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Unit-4 Cell Cycle
Answer: Synapsis is the pairing of homologous chromosomes that occurs during prophase I of meiosis.
Answer: Crossing over involves the exchange of segments between non-sister chromatids of homologous chromosomes.
Answer: Homologous chromosomes pair up (synapsis) during prophase I of meiosis.
Answer: Crossing over occurs during prophase I when homologous chromosomes are paired.
Answer: Crossing over occurs during the pachytene substage of prophase I, when chromosomes are fully paired.
Answer: A tetrad is the group of two homologous chromosomes, each with two chromatids, formed during synapsis.
Answer: A tetrad consists of two homologous chromosomes with two chromatids each, making four chromatids.
Answer: In anaphase I, homologous chromosomes separate from each other and move to opposite poles.
Answer: As homologous chromosomes separate in anaphase I, each pole receives one set (n), halving the chromosome number.
Answer: The synaptonemal complex is a protein structure that forms between paired homologous chromosomes during prophase I.
Answer: Meiosis II resembles mitosis because sister chromatids separate without any further reduction in chromosome number.
Answer: In anaphase II, the centromere divides and sister chromatids separate and move to opposite poles.
Answer: Interkinesis is a brief stage between meiosis I and meiosis II during which no DNA replication occurs.
Answer: Meiosis I reduces the chromosome number from diploid (2n) to haploid (n).
Answer: During diplotene, the homologous chromosomes begin to separate and the chiasmata (sites of crossing over) become visible.
Answer: Gametes are haploid, so they receive half the chromosome number, i.e., n = 4.
Answer: Homologous pairs align randomly on the equator during metaphase I, allowing maternal and paternal chromosomes to assort independently.
Answer: Crossing over and independent assortment during meiosis generate genetically different gametes, increasing variation.
Answer: Prophase I is divided into five substages: leptotene, zygotene, pachytene, diplotene and diakinesis.
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Answer: In leptotene, the first substage, chromosomes condense and appear as thin threads.