154 - ______ = ______ / 116 = 70.9%

Biology 332
Spring 1999

Exam III


Evolution of female gametophytes. List the parts of the female gametophyte as it changed through evolution. 16 points


In the evolution of the female gametophyte, there is some reduction at each step described above. However reduction is not the main theme of this line of evolution. Instead, the critical theme is a matter of coverings around the female gametophyte. Tell what the covering(s) are (if any) for the gametophytes you described above: 6 points.

none none megaspore wall megaspore wall
nucellus (megasporangium)

Vocabulary. Next to each common name, write in its technical (descriptive!) name. 12 points

Common nameTechnical name
pollen grain endosporic microgametophyte
nucellus megasporangium
male cone microsporangiate strobilus
female cone megasporangiate compound strobilus
fertilization syngamy
pignoli or
pine nut
pine seed without integument (most nucellus)
megagametophyte with contained young sporophyte

Because of the changes in the female gametophyte, pines now have seeds. What is a seed and where does it come from? 4 points.

parts of a seedbefore a seed it is called:
seed coatstorage tissueembryoovule

So what is this name "gymnosperm" all about anyway? 2 points

the ovule is carried on the outside of the megasporophyll OR
the ovule is not enclosed inside a fruit

Evolution of male gametophytes. List the parts of the male gametophyte as it changed through evolution. 14 points.

tube cell
generative cell

In the evolution of the male gametophyte, the major theme is reduction at each step. But there is also an increase in covering. What covering(s) surround the male gametophyte in the most advanced species above? How does this covering assist the male gametophyte in achieving its necessary functions? 2 points

Name of Covering(s)How Covering(s) Assist(s)
microspore wall bladders assist in wind pollination

In lab you have seen male gametophytes up close. Sketch and label the male gametophyte for the two species: 16 points.

megaspore wall
tube cell
generative cell
prothallial cells

Because of the changes in the male and female gametophyte coverings, a new process (-tion) had to evolve. What is it called? What agent accomplishes this process? What is the specific "target" ("receiver") of this process in pines? Where does the item processed end up? 4 points.

Process NameProcessing AgentProcessing ReceiverFinal Resting Place
pollination wind pollination droplet micropyle

What is the major change in the gamete produced in the male gametophyte? Why would that be important? 2 points.

lost its motilitydoes not need free water to achieve sygamy

In both the evolution of male and female gametophytes there is a change in nutritional metabolism which is...? 2 points.

Primitive Nutritional Metabolism Advanced Nutritional Metabolism
reserves respiration

Evolution of sporophyte. List the kind of sporophyte leaf as it changed through evolution. 4 points

none microphyll megaphyll euphyll

Evolution of sporophyte. The stem of the sporophyte changed in terms of many features. Fill-in the chart below to demonstrate those changes. 9 points

featuresPsilotum (wisk fern)FernPine
stele type protostele siphonostele eustele
xylem maturation exarch mesarch endarch
radial amphiphloic colateral

Evolution of sporophyte. The root of the sporophyte changed too during the evolution of plants. Give the main feature set. [Hint: No animals early in evolution, grazers arrive, is wind a problem?] 3 points.

Psilotum (wisk fern)FernPine
rhizoid fibrous root woody tap root

Evolution of sporophyte. The spore bearing structures of sporophytes have also changed during the evolution of plants. Name the special multiple-part spore-bearing assemblies. 4 points.

Psilotum (wisk fern)Equisetum (horse tail)FernPine
synangium strobilus sorus cone

The extreme reduction of size and fundamental change in nutritional status of the gametophyte phases of the life history had a fundamental impact on the sporophyte phase in the sexual life cycle. Describe the move of an exclusive gametophyte characteristic into the sporophyte in such genera as the Lycophyte, Selaginella, and the ferns, Marsilea ("four leaf clover fern"). How did this change impact the nomenclature of the spore and sporophyte? Where is all this change leading the higher plants in terms of the kind of life history demonstrated in the life cycle? Does sporic really apply in the end? 16 points.

sexual differetiation moved into the sporophyte
monoecious = both sexes on same plant
dioecious = sexes on separate plants
heterosporous = two kinds of spores micro/mega spores
micro/mega sporangia
micro/mega sporophyll
micro/mega sporangiate strobilus/cone
moving from sporic toward gametic life cycle!

Sporophyte evolution. As the gametophyte slipped into obscurity, the sporophyte became much larger through evolution. The herbaceous club mosses gave way to ferns, woody cycads, and finally conifer trees. In supporting its increased size, the sporophyte stem evolved from an herbaceous condition to a woody condition. It increased in diameter by growth from within. This growth required further elaboration of surface tissues. Describe the two quite-different growth zones that are responsible for this secondary growth. 10 points.

Diameter IncreaseSurface Change
meristematic layer vascular cambium cork cambium
derivative layer
secondary xylem cork
wall additive in
schlerenchyma cells
lignin suberin
derivative layer
secondary phloem phelloderm
parenchyma layer
matures toward
outside       inside outside       inside

In the remaining space on this page, make a sketch of a monocot root cross section and label it completely. Next to each labeled structure, also indicate its one, most-important function. Next to the function, indicate from which of the three primary tissues it is derived. Be sure each structure has THREE labels: name, function, origin. 28 points.

sketchepidermis ion exchange protoderm
cortex storage of starch ground meristem
endodermis selective mineral uptake x
pericycle branch roots x
phloem import of photosynthate provascular
xylem export of water and minerals provascular
pith storage of water ground meristem

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