LS1_Wk5_Demo

LS1_Wk5_Demo - The Photosynthetic World From Algae to...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
The Photosynthetic World: From Algae to Angiosperms DEMO 5 Objectives In this demo section you will learn: The major groups of multicellular photosynthetic organisms; The general adaptations that each group has for survival in their environments; The changes in reproductive, structural, vascular, and gas exchange strategies that have allowed for the Transition of plants from aquatic to terrestrial environments; The major adaptations of gymnosperms and angiosperms that have allowed them to be successful in terrestrial environments; The adaptations that have allowed angiosperms to become the dominant terrestrial plants. Introduction Life and the world we know today primarily exist because of the evolution of aquatic and terrestrial organisms capable of photosynthesis. These organisms are capable of converting the energy of sunlight into energy rich organic chemical bonds. Heterotrophs depend on this source of chemical energy to carry out their metabolic activities. Photosynthetic organisms use pigments to capture light energy and build sugars from inorganic carbon dioxide. The chemical energy stored in the sugar molecules is subsequently released when the plants (or other organisms feeding on the plants) digest this food source. Additionally, a vital by-product of photosynthesis is oxygen. Most aquatic and terrestrial organisms require oxygen for their survival, and photosynthesis accounts for almost all of the free oxygen in the world today. In this lab, you will look at the major groups of both aquatic and terrestrial photosynthetic organisms, and will consider the various adaptations that each group has for success. When looking at the different algae and plants consider their specific adaptations for success in their environments. Plant Life Cycles Sexual species typically have haploid and diploid phases in their life cycle. The diploid phase contains cells that undergo meiosis creating haploid gametes, and haploid gametes fuse to form a diploid cell. During this process, new gene combinations are formed. One important aspect of life cycles in multicellular organisms is whether the haploid, diploid, or both phases of the life cycle is multicellular. In animals, only the diploid phase is multicellular, and the haploid phase (the gametes) only exists as single cells. This in not the case in many organisms, including plants and algae. In “alternation of generations,” both the diploid and haploid stages are multicellular. In all terrestrial plants and many groups of algae, a multicellular diploid generation called the sporophyte alternates with a multicellular haploid generation called the gametophyte .
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The sporophyte generation of plants does not produce gametes directly (as the diploid generation of most animals does), instead the sporophyte, via meiosis, produces haploid cells called spores . The haploid spores then divide mitotically to produce a multicellular haploid gametophyte . This haploid gametophyte produces haploid gametes (eggs or sperm). If these gametes manage to find each other (not a trivial problem) they fuse to form a
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern