lab2_plant life cycles

lab2_plant life cycles - Laboratory 2 Plant Life Cycles 34...

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Plant Life Cycles Laboratory 2
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34 Laboratory 2: Plant Life Cycles INTRODUCTION This lab is an introduction to plant life cycles. When you review the diagrams of the moss, fern and angiosperm life cycles, understand that no matter how simple or complex the plant, their life cycles do not change. Only the structures that represent each stage of the life cycle differ. The life cycle stages themselves remain the same. Keep this in mind as you read and prepare for this lab. A. The Human Life Cycle To help you understand the plant life cycle, this lab begins with a review of the human life cycle, which is illustrated in Figure 2-1a. For comparison purposes the plant life cycle is illustrated in Figure 2- 1b. Note that the two diagrams differ in the lower half of the circle. The human life cycle starts with a diploid individual. Each somatic cell has two sets of chromosomes, one inherited from the mother and one inherited from the father. Recall that a somatic cell in a multicellular organism is any cell except the sperm or egg cell. Meiosis is the process of producing haploid cells in the reproductive structures of an individual. Haploid cells have only one copy of each chromosome pair. These haploid cells are called gametes . The word gamete comes from the Greek gamos and means marriage. The gametes ultimate purpose is to marry (or fuse with) another gamete, to produce a zygote which, in turn, is diploid. Syngamy refers to the period of time when two gametes come together. ( Syn means together and gamos means marriage.) When this happens, the resulting cell is diploid, for it will have two sets of chromosomes, one from each of the gametes. Therefore, syngamy marks the transition from a haploid stage to a diploid stage, just as meiosis marks the transition from diploid to haploid. OBJECTIVES FOR THIS LAB Teaching objectives 1. Differentiate between the plant and animal life cycle 2. Point out the major steps in the life cycle of mosses, ferns, and flowering angiosperms 3. Demonstrate how students will germinate seeds at home Student Learning Objectives (SLO) After this lab you will: 1. Discuss the difference between animal and plant life cycles 2. Examine the major steps of the plant life cycles 3. Understand, from the life cycles, some of the important alterations in plants in their migration from a water habitat to a dry habitat 4. Follow the germination of seeds at home and be able to identify their major parts
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Laboratory 2: Plant Life Cycles 35 B. The Plant Life Cycle In the plant life cycle (Figure 1-1b), there are two types of individuals (i.e., diploid and haploid) involved in the cycle, instead of only one type (diploid) as in the human cycle. In plants, the diploid individual is called the sporophyte ( spore = spore and phyte = plant) and the haploid individual is called the gametophyte ( gameto =gamete and phyte = plant). The diploid sporophyte and haploid gametophyte take turns producing one another. Hence this type of life cycle is called an alternation of generations
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lab2_plant life cycles - Laboratory 2 Plant Life Cycles 34...

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