The following list of events happens during meiosis:
Prophase I: Crossing over between homologous chromosomes occurs.
Metaphase I: Tetrads line up at the metaphase plate.
Anaphase I: Tetrads are separated.
Telophase I: Nuclear envelopes reform around the separated chromosomes.
Prophase II: Chromosomes condense.
Metaphase II: Chromosomes line up at metaphase plate.
Anaphase II: Sister chromatids separate into daughter chromosomes.
Telophase II: Nuclear envelopes reform around the daughter chromosomes.
Identify the answer choice that correctly lists the events from above that lead to new genetic combinations in the gametes.
(1 point)
Responses
5 and 6
5 and 6
5, 6, and 7
5, 6, and 7
1, 2, and 5
1, 2, and 5
1 and 2
1 and 2
To identify the events from the list that lead to new genetic combinations in the gametes, we need to understand which events involve the mixing of genetic material.
1. Prophase I: Crossing over between homologous chromosomes occurs. During this phase, sections of genetic material between homologous chromosomes are exchanged, leading to genetic recombination.
2. Metaphase I: Tetrads line up at the metaphase plate. At this stage, tetrads (pairs of homologous chromosomes) align along the metaphase plate, ready for separation.
3. Anaphase I: Tetrads are separated. In this phase, the homologous chromosomes segregate and move towards opposite poles of the cell.
4. Telophase I: Nuclear envelopes reform around the separated chromosomes. During telophase I, the chromosomes reach the poles and nuclear envelopes start to form around them.
5. Prophase II: Chromosomes condense. In this phase, the chromosomes recondense after the first division.
6. Metaphase II: Chromosomes line up at the metaphase plate. Similar to metaphase I, the chromosomes align along the metaphase plate.
7. Anaphase II: Sister chromatids separate into daughter chromosomes. Sister chromatids (formed by the replicated chromosomes) separate and move towards opposite poles.
8. Telophase II: Nuclear envelopes reform around the daughter chromosomes. Finally, nuclear envelopes form around the separated daughter chromosomes.
From the events listed above, we can see that events 1 (Prophase I: Crossing over) and 7 (Anaphase II: Sister chromatids separate into daughter chromosomes) are the ones that directly contribute to new genetic combinations in the gametes.
Therefore, the correct answer choice is:
1 and 2