Biology Demystified: A Self Teaching Guide
Format: PDF / Kindle (mobi) / ePub
Guide to understanding basic and applied scientific information, for those who've had not formal training in biology. Includes more than 150 illustrations, a pronunciation guide, self-tests, and reviews. Softcover. DLC: Biology.
13/6/03 N:/4058 LAYMAN.751/4058-Alltext.3d] Ref: 4058 Layman: Biology Demystified All-text Page: 22 1-388 CHAPTER 2 Patterns of Life 23 Cells to Organism: Where the Pyramid Comes to Life So far, we have been discussing the lowest levels of biological organization. Remember that the chemical level includes subatomic particles, atoms, and molecules. And just beyond the macromolecules lie the organelles. Finally, recall that the cell level begins ‘‘The Life-line,’’ because it is the
and gulps air into its oral cavity. The next step is the one that creates a 3, Order positive-pressure breathing effect: the frog closes its nostrils and raises the floor of its mouth. This action creates a pushing force, thereby increasing the atmospheric pressure within the frog’s mouth. Inspiration occurs because air from the mouth is then pushed down through the pharynx and trachea, and into the lung alveoli, which have a lower pressure. NEGATIVE-PRESSURE BREATHING In contrast to
we must go where it occurs – within the mitochon- drion. You may recall (from Chapter 3) that the mitochondria (my-toe- KAHN-dree-uh) are the organelles where the cell’s aerobic (oxygen-using) metabolism takes place. The mitochondria are literally ‘‘thread’’ (mito-) ‘‘granules’’ (chondr). This is evident from an examination of Figure 4.7. Some mitochondria are long and slender, like threads. Others are short and rounded, much like tiny granules. But whatever their shape, these mitochondria
Chapter 3 to help you keep these evolutionary developments in perspective.] During these early days (245 million to 65 million years ago), the planet was carpeted with ferns (nonvascular plants) and conifers (seedless vascular plants). As time wore on, however, the angiosperms (vascular plants with fruit- covered seeds and/or flowers) began to take over. How were they able to do this? The angiosperms (with flowers) had a unique reproductive advantage over the gymnosperms (without flowers). The
collagen fibers as calcium phosphate crystals. The bone once again remodels (changes its shape and size), but this time it goes in the opposite direction, by getting thicker and stronger. And as more and more free Caþþ ions are extracted from the bloodstream and put into calcium phosphate crystals, the blood [Caþþ] falls. By these contrasting processes involving osteoblasts, osteoclasts, bone remodeling, and bone resorption, therefore, homeostasis of blood [Caþþ] is usually maintained.