Practice Questions

TLS Online TPP Program

#Question id: 5128

During lens formation in the Xenopus, the following statements have been proposed. Which statement is incorrect?

#Unit 5. Developmental Biology

Expression of Pax6 protein may constitute the competence of the surface ectoderm to respond to the optic vesicle during the late neurula stage.
The optic vesicle secretes BMP and FGF family paracrine factors that induce the synthesis of the Sox transcription factors and initiate lens formation.
If Pax6 is lost, whether it is in fruit flies, frogs, rats, or humans, it results in a complete loss or reduction of the eyes.
If Pax6 is lost, still lens formation takes place in presence of Sox2 and L-maf.

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TLS Online TPP Program

#Question id: 5278

#Unit 8. Inheritance Biology

What is the co-transduction frequency for the A and B genes, from the following dataset?(Assume that there has been selection for the A+ form of the A gene). Genotype Number

A+B+C+ 10

A+B+C- 30

A+B-C+ 20

A+B-C- 40

TLS Online TPP Program

#Question id: 5279

#Unit 8. Inheritance Biology

In a transduction experiment, phage P1 is grown on a bacterial host of genotype A+ B+ C+ and the resulting lysate is used to infect a recipient strain of genotype A– B– C–. The genes are in an order such that B is in the middle, and the distance between A and B is greater than the distance between B and C. Based on this information, which of the following least genotype?

TLS Online TPP Program

#Question id: 5280

#Unit 8. Inheritance Biology

In the mating Hfr met- his+ leu+ trp+ × F- met+ his- leu- trp-. The met marker is known to be transferred very late. After a short time, the mating cells are interrupted and the cell suspensions plated on four different growth media. The amino acids in the growth media and the number of colonies observed on each are as follows:

histidine + tryptophan 250 colonies

histidine + leucine 50 colonies

leucine + tryptophan 500 colonies

histidine 10 colonies

What is the order of transfer of the genes

TLS Online TPP Program

#Question id: 5281

#Unit 8. Inheritance Biology

In the mating Hfr Strs met+ his+ leu+ trp+ Ala+ X F- Strres met- his- leu- trp- Ala-. At regular interval time, the mating cells are interrupted and the cell suspensions plated on four different growth media with streptomycin. The amino acids in the growth media and the number of colonies observed on each are as follows:

Interrupted time	Composition of media					Growth
	His	Leu	Ala	Trp	Met
2 min	+	-	+	+	+	Yes
10 min	+	-	-	+	+	Yes
12 min	+	-	-	+	-	No
15 min	+	-	-	-	+	Yes
20 min	-	-	-	-	+	Yes

What is the order of transfer of the genes?

TLS Online TPP Program

#Question id: 5282

#Unit 8. Inheritance Biology

Conjugation allowed between Hfr with genotype A B C D E and F- with genotype a b c d e. At regular intervals, a sample of cells was removed and agitated

vigorously in a kitchen blender to halt all conjugation and DNA transfer. After interrupted conjugation, ex-conjugate were selected on minimal media at regular interval and find different number of ex-conjugate?

abCde - 10, abCdE - 30 , aBCdE - 40 , ABCdE - 20 , ABCDE - 50

What is gene order of those genes?

TLS Online TPP Program

#Question id: 5283

#Unit 8. Inheritance Biology

A generalized transducing phage is used to transduce an a- b- c- d- e- recipient strain of E. coli with an a+ b+c+d+ e+ donor. The recipient culture is plated on various media with the results shown in the table below What can you conclude about the linkage and order of the genes?