Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division of the diploid parent cell shown in Figure 6. If two diploid (2n) gametes fuse at fertilisation, it can result in the growth of a tetraploid plant which has 4 copies of each chromosome. Red clover is a plant grown to produce cattle feed. Tetraploid red clover plants produce a higher yield than diploid red clover plants. Whether a red clover plant produces 2n gametes is genetically controlled. Scientists investigated the possibility of breeding red clover plants that only produced 2n gametes. In breeding cycle 0, they grew red clover plants and identified plants that produced 2n gametes. In breeding cycle 1, they used the plants producing 2n gametes to produce offspring. In breeding cycles 2 and 3, they identified plants producing 2n gametes and used these to produce offspring. The results are shown in Table 3. The scientists used the following null hypothesis. "The proportion of plants that produce 2n gametes will not change from one breeding cycle to the next." Complete Table 3 to show the expected number of plants that did not produce 2n gametes and the expected number of plants that did produce 2n gametes after 1 cycle. Give each answer to the nearest whole number. The scientists tested their null hypothesis using the chi-squared statistical test. After 1 cycle their calculated chi-squared value was 350 The critical value at P<0.05 is 3.841 What does this result suggest about the difference between the observed and expected results and what can the scientists therefore conclude? Use your knowledge of directional selection to explain the results shown in Table 3.

A-Level AQA Biology Cell Division in Eukaryotic & Prokaryotic Cells: Complete Figure 7 to show the ch

Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division of the diploid parent cell shown in Figure 6 - AQA - A-Level Biology - Question 6 - 2018 - Paper 1

Question 6

Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division of the diploid parent cell shown in Figure 6. If two ... show full transcript

Worked Solution & Example Answer:Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division of the diploid parent cell shown in Figure 6 - AQA - A-Level Biology - Question 6 - 2018 - Paper 1

Step 1

Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division

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Answer

After the first division of meiosis, the chromosome content would be:

Cell 1: 1 long and 1 short chromosome (each made up of 2 chromatids).
Cell 2: 1 long and 1 short chromosome (each made up of 2 chromatids).

After the second division of meiosis, the chromosome content would be four daughter cells:

Cell 1: 1 long chromosome.
Cell 2: 1 long chromosome.
Cell 3: 1 short chromosome.
Cell 4: 1 short chromosome.

Step 2

Complete Table 3 to show the expected number of plants that did not produce 2n gametes and the expected number of plants that did produce 2n gametes after 1 cycle.

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Answer

Breeding Cycle 0:

Observed: 14 produced 2n gametes
Expected: 14 (2n gametes); therefore, 0 did not produce 2n gametes.

Breeding Cycle 1:

Observed: 42 produced 2n gametes.
Expected: 42 (2n gametes); thus 0 did not produce 2n gametes.

Breeding Cycle 2:

Observed: 44 produced 2n gametes.
Expected: 44 (2n gametes); therefore, 0 did not produce 2n gametes.

Breeding Cycle 3:

Observed: 56 produced 2n gametes.
Expected: 56 (2n gametes); thus, 0 did not produce 2n gametes.

Step 3

What does this result suggest about the difference between the observed and expected results and what can the scientists therefore conclude?

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Answer

The calculated chi-squared value of 350 significantly exceeds the critical value of 3.841. This suggests that there is a highly significant difference between the observed and expected results, leading to the rejection of the null hypothesis. The scientists can conclude that the proportion of plants producing 2n gametes does change from one breeding cycle to the next.

Step 4

Use your knowledge of directional selection to explain the results shown in Table 3.

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Answer

Directional selection may have occurred in the red clover plants as those producing 2n gametes were favored. Over successive breeding cycles, plants that produced the trait for 2n gametes became more prevalent. Consequently, the frequency of alleles associated with the production of 2n gametes likely increased within the population.

Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division of the diploid parent cell shown in Figure 6 - AQA - A-Level Biology - Question 6 - 2018 - Paper 1

Worked Solution & Example Answer:Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division of the diploid parent cell shown in Figure 6 - AQA - A-Level Biology - Question 6 - 2018 - Paper 1

Complete Figure 7 to show the chromosome content of the cells that would result from a normal meiotic division

Complete Table 3 to show the expected number of plants that did not produce 2n gametes and the expected number of plants that did produce 2n gametes after 1 cycle.

What does this result suggest about the difference between the observed and expected results and what can the scientists therefore conclude?

Use your knowledge of directional selection to explain the results shown in Table 3.

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