two individuals with different phenotypes that resulted in approximately 50% of each type of offspring would indicate the cross was 

a heterozygous dominant crossed to a homozygous recessive 

Which of the following postulates was not attainable from a monohybrid cross?

independent assortment

Which of the following describes the product law?

The probability of two or more independent events occurring simultaneously is equal to the product of their individual probabilities

Which phenotypic ratio is likely to occur in crosses of two completely dominant, independently segregating gene pairs when both parents are fully heterozygous?

9:3:3:1

What is independent assortment? 

during gamete formation, a pair of unit factors segregates randomly from another pair of unit factors 

When performing a dihybrid cross fot the traits round/wrinkled and yellow/green, which of the following results best demonstrates that the unit factors from each trait was assorting independently? 

finding a 3:1 ratio of round: wrinkled and a 3:1 ratio of yellow: green in the F2 generation

Which types of phenotypic ratios are likely to occur in a trihybrid cross when dealing with three gene pairs with the dominant and recessive alleles for which all the genotypic combinations are of equal viability if both parents are heterozygous for all three traits? 

27:9:9:9:3:3:3:1

How many different possible gametes can be obtained from an organism with the following genotype AaBbCc?

8

According to Mendel’s model, because of the _______ of chromosomes during meiosis, all possible combinations of gametes will be formed in equal frequency? 

independent assortment 

A mutation in a gene that results in a loss of a functional product of that gene best defines what type of mutation?

null

Assume that a cross is made between two organisms that are both heterozygous for a gene that shows incomplete dominance. What phenotypic and genotypic ratios are expected in the offspring? 

1:2:1, 1:2:1

The MN blood group is a codominant trait as a result of which of the following?

presence of both M and N cell surface glycoproteins on the same blood cell

What is the proability of having a child with the N blood type, if both parents are MN?

1/4

Which of the following is not a characteristic of the ABO gene locos?

epistatis

A condition in which one gene pair masks the expression of a nonallelic gene pair is called 

epistatsis

The phenomenon of a gene which has multiple phenotypic effects on an individual is referred to as

pleiotropy

What is the difference between incomplete dominance and codominance?

in codominance, both phenotypes are expressed in a heterozygous. In incomplete dominance the heterozygous show a phenotype that is intermediate between the two homozygotes 

Why can multiple alllelism be studies only in populations? 

any individual diplooid organism can have, at most, two homologous loci that can carry different alleles 

Which of the following statements is always true when mutations occur in genes whose products are essential to an organism’s survival? 

the homozygous recessive is a lethal combination