Biology 332 Spring 1999	Exam II	Name_________________________

Among "fungi" you have seen three different life histories. Name the three types of life history, tell briefly the fundamental differences, and give an example "fungus" for each life history. 12 points.

Life History	Gametophyte	Sporophyte	Example
spor-ic	multicellular	multicellular	Allomyces
gamet-ic	spore-->gamete	multicellular	Saprolegnia
zygot-ic	multicellular	zygote-->sporocyte	Mucor

In studying the fungal-like organisms, you studied a table of six divisions (phyla) of organisms. Name the divisions and tell what distinguishes each division from the others. 12 points.

Division (Phylum)	Distinguishing Feature(s)
Myxomycota	plasmodium
Chytridoomycota	haustorium
Oomycota	oogonium
Zygomycota	zygospore
Ascomycota	ascus
Basidiomycota	basidium

You are on a trip to Bermuda and you are observing a particular species of Rhodophyte algae. While examining its distribution from the high-tide (exposed at low tide) mark to a depth of 30 meters on the flanks of the seamount, you collect specimens into netted bags and bring them to shore, making careful note of the depth at which each is collected. The specimens are one of three different colors (green, red, bluish-purple) depending upon the depth at which the alga was growing. Tell which colors are associated with each depth and explain why/how the colors change with depth. Hint: water is fairly transparent, but selectively absorbs lower-energy wavelenths. 12 points.

depth	exposed at low tide	continuous shallow	in deep water
algae color	green	blue-purple	red
why/how	There is plenty of 680/700 nm light, no critical accessory pigments are made	680/700 nm light absorbed by water, phycocyanin and phycoerythrin made to use yellow/orange and blue/purple for PSN	Even yellow/orange absorbed by water, phycoerythrin made to use blue/purple for PSN

Life Cycle
On this page, diagram the life cycle of a mushroom. Be sure to show all of the various parts of the life cycle, including reasonably-large sketches of microscopic stages. All parts of each sketch must be fully labeled. It is important to indicate processes on any arrows connecting sketches. It is important to show the chromosome condition (1N, 2N, etc.) for each sketch as well! 27 points.

basidiospore n
germination
Gametophyte
mycelium n
+/- mating types
isogamous
plasmogamy
Sporophyte? n+n
mycelium n+n
basidiocarp n+n
cap
pileus
annulus
volva
rhizomorph
lamellae
basidium n+n
karyogamy
syngamy
zygote 2n
sporocyte 2n
meiosis
sterigma

isogamous-fusing cells are the same size

sporic-dikaryotic mycelium is sporophyte
zygotic-only truly diploid in basidium (zygote become sporophyte)

indefinitely many

4

meiospores 1n
mitosis
"gametophyte"
isogametes
+/- mating types
syngamy
zygote 2n
zygotic
sporocyte 2n
meiosis

Chlamydomonas braunii is just like C. reinhardtii, except for the fact that it is anisogamous. Redraw whatever sketch(es) must be revised in the life cycle. 4 points both motile; female large, male small

Chlamydomonas coccifera is just like C. reinhardtii, except for the fact that it is oogamous. Redraw whatever sketch(es) must be revised in the life cycle. female = large, immotile; male = small, motile

Complex Green Algae
Not all algae are as simple as Chlamydomonas. Perhaps a more typical example is the common sea lettuce, Ulva lactuca. Sea lettuce is commonly observed in the wrack on the beach, but it is found naturally anchored in shallow tide pools. It is anisogamous, sporic, heterothallic and completely isomorphic. Gametes are biflagellate; two fundamentally-different motile cells in the sexual cycle are quadriflagellate. Assume there is no asexual reproduction. Using this information, sketch and label the life cycle of Ulva lactuca below. 19 points.

male gametophyte
female gametophyte
heterothallic
holdfast
1n
female gametangium
male gametangium
biflagellate female gamete
biflagellate male gamete
anisogamous
syngamy
quadriflagellate zygote
2n
sporophyte
holdfast
isomorphic
sporangium
sporocyte
meiosis
quadriflagellate meiospores

Bryophytes
In the following grid, make and label a sketch of each part of the life history of a moss. 25 points total.

haploid	diploid
spore 2 points spore wall spore wall nucleus	zygote 2 points zygote archegonium (calyptra)
gametophyte 3 points "leaf" "stem" rhizoid	sporophyte 3 points sporangium seta foot
gametangia 9 points archegonium neck neck canal cells egg venter antheridium sterile jacket spermatogenic tissue stalk	sporangium 6 points operculum peristome teeth diaphragm columella sterile jacket sporocytes-->

9 points:

What stage of the life history of a moss indicates an alga-like ancestor?	protonema
What characteristic of gametangia and sporangia in mosses shows good adaptation to life on land?	sterile jacket
What characteristic of moss gametophytes is adaptive for terrestrial existence?	hydroids and leptoids
What characteristic of moss sporophytes is adaptive for terrestrial existence?	cutin and stomata
What structural characteristic of moss spores is adaptive for terrestrial existence?	sporopollenin and wind dispersal
What characteristic of hornwort sporophytes expands their reproductive potential?	intercalary meristem
What characteritic of hornwort sporophytes is most-adaptive for independence from the gametophyte?	photosynthesis
What is the gamete condition found in all true plants (bryophytes and vascular plants)?	oogamous
What is the kind of life history found in all true plants (bryophytes and vascular plants)?	sporic

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