Free Gene Linkage and Crossing Over MCQs with Answers

• A. close together on the same chromosome
• B. on different chromosomes or far apart on the same one
• C. both recessive
• D. both on the X chromosome

Explanation: Independent assortment comes from the random orientation of different homologous pairs at metaphase I, so it requires the genes to be on…

• A. allelic
• B. linked
• C. homologous
• D. codominant

Explanation: All the genes on one chromosome form a linkage group, and the number of linkage groups in a species equals its haploid chromosome number.

• A. metaphase I
• B. anaphase I
• C. prophase I
• D. telophase II

Explanation: During the pachytene stage of prophase I the homologues are paired as bivalents, and non sister chromatids exchange equal segments at…

• A. 10 map units
• B. 1 map unit
• C. 90 map units
• D. 100 map units

Explanation: One map unit, or centimorgan, is defined as a recombination frequency of one per cent, so ten per cent recombinants means ten map units…

• A. keeps linkage groups permanently intact
• B. halves the chromosome number of the gametes
• C. ensures that all gametes are genetically identical
• D. produces new combinations of alleles on the same chromosome

Explanation: Exchange between non sister chromatids creates chromosomes carrying combinations of alleles that neither parent had, and this…

• A. The genotype of a dominant phenotype individual
• B. The number of chromosomes
• C. Mutation rates
• D. Linkage groups

Explanation: A test cross between an individual showing dominant phenotype and a homozygous recessive reveals whether the dominant is homozygous or…

• A. Complete dominance only
• B. Incomplete dominance
• C. Codominance and multiple alleles
• D. Sex linkage

Explanation: ABO system shows codominance (IA and IB both expressed in AB) and multiple alleles (IA, IB, i).

• A. Increases with distance on chromosome
• B. Decreases with distance
• C. Is unaffected by distance
• D. Only occurs on sex chromosomes

Explanation: Linkage decreases with distance; genes farther apart cross over more frequently. 1% recombination = 1 map unit.

• A. Genetic drift
• B. Small population
• C. Gene linkage
• D. Gene duplication

Explanation: Independent assortment requires the two genes to be on different chromosomes, so genes linked on the same chromosome travel together and…

• A. Duplication of chromosome
• B. Exchange of genes between non-sister chromatids
• C. Movement of chromosome to opposite poles
• D. Separation of sister chromatids

Explanation: During prophase I the homologues pair as bivalents and non sister chromatids exchange equal segments at chiasmata, producing chromosomes…

• A. 02
• B. 23
• C. 46
• D. 92

Explanation: All the genes on one chromosome form a single linkage group, and the number of linkage groups equals the haploid chromosome number, which…

• A. 7
• B. 67
• C. 85
• D. All

Explanation: Morgan studied about 85 inherited traits and mutations in Drosophila, using them to investigate genes, chromosomes and linkage.

• A. 1811
• B. 1927
• C. 1911
• D. 1990Educational Resources

Explanation: Crossing over was first observed and reported in 1911, during early genetic studies of linked genes and chromosome exchange.

• A. 2
• B. 4
• C. 5
• D. None of these

Explanation: Genomic mapping is commonly divided into two main types: genetic mapping, based on recombination frequency, and physical mapping, based on…

• A. Length of the chromosome
• B. Physical linkage between them
• C. Protein content of the chromosome
• D. Distance between the linked gene loci

Explanation: The correct answer is the 'distance between the linked gene loci.' Recombination frequency is a measure of how often crossing over occurs…

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Crossing over during meiosis involves the exchange of genetic material between homologous chromosomes, leading to new combinations of…

• A. Are linked on homologous chromosomes
• B. Have a wide range of phenotypes
• C. Are codominant
• D. Are pleiotropic

Explanation: The correct answer is that the alleles for body color and wing length are linked on homologous chromosomes.

• A. 46
• B. 22
• C. 80
• D. 23

Explanation: This phenomenon of staying together of all the genes of a chromosome is called linkage.

• A. Genetic recombination
• B. Mutation
• C. Meiosis
• D. Gene linkage

Explanation: Gene linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of…

• A. Recombination of genes
• B. New trait into species
• C. Reduction in number of chromosomes
• D. Segregation of genes

Explanation: Is correct as In genetics, the term "crossing over" refers to the exchange of genetic material between homologous chromosomes that occurs…