BIO 143 Lecture Notes - Lecture 1: Archaea, Road Running, Genetic Variability
8 Jun 2018
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Chapter 1: An introduction to life on Earth
1. What is life?
-characteristics of living things
2. How do scientists study life?
-levels of organization
-the scientific method
-science is a human endeavor
3. Scientific Theories
-evolution: the unifying theory of biology
4. Categorizing Life
-prokaryotic and eukaryotes
-ways organisms acquire energy
1. Defining Life
• Definition in dictionary: “the ability to grow, change, etc., that separates plants and
animals from things like water or rocks” (hUp://www.merriam-
webster.com/dic2onary/life)
• How Did Life Begin?
-scientists have several hypotheses as to how life on Earth first arose, but are
UNTESTABLE;
-the origin of life left no record, and researchers exploring the mystery can proceed only be
developing a hypothetical scenario and then testing them in the lab if the steps are chemically
and biologically possible and plausible!
• Life is an intangible quality that defies simple definition, even among biologists
• But, living things have been found to share certain characteristics that are not shared
by nonliving objects:
-actively maintain organized complexity composed of cells; maintain homeostasis)
-respond to stimuli
-acquire and use materials and energy
-grow
-reproduce
-the capacity to evolve
Living Things are Composed of Cells
• Living things are complex and organized
• An organism as little as only 1mm in length is considered complex; the water flea has
legs, a mouth, a digestive tract, reproductive organs, light-sensing eyes, and a simple
brain
Homeostasis
• Organisms must keep the conditions within their bodies constant; maintain
homeostatic
-for example, maintain proper body temperature via sweating, dousing oneself with cool
water; metabolizing more food in cold weather; basking in the sun adjusting the thermostat,
etc.
Living Things Respond to Stimuli
• Organisms sense and respond to internal and external environmental stimuli
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Science is a human endeavor: scientific theories. Evolution: the unifying theory of biology: categorizing life. Scientists have several hypotheses as to how life on earth first arose, but are. Actively maintain organized complexity composed of cells; maintain homeostasis) Homeostasis: organisms must keep the conditions within their bodies constant; maintain homeostatic. For example, maintain proper body temperature via sweating, dousing oneself with cool water; metabolizing more food in cold weather; basking in the sun adjusting the thermostat, etc. Living things respond to stimuli: organisms sense and respond to internal and external environmental stimuli. Sensory organs and muscular systems in animals detect external stimuli such as light, sound, touch, etc. Internal stimuli in animals are perceived by receptors for stretch, temperature, pain, and various chemicals. Plants and bacteria also respond to stimuli (i. e. , plants to light and bacteria to appropriate nutrient medium) Living things acquire and use energy: materials and energy are required to maintain organization, grow, and reproduce.
