PART A – Processes that determine heredity and contribute to genetic variationMeiosis guarantees that in a sexual life cycle, offspring will inherit one complete set of chromosomes (and their associated genes and traits) from each parent. The transmission of traits from parents to offspring is called heredity.Another important aspect of meiosis and the sexual life cycle is the role these processes play in contributing to genetic variation. Although offspring often resemble their parents, they are genetically different from both of their parents and from one another. The degree of variation may be tremendous.The following processes are associated with meiosis and the sexual life cycle:-DNA replication before meiosis-crossing over-chromosome alignment in metaphase I and separation in anaphase I-chromosome alignment in metaphase II and separation in anaphase II-fertilizationSort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both. (Note that a bin may be left empty.)
HEREDITY ONLY:noneGENETIC VARIATION ONLY:noneBOTH:all-fertilization-metaphase 1→anaphase 1-metaphase 2→anaphase 2-crossing over-DNA replication[In organisms that reproduce sexually, the processes of DNA replication, the precise pairing of homologs during crossing over, chromosome alignment and separation in meiosis I and II, and fertilization ensure that traits pass from one generation to the next.Unlike with asexual reproduction, offspring of sexual reproduction are genetically different from each other and from both of their parents. Mechanisms that contribute to genetic variation include-errors (mutations) that occur during DNA replication-the production of recombinant chromosomes due to crossing over-the independent assortment of homologous chromosomes in meiosis I-the separation of sister chromatids (which are no longer identical due to crossing over) in meiosis II-the random fusion of male and female gametes during fertilization]
Heredity Only:
– DNA replication before meiosis
– Fertilization
Genetic Variation Only:
– Crossing over
Both Heredity and Genetic Variation:
– Chromosome alignment in metaphase I and separation in anaphase I
– Chromosome alignment in metaphase II and separation in anaphase II
Note: While DNA replication and fertilization do not directly contribute to genetic variation, they are essential for the transfer of genetic information from parent to offspring.
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What Would Happen If Crossing Over Didn’t Occur During Meiosis? – A Discussion on the Importance of Genetic Diversity and Evolutionary AdaptationError 403 The request cannot be completed because you have exceeded your quota. : quotaExceeded