Biology Semester II

Sections:

Introduction  |   Section 1  |  Section 2  |  Section 3

Biology: Plant Structure: Introduction Plants are one of the largest taxonomic kingdoms. Kingdom Plantae and Kingdom Animalia were the first two kingdoms proposed by Linnaeus in the mid-1700s. Plants are at the base of our economy and form the foundation of most food chains. They also produce a large amount of the world’s oxygen through the process of photosynthesis. Many biology students are animal-oriented. However, plants are a great place to begin our study of how multicellular organisms are organized. Compared to most animals, plants are organized along a simpler body plan. Humans have eleven organ systems, whereas plants have only two. The Plant Kingdom All plants are autotrophs that make their own food by means of photosynthesis. This process takes place inside cells in specialized organelles called chloroplasts. These organelles contain chlorophylls a and b. In plant cells, a cellulose cell wall surrounds a cell membrane, and excess sugar is stored as starch. Plants exhibit an alternation of haploid generations and diploid generations that animals do not exhibit. The fossil record of the plants indicates that this kingdom is the most recently evolved. The oldest fossil plants have been found in rocks more than 400 million years old. From which organism did plants evolve? Scientists have long believed that plants evolved from a green algal ancestor (Phylum Chlorophyta). Both plants and green algae store sugar as starch and have cell walls made of cellulose. Plants and green algae also use the same photosynthetic pigments. Some fossils that were once thought to be plants have recently been restudied and determined to be some type of multicellular algae. Members of the plant kingdom are grouped into two broad categories: the bryophytes and the tracheophytes. The tracheophytes are also known as the vascular plants. This group contains the most specialized and highly evolved plants. Members include common plants such as palms, lilies, sunflowers, ferns, and pines. The bryophytes (the nonvascular plants) lack specialized tissues for conducting water and nutrients. These plants include the smaller, and less conspicuous, liverworts and mosses. The vascular plants are subdivided into smaller groups, which include the gymnosperms (the ferns and fern allies) and the angiosperms (the flowering plants). For our discussion of plant structure, we will focus on the last group, the flowering plants. Graded Activities: Lab: Plant Structure—100 points Plant Organs, Tissues, and Cells Quiz—25 points Lab: Flowers, Fruits and Seeds—100 points Flowering Plant Reproduction Quiz—25 points Journal: Plants in Motion—25 points Plant Hormones, Nutrition, and Transport Quiz—25 points Plant Structure Exam—100 points Writing is a good way to learn a language. Using the vocabulary journal, write down the definition and examples as you see them in your lessons. Include an example of your own and an image that you can use to help remind you what the word means. Click here to download the vocabulary journal. Now go on to the next section.

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