Question

crossing over plays a critical role in increasing the genetic variation among offspring of sexual reproduction. crossing over is unique to meiosis. its occurrence depends on specific events early in prophase i, and it has important consequences for the rest of meiosis and beyond. consider the following statements about crossing over. place \true\ or \false\ to the end of each statement. show instructions true false 1. for crossing over to occur, homologous chromosomes must align precisely early in prophase i so that nonsister chromatids can exchange corresponding segments of dna. 2. crossing over prevents homologous chromosomes from separating during meiosis l 3. crossing over occurs at the ends of chromosomes, rather than near the centromeres. 4. as a result of crossing over, sister chromatids are no longer identical to each other.

Explanation:

1. During prophase I of meiosis, homologous chromosomes pair up (synapsis) and align precisely. This alignment allows non - sister chromatids to exchange corresponding DNA segments (crossing over). So, this statement is True.
2. Crossing over does not prevent homologous chromosomes from separating during meiosis I. In fact, after crossing over, homologous chromosomes still separate. The statement is False.
3. Crossing over can occur at various locations along the length of chromosomes, not just at the ends. So, this statement is False.
4. Before crossing over, sister chromatids are identical (assuming no mutations). When crossing over occurs between non - sister chromatids (of homologous chromosomes), the sister chromatids (which now have parts from the non - sister chromatid of the homologous chromosome) are no longer identical. So, this statement is True.

Answer:

1. True
2. False
3. False
4. True