Download Figure 1: Life Cycle of a Moss

Kingdom Plantae: Division Bryophytes
Biology 11
Name:_____________________
Date:_____________Blk:_____
Lab: Life Cycle of a Moss
Purpose: To observe the structures of a moss with special attention paid to the
alternation of generations found within the moss life cycle.
Materials:
Dissecting microscope
Compound microscope
Fresh moss plant specimens
Slides & coverslips
Moss antheridium prepared slide
Moss archegonium prepared slide
Moss protonema prepared slide
Eye dropper & water
Procedure & Observations:
1. Examine a fresh moss gametophyte (the green part) under a dissecting
microscope. Describe how the leaf-like structures are arranged around the
stalk. __________________________________________________ How
does the plant benefit from having the leaf-like structures arranged in this
way? ________________________________________________________
_____________________________________________________________
Draw a diagram of the moss gametophyte and label the rhizoid, stalk, and
leaf-like structures.
_____________________________________ ________X (Magnification)
1
Kingdom Plantae: Division Bryophytes
2. With a dissecting microscope, examine the root-like structures, called
rhizoids at the base of the gametophyte. They are not true roots because
they do not contain vascular tissue. What might be the function of the
rhizoids? _____________________________________________________
_____________________________________________________________
3. Remove one of the leaf-like structures, prepare a wet mount and observe the
cells using the compound microscope. How many cell layers does the
structure have? _____________________ What organelle is abundant in the
cells?________________________________
4. The male and female sex organs of the moss are located at the tips of the
gametophyte. Using the compound microscope, observe and draw the
prepared slide of the moss antheridium (male) and the moss archegonium
(female). Use 10X objective lens. Label the egg and sperm. How does the
sperm cell reach an egg cell in order to fertilize it?
_____________________________________________________________
_______________________ _____X
________________________ _____X
5. Using the dissecting microscope, observe and draw the upper part of the
moss gametophyte with its attached sporophyte. Label the gametophyte,
sporophyte, stalk, sporangium/spore capsule. The sporophyte resulted
from the growth of a zygote inside the archegonium at the tip of the
2
Kingdom Plantae: Division Bryophytes
gametophyte. Try to loosen the foot of the sporophyte from the tip of the
gametophyte. Is it firmly attached or very loose? _____________ The
sporophyte receives its nourishment from the gametophyte. The capsule at
the tip of the sporophyte is the sporangium which produces haploid spores.
_____________________________ _______X
6. When a spore starts to grow it becomes a new moss gametophyte. The
young gametophyte is called a moss protonema. Using the compound
microscope (high power), observe and draw the prepared slide of a moss
protonema. Moss protonema looks like ____________________________.
This suggests an evolutionary link between _____________ and bryophytes.
______________________________ _______X
3
Kingdom Plantae: Division Bryophytes
7. Label Figure 1: Life Cycle of a Moss diagram using the following terms:
(18 marks)
antheridium
archegonium
gametophyte (N)
sperm (N)
egg (N)
female gametophyte (N)
zygote (2N)
spores (N)
male gametophyte (N)
protonema (N)
rhizoid
sporangium/spore capsule
fertilization
sporophyte (2N)
meiosis
leaf-like structures
stalk
drops of H2O with sperm
developing gametophyte(N)
Discussion Questions: (24 marks)
1. Give several reasons why moss plants need a moist environment. (3 marks)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
2. How might the lack of specialized vascular tissue relate to the height of
moss plants?
(1 mark)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
3. a) In mosses, which generation produces spores? ______________________
b) Which generation produces sperm and egg? ________________________
c) Is the spore-producing generation (N) or (2N)?______________________
d) Is the gamete producing generation (N) or (2N)?____________________
e) Which generation is photosynthetic? _____________________________
f) In what type of habitat is fertilization most likely to occur?____________
_____________________________________________________________
g) Which generation is most conspicuous/easiest to find? _______________
h) Are the spores (N) or (2N)?_____________________________________
i) Are the gametes (N) or (2N)?____________________________________
4
Kingdom Plantae: Division Bryophytes
4. Discuss 3 structural differences that allow moss to be more successful on
land than algae?
(3 marks)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
5. Why do moss plants grow close to the ground?
(1 mark)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
6. Gardeners often add sphagnum (peat) moss to soil. How might this be
helpful?
(1 mark)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
7. Is the sporophyte generation dependent on the gametophyte generation?
How?
(2 marks)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
8. a) Do both generations have vascular tissue? _________________
b) The capsule contains the sporangium where the cellular process
_________________________________ occurs during the production of
_________________________________. The latter disperse the species.
When they germinate, the (3)______________________________________
generation begins.
5
Kingdom Plantae: Division Bryophytes
Figure 1: Life Cycle of a Moss
6