ASRB NET - Agricultural Statistics (and Computer Application / Bioinformatics) · India · Agricultural Scientists Recruitment Board (ICAR)
Original practice questions written to the published syllabus · not past papersGenetics as a statistical science: segregation and linkage analysis, gene and genotype frequencies, Hardy-Weinberg and the forces that change it, polygenic models, breeding value and dominance, partitioning genetic variance, correlation between relatives and inbreeding. The Veterinary track teaches animal-genetics principles; this goes to the estimation theory.
In the exams: AICE-JRF Ag Stat Unit 3 (heavy: every unit named); ASRB NET Ag Stat (heavy); AICE-JRF Genetics & Plant Breeding (present)
ASRB NET / ARS Agricultural Statistics
The same theory with emphasis on estimation and interpretation.
How our questions for ASRB NET spread across the units of Statistical Genetics: Population & Quantitative Genetics. Difficulty: 13 easy, 55 medium, 21 hard.
| Selection, mutation, migration and their equilibria | 10 | |
| Detection and estimation of linkage | 9 | |
| Polygenic systems: breeding value, dominance, average effect and epistasis | 9 | |
| Regular systems of inbreeding and their effects | 9 | |
| Estimation of heritability, repeatability and genetic correlation | 9 | |
| Statistical analysis of segregation ratios | 8 | |
| Gene and genotypic frequencies; Hardy-Weinberg equilibrium | 8 | |
| Disequilibrium due to linkage and sex-linked genes | 8 | |
| Correlation between relatives | 7 | |
| Fisher's fundamental theorem of natural selection | 6 | |
| Partitioning of genetic variance | 6 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
What map distance does Kosambi's function give for r = 0.15?
C. 15.5 cM
d = (1/4) ln(1.3/0.7) = 0.155 M = 15.5 cM.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
Pooling subpopulations with different allele frequencies gives:
A. An excess of homozygotes
This is the Wahlund effect: pooled subpopulations show fewer heterozygotes than HWE predicts.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
For an X-linked recessive with q = 0.1, what fraction of females is affected?
D. 0.01
Females need two copies: q^2 = 0.01; males are affected at q = 0.1.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
X-linked allele frequencies are 0.6 in females and 0.3 in males. What is the frequency in males next generation?
D. 0.6
Males receive X from mothers: 0.6. Females become (0.6 + 0.3)/2 = 0.45.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
What is the mutation-selection equilibrium for a deleterious recessive?
C. q = sqrt(u/s)
For a dominant deleterious allele p = u/s.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
Robertson's secondary theorem gives the change in a trait mean as:
A. Additive covariance with fitness
It links natural selection to the breeder's equation.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
Why does the average effect depend on allele frequencies?
C. Substitutions change different genotypes
Rare A mainly converts aa to Aa (a + d); common A converts Aa to AA (a - d).
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
How does better experimental design affect heritability on a plot basis?
B. It raises it by reducing error
Smaller environmental variance raises sigma^2 G / sigma^2 P.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
What is the additive relationship between half sibs?
C. 0.25
Twice the coancestry (1/8).
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
Which covariance matrix of breeding values is used in BLUP?
B. A sigma^2 A
A is the numerator relationship matrix.
Further reading: Falconer and Mackay, Introduction to Quantitative Genetics; Hartl and Clark, Principles of Population Genetics
Ten here, 89 in the app. The Laisha app has every practice question we have written to ASRB NET in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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