IMO Practice Test — Plant Kingdom
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
Red algae can grow at greater ocean depths than green algae mainly because their pigment phycoerythrin:
Absorbs the blue-green light that penetrates deep water
Needs no light
Is the same as chlorophyll
Stores oxygen
Explanation: Phycoerythrin captures the blue-green light reaching deep water, letting red algae photosynthesise there.
Question 2 of 6
Heterospory in Selaginella is considered a precursor to the seed habit because:
The female gametophyte is retained and nourished on the parent sporophyte
It produces only one spore type
It needs no water
It forms a fruit
Explanation: Retention of the female gametophyte on the parent, as in heterospory, foreshadows the seed.
Question 3 of 6
Both bryophytes and pteridophytes still require water for reproduction because:
Their motile male gametes must swim to the female gamete
They live underwater
They have no spores
They are non-green
Explanation: In both groups the male gametes swim through water to reach the egg, so external water is needed.
Question 4 of 6
A diplontic life cycle is advantageous on land because the dominant diploid sporophyte:
Is better adapted, with vascular tissue, to survive land conditions
Needs no water at all
Has no chlorophyll
Is single-celled
Explanation: The robust, vascularised diploid sporophyte copes better with terrestrial life than a delicate gametophyte.
Question 5 of 6
Why are gymnosperm seeds called 'naked'?
The ovules/seeds are not enclosed within an ovary or fruit
They have no seed coat
They lack an embryo
They are colourless
Explanation: Gymnosperm ovules sit exposed on cone scales, not enclosed in an ovary, so the seeds are 'naked'.
Question 6 of 6
A botanist finds a plant with flowers, fruits enclosing seeds, two cotyledons and net-like leaf venation. It is a:
Dicot angiosperm
Monocot angiosperm
Gymnosperm
Pteridophyte
Explanation: Flowers + fruit-enclosed seeds = angiosperm; two cotyledons + reticulate venation = dicot.