69 - ___ = ___/61 = 66.4%
Biology of Plants
Fall 2001

Exam IV

Name___________________________

4 points
To get from seedless to seed plants, what was the evolutionary change required?
Megasporophyll overgrows megasporangium to make integument

What are the three components needed to call an object a seed:
seed coat, storage tissue, embryo

6 points
In what tissue are the storage reserves located in gymnosperm seeds?
Megagametophyte
What is the ploidy of that tissue?
1N

In what tissue are the reserves initially stored in angiosperm seeds?
endosperm
What is the ploidy of that tissue?
3N

Into what tissue are the are reserves finally stored in angiosperms such as bean?
cotyledon of embryo
What is the ploidy of that tissue?
2N

3 points
What is it about gymnosperms that makes them gymno?
ovule is exposed on megasporophyll
What is it about angiosperms that makes them angio?
ovule is hidden in the locule of the megasporophyll
What seed container is created by the evolution from gymno to angio?
fruit!

3 points
In the evolutionary step from gymno- to angio-sperm, pollination had to be fundamentally changed. Tell about the placement of pollen grains during pollination in...
gymnosperms:in micropyle     angiosperms:on stigma
What is the consequence of this placement in terms of tube cell action?
tube cell must digest through carpel length to get to micropyle

6 points
Make a sketch of a pollen grain for a gymnosperm here:
microspore wall
tube cell
generative cell
2 prothallial cells
What cell type must go from that diagram to make it an angiosperm pollen?
prothallial cells
What would be structurally different between a cycad sperm and a bean sperm?
bean sperm lacks flagella

3 points
In the evolutionary step from gymnosperm to angiosperm, what changed about the fate (destination) of the sperm cells in syngamy (aka fertilization)?
in gymnosperms: joins egg to become zygote
in angiosperms: one joins egg to become zygote
      the other joins central cell to become endosperm

4 points In the evolutionary step from gymnosperm to angiosperm, what were the changes in the composition of the megagametophyte (aka embryo sac)?
The sterile cells are reduced to just 3 antipodals that disintegrate
The archegonium are mostly lost (synergids?)
The neck cells now do this: burst pollen tube-sperm release
The true innovation in angiosperms (no gymnosperm equivalent) is the central cell joins with sperm to form triploid endosperm

2 points
Syngamy (aka fertilization) also changed fundamentally as the step from gymnosperm to angiosperm evolved. What are the names of the two resulting cells in angiosperms?
zygote     endosperm

4 points
The pollination vector in gymnosperms is wind
The pollination vector in primitive angiosperms (Magnolia) is beetle
The pollination vector in one group of advanced angiosperms (grasses) is wind
This last evolutionary step is a homoplasy known as a reversal

5 points
Through evolution of plants, the female gametophyte has been increasingly reduced in size and complexity. It has also been increasingly buried inside other layers. For example, in the step from gymnosperm to angiosperm there was an additional layer. As we move through the evolution of angiosperms (Magnolia to Aster or to Orchid) yet another layer is added. Starting with the outermost layer of these most-advanced angiosperms, list the layers that one must pass through to get to the egg.
outer: receptacle, ovary, integument, nucellus, Mspore wall, egg

6 points
Assuming that all goes well after syngamy, what are the two different products of the zygote?
suspensor       embryo
What are the three stages through which a dicot embryo passes (hint: these are shape names)?
globular - - heart - - torpedo
While those stages are being accomplished in the embryo, what is happening to the endosperm?
free-nuclear (liquid) to cellular (solid)

7 points
Think of just one species of plant...
Its flower has an inferior ovary, therefore its flower is epi-gynous.
And its fruit will therefore include an (composition) accessory
This comes from what part of the flower? receptacle
If the inferior ovary has five locules, the pistil is compound
If the pistil from that one flower becomes a fruit, the fruit is (origin) simple
If that fruit is fleshy with a cartilaginous core, the fruit is a pome
If the fruit is dry and opens by splitting along each carpel, the fruit is a capsule

16 points
Write P or A in the blank depending on whether the condition is Plesiomorphic or Apomorphic.
P flower symmetry radial
A floral axis short
A whorled parts
P large numbers of parts per whorl
A ovary inferior
P fruit is follicle
P flower is beetle pollinated
A perianth whorl is missing (incomplete)
A flowers are unisexual (imperfect)
A perianth parts are fused into a tube
A stamens are fused to the petals
A flowers are in a large inflorescence
A sterile flowers found in cluster
A accessory fruit
P aggregate fruit
A multiple fruit

Bonus: 5 points
Name 2 events in prophase I of meiosis that are different from prophase of mitosis
1. synapsis 2. recombination (cross-over)

What is separated in anaphase I? 3. homologous chromosomes

What is separated in anaphase II? 4. sister chromatids

What does not happen in metaphase I that does happen in mitosis?
5. centromere breakdown



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