Chapter 1: Additional Readings
The Life Around Us
Next time you walk across campus, look at the astonishing array of creatures thriving in a place as domesticated as a college campus. Sparrows and squirrels communicate with others of their species through chirps and chatters. Within the trees, bushes, grass, and moss that blanket the campus with green, you may see honeybees or a butterfly flitting from flower to flower, gathering the sweet nectar that powers their flight and their own reproduction. Meanwhile, a spider, using several types of protein fibers, spins a web to trap these insects and harvest the energy in their bodies for its own uses. Mushrooms hiding in the grass are only the reproductive tips of a large underground network of fungal fibers. In addition to these obvious life-forms, countless microscopic organisms swim in the puddles left by the sprinklers or rain and thrive in the soil. And living on, in, and around all these organisms, and the humans observing them, are billions of bacteriasimple, single-celled organisms that have survived with little change for billions of years.
How did such an astounding variety of organisms evolve? How do they interact? How are these bacteria, fungi, plants, and animals alike, and how do they differ? What processes must occur for each organism to survive and reproduce? And how do living things differ from nonliving things? Questions such as these form the basis of the science of biology. They also relate to the very survival of the human species, because we too are part of the web of life. We evolved in response to the same sorts of survival needs and consist of chemicals found in all other living creatures. Similar processes allow us to survive and reproduce. As we journey through this book, we hope you will begin to sense the excitement and awe that comes with understanding life on Earth.
Case Study Revisited: The Life Around Us
As you walk to class observing life, think about the "why" behind the "what" that you see. The plants on campus are green: This color allows a unique molecule, chlorophyll, to trap specific wavelengths of solar energy and use them to power the life of the plant. Bees and butterflies are gathering nectar containing sugar; the sugar was synthesized using energy trapped by chlorophyll and the simple ingredients of carbon dioxide and water. Why have plants evolved in ways that place this energy-rich nectar where it can be "stolen" by insects? Look more carefully at a bee. You may see yellow pollen clinging to its legs or to the hairs coating its body. The plants are "using" the insects to fertilize each other, and both are benefiting. Although the campus groundskeepers planted the flowers for you to enjoy, showy flowers evolved as a signal to insects saying "nectar is herecome and get it." With each breath you take, you are inhaling a "waste product" from the plants around you: oxygen. Wherever you look, if you look in the right way, youll see evidence of the interdependence of living things, and youll never take life on Earth for granted.
Identify two different types of organisms that you have seen interacting, such as bees and flowers. Now form a simple hypothesis about this interaction. Use the scientific method and your imagination to design an experiment that tests this hypothesis. Be sure to identify variables and control for them.