IMO Practice Test — Sexual Reproduction in Flowering Plants
7 Questions • 15 min • Olympiad level
15:00
Question 1 of 7
Pollen grains survive for thousands of years as fossils mainly because their exine contains:
Sporopollenin, one of the most resistant biological substances
Water
Sugar
Soft cellulose
Explanation: Sporopollenin resists acids, bases and high temperature, so pollen walls are extremely durable.
Question 2 of 7
Double fertilisation is considered unique because it produces both a:
Zygote and a triploid endosperm
Two zygotes
Two pollen grains
Root and a shoot only
Explanation: Two fusion events form the diploid zygote and the triploid nutritive endosperm — found only in angiosperms.
Question 3 of 7
Brightly coloured, scented flowers with nectar are usually adapted for pollination by:
Insects (and birds)
Wind only
Water only
No agent
Explanation: Colour, scent and nectar attract animal pollinators like insects and birds.
Question 4 of 7
The endosperm is important to the developing seed because it:
Provides nourishment to the embryo
Forms the seed coat
Becomes the fruit wall
Makes pollen
Explanation: The triploid endosperm stores food that nourishes the growing embryo.
Question 5 of 7
Cross-pollination promotes variation in offspring because it brings together:
Genes from two different parent plants
Only one parent's genes
No genes
Identical genes
Explanation: Mixing genes from two parents increases genetic variation, unlike self-pollination.
Question 6 of 7
If the synergids guide the pollen tube into the embryo sac, removing them would most likely:
Hinder the entry of the male gametes
Speed up fertilisation
Form more pollen
Make the fruit larger
Explanation: Synergids help direct the pollen tube to the egg; without them, gamete delivery is impaired.
Question 7 of 7
Apomixis is useful in agriculture because the seeds it produces are:
Genetically identical to the parent, preserving hybrid traits
Always seedless
Different from the parent
Unable to germinate
Explanation: Because no fertilisation occurs, apomictic seeds are clones of the parent, keeping desirable hybrid qualities.