Meselson and Stahlʹs experiments involved growing E. coli on a medium containing 15N (heavy nitrogen) which increased the density of the bacterial DNA. Cells were then grown on a medium containing only 14N. DNA samples were obtained for analysis after one, two and three rounds of replication (generations) and centrifuged on a density gradient. The double-helical DNA forms bands in the gradient depending on its density. How many bands did Meselson and Stahl see after two generation of cells were grown on the 14N medium?

#Question id: 3593

#Unit 8. Inheritance Biology

In the cross Aa Bb Cc Dd X Aa Bb Cc Dd, in which all genes undergo independent assortment, what proportion of offspring are expected to be at least one heterozygous for locus gene?

#Question id: 3594

#Unit 8. Inheritance Biology

following different cross allowed and their respective phenotype.

Which of the following observation conclude correct mode of dominance?

#Question id: 3595

#Unit 8. Inheritance Biology

Ranch mink with the dark gray coat color known as Aleutian is homozygous recessive aa. Genotypes AA and Aa have the standard deep brown color. A mating of Aa  X Aa produces  four  pups. What is the probability of a perfect 3 : 1 distribution of standard to Aleutian?

#Question id: 3596

#Unit 8. Inheritance Biology

Which of the following correct regarding test cross?

a) A testcross tests reveals the genotype of the individual

b)  Test cross detect linkage between gene

c) Same genotype and phenotype ratio present in test cross progeny

d) Phenotype ratio of test cross used to determine mode of inheritance either complete dominance or incomplete dominance

#Question id: 3597

#Unit 8. Inheritance Biology

In a family of four children, what is the probability of obtaining the following numbers of boys and girls?

(a) All boys(b) All children of the same sex(c) two girls and two boy(d) three boys and one girls

#Question id: 3598

#Unit 8. Inheritance Biology

Mendel crossed, round tall pea plants RRTT with wrinkle dwarf rrtt. The F1 plants were all round tall. These F1 plants were selfing, following genotype are selected from F2 generation

A- RrTT       B- RrTt        C- RRtt 

Which of the following decreasing frequency of this genotype?