The cycads, a mostly tropical phylum of gymnosperms, evolved about 300 million y

Question

The cycads, a mostly tropical phylum of gymnosperms, evolved about 300 million years ago and were dominant forms during the Age of the Dinosaurs. Though their sperm are flagellated, their ovules are pollinated by beetles. These beetles get nutrition (they eat pollen) and shelter from the microsporophylls. Upon visiting megasporophylls, the beetles transfer pollen to the exposed ovules. In cycads, pollen cones and seed cones are borne on different plants. Cycads synthesize neurotoxins, especially in the seeds, that are effective against most animals, including humans.

Which feature of cycads distinguishes them from most other gymnosperms?

1. They have exposed ovules.

2. They have flagellated sperm.

3. They are pollinated by animals.

1 only

2 only

3 only

2 & 3

1, 2 & 3

1 only

2 only

3 only

2 & 3

1, 2 & 3

Explanation / Answer

the correct answer is (2) & (3)

Normally gymnosperms have exposed ovules, but they normally produce sperms with no flagella that are conveyed to the egg along a pollen tube.

Also, the mode of pollen transfer in most gymnosperms is via wind; not by insects ( may be this is due to the lack of flowers which act as insect-attractors in angiosperms).

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