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Biology Asked by a SnapAndSolve user · about 18 hours ago

...........and........... of meiosis 1 are responsible for the constancy in chromosome number 7....

6. ...........and........... of meiosis 1 are responsible for the constancy in chromosome number
7. ...........and........... are the reasons for variation in organisms
8. End products of meiosis 1 are...........and meiosis 2 are...........
9. In ........... the daughter cells are the same in genetic material with the mother cell
10. In plants meiosis takes place in...........
SECTION B
Answer ANY THREE questions
1a. Define the concept of hybridisation in flowering plants
1b. Briefly discuss the ways hybridisation can stimulate evolutionary change in flowering plants.(10maks)
2. Write short note on the following:
(i.) transgressive breeding (ii.) intervarietal hybridisation (iii.) distant hybridisation (iv.) hybrid varieties(10mks)
3a. Define mutation and explain its role in evolution
b. describe the different types of mutations you know(10mks)
4a. Explain the origin of the following chromosomal structural variations
(i) duplication (b) deletion (c) inversion (iv) translocation
4b. Discuss the adaptive significance of each of the above variations (4a) in plants.(10mks)

Answer

  1. Answer: Synapsis and crossing over of meiosis 1 are responsible for the constancy in chromosome number.

  2. Answer: Mutation and recombination are the reasons for variation in organisms.

  3. Answer: End products of meiosis 1 are two haploid cells and meiosis 2 are four haploid cells.

  4. Answer: In mitosis, the daughter cells are the same in genetic material with the mother cell.

  5. Answer: In plants, meiosis takes place in the anthers and ovules.

  6. Answer: Hybridisation in flowering plants is the process of crossing two genetically different plants to produce a hybrid with desirable traits.

  7. Answer: Hybridisation can stimulate evolutionary change in flowering plants by introducing new genetic combinations, increasing genetic diversity, and potentially leading to the development of new species.

  8. Answer:

    1. Transgressive breeding: This involves crossing two different species or varieties to produce offspring with traits that exceed the range of the parent species.
    2. Intervarietal hybridisation: This is the crossing of different varieties within the same species to combine desirable traits.
    3. Distant hybridisation: This involves crossing species from different genera or families to create hybrids with unique characteristics.
    4. Hybrid varieties: These are the offspring resulting from hybridisation, often exhibiting improved traits such as higher yield or disease resistance.

  9. Answer: Mutation is a change in the DNA sequence that can lead to genetic variation. It plays a crucial role in evolution by introducing new genetic variations that can be acted upon by natural selection.

  10. Answer: Types of mutations include point mutations, insertions, deletions, and frameshift mutations.

  11. Answer:

    1. Duplication: This occurs when a segment of a chromosome is copied and inserted into the genome, leading to gene redundancy.
    2. Deletion: This involves the loss of a chromosome segment, which can result in the loss of genetic material and potentially harmful effects.
    3. Inversion: This occurs when a chromosome segment breaks off, flips around, and reattaches, potentially altering gene function.
    4. Translocation: This involves the exchange of chromosome segments between non-homologous chromosomes, which can lead to genetic disorders.

  12. Answer:

    1. Duplication: Can lead to gene redundancy, which may provide raw material for evolution by allowing one copy to mutate and potentially gain new functions.
    2. Deletion: Can result in the loss of essential genes, but in some cases, it may remove deleterious alleles, providing an adaptive advantage.
    3. Inversion: Can suppress recombination in the inverted segment, potentially preserving advantageous gene combinations.
    4. Translocation: Can create new gene combinations and potentially lead to speciation, but may also cause genetic disorders if it disrupts essential genes.

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