 and use your sharpest powers of observation to see how fern spores develop. To do this investigation you will need: C-Fern spores, one cotton-tipped swab, one Petri dish containing agar-solidified nutrient medium, one plastic sandwich bag a marker and a place to grow your culture
A spore is a single cell. Under the right conditions, spores grow by mitotic divisions and differentiate into multicellular plants that eventually produce gametes. Look at the vial of C-Fern spores. These are spores of a tropical fern called Ceratopteris. you may have seen this fern sold as an aquarium plant named water sprite. How many spores do you think are in the vial? Are the spores dry? If they are dry, how can they survive? What do you think would be necessary for them to germinate?
Take a cotton-tipped swab and carefully dip it into the spores so that some spore adhere to the cotton. Take only a few spores! Since spores are very small, only a slight brown coloration on the cotton end is plenty. Tilt the Petri dish lid only enough to position the swab tip over the agar and tap off some of the spores onto the agar surface. After distributing the spores as sparsely and as evenly as possible, replace the petri dish lid. It is important to work quickly while the lid is up so that you reduce the chance that foreign air-borne spores and other contaminants enter your culture. Using the marker, write your initials, and date on the lid and bottom of the Petrid dish. Place your dish into a plastic sandwich bag.
Prepare a wet mount of some of the spores remaining on the swab. Sprinkle some spores into a small drop of water on a microscope slide and place a coverslip over them. Observe this wet mount of spores under the microscope at different powers. Can you see any patterns on the spore walls? What variations in the spore wall ornamentation occur on different surfaces of the spores? Draw a few spores showing the wall pattern or ornamentation.
Observe the spores on your dish with the microscope. Describe and record the general size and color and distribution of spores on the dish. Over the next several laboratory session, it will be your job to carefully observe these spores and what happens to them. When you arrive for your lab period the first thing that you should do is check your fern cultures – it will only take a few minutes! Make good notes and drawings of what you see. You will be given additional instructions and questions to aid in your observations.
Have you observed the fern cultures that you inoculated last week?. By this time many spores should be germinated. Can you see anything without a microscope? Observe the size, color, and distribution of germinated spores through the lid of the dish with the dissecting microscope and compare and contrast the appearance of your spores with the observations you made last week. You can identify the developing ferns because they will always be growing out of spores. What is happening when spores germinate? Have all the spores germinated? What could be the reasons for the germination of some spores and not others? Are there fungal, bacterial or algal contaminants on the plate? Where do these contaminants come from?
Carefully lift the lid of the culture and remove a few of the germinated spores using a probe. Prepare a wet mount of the germinated spores and observe them under the microscope. Locate the original spore walls. What has happened to the spore wall? The minute plants poking out of the spore wall should be green. Locate the rhizoids. What is the function of rhizoids in a plant that is composed of only a few cells? Locate cells that contain chloroplasts. Draw several of these young plants and label the spore wall, rhizoids, and photosynthetic cells with chloroplasts. What differences are there, if any, among the young plants that you observed? Replace your dish into the sandwich bag and put it back in the culture area.
As in the last laboratory, you should start by observing your fern cultures. As before, observe the fern plants on the dish and record your observations. Can you see anything