Free Plant Breeding and Genetics MCQs with Answers
329 Plant Breeding and Genetics MCQs from Agriculture, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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329 questions · page 9 of 17
- A. Backcross
- B. Hybridization
- C. Test cross
- D. Biohybrid
Explanation: A backcross is made by crossing a hybrid with either of its parents to recover or study parental traits.
Correct answer: Backcross- A. Phenotype
- B. Genotype
- C. Allele
- D. Genome
Explanation: Genotype means the genetic constitution of an organism, whereas phenotype means its observable characteristics.
Correct answer: Genotype- A. Mecrosome
- B. Disome
- C. Episome
- D. Peroxisome
Explanation: An episome is a genetic element that can occur either independently in the cytoplasm or integrated into a chromosome.
Correct answer: Episome- A. Affects more than five characters
- B. Affects more than ten characters
- C. Affects only one character
- D. Affects more than one character
Explanation: The term is generally written pleiotropic gene, meaning one gene influences more than one character.
Correct answer: Affects more than one character- A. The failure of homologous chromosomes to separate during meiosis
- B. The crossing over between non homologous chromosomes
- C. Occurrence of karyokinesis
- D. Occurrence of crossing over
Explanation: Failure of chromosome separation can produce unreduced gametes, and their fusion may create polyploid plants.
Correct answer: The failure of homologous chromosomes to separate during meiosis- A. 1:2
- B. 1:1
- C. 2:1
- D. 3:1
Explanation: The cross TT × tt produces all Tt tall plants in F1; selfing them gives F2 genotypes TT:Tt:tt = 1:2:1. Thus pure tall TT to dwarf tt is 1:1.
Correct answer: 1:1- A. Confers
- B. Mosses
- C. grasses
- D. Gymnosperm
Explanation: Grasses are flowering plants and represent a relatively recent evolutionary group compared with mosses and gymnosperms.
Correct answer: grasses- A. Cross breeding
- B. Inbreeding
- C. Self fertilization
- D. Back crossing
Explanation: A test cross determines an unknown genotype by crossing the individual with a homozygous recessive; this is a special type of backcross.
Correct answer: Back crossing169. Presence of slight differences in identical twins support the hypothesis that___________________?
- A. Single gene may produce multiple effects
- B. The environment effects the expression of genetic character
- C. Dominance may be incomplete
- D. Genetic trails are influence by many genes
Explanation: Identical twins have essentially the same genotype, so differences between them show that environmental conditions can alter the…
Correct answer: The environment effects the expression of genetic character- A. 12
- B. 24
- C. 22
- D. 23
Explanation: With a haploid number of 12, the diploid number is 24; a monosomic has one chromosome fewer, so its number is 2n − 1 = 23.
Correct answer: 23- A. Dominant lethal genes in heterozygous individuals
- B. Dominant lethal genes in homozygous individuals
- C. Dominant epistasis
- D. None of the above
Explanation: A 2:1 surviving phenotypic ratio results when the homozygous dominant genotype is lethal: the usual 3:1 ratio loses one lethal class.
Correct answer: Dominant lethal genes in homozygous individuals- A. Incomplete dominant
- B. Recessive
- C. Mutant
- D. Dominant
Explanation: When the heterozygote Rw is pink rather than red, neither allele completely masks the other, which is incomplete dominance.
Correct answer: Incomplete dominant- A. There are many alleles of each gene in each call
- B. There are two alleles of each gene in each cell
- C. There is only one alleles of each gene present in each cell
- D. Non3e4 of the above
Explanation: A haploid cell has only one allele of each gene, so a mutation cannot be hidden by a second normal allele and is expressed whether it…
Correct answer: There is only one alleles of each gene present in each cell- A. Heterogeneous
- B. Homozygous
- C. Homogenous
- D. Heterozygous
Explanation: White offspring from red-flowered parents show that each red parent carried a hidden white allele, so the parents were heterozygous.
Correct answer: Heterozygous- A. One pair of gene can completely mask the expression of another gene pair
- B. Many gene together control a parucular phenotype
- C. One gene pair enhances phenotype expression of another gene pair
- D. One gene pair independently controls a phenotype
Explanation: Epistasis occurs when one gene or gene pair masks the expression of another gene or gene pair.
Correct answer: One pair of gene can completely mask the expression of another gene pair- A. Mathis
- B. Mendel
- C. Darwin
- D. Haldane
Explanation: Thomas Malthus proposed that populations tend to increase faster than the food supply, an idea that influenced Darwin's theory of natural…
Correct answer: Mathis- A. Watson
- B. Crick
- C. Morgan
- D. Koruna
Explanation: Har Gobind Khorana is associated with molecular genetics and recombinant-DNA-related advances; “Koruna” is evidently a misspelling of…
Correct answer: Koruna- A. Phenotypic ratio corresponds to the genotypic ratio
- B. Ratio of genotypes is 3:1
- C. Ratio of phenotypes is 3:1
- D. None of the above
Explanation: With incomplete dominance, the heterozygote has its own intermediate phenotype, so the three F2 genotypes produce three phenotypes in the…
Correct answer: Phenotypic ratio corresponds to the genotypic ratio- A. Incomplete
- B. All the above
- C. Over dominance
- D. Complete dominance
Explanation: Reciprocal recurrent selection improves two populations using their cross-performance and can exploit additive as well as dominance…
Correct answer: All the above- A. Incompatible
- B. Partially fertile
- C. Fully fertile
- D. Sterile
Explanation: Avena sativa and Avena byzantina are both hexaploid oats with essentially the same A, C and D genome constitution.
Correct answer: Fully fertile