Lab 7 pre-lab.
Lab 7 is organized to give you a general overview of the biodiversity of three important taxonomic groups: terrestrial plants, protists, and fungi. You will view diverse specimen in each group, learn about their evolution, life cycles, reproductive strategies, and how to identify them. This introduction to protist, which we will use in our upcoming biodiversity research project, will help prepare you for labs 8 and 9.
How much do you know about about these three taxonomic groups?
Cataloging and measuring biodiversity, the variety of life in the world or in a particular habitat or ecosystem, is an important part of many evolutionary and ecological studies, as well as conservation efforts. In this lab you familirize yourself with these three groups.
ProtistsThe word protist is used to define a group of organisms that are small, usually single-celled, and that have evolved multiple times. The term once defined a monophyletic kingdom of eukaryotes. We now know that the group is paraphyletic, and its members can be found across many eukaryotic clades. Many protists are colonial, living and cooperating in groups. Some are consumers (like animals), while others photosynthetic (like plants), or decomposers (like fungi). Although they are incredibly diverse, we study them together for two primary reasons: 1) The same tools are required to view and understand these organisms (microscopes), and 2) they are key to understanding the evolution of plants, fungi, and animals.
In this lab, you will be examining slides under microscope to better understand: 1) what they look like; 2) how/what they eat; 3) if/how they move; 4) if they are single-celled, colonial, or multicellular, and 5) what effect they have on the ecology or health of biological systems. |
PlantsPlants evolved from green algae ancestors and were initially restricted to moist environments for survival and reproduction. Mosses, among the first to colonize land, led to the evolution of ferns and their relatives which possess poorly developed vascular tissues. As mechanical support cells evolved and vascular tissues became more capable of transporting water to greater heights, taller herbaceous plants (angiosperms and gymnosperms) evolved. These groups evolved seeds, and the angiosperms evolved flowers and fruits for reproduction. The evolution of plants is marked by these key evolutionary innovations and a transition from a gametophyte to a sporophyte-dominated life cycle.
In this lab, you will examine many of these features to better understand the evolution of plants and their functions. You will view various live specimen in each major terrestrial plant group, and learn to distinguish ovulate and staminate cones and the parts of a flower. You will also use a key for tree identification on campus. |
FungiFungi are the master recyclers on the planet and their study is called mycology. It is easy to quantify the importance of plants and animals because we see and use them everyday. However, without the activity of fungi, plants and animals would not exist. Fungi are largely saprophytic; they break-down dead, organic matter to extract nutrients. Their actions also release nutrients into the soil that other organisms, especially plants, need for growth. Without the activity of fungi, the planet would be miles deep in dead, rotting carcasses amid mountains of dead trees. Not surprisingly, the largest organisms on the planet are fungi reaching kilometers in size. Other fungi obtain their nutrition through parasitism (e.g., athlete’s foot), interaction with algae in a mutualistic symbiosis (lichens), and even predation. We rely on fungi for breads, alcohol, antibiotics (like penicillin), and other food products.
In this lab, you will view specimen that represent the range of this group from mushrooms to microscopic molds. |
Read the introduction to protists and learn the bold-faced terms.
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DO you know enough about microscopy?
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As early scientists and naturalists began observing the natural world, they noticed that many things were simply too small to observe with the naked eye. In 1590, eyeglass makers noticed that multiple lenses used together greatly magnified small items. In 1625, Galileo built the first compound microscope and by the mid 1600's it was used by researchers everywhere to examine biological material such as: red blood cells, spermatozoa, micro-organisms, and insects. Many types of microscopes have evolved over the years for use in many different applications. Use of microscopes is required to view protists, some fungi, and the various plant parts.
You will use both dissecting and compound scopes in this lab. Both are examples of optical, or light, microscopes because they use reflected light to see details at different magnifications. Dissecting scopes have lower magnification, no internal light source, and use only only lense for magnification. Compound scopes have an internal light source, multiple levels of higher-powered magnification, and use more than one lens (this is why they called compound scopes). Other microscopes, such as electron microscopes, use reflection (or absorption) of small charged particles for visualization. |
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Diagram of a dissecting microscope. These have an external light source, but can be used in the field with light from the sun, making them a valuable tool in vivo.
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Diagram of a compound microscope. The magnification and compound nature (two lenses) make these more powerful. We will use binocular compound scopes in lab.
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What will we do in lab & how will we do iT?
Throughout this lab you will observe various specimen from each taxonomic group (pictured in the sidebar). This is an information heavy lab meant to prepare you for later labs that will require some species-level identification and to give you a broad view of these groups. Images of what you will ID are included below and also included in the protocol section for each group.
Lab 8 contains three exercises:
Lab 8 contains three exercises:
- Protists. You will view preserved specimen of 7 types of protists under the microscope and take notes on your observations. You will use this expertise in later labs to ID protists as a measure of water quality.
- Terrestrial Plants. You will view sporophyte and gametophyte examples of moss, several varieties of ferns, ovulate (female) and staminate (male) cones of gymnosperms, and the flowers and fruit structure of angiosperms.
- Fungi. You will observe fungi across three phyla: Zygomycota (bread molds), Ascomycota (yeasts, morels, truffles and other molds), and the Basidiomycota (mushrooms, toadstools, and shelf fungi). You will also view reproductive structures under the microscope.
Protists
Plants
Fungi
If you feel confident with this material, click the bridge icon below and navigate to Blackboard to take the LABridge for this week. Be ready to be tested on this material before you go to the quiz, and make sure you have your Lab Notebook Guide ready to submit as well.
Click here to get to WKU's blackboard to take your LABridge for this week.
Lab 7 Protocol
Following this lab you should be able to...
- Identify various species of protists under the microscope and describe key characteristics including: how/what they eat, if/how they move, key organelles and life history traits
- Identify various plant types, describe key aspects of their life cycles and primary anatomy.
- Identify various types of fungi, including microscopic molds, and describe key characteristics.
- Exercise I. You will view preserved specimen of 7 types of protists under the microscope and take notes on your observations. You will use this expertise in later labs to ID protists as a measure of water quality.
- Exercise II. You will view sporophyte and gametophyte examples of moss, several varieties of ferns, ovulate (female) and staminate (male) cones of gymnosperms, and the flowers and fruit structure of angiosperms. You will also use a key to ID trees on campus.
- Exercise III. You will observe fungi across three phyla: Zygomycota (bread molds), Ascomycota (yeasts, morels, truffles and other molds), and the Basidiomycota (mushrooms, toadstools, and shelf fungi). You will also view reproductive structures under the microscope.
Exercsie i. Protist Identification & key cahracteritics
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Read over the procedure below. Each step provides information about each respective protist. The prepared slides are available in your group's slide tray. Examples of what each protist looks like under the scope are provided in the sidebar. Open your Lab Notebook Guide before you begin, so you can can complete it as you move through each step.
Caution: If what you are "seeing" in your scope does not match the image provided, you are not looking at the right specimen. Use each other and the TA to help ensure you are viewing the organism. |
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Click to enlarge.
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Procedure.
1. Refer to the tips and tricks to get started. 2. Amoeba proteus: Amoebozoans are amazing creatures that inhabit mainly aquatic or moist systems, though some live symbiotically inside other species and others are internal parasites. They move around using extensions of their cell membrane called pseudopodia. These "false feet", are projections of the plasma membrane that get filled with cytoplasm from inside the cell. These pseudopods reach out into the world around the Amoeba and pull the rest of the body forward as they move about. The pseudopods can also wrap around anything perceived as food and envelop the food in a vacuole. The vacuole is then inside the Amoeba and can be digested for nutrients. This process of enveloping their prey is known as phagocytosis. Use a compound microscope to examine a prepared slide of Amoeba proteus. Try to identify: pseudopodia, cytoplasm, plasma membrane, food vacuole, and nucleus. 3. Paramecium caudatum: P. caudatum is a relatively large protist covered in small, hair-like structures called cilia. These cilia move at a rapid rate like a wave in one direction along the plasma membrane of the cell. This wave works against the water to propel the Paramecium around. In fact, some species are capable of moving 12 body lengths per second. This would be the equivalent of a 6-foot (1.85-meter) man, running at 50 miles per hour (80 kilometers per hour). Ciliates, like P. caudatum, move quickly through water in search of smaller prey, such as bacteria, which they propel into their oral groove with even more cilia.Use a compound microscope to examine a prepared slide of Paramecium caudatum. Try to identify: cilia, plasma membrane, oral groove, food vacuoles, and macronucleus. 4. Euglena gracilis: This species is an odd one. It possesses a whip-like flagellum that it uses to propel itself through water, much like the sperm of many animals, though a Euglena flagellum pulls it through the water, not pushes. However, they also possess chloroplasts which function for photosynthesis, like in plants. Euglena can eat smaller organisms using phagocytosis, like Amoeba. Or, they can sit back and photosynthesize in the sun. E. gracilis is a great example of the diversity of form and function within protists. Use a compound microscope to examine a prepared slide of Euglena gracilis. Try to identify: flagella, plasma membrane, chloroplast, and nucleus. 5. Plasmodium falciparum: This infectious protist is responsible for more deaths than any other. Infections from Plasmodium are known as malaria and are transmitted by female mosquitoes as they suck blood from an infected individual and subsequently visit an uninfected individual. The parasite invades red blood cells (erythrocytes), among others, and eats portions of the cells interior, thus compromising the cell. Infected individuals experience fever, shivering, joint pain, vomiting, anemia, retinal damage, and convulsions. Over 200 million people are infected with malaria each year and around 700,000 die from the disease. Use a compound microscope to examine a prepared slide of Plasmodium falciparum. 6. Volvox sp.: Volvox is interesting in that it forms spherical colonies of up to 50,000 individuals that work much like a multicellular organism. The cells swim in a coordinated fashion with flagella that resemble those of Euglena. They swim toward light because Volvox are photosynthetic. They are found in freshwater systems and sometimes bloom in such large numbers that they turn lakes as green as pea soup. Use a compound microscope to examine a prepared slide of Volvox. Try to identify: flagella, plasma membranes of individual cells, and chloroplasts. 7. Diatoms: Diatoms are photosynthetic protists that inhabit mainly cool, marine environments, though some are found in freshwater, in moist soils, and on damp surfaces. They are the foundation of marine food webs contributing up to half of the oceanic primary production, and are a tremendous sink for the over-production of carbon dioxide by humans. Greenhouse gases are absorbed and used by diatoms during photosynthesis. By polluting our oceans we make the water toxic to helpful diatoms while we continue to increase our over-production of greenhouse gases, exacerbating global warming. Diatoms have a unique cell wall called a frustule that is made of silica (glass), often with sharp spines. This helps increase their surface area so they sink slowly, since they have no means of locomotion, and helps protect them from predators. As diatoms die they fall to the seafloor as marine snow. Over millions of years these tiny shards of glass build-up on the ocean floor. In places that are now dry land where the ocean used to be, the diatomaceous earth can be mined and used in polishes such as toothpaste and abrasive cleaners, as well as in natural insecticides.Use a compound microscope to examine a prepared slide of diatoms 8. Spirogyra: Algae are plant-like protists that can be unicellular, colonial, or multicellular. Because they lack any sort of structural support, nearly all are aquatic and use the water around them for buoyancy and support. Some algae, such as giant kelp, can grow 0.5 m per day and are the fastest growing organisms on the planet. Green algae are considered the ancestors of all land plants because of the numerous characters of commonality they share. One example of a green alga is Spirogyra. This species is colonial; individuals attach end-to-end to make long filaments. The chloroplasts inside each cell are spiral shaped. Use a compound microscope to examine a prepared slide of Spirogyra. Try to identify: cell wall, chloroplast, nucleus, and junction between adjacent cells. 9. Be sure you have completed your Lab Notebook Guide for Exercise I. |
Amoeba proteus
Paramecium cadatum
Euglena gracilis
Plasmodium falciparum
Volvox sp.
Diatoms
Spirogyra sp.
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Exercsie II. Terrestrial Plants
Read over the procedure below. Each step provides information about each respective plant group. Examples and supplementary information is provided in the sidebar. Be sure to work through your Lab Notebook Guide at each step.
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Procedure.
1. Nonvascular Plants - Bryophytes. Liverworts, hornworts (wort is the Old English word for plant), and mosses, comprise the three most ancestral plant lineages. They are distinguished by a dominant gametophyte generation, lack of vascular tissues and mechanical support cells, and consequently small size. As these organisms are derived from green algae, bryophytes retain many traits associated with aquatic habitats such as flagellated sperm thereby requiring at least a thin layer of water for reproduction because they still have swimming sperm. More recently derived plants (e.g., pine trees, magnolias, and sunflowers) have their sperm enclosed within a pollen grain instead and are thus capable of surviving many years without water. The life cycle of all plants comprises two phases: the gametophyte (literally “gamete plant”) and the sporophyte (“spore plant”). In mosses and other bryophytes, the gametophyte is the dominant phase and is larger and lives longer. It is the green, "leafy" part of a moss. The sporophyte phase is composed of a stalk bearing a spore-producing sporangium at its tip; inside this structure, spores are produced via meiosis. The sporophyte phase is physically attached to and nutritionally dependent on the gametophyte. Examine a moss specimen in both the gametophyte phase and the sporophyte phase under a dissecting microscope. 2. Ancestral Vascular Plants - Ferns. These plants include ferns and their relatives and are characterized by a dominant sporophyte phase and the vascular tissues, xylem and phloem. We will examine ferns belonging to the Phylum Pteridophyta only. Ferns possess many features that suggest they are intermediate between mosses and seed plants, such as: 1) a horizontal, underground stem called a rhizome to anchor the plant to its substrate, 2) roots, arising from the rhizome to facilitate water and nutrient absorption from the soil, and 3) poorly developed vascular tissue. However, ferns are also found only in moist environments because they too have flagellated sperm. On the underside of a fern leaf (called a frond), notice the small, brown bumps. These bumps are called sori and are composed of spore-producing sporangia; inside these sporangia, spores are produced via meiosis and are dispersed into the environment. These haploid (n) spores develop into tiny gametophytes that produce the egg and sperm. Once an egg is fertilized by a swimming sperm, a diploid (2n) embryo sporophyte forms then develops into a new adult fern plant. Examine a fern leaf under a dissecting microscope. Locate the sori on the underside of a leaflet. Try to find both intact and erupted sporangia. Seed Plants. We will examine two types of seed plants, conifers representing Gymnosperms and flowering plants (Angiosperms). These plants are well adapted to life away from water and have numerous specializations that allow them to live even in harsh environments like deserts. The two most significant adaptations facilitating this are enclosing the sperm in an environmentally resistant pollen grain and the packaging of the new plant embryo in a seed. In conifers, seeds are present inside cones that eventually open and release the seeds that are carried away primarily by wind. In angiosperms seeds are sometimes surrounded by fruit. 3. Gymnosperms - Conifers (Phylum Coniferophyta). have leaves that are needle- or scale-like, such as pine trees and junipers. Pollen is transferred from pollen cones to ovulate (seed producing) cones by wind. These trees often reside in relatively dry and cold environments; the reduced surface area of their leaves and thick, waxy coating prevents excessive water loss. Examine pollen cones and ovulate cones. Be sure you can distinguish between the two types. 4. Angiosperms - Flowering Plants. are the most recently derived plants and are the ones you typically think of when asked about plants. Examples include oak trees, roses, and gladiolas, among many, many others. These plants possess flowers that lead to seed-containing fruits. The flower is supported by the receptacle at the tip of a stem. Beginning from the outside, the flower is composed of four whorls of modified leaves: 1) the outermost comprises the sepals, 2) next are the petals, 3) the male reproductive structures called the stamens, and 4) innermost is the pistil. The stamen is composed of the anther (pollen producing tip) sitting atop the filament. At the top of the pistil is the sticky stigma that receives the pollen which sits atop a tube called the style that leads to the ovary housing the ovules/eggs. Nectar is commonly secreted near the base of the ovary to attract pollinators to the flower. Be sure you could ID these parts on the model provided. 5. Be sure you have completed Exercise II. in your Lab Notebook Guide. |
Non-vascular plants, bryophytes.
Fern reproduction.
Gymnosperm cone cycle (modification of work by Roger Griffith).
Angiosperms, parts of the flower.
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Exercise III. Fungi
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Read over the procedure below. Each step provides information about each respective fungal example. Please note, they are listed by phylum, which you do need to know. The prepared slide of molds is in your group's slide tray and contains the Rhizopus sp., Aspergillus sp., and Penicillium sp, all together on one slide.
Supplemental content is provided in the sidebar. Be sure to take pictures as you move through the procedure. Procedure. 1. Zygomycota: Rhizopus sp. In zygomycete fungi, haploid hyphae of different mating types will meet underground and fuse together. When they do, they form a large, environmentally-resistant structure called a zygosporangium which contains several pairs of nuclei of different mating strains. Fusion of the different nuclei occurs within the zygosporangium forming diploid zygotes. Shortly after being formed, the diploid zygotes undergo meiosis yielding haploid structures. After several months, the zygosporangium ruptures dispersing the haploid spores into the environment where they settle on fresh organic matter and begin to grow into a new fungus. A common zygomycete fungus is Rhizopus, known for forming black mold on breads and fruits like strawberries. This is one of the reasons we store these items under refrigeration; to keep fungal spores from germinating on our food. Examine the Rhizopus sp. on your mold slide under 10X magnification. 2. Basidiomycota: Club Fungi. Club fungi are the ones with which you are likely most familiar. They include mushrooms, puffballs, jelly fungi, coral fungi, buttons, and shelf fungi. Remember that the mushroom we consume is only a small portion of the actual fungal organism, the majority of which resides underground as a mycelium. The mushroom is actually the sexual reproductive structure or “fruiting body” that has erupted from the soil or rotting wood to facilitate dispersal of spores, mainly by wind. Club fungi get their name from the club-like structures (basidia) that produce, and forcibly eject, four spores. Club fungi basidia and spores are located on the gills of a mushroom. The gills are thin sheets of tissue that reside under the cap of the mushroom and offer a massive amount of surface area for spores to be produced. The cap sits atop the stipe and both are simply very dense collections of hyphae packed together much tighter than those that are creeping through the soil because their function is spore production, not absorption of nutrients. Examine the shelf fungi, puffballs, oyster and button mushrooms provided. 3. Ascomycota (sac fungi) This diverse group of fungi gets their name from the elongate sacs that house their spores (8 specifically) in these multicellular, cup-shaped "fruiting bodies".
Lichens. Lichens are one of nature's most interesting and highly adapted groups of organisms. They represent a symbiotic relationship between a fungus and most commonly a green alga; specifically a mutualistic relationship where both benefit. The alga is sandwiched between layers of dense fungal hyphae and is provided protection from the outside environment and water. Meanwhile, the fungus benefits from the excess carbohydrates produced by the photosynthesizing alga. Because of this amazing relationship between two distantly related groups of organisms, lichens are able to live in places and on substrates that others can not. For example, lichens are often found on bare rock surfaces and contribute to the building of soil for other organisms; plants would not be able to root here and animals would not find any nutrients here. Lichens, though, can photosynthesize here with an unobstructed view of the sun, providing nourishment for both the alga and the fungus. Examine specimens of: crustose (flat, encrusting). foliose (peeling paint), and fruticose (bushy or branching) lichen. Be sure your Lab Notebook Guide is complete for submission with your next LABridge. |
1. Zygomycota: Rhizopus sp.
2. Basidiomycota: Club Fungi.
2. Gills on club fungi (portobello mushroom).
3. Ascomycota: Apsergillus and Penicillium as viewed under the microscope.
4. Lichen structure.
4. Lichen types with examples.
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Faculty spotlight: Mark clauson
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Mr. Clauson has been the Microbiology Laboratory Coordinator and an instructor in our department since 1987. He is a fixture in both BIOL 121 and BIOL 123 as he coordinates all the behind-the-scenes prep-work for both introductory biology labs to run smoothly. Mr. Clauson has helped establish many other labs as well, including Microbiology, Bacteriology, Pathogenic Microbiology and Applied and Environmental Microbiology. He is a trained microbiologist and has also spent time working in industry. He coordinates a valuable team of undergraduate student-workers, so please reach out to him if you're interested in a role like that in our department. Mr. Clauson is spotlighted here because he is is also our resident mycologist, culturing both molds and other fungi for classroom use.
Fun fact: He's also an excellent banjo player! Contact: [email protected] Anti-yeast activities of Origanum oil against human pathogenic yeasts.... Microbiology Laboratory for the Health Science Student; A Clinical Approach (manual used in BIOL 208) |