2. Gregor Mendel has been called the “father of genetics,” having formulated law
ID: 3242519 • Letter: 2
Question
2.
Gregor Mendel has been called the “father of genetics,” having formulated laws of inheritance even before the function of DNA was discovered.
In one famous experiment with peas, he crossed pure breeds of plants producing smooth peas and plants producing wrinkled peas.
The first-generation peas were all smooth. In the second generation (F2), he obtained 5474 smooth-pea plants and 1850 wrinkled-pea plants.
Do these data agree with the conclusion that F2 is made up of 75% dominant-trait (in this case “smooth”) and 25% recessive-trait (“wrinkled”) pea plants?
An experiment described one of the crossing experiments that led Mendel to formulate his first law of inheritance, a model with a dominant and a recessive phenotype.
The first law says that we can expect a 3:1 ratio, that is, 3/4 with the dominant and 1/4 with the recessive phenotype, in F2.
When Mendel crossed tall and dwarf pea plants, he obtained 787 tall plants and 277 dwarf plants in F2.
Step 2:
What are the null and alternative hypotheses for this test.
Step 3:
What are the expected counts under the null hypothesis?
Match your answer below.
Enter the number of the term that corresponds to each choice:
tall plants
dwarf plants
Step 4:
Compute the chi-square statistic and use software or Table D to find the P-value.
Step 5:
The following conclusion can be made:
Gregor Mendel has been called the “father of genetics,” having formulated laws of inheritance even before the function of DNA was discovered.
In one famous experiment with peas, he crossed pure breeds of plants producing smooth peas and plants producing wrinkled peas.
The first-generation peas were all smooth. In the second generation (F2), he obtained 5474 smooth-pea plants and 1850 wrinkled-pea plants.
Do these data agree with the conclusion that F2 is made up of 75% dominant-trait (in this case “smooth”) and 25% recessive-trait (“wrinkled”) pea plants?
An experiment described one of the crossing experiments that led Mendel to formulate his first law of inheritance, a model with a dominant and a recessive phenotype.
The first law says that we can expect a 3:1 ratio, that is, 3/4 with the dominant and 1/4 with the recessive phenotype, in F2.
When Mendel crossed tall and dwarf pea plants, he obtained 787 tall plants and 277 dwarf plants in F2.
Step 2:
What are the null and alternative hypotheses for this test.
Step 3:
What are the expected counts under the null hypothesis?
Match your answer below.
Enter the number of the term that corresponds to each choice:
tall plants
dwarf plants
Step 4:
Compute the chi-square statistic and use software or Table D to find the P-value.
Step 5:
The following conclusion can be made:
Explanation / Answer
Answer:
Gregor Mendel has been called the “father of genetics,” having formulated laws of inheritance even before the function of DNA was discoveredI. In one famous experiment with peas, he crossed pure breeds of plants producing smooth peas and plants producing wrinkled peas. The first-generation peas were all smooth. In the second generation (F2), he obtained 5474 smooth-pea plants and 1850 wrinkled-pea plants.
Do these data agree with the conclusion that F2 is made up of 75% dominant-trait (in this case “smooth”) and 25% recessive-trait (“wrinkled”) pea plants?
Goodness of Fit Test
observed
expected
O - E
(O - E)² / E
5474
5493.000
-19.000
0.0657
1850
1831.000
19.000
0.1972
Total
7324
7324.000
0.2629
.2629
chi-square
1
df
.6081
p-value
Calculated chi square =0.2629, P=0.6081 > 0.05 level.
The data agree with the conclusion that F2 is made up of 75% dominant-trait (in this case “smooth”) and 25% recessive-trait (“wrinkled”) pea plants.
An experiment described one of the crossing experiments that led Mendel to formulate his first law of inheritance, a model with a dominant and a recessive phenotype. The first law says that we can expect a 3:1 ratio, that is, 3/4 with the dominant and 1/4 with the recessive phenotype, in F2.
When Mendel crossed tall and dwarf pea plants, he obtained 787 tall plants and 277 dwarf plants in F2.
Step 2:
What are the null and alternative hypotheses for this test.
H 0: ptall = 0.7397, pdwarf = 0.2603 vs. Ha: H0 is not true
H 0: ptall = 0.75, pdwarf = 0.25 vs. H0: ptall 0.75, pdwarf 0.25
H 0: ptall = pdwarf vs. Ha: ptall pdwarf
Answer: H 0: ptall = 0.75, pdwarf = 0.25 vs. Ha: H0 is not true
Step 3:
What are the expected counts under the null hypothesis?
Match your answer below.
1. 787 4. 277
2. 798 5. 787.04
3. 266 6. 276.96
Enter the number of the term that corresponds to each choice:
tall plants: 2 (798)
dwarf plants: 3 (266)
Step 4:
Compute the chi-square statistic and use software or Table D to find the P-value.
2 = 0.6065, P > 0.5.
2 = 0.7788, P > 0.25.
2 = 0.7788, P > 0.5.
Answer: 2 = 0.6065, P > 0.25.
Goodness of Fit Test
observed
expected
O - E
(O - E)² / E
787
798.000
-11.000
0.1516
277
266.000
11.000
0.4549
Total
1064
1064.000
0.6065
.6065
chi-square
1
df
.4361
p-value
Step 5:
The following conclusion can be made:
There is significant evidence that the proportion of tall and dwarf pea plants in the F2 population are not 0.75 and 0.25 respectively.
The test results provide strong evidence that the two proportions are different.
Answer: The test results are consistent with the Mendel's first law.
The test results prove that the proportions of tall and dwarf pea plants in the F2 population are 0.75 and 0.25 respectively.
Goodness of Fit Test
observed
expected
O - E
(O - E)² / E
5474
5493.000
-19.000
0.0657
1850
1831.000
19.000
0.1972
Total
7324
7324.000
0.2629
.2629
chi-square
1
df
.6081
p-value
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