Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
Russian scientists uncovered the fruits of the flowering plant, Silene stenophylla, preserved in a ground squirrel burrow within frozen sediments in Siberia. Dating methods indicate that the ground squirrel stored the fruits about $32\ 000$ years ago, just before the ground became permanently frozen. Tissue samples were removed from the fruits and cultured on a nutrient medium. After treatment with plant hormones to promote root and shoot development, $36$ whole plants were obtained. These regenerated plants, which were identical in appearance to each other, flowered and, after cross-pollination, formed seeds that could germinate.
(a)[3]
Explain why cross-pollination gives rise to greater genetic variation among the offspring than self-pollination.
(b)[4]
The flowers of modern-day $S.\ stenophylla$ resemble, but are not identical to, those of the regenerated plants. Outline how DNA sequencing could be used to compare the DNA of modern-day and regenerated $S.\ stenophylla$.
(c)[2]
Suggest a straightforward experiment, using plants of modern-day and ‘regenerated’ $S.\ stenophylla$, to determine whether, after 32000 years, they are still the same species.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “cross-pollination requires two parents; self-pollination requires one parent” …