Name: Colwyn Sleep
Date: May 21 2016
Biology 11 Unit 6 Assignment 1: What is the life cycle of a Simple Plant Virtual Lab
Journal Questions:
1. What is meant by an alteration-of-generations life cycle?
The term “alteration-of-generations” life cycle refers to organisms that have life stages which are
haploid (1 set of chromosomes) and diploid (2 sets of chromosomes). The organism may spend
an equal amount of time as haploid or diploid, or it may also spend more of its life in either the
haploid or diploid stage.
A mature sporophyte (“diploid” or “2n”) produces spores by meiosis. The process of meiosis
halves the number of chromosomes resulting in spores which have one chromosome (“haploid”
or “n”) .
A spore grows into a gametophyte and produces “gametes” which are male and female
reproductive sex cells, each containing one chromosome. Two gametes combine and form a
“zygote”, which contains the genetic information necessary to form a new individual. The zygote
grows into a diploid (2n) sporophyte completing the alteration of generations life cycle.
2. What is the main function of the mature gametophyte?
The main function of the gametophyte, once mature, is to produce the gametes, the reproductive
sex cells which will fuse to form a zygote.
3. What is the main function of the mature sporophyte?
The main function of the mature sporophyte is to grow and produce food energy via
photosynthesis, and to produce spores by meiosis to allow continuation of the species in future
generations.
4. Discuss in detail how a fern plant can reproduce both sexually and asexually. You
may want to use or sketch out images to reference your explanation.
Ferns are plants which utilize both sexual, and asexual processes during reproduction. Ferns
produce tiny structures called spores. These spores are produced asexually through meiosis so
their genetic material is identical to that of their parent fern. When the environmental conditions
are met, the spores germinate and grow into a tiny plant called a gametophyte. The gametophyte
develops both male and female sexual organs which produce sperm and an egg. The egg may
then be fertilized by sperm from the same gametophyte, or in some cases by a nearby
gametophyte. The result is a zygote, a new plant which now contains a combination of genetic
material from both a sperm cell and an egg cell, defining this reproductive stage in the
alternation of generations life cycle as a sexual one.
Alternatively, some ferns are also capable of asexual reproduction in a process called
“fragmentation” when a part of the ferns root structure called a rhizome breaks off and forms a
new plant. This plant is an identical genetic clone to the original fern, and the process does not
result in the creation of new genetic material, or an increase of genetic diversity.
5. Based on what you know about fern reproduction, why do you think ferns tend to
inhabit moist environments? What adaptations does it have to this environment?
Part of the fern reproductive process involves the growth of a spore into a mature gametophyte,
which then develops sex cells in the form of sperm and eggs. In order for the sperm to swim to
meet the egg, and fertilize the gametophyte, there must be water present or the sperm cannot
travel. It is for this reason that ferns tend to inhabit moist environments. One adaptation ferns
have developed to be more fit within their environment is their root structure called rhizomes.
These rhizomes contain vascular tissue that transport minerals, water, and food to the rest of the
plant. Another adaptation by ferns in their environment is the development of compounded
leaves. This leaf design allows the fern to increase its overall surface area, which in turn
increases the amount of the plant capable of using photosynthesis to produce food. This allows
the fern to maximize the potential sun energy while existing in partially shaded conditions such
as under the canopy of a coniferous forest.
Image of your Lab:
Please include a screenshot image of your completed life cycle from your virtual lab below
(which will reveal the fern life cycle).
!