Which of the listed examples is evidence provided by living gymnosperms of an evolutionary transition between seedless and seed plants?
A
The sperm of gymnosperms do not require water or mobility for fertilization.
B
Some gymnosperms do not have reduced gametophytes.
C
Gymnosperms only have one integument.
D
In gymnosperms, two sperm are discharged into the pollen tube.
E
The sperm of some gymnosperms have flagella.
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1
Understand the evolutionary transition from seedless to seed plants: Seedless plants, like ferns, rely on water for sperm mobility and fertilization, whereas seed plants have adaptations that allow fertilization without water.
Identify the characteristics of gymnosperms: Gymnosperms are seed plants that do not require water for fertilization, as their sperm are delivered directly to the ovule via pollen tubes.
Examine the role of sperm in gymnosperms: Some gymnosperms have sperm with flagella, which is a trait reminiscent of seedless plants that required water for sperm mobility.
Consider the significance of flagella in gymnosperm sperm: The presence of flagella in some gymnosperm sperm suggests an evolutionary link to seedless plants, which used flagella for movement in water.
Conclude the evolutionary evidence: The sperm of some gymnosperms having flagella provides evidence of an evolutionary transition, as it shows a retained trait from seedless ancestors while adapting to a seed-based reproductive strategy.