This set of Marine Biotechnology Questions and Answers for Entrance exams focuses on “Fish Genetics – Broodstock Development – Set 3”.
1. Inbreeding in fish does not lead to ____________________
a) increased size
b) reduced growth rate
c) less survival
d) susceptibility to disease
View Answer
Explanation: Inbreeding in fish leads to greater homogeneity in fish genome leading to elevated effect of harmful genes in most cases. This results in reduced growth rate, reduced size, less survival, and higher susceptibility to diseases.
2. Heterosis occurs in all cases of intraspecific crossbreeding of fish.
a) True
b) False
View Answer
Explanation: Heterosis is the phenomena where the offspring have varied and better phenotypic characteristics than the parents. In case of fish this does not always occur. Exhibition of heterosis are the basis of carp culture in Vietnam, China, Israel and Hungary.
3. Interspecific breeding can lead to production of ______________ offspring.
a) low quality
b) sterile
c) slow growing
d) low meat quality
View Answer
Explanation: Interspecific breeding takes place when two strains of a particular species are bred. The results of interspecific hybridization are almost always positive. To enhance growth rate sterile animals are produced using this technique.
4. _________________ is the cross between white bass and striped bass.
a) Channel catfish
b) Sunshine bass
c) Sea bass
d) Moon light bass
View Answer
Explanation: Sunshine bass is the product of interspecific breeding between white bass (Morone chrysops) and striped bass (Morone saxitillis). The sunshine bass grows faster as compared to the parents.
5. Which is not a method of manipulation ploidy level in fish?
a) Sperm inactivation
b) Heat shock
c) Chemical treatment
d) Changing pH
View Answer
Explanation: Ploidy is defined on the basis of number of chromosome sets in a cell. This can be changed by inactivation of sperm/egg before in vitro fertilization, heat shock, and chemical treatments.
6. _____________________ fish are sterile
a) Triploid
b) Tetraploid
c) Haploid
d) Diploid
View Answer
Explanation: Triploid fish are sterile and can be used for ecological testing of various environmental pollutants. Triploids can be produced through retention of second polar body in eggs during meiosis II.
7. Hybrid triploids grow faster than hybrid diploids.
a) True
b) False
View Answer
Explanation: Hybrid triploids grow at least 1.5 times faster than the hybrid diploids because the energy required for gonadal development is diverted towards body growth. Triploids are also used to assess the effect of environmental parameters before the introduction of an exotic species in an area.
8. Compared to diploids, physiological reactions are less in tetraploids because of _________________
a) more number of cells
b) less number of cells
c) low GC content
d) high GC content
View Answer
Explanation: The genome set (in a single cell) is double that of diploids, in tetraploids. The number of cells however is less which leads to lower physiological interactions and cellular metabolism in tetraploids.
9. Match the options given below.
| 1. Androgenesis | a. hormonal injection |
| 2. Gynogenesis | b. all maternal inheritance |
| 3. Hyphophysation | c. all paternal inheritance |
a) 1-b 2-a 3-c
b) 1-b 2-c 3-a
c) 1-c 2-b 3-a
d) 1-a 2-b 3-c
View Answer
Explanation: Androgenesis is the production of individuals that contain only paternal contribution in their genetic material while gynogenesis produces individuals with all maternal inheritance.
10. Which is not a method of sperm inactivation in gynogenesis?
a) Gamma-irradiation
b) X-ray inactivation
c) DMSO-inactivation
d) PBS-inactivation
View Answer
Explanation: In gynogenesis the sperms are inactivated before in vitro fertilization of fish eggs. This leads contribution of only maternal genetic material in the formation of embryo. Phosphate buffered saline is a buffer and does not inactivate the sperm.
11. In aquaculture ___________________ is used in marker assisted selection.
a) transgenes
b) reporter genes
c) molecular markers
d) bio-synthetic gene clusters
View Answer
Explanation: Molecular markers are used in marker-assisted selection (MAS) of aquaculture species. Type-I molecular markers are the genes with known function while type-II markers are the unknown genomic segments.
12. Which of the following is the correct option?
| i. Type-I markers | a. SNPs |
| ii. Type-II markers | b. Microsatellites |
| c. ESTs |
a) a-i b-i c-ii
b) a-ii b-ii c-i
c) a-ii b-i c-ii
d) a-i b-ii c-i
View Answer
Explanation: Single nucleotide polymorphisms (SNPs) are type-ii markers because they are products of unknown genes unlike expressed sequence tags (ESTs). Microsatellites are segments of unknown genes.
13. Hardy-Weinberg principle is associated with _________________
a) allele frequencies
b) mutations
c) heterosis
d) homozygosity
View Answer
Explanation: In population genetics, the Hardy-Weinberg principle states that allele and genotype frequencies remain constant in a population provided there are no environmental alterations/ pressures.
14. The polymorphism information content (PIC) is the value of a __________________
a) marker
b) reporter gene
c) enhancer
d) micro-RNA
View Answer
Explanation: The polymorphism information content value is a measure of informativeness of a genetic marker. Genetic markers are used for linkage studies, in species identification, and population genetics.
15. ________________ are simple sequence repeats of 1-6 bases in length.
a) Microsatellites
b) Minisatellites
c) siRNA
d) miRNA
View Answer
Explanation: Microsatellites are tandemly arranged simple sequence repeats (SSRs) of 1-6 base pairs in length. These genomic segments occur as often as every 10 kbps in fish and therefore used as molecular markers.
Sanfoundry Global Education & Learning Series – Marine Biotechnology.
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