126 - ___ = ____/____ = ______ Biology of Plants
Spring 1998

Exam II


In the "fungi" you were introduced to various gamete mating types. Name and describe the three fundamental kinds of gametes and give an example "fungus" for each type. 12 points.

Gamete TypeDescription (2 pts each)Example "Fungus"
iso-gamousboth gametes motile and same sizemyxomycete, zygomycete, or basidiomycete
aniso-gamousboth gametes motile, one larger and the other smallerchytridiomycota
oo-gamousone gamete small and motile (sperm), the other large and sessile (egg)myxomycete, zygomycete, or basidiomycete

In "fungi" you have been introduced to three types of life cycle. Name each one, completing the description, and give an example "fungus" for each type. 10 points.

Life Cycle TypeDescriptionExample "Fungus"
spor-icThere is both a gametophyte and a sporophyte because both the spores and the zygote divide by mitosis.chytridiomycota, (myxomycota, ascomycota, basidiomycota)
gamet-icThere is a sporophyte but no gametophyte because the spore becomes the gameteoomycota, (myxomycota)
zygot-icThere is a gametophyte but o sporophyte because the zygote becomes the sporocytezygomycota, (ascomycota, basidiomycota)

In addition to many examples of "fungi", you have seen them grouped into divisions. In the table below, name each division and tell the key feature that distinguishes it from all the other "fungal" divisions. 12 points.

Division Name (formal or informal)Distinguishing Feature

4 points
What is the nuclear condition (haploid, diploid, etc.) in a basidiospore?haploid
...in a basidium just before basidiospore formation?diploid
...in the stipe (stalk) of a basidiocarp (mushroom)?dikaryotic
...in the mycelium (hyphae) in the substrate under a mushroom?dikaryotic

Use any "alga" as an example to diagram a life cycle. Be sure to include by sketch and label all of the various stages of its life history. You may not use Ulva nor Chlamydomonas as the example. 25 points.

1 point for the name
3 points each for the phases:
spore, gametophyte, gametes, syngamy, zygote, sporophyte, sporocyte, meiosis

See figures in the textbook for Cladophora (fig. 27.14 on page 643), Fucus (fig. 27.24 on page 649) , Ectocarpus (fig. 27.22 on page 647) , Polysiphonia (fig. 27.27 on page 651) for inspiration.

If your life cycle above is missing any parts of the sporic life cycle, explain here what exactly is missing or subject to interpretation.

Of all the eukaryotic algae, one is extremely simple. It is Chlamydomonas. It is completely unicellular, never filamentous. Vegetative haploid cells can reproduce by mitosis, but this is not true of any diploid cells. Chlamydomonas is isogamous and syngamy is instantaneously complete. Using this information, sketch and label the life cycle of Chlamydomonas below: 14 points

2 points each for the various phases
spore, mitosis, gametes, syngamy, zygote, sporocyte, meiosis

See figure 27.8 on page 640 in the textbook for inspiration

If someone were to call this Chlamydomonas life cycle "gametic", what else would it have to be? Explain. 3 points

zygotic because the zygote becomes the sporocyte

If someone were instead to call this Chlamydomonas life cycle "zygotic", what would constitute the gametophyte? 2 points

the population of dividing haploid cells.

5 points:
Syngamy is a two-step process.
name the first step
name the second step.karyogamy
what would the cells be called before the first step?haploid, gametes
what would the cells be called between the two steps?dikaryotic, heterokaryotic
what would the cells be called after the second step?zygote, diploid

You are given a mystery "alga" which has phycobilin pigments (phycocyanin = blue, phycoerythrin = red) in addition to chlorophyll a. How can you tell what division of "algae" it belongs to? Tell what you would DO and how the results of what you do would help you make a decision. 3 points.

If we think of bryophytes as the most primitive of terrestrial plants, give one reason that each stage of the life cycle is well-adapted to life on land compared to more-primitive aquatic algae. 8 points

cutinized to prevent desiccation
held in archegonium sterile jacket
hydroids, leptoids for water transport
lifts sporangium up for wind dispersal
release gametes only when water available
dispersal mechanism for dry wind dispersal
one motile but other held in sterile jacket
held in sterile jacket to prevent desiccation

1 point
The life cycle of all true plants (bryophytes and vascular plants)
is: (circle)       gametic       sporic       zygotic

1 point
The gametes of all true plants (bryophytes and vascular plants)
are: (circle)       isogamous anisogamous       oogamous

5 points
In as few words as possible describe a bryophyte gametophyte (list the parts).
thallus, rhizoid, antheridium, archegonium
Would a fern gametophyte be any different
in terms of these parts? (circle)       yes       no

4 points
In as few words as possible describe a bryophyte sporophyte (list the parts).
foot, stalk, sporangium
Would a fern sporophyte be any different
in terms of these parts? (circle)       yes       no

3 points
What features of the fern sporophyte led you to your decision above?
root, stem, leaf

2 points
In the space below, tell why bryophytes are relatively short in stature (why do we not have bryophyte "trees" when we DO have tree-ferns?).

bryophytes lack lignin which means they cannot support a large plant body and
their vascular tissue is too limited to permit large body size

In the space below, sketch out and label the gametophytes and sporophyte of a fern. Be sure to label their parts and the important end-product of each plant's life. 12 points.

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