Sexual reproduction in plantsEdexcel A-Level Biology B: Flashcards

What these 14 flashcards ask

Where are pollen grains formed?
How many microspores form from one pollen mother cell?
What two nuclei are in a pollen grain?
Where is the embryo sac formed?
What happens to the four megaspores?
Where is the egg cell in the embryo sac?
What does the tube nucleus do?
Why does the pollen tube secrete enzymes?
What does the generative nucleus form?
What forms when one male nucleus fuses with the egg nucleus?
What forms when the other male nucleus fuses with the two polar nuclei?
What is the function of the endosperm?
Why does pollen germination fall at very high sucrose concentration?
Name three variables to control in the sucrose investigation.

Exam questions on Sexual reproduction in plants

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
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
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

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).