Biology Lab: The Diversity of the Plant Kingdom

Transcription

1 Biology Lab: The Diversity of the Plant Kingdom Name Date Introduction: Simply put, life on Earth relies on the plants for survival. By carrying out photosynthesis, plants provide enough food for themselves and nearly the entire animal world. Plants fill the atmosphere with oxygen. Plants provide the base for every food chain on land. They provide shade, shelter and oxygen for many animals. The plants have adapted to survive in a wide variety of habitats and environments. In this lab, you will observe a variety of living specimens that represent the plant life on Earth today. Purpose: 1. To observe representatives from the four most common plant phyla. 2. To identify the similarities and differences among the sample plants. 3. To identify the characteristics that make the specimen well suited to its environment. Safety Precautions: 1. Any plant allergies should be reported to the instructor. Materials List: Living specimen of moss Living specimen of fern Living specimen of gymnosperm Living specimens of angiosperms Stereomicroscope or hand lens Prepared slide of Fern gametophyte Compound microscope Dissecting Scissors Microscope slides Cover slips Prepared slide of pine pollen Apple Strawberry Peanut in shell Directions: Several different stations have been set up for you. You will move from station to station, observing the plants, and recording your observations. It does not matter what order you visit each station. When you are finished with one station, simply move to an unoccupied station. Continue moving through the stations until all 8 stations have been completed. Be sure to complete all observations and answer all questions before proceeding to the next station. 1

2 Station 1: Living Mosses Drawing of Moss Procedure: Examine the clump of moss. You may use the magnifying glass or the stereomicroscope. Draw a small portion of the moss. Label the gametophyte, the sporophyte, the capsule, the leaf like structures, the stalk, and the rhizoids. 1. What is the dominant generation in the moss? 2. To what group of plants do the mosses belong? 3. What stage of the moss is photosynthetic and has the root like structures? 4. What is the relationship of the nondominant generation to the dominant generation? 5. Where are the spores of the moss produced? Procedure: Using a small pair of dissecting scissors, remove the capsule from a small piece of moss. Place the capsule in a single drop of water on a microscope slide. Cover with a coverslip. Press down gently on the coverslip to crush the capsule. Make a sketch of a few of the spores in the space provided. 6. Mosses are not completely adapted to a life on land. List three reasons why they are tied to a watery existence. Drawing of Moss Spores a) b) c) 7. Is there any evidence of the presence of a cuticle? (Does the leaf look shiny?) 2

3 Station 2: Living Fern Drawing of Fern Procedure: Examine the fern at this station. Make a drawing of the fern and label the following structures: sporophyte, frond, stem, and roots. 1. Is there any evidence of a cuticle? (A shiny leaf indicates the presence of a waxy layer.) 2. Examine the underside of the frond. Look for evidence of reproductive structures. What are these reproductive structures called? 3. To what group of plants do the ferns belong? 4. What is the dominant generation in the fern? 5. What is the relationship of the nondominant generation to the dominant generation? 6. In what ways are the ferns better suited to a life on land than the mosses and liverworts? Directions: Place a drop of water on a clean microscope slide. Use a scalpel to scrape a sorus into the drop of water. Examine under the microscope. Locate the sporangia which are club- shaped structures. Sketch a single sporangium. Prepare a second slide by placing a sorus into a drop of ethyl alcohol. Observe what happens to the spore cases of the sporangium. Sketch the sporangium and spores as they now appear. Sketch of sporangium Sporangium in alcohol 3

4 Station 3: Slide of Fern Gametophyte Drawing of Fern Gametophyte Procedure: Examine the prepared slide of the fern gametophyte using a compound microscope. Draw the gametophyte in the space to the right. Label: gametophyte, rhizoids, photosynthetic cells. In the region of the indentation of this heart- shaped structure, try to locate the archegonia. Add these to your drawing. In the region of the rhizoids of this heart- shaped structure, try to locate the antheridia. Add these to your drawing. 1. Are these structures haploid or diploid? 2. What are archegonia? 3. What are antheridia? 4. In what way are the ferns still not completely adapted to a life on land? 5. What name is given to the fern gametophyte? 6. Does the fern gametophyte grow from a spore, a seed or a zygote? 7. What does the prothallus grow into? 8. Why can ferns grow taller than the mosses and liverworts? 4

5 Station 4: Living Gymnosperm Procedure: Examine the pine branch at this station. Note the size and shape of the leaves. Look at the tip of the branch for the pollen cones and the seed cones. In the space below, draw a small portion of the pine branch. Be sure to draw and label the needles, stem, pollen cones, and seed cones. Drawing of Gymnosperm Branch 1. Are the pollen cones male or female? 2. Are the seed cones males or female? 3. Describe the relationship between the pollen cones and the seed cones. _ 4. Ate the stems and leaves part of the sporophyte plant or part of the gametophyte plant? 5. Are the pollen grains part of the sporophyte generation or gametophyte generation? 6. Of what evolutionary important are the needles on a gymnosperm? 7. Where are the seeds in this living specimen? Describe their location. How are these seeds different from those produced by angiosperms? 5

6 Station 5: Slide of Pine Pollen Drawing of Pine Pollen Procedure: Gently shake the male pollen cone over a drop of water to release some pollen into the water drop. Add a coverslip, and examine the pollen grains under a compound microscope. Examine a prepared slide of pine pollen if living samples are not available. Draw a few of the pollen grains in the space provided. 1. What is inside the pollen grain? 2. What is the advantage of pollen to a land plant? 3. What features of the pine pollen grain aid its dispersal by wind? 4. The male cones produce huge amounts of pollen. Why are so many pollen grains produced? 5. Hopefully, the wind will blow the pollen to a neighboring tree. However, it is possible for the pollen to land on the female cone of the same tree resulting in self- fertilization. Why is this not preferable? _ 6

7 Station 6: Living Angiosperm with Flower Procedure: Examine the living angiosperm at this station. Make a drawing of the plant in the space provided. Be sure to label leaf, stem, root, and flower. Drawing of Living Angiosperm 1. Are the structures in your drawing part of the sporophyte or gametophyte generation? 2. Where are the gametophytes? 3. Is this plant is a monocot or dicot? List the characteristics that you observed that led you to this conclusion. 4. What is the purpose of the flower? 5. Angiosperms produce much less pollen than gymnosperms. Why? 6. Some flowering plants attract specific pollinators. What is the advantage to a flowering plant if it attracts only one specific pollinator? 7. What might happen if every type of flower was attractive to every type of pollinator? 7

8 Station 7: Living Angiosperm Procedure: Examine the living angiosperm at this station. Make a drawing of the plant in the space provided. Be sure to label leaf, stem, root, and flower, if present. Drawing of Living Angiosperm 1. Are the structures in your drawing part of the sporophyte or gametophyte generation? 2. Is this plant is a monocot or dicot? List the characteristics that you observed that led you to this conclusion. 3. What is the difference between pollination and fertilization? Pollination: Fertilization: 8

9 Station 8: Fruits Procedure: There are so many different kinds of fruits! A fruit is a modified flower part that encloses a seed or seeds. Examine the apple, the peanut and the strawberry at this station. The apple has been cut in half so that you can view the seeds. In the space provided, make a sketch of the apple, peanut and strawberry showing the arrangement of the seeds. Drawing of Apple Drawing of Peanut Drawing of Strawberry There are many categories and classifications of fruits. You have only seen a very few examples. Of the fruits seen at this station, one is a legume, one is a pome, and one is an aggregate fruit. Legume: A simple fruit, dry at maturity, splits along two sides to form two halves. Pome: A simple fruit, fleshy at maturity, an inner core containing seeds. Aggregate: Formed from many pistils of a single flower. 1. From the definitions above, classify each fruit. Apple: Peanut: Strawberry: 2. What group of plants produces fruits? 3. What difference do you notice in the seeds of the apple, the peanut and the strawberry? 4. How have fruits been of benefit to the plants that produce them? 5. You observe two people in a dispute over whether a tomato is a fruit or a vegetable. What could you tell them to settle this argument? 9

10 Final Analysis Questions: 1. By what process do all of the specimens viewed in this lab reproduce? Describe this method of reproduction. 2. What are the four major groups of plants on earth today? 3. What four characteristics do ALL members of the Kingdom Plantae have in common? 4. What structures are produced inside the moss capsule? How are these structures dispersed? 5. What is the name of the female gametophyte in the moss? 6. What is the name of the male gametophyte in the moss? 7. Why are all mosses found growing close to the ground? 8. How are ferns similar to mosses and liverworts? 9. Why are ferns classified as tracheophytes? 10. Given the large number of spores produced by a fern, why are there not more ferns growing on earth? 10

11 11. List two evolutionary innovations that are present in the gymnosperms and the angiosperms, but are absent in the bryophytes and the ferns. Explain why these innovations led to the success of the gymnosperms and angiosperms. a) b) 12. Compare and contrast the mosses, ferns, gymnosperm, and angiosperms in the following chart: Characteristic Mosses Ferns Gymnosperms Angiosperms What is the dominant generation? Describe the nondominant generation. Are true roots, stems and leaves present? What generation performs photosynthesis? How does the sperm reach the egg? Is there a cuticle present? Vascular or Nonvascular? 13. In what ways are roots and rhizoids similar? How are they different? Similarities: Differences: 14. How are seeds adapted to a life on land? 15. How are the seeds in an angiosperm different from those produced by gymnosperms? 16. A fruit, by definition, develops from a flower and encloses seeds. There are many common produce items that we refer to as vegetables that are really fruits. Name four. Copyright March 2013 Amy Brown (aka Science Stuff 11

12 ***Teacher Guide*** 1. This lab requires a variety of living plant specimens. In advance of the lab, you will need to collect the plants you want to use in the lab. You will need a living moss, a fern, a branch from a gymnosperm and several examples of angiosperms. You may be able to collect all of these in your area. I often give extra credit to my students for bringing in specimens to use during this lab. I have also purchased specimens for use in this lab. This is the most convenient option, especially if money is available in your science lab budget. 2. I have ordered these in the past from Carolina Biological: RE RE Basic Plant Kingdom Survey Set Moss Set Note: I am in no way affiliated with Carolina Biological, but I am a huge fan. I have always found their living specimens and customer service to be of the highest quality. Materials List: Living specimen of moss Living specimen of fern Living specimen of gymnosperm Living specimens of angiosperms Stereomicroscope or hand lens Prepared slide of Fern gametophyte Compound microscope Dissecting Scissors Microscope slides Cover slips Prepared slide of pine pollen Apple Strawberry Peanut in shell 3. Try to find an example of a gymnosperm branch that shows the pollen cones and the seed cones. I have many pines in my area and these are great specimens. A pine branch that shows all three types of cones (first year, second year, and third year) is best. 4. I use at least three examples of angiosperms: A dicot with a flower, a monocot, and 3 fruits. For the fruit station you will need an apple, a strawberry and peanuts. Have one peanut with seeds still within the shell, and one peanut that has been cracked open. 5. I live in a wooded area and am able to collect several different types of ferns. If you do not have living ferns available, they can be ordered with other lab supplies. 6. You will need to set up at least 8 stations: Station #1) Living moss station Station #2) Living Ferns Station #3) Fern Gametophyte Station #4) Living Gymnosperm Station #5) Pine Pollen Station #6) Living Angiosperm with Flower (Dicot) Station #7) Living Angiosperm (Monocot) Station #8) Fruits All 8 of these stations will be different, and will require different observations from the students. If I have a large class, I will set up duplicate stations of these 8 so that students do not have to wait to move to another station. 12

13 ***Answers to Questions*** Station 1: Living Mosses 1. The dominant generation is the gametophyte generation. 2. Mosses are nonvascular plants and are bryophytes. 3. The gametophyte generation is green and photosynthetic and has rhizoids. 4. The sporophyte generation is reduced in size. It grows inside the archegonium of the gametophyte plant. The sporophyte is completely dependent upon the gametophyte for food, water, and protection. 5. The spores of the moss are produced within the capsule which is the sporangium. 6. List three reasons why mosses are tied to a watery existence: a) They do not have vascular tissue. b) They do not have true roots, stems or leaves. c) They have a swimming sperm. Water is required for this sperm to swim to the egg. d) They do not have much protection from dehydration. Some mosses have a thin cuticle, but most bryophytes have little or no protection from dehydration. 7. Student answers will vary depending on the specimen of moss you have selected to display. Station 2: Living Fern 1. Ferns do posses a cuticle. Students should report that the frond has a waxy look to it, which is indicative of a cuticle. 2. The reproductive structures are called sori. 3. Ferns are vascular plants. Ferns are tracheophytes. 4. The sporophyte generation is the dominant generation in the ferns. 5. The gametophyte of the fern is the prothallus. It is a separate and independent plant from the sporophyte plant. The gametophyte is green and can carry out its own photosynthesis. It has rhizoids to absorb water. 6. Ferns are better suited to a life on land because they posses vascular tissue and a cuticle. Note: Placing the sorus in ethyl alcohol should cause the sporangium to rupture releasing the spores. Station 3: Slide of Fern Gametophyte 1. The structures of the gametophyte generation are haploid. 2. The archegonia are the female sex organs that produce egg cells. 3. The antheridia are the male sex organs that produce sperm cells. 4. Like the bryophytes, ferns posses a swimming sperm. This is not advantageous for a life on land. Water is required for reproduction. 5. The fern gametophyte is called the prothallus. 6. The gametophyte grows from a spore. 7. The prothallus grows into the mature gametophyte plant. After fertilization, the sporophyte will grow out of the gametophyte plant. 8. Ferns have vascular tissue. Vascular tissue is required for a plant to grow upward. The plant must have a mechanism for transporting water long distances. The vascular tissue also provides structural support. 13

14 Station 4: Living Gymnosperm 1. Pollen cones are male. 2. Seed cones are female. 3. The answer to this question depends upon the specimen of gymnosperm you have chosen for the lab. Both the seed cones and the pollen cones are found at the very tips of the branches. In some pines, the seed cone will be located in the center of a surrounding circle of pollen cones. In other species, the female seed cones are located on separate branches from the male pollen cones. 4. The stems and leaves are part of the sporophyte generation. 5. The pollen grains are part of the gametophyte generation. 6. The gymnosperms evolved during a period of Earth s history when the continents were becoming much dryer. The gymnosperms were well suited to this environmental change. The reduced leaf surface of the needle prevented excess water loss from the leaf. 7. The seeds are located further back on the branches in the second and third year cones. The seeds of gymnosperms are naked seeds and are exposed. Angiosperms produce seeds surrounded by an additional layer of tissue. Station 5: Slide of Pine Pollen 1. The pollen grain contains sperm cells. 2. Plants that produce pollen no longer require water for reproduction. These plants do not have a swimming sperm. The pollen is carried in the air by wind or pollinators. Since water is not always available on land, a plant that delivers the sperm to the egg via pollen has a distinct advantage. 3. There are small wings on each side of the pollen grain, allowing the pollen grain to be carried on wind currents. 4. Since the pollen of gymnosperms depends on wind for pollination, the likelihood of the pollen reaching the female cone of another plant of the same species is remote. The large volume of pollen produced helps to insure that at least a few pollen grains will make their way to the egg cell. 5. Self- fertilization leads to the production of identical offspring. Variation among the offspring is always preferable. Variation among the offspring leads to the possibility that some of the offspring will be better suited to the environment (natural selection). Station 6: Living Angiosperm with Flower 1. These structures are part of the sporophyte generation. 2. The gametophytes are within the flower. 3. This plant is a dicot. The leaves have netted venation. Flower parts appear to be present in multiples of 4 s or 5 s. 4. The flower is the reproductive structure of an angiosperm. The stamens and the pistils produce the egg and sperm cells. 5. Angiosperms rely on insect pollinators rather than on wind pollination. When an insect leaves the flower, it is likely that it will fly to another flower of the same species. This increase the chances of pollination and fertilization. As a result, less pollen can be produced. 6. If a plant has one specific pollinator, the chances are greater that this pollinator will carry pollen to another flower of the same species. 7. Pollinators would deliver all sorts of pollen grains to all sorts of flower, reducing the probability of pollinating the correct flower. 14

15 Station 7: Living Angiosperm 1. These structures are part of the sporophyte generation. 2. This plant is a monocot. The leaves have parallel venation. Flower parts are present in multiples of three. 3. Pollination: The transfer of pollen from the stamen of one flower to the stigma of another flower. The completion of pollination does not guarantee fertilization. Fertilization: The union of sperm and egg producing a zygote, and leading to the production of seeds. Station 8: Fruits 1. The apple is a pome. The peanut is a legume. The strawberry is an aggregate. 2. The angiosperms produce fruits. 3. Student answers will vary. Students will frequently comment on the size of the seeds and on the different locations of the seeds. 4. Fruits provide protection to the seeds. Fruits provide an excellent means of seed dispersal. Animals are attracted to the fruits, dispersing the seeds far away from the parent plant. 5. Any tissues that surround and enclose seeds are considered to be fruits. Since a tomato contains seeds, it is a fruit. Final Analysis Questions: 1. All of the specimens viewed in this lab reproduce by alternation of generation. Alternation of generations is the alternation of a haploid sexual phase with a diploid asexual phase. 2. The four main groups of plants alive today are: a) Bryophytes mosses, liverworts and hornworts b) Ferns c) Gymnosperms d) Angiosperms 3. All true plants are: (1) multicellular, (2) eukaryotic, (3) have cell walls composed of cellulose, (4) carry out photosynthesis using chlorophylls a and b, and (5) reproduce by alternation of generations. 4. The moss capsule is a sporangium and produces spores. The sporangium will burst open, and the spores fly away on air currents. 5. The female gametophyte in the moss is the archegonium. 6. The male gametophyte in the moss is the antheridium. 7. Mosses do not have vascular tissue. Water moves through the tissues of the plant body by diffusion. The moss cannot grow tall because it would have no way of transporting water up the plant. 8. The ferns are similar to the mosses and liverworts in that they have a motile, swimming sperm that requires water for reproduction. 9. The ferns are classified as tracheophytes because they contain vascular tissue, xylem and phloem. 10. The germination rate of a spore is low. Of billions of spores produced, only a few will germinate and grow into the prothallus (gametophyte). 15

16 11. Two evolutionary innovations are: a) Production of pollen: This eliminated the need for water for reproduction. This is a major advantage to a land plant. b) Production of seeds: Seeds can be produced on land like the amniote egg of the reptiles. The embryo is contained within the seed along with a source of nutrition (endosperm). The seed is covered by a protective seed coat. The seed can withstand adverse conditions such as heat, cold, and drought. The seed can remain dormant until favorable growth conditions are present. 12. Characteristic Mosses Ferns Gymnosperms Angiosperms What is the dominant Gametophyte Sporophyte Sporophyte Sporophyte generation? Describe the nondominant generation. Dependent on gametophyte Independent of sporophyte Dependent on sporophyte Dependent on sporophyte Are true roots, stems and leaves No Yes Yes Yes present? What generation performs photosynthesis? How does the sperm reach the egg? Is there a cuticle present? Vascular or Nonvascular? Gametophyte Both the gametophyte and the sporophyte Sporophyte Sporophyte Swims in water Swims in water Pollen Pollen Little, if any Yes Yes Yes Nonvascular Vascular Vascular Vascular 13. Roots and rhizoids have similar functions. They both absorb water and anchor the plant to the ground. The difference is that rhizoids do not have vascular tissue. Roots do have vascular tissue. 14. Seeds can be produced on land like the amniote egg of the reptiles. The embryo is contained within the seed along with a source of nutrition (endosperm). The seed is covered by a protective seed coat. The seed can withstand adverse conditions such as heat, cold, and drought. The seed can remain dormant until favorable growth conditions are present. 15. Gymnosperms have naked seeds. The seeds are exposed on the edge of the cone. In angiosperms, the seeds are protected within a fruit. 16. Examples include: Tomato, cucumber, peppers, eggplant, pea pods. Created by Amy Brown Science Stuff Copyright March 2013 Amy Brown (aka Science Stuff) All rights reserved by author. This document is for your classroom use only. This document may not be electronically distributed or posted to a web site. 16