Sexual reproduction in plantsEdexcel A-Level Biology B: Mind map

Exam questions on Sexual reproduction in plants

1. A student investigated the effect of sucrose concentration on pollen germination. She placed pollen grains from one flower in sucrose solutions of 0%, 5%, 10% and 20% on cavity slides and kept them at 25 °C for 30 minutes. She then counted 100 grains in each solution and recorded the percentage that had produced a pollen tube: 8%, 52%, 81% and 23% respectively.
   Suggest why only 8% of the pollen grains germinated in the 0% sucrose solution.2 marks
2. In a lily flower, pollen grains form in the anthers from pollen mother cells. In the ovules, the embryo sac forms from a megaspore mother cell. Both types of mother cell are diploid.
   Explain why the pollen mother cell divides by meiosis.2 marks
3. In flowering plants the male gametes cannot swim to the egg, which lies deep inside the ovule. Each pollen grain contains a generative nucleus and a tube nucleus. After a pollen grain lands on the stigma of a compatible flower, it germinates.
   Explain how the pollen tube grows through the style to reach the ovule.3 marks