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Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

metaphase I
prophase II
anaphase I
metaphase II
telophase II
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Part B
Crossing over, resulting in an increase in genetic variation, occurs between _____.

nonsister chromatids of homologous chromosomes
sister chromatids of nonhomologous chromosomes
sister chromatids of homologous chromosomes
sex cells and somatic cells
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Part C
In human gamete production there is an average of _____ crossover events per chromosome pair.

10+
2–3
9–10
5–6
0–1
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Part D
Which of these gametes contain one or more recombinant chromosomes?
Gamete arrangement after meiosis with a crossing over. A cell contains one large blue chromosome, one large red chromosome, one small blue chromosome, and one small red chromosome. This cell can form 8 types of gametes, 5 of them are labeled A through E. Gamete A contains 1 long blue and 1 short blue chromosomes. Gamete B contains 1 long blue and 1 short blue chromosomes; both have red ends. Gamete C contains 1 long red and 1 short red chromosomes; both have blue ends. Gamete D contains 1 long red and 1 short red chromosomes. Gamete E contains 1 long red and 1 short blue chromosomes.

A, B, and C
B, C, D, and G
B, C, and G
B, C, F, and G
C, D, E, F, and G

1 answer

Let's answer each part of your question step by step.

Part A

Homologous pairs of chromosomes are lined up independently of other such pairs during:

  • Answer: metaphase I
    During metaphase I of meiosis, homologous chromosomes line up at the cell's equatorial plane independently of other pairs, a process known as independent assortment.

Part B

Crossing over, resulting in an increase in genetic variation, occurs between:

  • Answer: nonsister chromatids of homologous chromosomes
    Crossing over occurs during prophase I of meiosis between homologous chromosomes, specifically between the nonsister chromatids.

Part C

In human gamete production, there is an average of _____ crossover events per chromosome pair.

  • Answer: 2–3
    Human gametes typically experience an average of 2 to 3 crossover events per chromosome pair during meiosis.

Part D

Which of these gametes contain one or more recombinant chromosomes? From the provided descriptions:

  • Gamete A: 1 long blue and 1 short blue (no crossing over)
  • Gamete B: 1 long blue and 1 short blue, both have red ends (indicates crossing over)
  • Gamete C: 1 long red and 1 short red, both have blue ends (indicates crossing over)
  • Gamete D: 1 long red and 1 short red (no crossing over)
  • Gamete E: 1 long red and 1 short blue (indicates crossing over)

Based on the definitions:

  • Recombinant chromosomes have combinations of alleles that are different from the parents.

Gametes B, C, and E would therefore contain recombinant chromosomes due to the crossing over that has taken place.

  • Answer: B, C, and E

It appears that the options for this part were not presented accurately in your question. The choices hint at overlapping designations without an option that accurately describes the gametes with recombinant chromosomes. Nevertheless, based on your original description, B, C, and E are the correct recombinant gametes.

If you have any other questions or need clarification, feel free to ask!