Question

 

QUESTION 71

Most forms of cancer are caused by

		The presence of two or more active copies of X chromosome in the genome.
		exposure to environmental mutagens and infection by certain viruses.
		exposures to cold temperature.
		paternally inherited mutant alleles of mitochondrial genes only.
		adopting liberal ideas.

  

QUESTION 72

Which description is the best definition of a stem cell?

		A type of blood cell that does not have a nucleus, mitochondria or any other organelle.
		A type of highly specialized lymphocyte which functions in adaptive immunity.
		A cell that synthesizes autocrine signals and divides in an uncontrolled manner
		A cell that metastasizes to other organs.
		An undifferentiated cell that can differentiate into various types of cells when needed.

QUESTION 73

Which biotech method requires the use of the reverse transcriptase enzyme?

		Therapeutic cloning
		Genetic tarnsformation of planbts using Agrobacterium vectors
		Pre-implantation diagnosis
		Construction of a cDNA library.
		Reproductive cloning

QUESTION 74

In eukaryotes, RNA processing of a pre-mRNA to create a mature mRNA includes

		Removal of introns
		Ligating exons together into continuous RNA strand
		Addition of a poly A tail at the 3´-end of the RNA
		Addition of the methylated G-cap at the 5â -end of the RNA
		All of the above.

  

QUESTION 75

Genomic imprinting is

		Suppression of a mutant phenotype because of a mutation in a different gene
		Inactivation of a gene by interruption of its coding sequence
		Organization of molecules in the cytoplasm to provide positional information
		A mechanism by which enhancers distant from the promoter can still regulate transcription
		The process of sex-specific DNA methylation during the formation of mammalian sperm and egg cell that differentially affects gene expression in the zygote.

QUESTION 76

When cells are exposed to DNA-damaging radiation (such as UV light), the p53 protein _______ the repair of the damaged DNA, and ________the transition from G1 to S phase to allow time for the DNA damage to be repaired.

		induces; halts
		inhibits, induces
		inhibits; halts
		induces; induces
		All of the above is totally incorrect.

  

QUESTION 77

Familial Down syndrome is a result of which of the following?

		Inversion
		meiotic nondisjunction
		DNA methylation
		Gene duplication
		Translocation

QUESTION 78

Eastern Europeans like to feast on smoked meats. Those first-generation Americans of Eastern European descent who adopt the North America diet have a much lower rate of stomach cancer than those who maintain their traditional old-country diet. This suggests that cancer is

		primarily inherited, but the hemisphere of Earth on which people live influences cancer rate.
		primarily inherited, but the Earthâ s magnetic field influences cancer rates
		primarily inherited, and diet and other environmental factors have no influence on cancer rates
		caused by environmental factors, therefore diet strongly influences cancer rate
		caused by regularly listening to people with heavy Easter European accent in 50-min intervals.

QUESTION 79

Pericentric inversion occurs when a chromosomal segment is

		translocated from one chromosome to its homologous pair.
		broken off and lost forever.
		translocated from one chromosome to an entirely different non-homologous chromosome.
		broken off, ligated back to its original chromosome in an opposite orientation and it contains the centromere.
		broken off and ligated back to its original chromosome in two copies in the proper orientation.

  

QUESTION 80

The phenomenon in which a gene determines a trait only under certain environmental circumstances (for example, below a certain temperature) but not under other conditions, is described as

		Pleiotropy
		Codominance
		Conditional phenotype
		Gene interaction
		Expressivity

Answer 1

Answer :

71)

Exposure to environmental mutagens and certain viruses.

Environmental mutagens include UV radiation, radioactive particles, certain chemicals etc.

Example of cancer causing virus is Epstein barr virus.

72)

A stem cell is An undifferentiated cell that can differentiate into various types of cells when needed.

There are different stem cells. Most used now a days are embryonic stem cells, stem cell extracted from blood, bone marrow etc.

73)

Construction of a cDNA library.

cDNA library is created from mature mRNA from a eukaryotic cell.

So it requires reverse transcriptase.

74)

All of the choices are correct.

This is called post transcriptional modifications.

Introns dont code anything. So the are spliced. Exons are coding part and are glued.

75)

Genomic imprinting is the process of sex specific DNA methylation during formation of mammalian sperm and ovumthat differentially affect gene expression in zygote.

DNA methylation is done to silence a specific sequence.

There is maternal imprinting and paternal imprinting.

76)

P53 induce repair and halt G1/S transition.

P53 is tumour suppressor gene. They help to avoid error in DNA Processing.

77)

Translocation.

Translocation Down's is generally called familial down's syndrome.

78)

Caused by environmental factors and diet strongly influences cancer rate.

There is genetic predisposition and environmental factors. Stomach cancer has got a good association with smoked meat.

79)

Include breakage and ligated back to its original chromosome in a reversed manner. This includes centromere.

In paracentric inversion centromere is not present.

80)

Conditional phenotype.

This occurs in mutation.

Only under certain environmental factors the mutation is expressed.