Question

Generation

Number of purple flowers

Number of white flowers

1

705

224

2

792

189

3

834

102

4

889

84

5

938

21

6

952

0


Ralph wanted to breed a pea plant that produced only purple flowers. He continued to breed purple-flower producing pea plants together over six generations. The results of Ralph's selective breeding are shown above. What did the selective breeding do to the population of pea plants?
A.
caused a pea plant to exhibit a new characteristic
B.
decreased its genetic diversity
C.
caused a new species of pea plant to form
D.
increased its genetic diversity

Answer 1

B. decreased its genetic diversity

Explanation: By repeatedly breeding only purple-flowered plants, Ralph selected against the allele(s) for white flowers. The data show white-flowered plants went from 224 to 0 over six generations, so allelic variation for flower color was reduced. This is artificial selection increasing the frequency of purple alleles (and likely homozygosity) rather than creating a new trait or species.