Although almost 80% of our atmosphere consists of nitrogen gas, plants cannot convert the nitrogen gas to usable forms. A few species of bacteria, however, produce enzymes with which they can convert nitrogen into nitrates and other nitrogenous substances readily absorbed by roots. Members of the Legume Family (Fabaceae), which includes peas and beans, and a few other plants such as alders, form associations with certain soil bacteria that result in the production of numerous small swellings called
Stern-Jansky-Bidlack: I 5. Roots and Soils I Text I I © The McGraw-Hill
Introductory Plant Biology, Companies, 2003
Ninth Edition cortex of root epidermis cortex of root epidermis
hyphae normal — roots mycorrhizal sheath
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.