BIOL-1010
Name: ____________________________
Introduction to Biology
Instructor/TA Name: _________________
Rubric: C -Fern Lab Report
Introduction (4 points):
This was a multi-week genetics project, which began with the sowing of spores
on nutrient agar. You observed growth and development over many weeks and
recorded these changes in the images you took. You also observed the results of
mitotic and meiotic cell divisions and should be able to identify where in the
fern’s life cycle each type of division occurred based on what you have learned.
Additionally, from the phenotypes of the gametophytes and the sporophytegametophyte combinations, you should be able to determine the genotype of the
mature fern that produced the spores you used and also whether the mutant
trait is dominant or recessive.
Begin the Introduction by describing the life cycle of the fern. First explain what
is meant by alternation of generations, tell which parts of the life cycle are
haploid and diploid and define these terms. Be specific with your definitions.
Then, begin your description of the life cycle starting with the spore. In your
narrative, indicate what type of cell division occurs at each developmental step.
For example, by which process - mitosis, meiosis or fertilization - does the spore
develop into a gametophyte? Gametophyte into zygote? Zygote into sporophyte?
What type of cell division is used to produce spores from the sporophyte?
State the purpose of this multi-week genetics experiment explaining that you are
following the inheritance pattern of the mutant allele as you learn the life cycle of
the fern. Additionally, you learned how to use both dissecting and stereomicroscopes to image stages in the life cycle. Include a statement your
hypothesis about the mode of inheritance of the mutant trait. Based on your
hypothesis, state the expected proportions of mutant and wild types of the
hermaphroditic gametophytes; and the expected proportions of mutant and wild
phenotypes of the sporophytes.
Methods (2 points):
Describe how you sowed the spores on a 60mm Petri dishes containing sterile Cfern medium with a sterile plastic spreader. How many drops of suspended
spores were placed on the dish? Between observations your dish was kept in a
culture tray with dome. Where was the tray kept? Under what conditions (light
and temperature) were the plants maintained? The plant grow stand had full
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spectrum lighting 24hrs/day and was held at a temperature of 28-30oC.
When did you make observations and what structures did you take pictures of?
Use days from sowing (dsf) as the time frame between observations. When were
your first images taken? What did you see? What is the trilete mark (the
Mercedes Benz-like emblem)? When did you image the wild and mutant
hermaphroditic gametophytes? Male gametophytes? When did you count the
numbers of wild and mutant hermaphroditic gametophytes? Wild and mutant
sporophytes? What did you do to fertilize your gametophytes and when did you
do this (dsf)? Describe what you did in transferring sporophytes to soil. How did
you prepare the soil? How many sporophytes did you transfer and what were
their phenotypes?
Results (5 points)
Present your data here, but save the interpretation for the Discussion. Give the
numbers of wild and mutant phenotypes for the hermaphroditic gametophytes
for your own data and include the Chi square and P-values. State whether the
results are significant or not. Refer the reader to the appropriate Table. Give the
numbers and proportions of wild and mutant phenotypes of the sporophytes for
the pooled results for your lab section and all of BIOL-1010 as well. Include
the Chi square analyses and P-values for the pooled data (your lab section and
all BIOL-1010), and tell whether you should or should not reject your null
hypotheses. Remember that a P-value of less that 0.05 is considered significant;
a value less than 0.01 is highly significant. You must include tables showing the
numbers of mutant and wild hermaphroditic gametophytes; and also the
numbers of mutant and wild sporophytes for your lab section’s data and as well
as for all BIOL-1010. Additionally, include a table of the BIOL-1010 data
showing the numbers of sporophyte/gametophyte combinations observed:
wild/wild, wild/mutant, mutant/mutant and mutant/wild.
You must a include a figure of the fern life cycle that you have made yourself
using the photos you took in lab. Create a sequence of images showing the
developmental stages from spore (first image) to young and mature
gametophytes to developing sporophytes (last images). You must include
images of spores with trilete marks and the following gametophytes: male,
hermaphrodite, wild and mutant; and sporophyte/gametophyte combinations:
wild/wild, wild/mutant, and mutant/mutant. Include arrows between each
image. Near each arrow, you must tell what kind of cell division or
fertilization process occurred to lead to the next pictured structure. Each
image must be clearly label and include all of the following information:
•
•
•
Figure number (e.g., Figure 1a)
Name and phenotype of structure (e.g., wild male gametophyte)
Whether the structure is haploid or diploid
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Discussion and Conclusion (5 points)
Fully discuss and interpret your results here. Were the spores that you sowed
from a homozygous or heterozygous fern? You can determine this from the
proportions of wild and mutant hermaphroditic gametophytes. Justify your
answer based on what you know about the products of mitosis and meiosis.
What is the genotype of this fern? Is the mutant allele dominant or recessive?
You can determine this by examining the proportions of wild and mutant
sporophytes that you observed. Again, use the proportions of the two
phenotypes to justify your answer. Was your hypothesis correct, why or why
not? You must support your hypothesis by including the Chi-square and Pvalues. If the P-value for your Chi-square analysis is not significant then you
would say that your null hypothesis should not be rejected. If the P-value is
significant, then you must explain what happened. What were the possible
sources of error? Why will you never find a mutant sporophyte growing on a
wild gametophyte?
Citations (1 point)
Full citation must be given in order to receive any credit.
Include the following images and tables with your lab report (4 points):
Images:
1. Sequence of images showing development stages from spore to
mature gametophyte to developing sporophyte over multiple weeks.
Each image must have a figure number, be labeled by name of the
structure and phenotype (e.g., wild gametophyte), and whether the
structure is haploid or diploid. Include arrows between each pair of
images in the sequence and tell what process generated the next
structure in the sequence (mitosis, meiosis, or fertilization). The
following is a list of the images that you must include:
• spore showing trilete mark
• wild type male gametophyte
• mutant male gametophyte
• wild type hermaphroditic gametophyte
• mutant hermaphroditic gametophyte
• wild sporophyte on wild gametophyte
• wild sporophyte on mutant gametophyte
• mutant sporophyte on mutant gametophyte
• If you have additional images (e.g., gametophyte emerging
from the spore, young gametophyte, etc.) include them.
2. Extra: Video of sperm release from antheridia (submit CD)
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Tables:
1. Table 1. Number of Wild and Mutant Hermaphroditic Gametophytes
(your own data)
2. Table 2. Number of Wild and Mutant Sporophytes (your lab’s data)
3. Table 3. Number of Wild and Mutant Sporophytes (all BIOL-1010)
4. Table 4. Numbers of Wild and Mutant Sporophytes Growing on Either
Wild or Mutant Gametophytes (all BIOL-1010) (See Table 4 on p. 6.)
Note: For Tables 1-3 you must include calculations for Chi square
and P-values.
Completed C-fern Genetics Packet
Attached Worksheet
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Worksheet for Calculations
Table 1. Phenotypes of Hermaphroditic Gametophytes
(Your own Data)
Wild
Phenotype
Mutant
Phenotype
Observed
(Number counted)
Expected
Difference
(Difference)2
Expected
Chi square:
P-value:
Is this result significant?
Should you accept or reject the null hypothesis (Ho)?
Table 2. Phenotypes of Sporophytes – Your Section’s Data
Wild
Phenotype
Mutant
Phenotype
Observed
(Number counted)
Expected
Difference
(Difference)2
Expected
Chi square:
P-value:
Is this result significant?
Should you accept or reject the null hypothesis (Ho)?
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Table 3. Phenotypes of Sporophytes – BIOL-1010 Data
Wild
Phenotype
Mutant
Phenotype
Observed
(Number counted)
Expected
Difference
(Difference)2
Expected
Chi square:
P-value:
Is this result significant?
Should you accept or reject the null hypothesis (Ho)?
Table 4. Phenotypes of Sporophytes – BIOL-1010 Data
Count the numbers of sporophyte/gametophyte combinations observed:
wild/wild, wild/mutant, mutant/mutant and mutant/wild.
# of Mutant
# Wild
Gametophytes Gametophytes
Wild type
sporophyte
Mutant
sporophyte
Did you find any mutant sporophytes growing on wild gametophytes?
Why or why not?
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