Free Animal Breeding and Genetics MCQs with Answers

• A. 1 red:2 roan:1 white
• B. 3 red:1 white
• C. 1 red:1 roan
• D. 2 roan:1 white

Explanation: Each roan parent produces R and W gametes in equal numbers. Their offspring are expected in the genotypic ratio RR:RW:WW of 1:2:1, giving…

• A. Sex-linked trait
• B. Sex-limited trait
• C. Sex-influenced trait
• D. Y-linked trait

Explanation: Sex-limited traits are controlled by genes present in both sexes but expressed in only one sex.

• A. Genetic drift
• B. Inbreeding depression
• C. Correlated response to selection
• D. Phenotypic plasticity

Explanation: A correlated response occurs when selection for one trait changes another genetically correlated trait.

• A. Incomplete dominance
• B. Pleiotropy
• C. Linkage
• D. Epistasis

Explanation: Epistasis is interaction between genes at different loci, where one locus affects the expression of another.

• A. Unbalanced gametes during meiosis
• B. Excessive mutation in somatic cells
• C. Complete loss of all chromosomes
• D. Permanent suppression of gene expression

Explanation: During meiosis, a translocation heterozygote may form gametes with duplicated or deleted chromosome segments.

• A. Simple phenotypic ranking
• B. Best linear unbiased prediction
• C. Random mating analysis
• D. Microsatellite exclusion testing

Explanation: Best linear unbiased prediction, or BLUP, uses records from several sources while accounting for systematic environmental effects.

• A. The sire's chromosome number
• B. The calf's own genotype only
• C. Maternal care and milk production
• D. Random environmental mutation

Explanation: Maternal genes can affect traits such as weaning weight through milk yield, mothering ability, and the uterine environment.

• A. The number of offspring per mating
• B. Only the animal's visible phenotype
• C. The average age of its herd
• D. Genome-wide DNA marker information

Explanation: Genomic selection uses many DNA markers distributed across the genome to predict breeding values before extensive performance or progeny…

• A. Mating related animals
• B. Mating unrelated animals
• C. Randomly sampling sires
• D. Crossing different breeds

Explanation: Related animals are more likely to carry copies of the same ancestral allele, so mating them increases homozygosity and the expression of…

• A. A neutral environmental effect
• B. An antagonistic genetic correlation
• C. A Mendelian segregation ratio
• D. A chromosome counting error

Explanation: An antagonistic genetic correlation means improvement in one trait is genetically associated with deterioration in another.

• A. Additive effects only
• B. Environmental effects only
• C. Additive, dominance and epistatic effects
• D. Maternal effects only

Explanation: Broad-sense heritability is the proportion of phenotypic variance due to total genetic variance.

• A. DNA replication
• B. Protein synthesis
• C. Fertilisation
• D. Gamete formation

Explanation: The two alleles at a locus separate during meiosis, so each gamete normally receives one allele.

• A. Animals rank differently across environments
• B. Genes change their DNA sequence in each environment
• C. Environmental variance becomes zero
• D. All animals show the same phenotype

Explanation: Genotype by environment interaction means genetic performance depends on the environment.

• A. A sex-linked trait
• B. A polygenic trait
• C. A monogenic trait
• D. A mitochondrial trait

Explanation: Polygenic traits are influenced by many genes and usually show continuous variation, as seen in growth, milk yield and fertility.

• A. Sire's sperm
• B. Both parents equally
• C. Dam's ovum
• D. Male Y chromosome

Explanation: The ovum contributes most of the cytoplasm and mitochondria to the embryo, so mitochondrial genes are usually inherited maternally.

• A. 25 percent
• B. 50 percent
• C. 75 percent
• D. 100 percent

Explanation: Unlinked loci, or loci far apart on the same chromosome, can show a maximum recombination frequency of 50 percent.

• A. Heterozygosity and performance
• B. Homozygosity and performance
• C. Mutation rate and fertility
• D. Chromosome number and growth

Explanation: Inbreeding increases homozygosity and can expose harmful recessive alleles, reducing traits such as fertility, survival and growth.

• A. Close breeding
• B. Outcrossing
• C. Self-fertilisation
• D. Linebreeding

Explanation: Outcrossing involves mating animals that are not closely related, often within the same breed, and helps maintain genetic variation.

• A. A very large effective size
• B. High artificial selection only
• C. A small effective size
• D. Complete random mating only

Explanation: Genetic drift is random change in allele frequency and is strongest when the effective population size is small.

• A. It estimates environmental temperature effects
• B. It measures only the animal's physical size
• C. It records only the number of offspring
• D. It ranks animals using several sources of information

Explanation: A selection index combines information on several traits or records using economic and genetic relationships to rank animals for…