Plant Diversity II Exam Questions and Answers 100% Pass
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Course
Plant Diversity II
Institution
Plant Diversity II
Plant Diversity II Exam Questions and Answers 100% Pass
What are the five adaptations common to all seed plants that ensure their success in the adaptation to land? - Answers Heterospory, highly reduced gametophytes, ovules, pollen, seeds
Explain the difference between homospory and heterospory. ...
Plant Diversity II Exam Questions and Answers 100% Pass
What are the five adaptations common to all seed plants that ensure their success in the adaptation to
land? - Answers Heterospory, highly reduced gametophytes, ovules, pollen, seeds
Explain the difference between homospory and heterospory. - Answers Homospory characterizes plants
that produce spores that are all the same size (as in bryophytes and most seedless vascular plants).
Homospory can result in bisexual gametophytes (as in ferns, pg 611) or unisexual gametophytes (male
or female) as in mosses - see pg 607 in the text.
Heterospory characterizes plants that produce spores of different sizes: megaspores and microspores
which give rise to separate female and male gametophytes, respectively.
Contrast sperm delivery in seedless plants with sperm delivery in seed plants. - Answers Sperm delivery
in seedless plants is dependent upon the presence of water. The sperm of these organisms have flagella
and require a pool in which to swim in order to get to the egg, which is usually not too far away. Sperm
delivery in seed plants depends upon the pollen grain, an invention that obviates the need for water.
The pollen grain delivers the sperm (nucleus) to the ovule through the air, thus eliminating the need for
water for this purpose.
What features not present in seedless plants have contributed to the enormous success of the seed
plants on land? - Answers Three things: The gametophytes of seed plants are reduced and dependent
upon the parent sporophyte which protects them (particularly in the case of the female gametophyte).
Pollen is covered with sporopollenin which is resistant to physical factors in the environment. The
structure of the seed protects the next generation sporophyte and allows it to remain dormant until
conditions are right for germination, development and growth.
Explain how the pine life cycle in Figure 30.6 reflects the five adaptations common to all seed plants. -
Answers The ovule contains the megasporangium which gives rise to the female gametophyte; this
structure remains protected within the sporangium and integument. Archegonia develop within each
gametophyte, each containing an egg cell. Pollen is produced in the microsporangia of the male cones.
Each pollen grain contains a generative nucleus, tube nucleus and two body cells. Pollen is delivered via
the air (wind, usually) to the opening of the ovule (micropyle). The tube cell forms a pollen tube through
which the sperm nucleus (derived from one division of the generative nucleus) is delivered to the ovule.
After fertilization the embryo develops within the ovule and a seed is formed from the integument (seed
coat), nutritive tissue (gametophyte) and embryo (next generation plant or sporophyte).
How do the life cycles of seedless vascular plants differ from that of gymnosperms? - Answers Seedless
vascular plants require water for the sperm to get to the egg; this takes place on an independent
(stranded) gametophyte. Most seedless plants are also homosporous. Seed plants are heterosporous
and therefore have different sized spores. The female gametophyte of seed plants is derived from a
functional megaspore and is retained on the parent plant until seed dispersal. This provides a protected
environment for the developing young sporophyte.
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