Question

An inbred strain of plants has a mean height of 20 cm. A second inbred strain also has a height of 40 cm. Crossing the two strains produces an F1 that has a mean height of 30 cm. The F2 have a continuous range of heights was observed with most plants around 30 cm and 1 out of 1000 at 20-cm, and 1 out of 1000 at 40 cm. How much does each additive allele contribute to height?

1.

1-cm

2.

2-cm

3.

3-cm

4.

4-cm

5.

5-cm

Answer 1

Answer:

Based on the given information:

• Mean height of first inbred strain of plants = 20 cm.
• Mean height of second inbred strain of plants = 40 cm.
• 1st inbred strain x 2nd inbred strain ----> F1 that has a mean height = 30 cm.
• The F2 have a continuous range of heights was observed with
  • most plants around 30 cm
  • 1 out of 1000 at 20cm
  • 1 out of 1000 at 40 cm

Number of alleles involved in controlling plant height = 5 (closest expected ratio is 1/1000 is ~1/2¹⁰)

• Number of genes involved = 5
• Number of aditive alleles = 2*5 = 10
• Maximum contribution of additive alleles = (40-20) / 10 = 20cm / 10 = 2cm

How much does each additive allele contribute to height

• 1) 1-cm
• 2) 2-cm - Correct Option
• 3) 3-cm
• 4) 4-cm
• 5) 5-cm