Question

another feature of sexual reproduction that increases genetic variation is that one individual produces a variety of gametes with different combinations of alleles. gametes are produced when specialized diploid cells, called germ cells, divide during a process called meiosis. this model shows a germ cell from an organism that has two pairs of homologous chromosomes in each of its somatic cells. to prepare for meiosis, a diploid germ cell replicates, or copies its dna. once replicated, each chromosome is connected to its identical copy at a region called the centromere. each copy of a chromosome is called a sister chromatid. two sister chromatids connected at a centromere are still referred to as a single chromosome. complete the paragraph. the gametes produced by one organism are genetically. before meiosis begins, a germ cell makes a copy of its dna. after dna replication, the germ cell is and contains chromosomes as it did before it copied its dna.

Explanation:

1. The first blank: The text states "one individual produces a variety of gametes with different combinations of alleles", so gametes are genetically "different".
2. The second blank: The model shows a germ cell (diploid, as somatic cells have two pairs of homologous chromosomes, so germ cells are diploid before meiosis) makes a copy of its DNA, so "diploid".
3. The third blank: After DNA replication, the cell is still diploid (but with replicated chromosomes), and the number of chromosomes (counting each chromosome, even with sister chromatids, the chromosome number - counting centromeres - remains the same as before replication for the cell's ploidy - related chromosome count here). Wait, actually, before replication, a diploid germ cell (say 2n) replicates DNA, so the cell is still diploid (2n) but each chromosome has two sister chromatids. The number of chromosomes (in terms of centromeres) is the same as before replication? Wait, no - wait, the original germ cell (diploid, 2n) replicates DNA, so the cell is now with duplicated chromosomes, but the chromosome number (count of centromeres) is still 2n? Wait, maybe the third blank is "diploid" (since it's still a diploid cell, just with replicated DNA), and the fourth blank: the number of chromosomes (centromeres) is the same as before, so "the same number of" or "the same" (but in the context, after replication, the cell has the same number of chromosomes (centromeres) as before, even though each chromosome has two chromatids. So putting it together:

The gametes produced by one organism are genetically different (because of different allele combinations). Before meiosis begins, a diploid germ cell makes a copy of its DNA (germ cells are diploid, somatic cells too in this case). After DNA replication, the germ cell is diploid (still diploid, as ploidy is about chromosome sets, and replication doesn't change ploidy, just chromatids) and contains the same number of chromosomes as it did before it copied its DNA (since each chromosome is replicated but still one centromere, so chromosome count - by centromere - is same).

Answer:

1. different
2. diploid
3. diploid
4. the same number of