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Homework Help: Biology test questions - How are my answers

  1. Jan 11, 2010 #1
    Q.) Name five organelles found in Eukaryotic cells and outline their function.

    Endoplasmic reticulum - Network of membranes which are continuous with the nuclear envelope. The is involved in protein synthesis. It can produce these proteins because it has ribosomes embedded in its membranes. The smooth endoplasmic reticulum is involved in the synthesis of lipids such as steroids.

    Golgi apparatus - The golgi apparatus is an organelle consisting of plate like structures called cisternae. The golgi apparatus acts as the cells molecule packaging and processing center by processing molecules received from the endoplasmic reticulum and sending them to other organelles or the cell membrane for exocytosis.

    Mitochondrion - Is a double membrane bound organelle which produces all of the cells ATP through cellular respiration.

    Lysosome - Is a spherical membrane bound organelle which contains digestive enzymes called acid hydrolases. Lysosomes digest small molecules for the cell as well as foreign invaders such as bacteria delivered by macrophages.

    Centrosome - Is an organelle consisting of 2 barrel shaped subunits called centrioles. The centrosome acts as the microtubule organiing center for animal cells during.

    Q.) Describe the 4 key events in the evolution of plants.

    1.) Marine plants moved to land forming the first land plants which were bryophytes.
    2.) Land plants developed a waterproofing system consisting of cuticles and stroma. This allowed to store water and as a result to inhabit dryer land because they could store rain water rather than relying a constant supply of water from their surroundings.
    3.) Land plants developed vascular tissue consisting of cells with secondary cell walls with a tough structural protein called lignin. This new vascular system allowed plants to grow upright and tall because the vascular tissue could resist gravity and deliver water to all the cells throughout the plant and the lignin in the secondary cell walls was the key to the plants structural stability.
    4.) Plants developed the ability to reproduce through seeds forming the first gymnosperms.
  2. jcsd
  3. Jan 11, 2010 #2
    first one looks okay, albeit spelling mistakes
    i'm not sure about the second one since i never learned about the evolution of plants
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