1. Review the structures and processes observed and then label the diagram of the moss
life cycle in your lab manual.
2. Using colored pencils, indicate if structures are haploid or diploid and circle the
processes of mitosis and meiosis in Figure 14.5 in your lab manual.
Discussion
1. Are the spores produced by the moss sporophyte formed by meiosis or mitosis? Are
they haploid or diploid? Do the spores belong to the gametophyte or sporophyte
generation? (3 points)
Spores are produced in the moss sporophyte by meiosis. Moss sporophytes are diploid.
So, they produce spore via meiosis are haploids. As the spore are haploid, they belong to
the gametophytic generation.
2. Are the gametes haploid or diploid? Are they produced by meiosis or mitosis? (2 points)
Gametes are produced from the gametophytic plant body which is haploid. So, the
gametes produced via mitosis. So, the gametes will also be haploid.
3. Is the dominant generation for the mosses the gametophyte or sporophyte? (3 points)
Dominant stage of the moss plants are gametophytic plant body. It is haploid body. It is
produced from the spore which are produced via meiosis from the sporophytic plant
body.
1
, 4. Describe the structure of the archegonium and the sporangium? Relate these structures
to their functions for moss survival in the terrestrial environment. (5 points)
An archegonium is a multicellular structure or organ of the gametophyte phase of certain
plants, producing and containing the ovum or female gamete. The archegonium has a
long neck canal or venter and a swollen base. A sporangium is the capsule structure
belonging to many plants and fungi, in which the reproductive spores are produced and
stored. Mosses are bryophytes, primitive plants believed to be among the first to develop
the ability to live on land. Mosses have no vascular tubes to transfer water or nutrients,
and no true stems or roots. Moss plants reproduce sexually using separate plants
produced at different times. In the moss archegonia are not embedded but are located on
top of the leafy gametophore. Gametophytes are tipped with either inverted cone-shaped
areas (archegonia) or male reproductive organs (antheridia). Released sperm
(antherizoids) need water since they swim to the archegonium. Sprouting from the
gametophyte tip after fertilization, a sporophyte holds itself in place by anchoring a foot
in the archegonium. The sporophyte stalk, called the seta, bears the sporangium (spore
capsule) on its tip. One sporangium may produce up to a million spores. Maturing spore
capsules are guarded by a covering called the calyptra that shrivels and falls off when the
spores are mature. A cap called the operculum tops the capsule's opening under the
calyptra. The capsule opening (peristome) can have teeth that help hold it closed.
Matured spores are released when the capsule top ruptures and drift off to form new
plants.
5. Can you suggest any ecological role for mosses? (3 points)
Mosses are best indicator of the ecosystem or environment pollution. They retain water,
so has good water absorbing capacity. They are also best in increasing the fertility of the
soil. They also have many other ecological roles.
6. What feature of the life cycle differs for bryophytes compared with all other plants? (3
points)
In bryophytes the life cycle is haplontic life cycle. The dominant stage of the bryophytes
is haploid, gametophytic plant body. In other plants, the dominant stage is the diploid
plant stage, the sporophytic plant body. It is the main difference between bryophytes life
cycle and other land plants.
Lab Study B. Hepatophyta: Liverworts
Discussion
2
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