Let’s go through each question one by one, using the diagram and what we know about meiosis.
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Question 1: According to Model 1, in what type of organs are the cells that enter meiosis I found?
Look at the top right of Model 1 — it says “Homologous chromosomes come together to form a tetrad” and there’s a label pointing to “Ovary or Testes.” That means the cells entering meiosis I are found in reproductive organs — specifically, ovaries (in females) or testes (in males). These are called gonads.
✔ So the answer is:
Ovaries or testes (reproductive organs)
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Question 2: Considering what you already know about mitosis in cells, what event must take place during interphase before a cell proceeds to division?
Before any cell divides — whether by mitosis or meiosis — it must copy its DNA. This happens during interphase, specifically in the S phase (“S” stands for synthesis). Without copying the DNA, each new cell wouldn’t have a full set of chromosomes.
In the diagram, you can see that before Meiosis I starts, the cell has duplicated chromosomes (each chromosome looks like an X — two sister chromatids). That duplication happened in interphase.
✔ So the answer is:
DNA replication (or copying of chromosomes)
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Question 3: What two structures make up a single replicated chromosome?
A replicated chromosome is made of two identical copies held together at a point called the centromere. Each copy is called a
sister chromatid.
You can see this in the diagram — for example, in Early Prophase I, each chromosome is shown as an “X” shape. The two arms of the X are the sister chromatids.
✔ So the answer is:
Two sister chromatids
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Question 4: In Model 1, how many replicated chromosomes does the cell contain during prophase I?
Let’s count!
In Early Prophase I, you can see 4 chromosomes total — but they’re paired up into 2 homologous pairs. Each chromosome is already replicated (so each is an “X” shape = 2 sister chromatids).
But the question asks for
replicated chromosomes, not chromatids.
Each “X” is one replicated chromosome.
Count them:
- Top left pair: 2 replicated chromosomes
- Bottom right pair: 2 replicated chromosomes
Total =
4 replicated chromosomes
Even though they’re paired into tetrads later, during prophase I, before pairing is complete, you still have 4 individual replicated chromosomes.
Wait — let’s double-check with Late Prophase I / Metaphase I.
In Metaphase I, you see 2 tetrads. Each tetrad = 2 homologous chromosomes → so 2 tetrads × 2 chromosomes each = 4 chromosomes total. And since each is replicated, that’s still 4 replicated chromosomes.
Yes — the cell started with 4 chromosomes (2 from mom, 2 from dad), and after DNA replication, it still has 4 chromosomes — just now each is made of 2 chromatids.
✔ So the answer is:
4
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Final Answer:
1. Ovaries or testes
2. DNA replication
3. Two sister chromatids
4. 4
Parent Tip: Review the logic above to help your child master the concept of meiosis worksheet answer key.
