11.6.2 Alternation of Generations: Ferns

Question 1

Alternation of Generations: Ferns

Answer 1

• With the development of vascular tissue, plants were able to grow taller because they had a mechanism for the transport of water and nutrients to plant tissues. Tall vascular plants could compete better for sunlight, but had to overcome the problem of not having water readily available for gametic transfer.
• In order to utilize water for gametic transfer, the gametophyte generation of seedless vascular plants remains close to the ground.
• Alternation of generations in vascular plants, in contrast to the mosses, involves a larger, more complex sporophyte generation than the gametophyte generation.

Question 2

note

Answer 2

• While all plants exhibit alternation of generations, the features of the life cycles of different plant species may differ greatly.
• For example, in mosses the gametophyte is the more
  prominent generation, while in ferns the sporophyte is the more prominent generation.
• Beginning in the lower left-hand corner of the diagram,
  structures on the underside of sporophyte leaves consist of sporangia, which contain haploid spores.
• Spores are released, germinate, and develop into the
  heart-shaped gametophyte generation. The gametophyte of the fern is hermaphroditic, having both male and female reproductive structures.
• Flagellated sperm swim through moisture from the
  antheridium to the archegonium, where they will fertilize an egg.
• The diploid zygote that results from fertilization develops into the sporophyte. Notice that the sporophyte grows out from the gametophyte.

Question 3

In ferns, spores directly give rise to

Answer 3

• gametophytes

Question 4

A __________ is formed from a cluster of sporangia on the underside of a frond.

Answer 4

• sorus

Question 5

Which of the following statements is correct regarding the fern?

Answer 5

• Ferns produce flagellated sperm.

Question 6

Plants such as ferns, lycophytes, and horsetails are

Answer 6

• seedless and vascular

Question 7

The fern gametophyte

Answer 7

• is a small heart-shaped structure.

Question 8

Meiosis in ferns results in the formation of what structures?

Answer 8

• haploid spores