Engineering Questions with Answers - Multiple Choice Questions

MCQs on Genes, Chromosomes and Genomes – 2

1 - Question

. In FISH technology, which fluorescence confirms a BCR/ABL translocation?
a) Red signal
b) Green signal
c) Yellow signal
d) Orange signal

View Answer

Answer: c
Explanation: In FISH, the green signal indicates presence of the BCR gene and the red signal indicate the presence of the ABL gene. The red-green fusion (yellow) signal confirms a BCR/ABL translocation

2 - Question

The nucleosome is composed of how many histone proteins?
a) 7
b) 9
c) 8
d) 10

View Answer

Answer: b
Explanation: The nucleosome is composed of 8 histone proteins known as Histone Octamer and a separate H1 protein. The histone proteins present are two H2A, two H2B, two H3 and two H4 proteins along with a single H1 protein. The DNA strand wounds around the DNA Octamer to produce a nucleosome unit.

3 - Question

An example of extensively polyploid organism is _________
a) Xenopus laevis
b) Homo sapiens
c) Drosophila melanogaster
d) Equus caballus

View Answer

Answer: a
Explanation: Polyploidy means having more than 2 sets of each chromosome. Polyploidy can occur as a genetic disorders (such as Down’s Syndrome). Polyploidy which is not caused by genetic disorder is common in plants (eg. Banana) and amphibians( Xenopus sp.).

4 - Question

Hybrid vigour is referred to __________
a) superior phenotype of a hybrid
b) increased fertility of a hybrid
c) increased mortality of a hybrid
d) decreased function of a hybrid

View Answer

Answer: a
Explanation: Hybrid vigour is the phenomenon of increased vigour in the hybrids as compared to both of its parents. This phenomenon came to light in the 20th century in corn F1 hybrids. The resulting hybrid plant had a higher growth rate, was phenotypically superior and had increased yield as compared to both the parents.

5 - Question

Hybrid vigour results from ____________
a) dominance
b) co-dominance
c) over dominance
d) incomplete dominance

View Answer

Answer: c
Explanation: In case of dominance, the expression of dominant allele masks the expression of recessive allele. In co-dominance, both the alleles are equally expressed. In over dominance, the combination of genotypes from two different parents leads to supplementing the effect of each other and thus the effects lead to increased vigour.

6 - Question

Application of non-ionizing ultraviolet radiation causes _________
a) formation of pyrimidine dimers
b) deletion of pyrimidine bases
c) formation of methyl guanine
d) formation of methyl thymine

View Answer

Answer: a
Explanation: During application of UV rays, as photons are absorbed by DNA molecules, an excited state is produced which allows for the rearrangement of electrons resulting in the formation of photoproducts.These photoproducts are cyclobutane pyrimidine dimer (CPD) and 6-4 pyrimidine –pyrimidone, both of which are pyrimidine dimers.

7 - Question

During translation of proteins, the aminoacyl tRNA arrives at ____________
a) Ribosomal A site
b) Ribosomal P site
c) Ribosomal T site
d) Ribosomal S site

View Answer

Answer: a
Explanation: During translation, the aminoacyl tRNA carrying the desired amino acid approaches the A site on the ribosome. It then further moves to the P site and becomes peptidyl tRNA, which initiates the formation of a peptide bond between the amino acid and the growing peptide chain. The peptidyl tRNA leaves through the E site of ribosome.

8 - Question

Which of the following is a consensus sequence?
a) Promoter sequence
b) Enhancer sequence
c) Terminator sequence
d) All of the mentioned

View Answer

Answer: d
Explanation: Consensus sequence is the most common version of conserved gene sequence which has minute variations from gen to gene. A promoter sequence, enhancer sequence and terminator sequence of a particular gene is conserved and are consensus sequences.

9 - Question

Which of the following is the start codon in protein translation?
a) AUG
b) UAA
c) UAG
d) UGA

View Answer

Answer: a
Explanation: The start codon indicates the start of protein translation after the 5’-untranslated region (UTR) and the ribosome binds to the start codon in the mRNA. AUG is the sole start codon and codes for the amino acid Methionine. UAA, UAG and UGA are the three stop codons that indicate the termination of protein translation.

10 - Question

What is the approximate fraction of genetic variation in the nuclear genome that is expected to have a harmful effect on gene function?
a) 50%
b) 25%
c) 10%
d) 1%

View Answer

Answer: d
Explanation: Genetic variation due to mutation causes harmful effects on gene function. Ad low as 1% genetic variation can cause noticeable harmful changes the expression and function of genes. It may lead to congenital diseases or may be fatal.

11 - Question

Which of the following statements is correct according to Chargaff’s rules?
a) All DNA molecules contain the same proportions of A, C, G and T
b) Single-stranded RNA molecules contain the same amount of A and U
c) In double-stranded DNA, the amount of T equals the amount of C
d) In double-stranded DNA, the amount of G equals the amount of C

View Answer

Answer: d
Explanation: Chargaff rule states that the amount of A is equal to the amount of T whereas the amount of C is equal to the amount of G. This is because during base pairing, A binds with T with two hydrogen bonds and C binds with G with three hydrogen bonds.

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