Topic: Hybridization
Subtopic: Interspecific Hybridization
Keyword Definitions:
• Interspecific hybridization: Mating between two different but related species.
• Breed: Group of animals with similar characteristics and common ancestry.
• Species: Group of organisms capable of interbreeding to produce fertile offspring.
• Hybridization: Crossing individuals to produce offspring with desired traits.
• Superior males and females: Individuals selected for their desirable genetic traits.
Lead Question - 2016 (Phase 2):
Interspecific hybridization is the mating of :
(1) More closely related individuals within same breed for 4-6 generations
(2) Animals within same breed without
(3) Two different related species
(4) Superior males and females of different breeds
Explanation: Interspecific hybridization refers to the mating of two different but related species, aimed at combining beneficial traits from both species. This process leads to offspring with mixed genetic features and can be used in agriculture and animal husbandry to improve productivity. Correct answer is (3) Two different related species.
1. Single Correct Answer MCQ:
What is the primary purpose of interspecific hybridization?
(1) Increase inbreed traits
(2) Combine desirable traits from two species
(3) Preserve pure species
(4) Select superior individuals of the same species
Explanation: Interspecific hybridization is primarily done to combine desirable traits from two different species, such as disease resistance and productivity. Correct answer: (2) Combine desirable traits from two species.
2. Single Correct Answer MCQ (Clinical-type):
Interspecific hybridization may cause:
(1) Enhanced genetic diseases
(2) Heterosis (hybrid vigor)
(3) Complete infertility always
(4) No genetic changes
Explanation: Interspecific hybridization often leads to heterosis, or hybrid vigor, where offspring perform better than parents, though sometimes infertility may occur. Correct answer: (2) Heterosis (hybrid vigor).
3. Single Correct Answer MCQ:
Which of the following is NOT an example of interspecific hybridization?
(1) Mule (horse × donkey)
(2) Liger (lion × tiger)
(3) Hybrid maize (corn × corn)
(4) Triticale (wheat × rye)
Explanation: Hybrid maize involves cross between varieties of the same species, not interspecific hybridization. Correct answer: (3) Hybrid maize (corn × corn).
4. Single Correct Answer MCQ:
Interspecific hybrids are often:
(1) More fertile
(2) Always sterile
(3) Sometimes sterile or fertile
(4) Genetically identical to parents
Explanation: Interspecific hybrids can be fertile or sterile depending on species compatibility; mules are sterile but some plant hybrids are fertile. Correct answer: (3) Sometimes sterile or fertile.
5. Single Correct Answer MCQ:
An example of interspecific hybrid in plants is:
(1) Wheat
(2) Triticale
(3) Corn
(4) Rice
Explanation: Triticale is a hybrid of wheat and rye, combining traits from both species. Correct answer: (2) Triticale.
6. Single Correct Answer MCQ:
What is a common problem in interspecific hybridization?
(1) Increased disease resistance
(2) Uniform traits
(3) Hybrid sterility
(4) Faster growth
Explanation: A frequent challenge in interspecific hybridization is hybrid sterility due to genetic incompatibility between the parent species. Correct answer: (3) Hybrid sterility.
7. Assertion-Reason MCQ:
Assertion (A): Interspecific hybridization is between different species.
Reason (R): It allows combining favorable traits of both species.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true
Explanation: Interspecific hybridization combines favorable traits of two species to produce offspring with improved traits. Correct answer: (1) Both A and R are true and R explains A.
8. Matching Type MCQ:
Match Column – I with Column – II:
A. Mule
B. Triticale
C. Liger
D. Hybrid maize
1. Horse × Donkey
2. Lion × Tiger
3. Wheat × Rye
4. Corn × Corn
Options:
(1) A-1, B-3, C-2, D-4
(2) A-3, B-1, C-4, D-2
(3) A-1, B-2, C-3, D-4
(4) A-4, B-3, C-2, D-1
Explanation: Correct pairings: A-1 Mule (Horse × Donkey), B-3 Triticale (Wheat × Rye), C-2 Liger (Lion × Tiger), D-4 Hybrid maize (Corn × Corn). Correct answer: (1) A-1, B-3, C-2, D-4.
9. Fill in the Blanks MCQ:
Interspecific hybridization combines genes from ________ to improve traits.
(1) Same species
(2) Related species
(3) Different families
(4) Unrelated species
Explanation: Interspecific hybridization involves two related species to combine beneficial genes. Correct answer: (2) Related species.
10. Choose the Correct Statements MCQ:
Select correct statements about interspecific hybridization:
(1) Used in plant and animal breeding
(2) Always produces fertile offspring
(3) Combines traits from two species
(4) May result in hybrid sterility
Options:
(1) 1, 3, and 4 only
(2) 1 and 2 only
(3) 2 and 3 only
(4) All statements correct
Explanation: Statements 1, 3, and 4 are correct; hybrid sterility is common. Correct answer: (1) 1, 3, and 4 only.
Topic: Mendelian Genetics
Subtopic: True Breeding and Hybridization
Keyword Definitions:
• True Breeding: Plants that are homozygous for a trait and consistently produce offspring with the same trait.
• Homozygous: Having identical alleles for a specific gene.
• Heterozygous: Having two different alleles for a specific gene.
• Cross-pollination: Transfer of pollen between flowers of different plants.
• Self-pollination: Transfer of pollen within the same flower or plant.
• Hybrid: Offspring resulting from the cross of two genetically different plants.
Lead Question - 2016 (Phase 2):
A true breeding plant is:
(1) Always homozygous recessive in its genetic constitution
(2) One that is able to breed on its own
(3) Produced due to cross-pollination among unrelated plants
(4) Near homozygous and produces offspring of its own kind
Explanation: A true breeding plant is nearly homozygous and consistently produces offspring of the same phenotype when self-pollinated. It is not necessarily recessive and is distinct from hybrids obtained via cross-pollination. Correct answer: (4) Near homozygous and produces offspring of its own kind.
1. Single Correct Answer MCQ:
A plant homozygous for tallness crossed with a homozygous dwarf plant produces:
(1) All tall offspring
(2) All dwarf offspring
(3) 1:1 ratio of tall and dwarf
(4) 3:1 ratio of tall and dwarf
Explanation: Crossing a homozygous tall (TT) with a homozygous dwarf (tt) produces all heterozygous tall (Tt) offspring, displaying the dominant tall phenotype. Correct answer: (1) All tall offspring.
2. Single Correct Answer MCQ:
Which of the following is characteristic of a homozygous recessive plant?
(1) Produces only dominant traits
(2) Produces only recessive traits
(3) Produces variable offspring
(4) Cannot produce seeds
Explanation: A homozygous recessive plant has two identical recessive alleles, producing only recessive phenotype offspring when self-pollinated. Correct answer: (2) Produces only recessive traits.
3. Single Correct Answer MCQ (Clinical-type):
Consanguineous mating in humans is analogous to:
(1) Cross-pollination
(2) Hybridization
(3) Self-pollination
(4) Mutation
Explanation: Consanguineous mating, or reproduction within closely related individuals, increases homozygosity, similar to self-pollination in plants. It can lead to higher incidence of recessive genetic disorders. Correct answer: (3) Self-pollination.
4. Single Correct Answer MCQ:
A hybrid plant is produced by:
(1) Self-pollination
(2) Cross-pollination of two different true breeding plants
(3) Vegetative propagation
(4) Mutation
Explanation: Hybrid plants are produced by cross-pollination of two true breeding plants with contrasting traits, combining genetic material to form heterozygous offspring. Correct answer: (2) Cross-pollination of two different true breeding plants.
5. Single Correct Answer MCQ:
Which of the following will always breed true?
(1) F1 hybrids
(2) Heterozygotes
(3) Homozygous plants
(4) Polyploid plants
Explanation: Homozygous plants have identical alleles for all traits and will produce offspring with the same phenotype, breeding true over generations. Correct answer: (3) Homozygous plants.
6. Single Correct Answer MCQ:
Self-pollination in true breeding plants ensures:
(1) Increase in heterozygosity
(2) Uniform offspring
(3) Hybrid vigor
(4) Genetic variability
Explanation: Self-pollination in true breeding (homozygous) plants maintains genetic uniformity, producing offspring identical to parents and preserving specific traits. Correct answer: (2) Uniform offspring.
7. Assertion-Reason MCQ:
Assertion (A): True breeding plants are homozygous for most traits.
Reason (R): Homozygous plants produce offspring identical to themselves.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true
Explanation: True breeding plants are homozygous, which ensures they produce identical offspring. The reason directly explains the assertion. Correct answer: (1) Both A and R are true and R explains A.
8. Matching Type MCQ:
Match plant types with their characteristics:
A. True breeding
B. Hybrid
C. Homozygous dominant
D. Heterozygous
1. Produces uniform offspring
2. Produced by cross-pollination of two different plants
3. Carries identical dominant alleles
4. Carries two different alleles
Options:
(1) A-1, B-2, C-3, D-4
(2) A-2, B-1, C-4, D-3
(3) A-3, B-4, C-1, D-2
(4) A-4, B-3, C-2, D-1
Explanation: True breeding (A-1), Hybrid (B-2), Homozygous dominant (C-3), Heterozygous (D-4). These associations clarify plant breeding types. Correct answer: (1) A-1, B-2, C-3, D-4.
9. Fill in the Blanks MCQ:
A plant that consistently produces offspring identical to itself is called ______.
(1) Hybrid
(2) Heterozygote
(3) True breeding
(4) Polyploid
Explanation: True breeding plants are homozygous and produce uniform offspring, making them predictable for specific traits. Correct answer: (3) True breeding.
10. Choose the Correct Statements MCQ:
Select correct statements:
(1) True breeding plants are homozygous
(2) Cross-pollination produces heterozygotes
(3) Self-pollination in heterozygotes increases uniformity
(4) Hybrids always breed true
Options:
(1) 1 and 2 only
(2) 1, 2, 3 only
(3) 2 and 4 only
(4) All statements are correct
Explanation: Statements 1 and 2 are correct. True breeding plants are homozygous, and cross-pollination produces heterozygotes. Self-pollination in heterozygotes produces variable offspring, and hybrids do not breed true. Correct answer: (1) 1 and 2 only.