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Published byLouise Jenkins Modified over 8 years ago
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Pollen producing plants
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Gymnosperms Have long thin needle like leaves – to conserve water. Largest group are the conifers – “Christmas” trees Are “evergreens” – retain their leaves all year long. Seeds are on the cone – exposed, not protected. Have “male” and “female” cones. Female cones contain ovules Male cones produce pollen, in large quantities Pollen is dispersed by the wind Why do you think these plants produce such a LARGE amount of pollen??
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Angiosperms Develop flowers for the purpose of reproduction This is an evolutionary advantage because flowers attract insects which can then transport pollen from one flower to another Can produce less pollen There is an ovary in each flower that protects the seed After pollination, the ovary develops into a fruit which protects the seed and aids in its dispersal. In comparison with Gymnosperms, where is the effort placed in angiosperms? (Flower? Pollen? Fruit?)
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World global diet What percent of the global diet comes from plants? Hint: you may need to add some pies slices together here. What about the 13.5% that is not plant based… is it also dependent upon plants in any way?
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Pollination vs Fertilization What’s the difference?
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Seed dispersal Seeds can be dispersed by wind, water, animals…
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Spore producers Bacillus anthracis (anthrax) Algae Fungi Ferns
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Spores Understanding spore production and the different organisms that produce spores can help create a spore profile for an area. Spore producers include protists (algae), fungi, and plants. Bacteria produce endospores. Endospores are not used in reproduction, they are a dormant capsule of the bacteria. Some endospores cause disease – Anthrax & botulism are examples. Spores are dispersed by wind or water. Spores have widespread coverage in certain geographic areas, just like pollen. Spores are able to be grown to identify the species exactly.
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Pollen and Spore Identification The hard outer layer of a pollen grain and spore is called the exine. Exines have a unique structure when viewed under a microscope. Size, shape, wall thickness, & surface texture Wind dispersed pollen grains have thinner walls Animal dispersed pollen are larger, “stickier”, and thick- walled. Spores are much smaller than pollen grains and produced in greater quantities. Spores are more difficult to identify than pollen, but they can be grown into a full sized organism for identification.
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Pollen and Spores in Forensics If the pollen or spores found on the victim are not native to the crime scene, it may indicate the body was moved. Pollen and spores are difficult to remove and/or get rid of. Pollen and spores are drought resistant and are very hardy. Pollen and spores can give investigators a timeline for the crime. Criminals may pick up pollen or spores on their clothing from a crime scene without knowing or thinking of it.
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Pollen and Spores in Forensics
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Collecting Pollen and Spores Control and evidence samples must be collected. Contamination is a major problem with collection and a good defense lawyer will target this to look for holes in the prosecution’s case. Pollen and spores can be found everywhere, some areas to look are: Hair, fur, rope, feathers, clothing, mucus membranes, & sticky surfaces When collecting samples: Wear clean gloves Place samples in a sterile container Use clean or new sampling instruments
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Analyzing Pollen and Spore Samples Pollen and spores are chemically extracted from samples in a lab Tools specialists use to examine and identify include: compound light microscope scanning electron microscope (SEM) reference collections (photos, illustrations, dried specimens) Pollen and spore evidence—collected, analyzed, and interpreted—can be presented in court
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Making a wet mount Materials Microscope slide Cover slip Water Dropper Specimen Stain (if required) Procedure Place a drop of water on the center of a clean dry slide (if the specimen you plan to observe is already in a liquid environment, you can skip this step). Next, place your specimen in the middle of the drop. Carefully place one edge of the cover slip next to the water, holding the cover slip at a 45 degree angle to the microscope slide. Slowly lower the cover slip onto the water, trying to minimize the number of air bubbles that can form under the cover slip. Lastly, you may want to use a paper towel, placed at the edge of the cover slip, to draw out some of the extra water. If using a stain, place a drop of stain at one side of the cover slip while holding a paper towel at the other side. This will draw the stain across the specimen.
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Calculating size of an object in micrometers Determine the size of the field of view in millimeters using a ruler at 100x (that’s your medium power). Now convert to micrometers: 1mm = 1000μm. You now know what the size of your field of view is in μm. Estimate the size of your pollen (or cell, hair, fiber, etc.) with respect to how many can fit across the field of view. Then calculate the size of the object: Field of view (in μm)= size of object Number of objects across field
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