BIO 143 Study Guide - Fall 2018, Comprehensive Midterm Notes - Protein, Dna, Chromosome
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BIO 143
MIDTERM EXAM
STUDY GUIDE
Fall 2018
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
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-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
-nutrients acquired from air, water, soil, or other living things
-minerals, oxygen, water, and other chemical building blocks are continuously exchanged
among living and non-living things
• Organisms obtain energy (the ability to do work) in two ways
-plants and some single-celled organisms capture energy of sunlight in a process called
photosynthesis
-other organisms acquire energy from bodies of other organisms (human from plant, bee from
plant, lion from bird, or coyote from road running, etc.)
Living Things Grow
• Every organism becomes larger over time
-plants, bird, mammals, etc. grow by producing more cells to increase their mass
-bacteria grow by enlarging their cells; they also divide to produce more of themselves
• Growth involves the conversion of acquired materials to molecules of the organism’s
body
Living Things Reproduce
• Organisms give rise to offspring of the same type (reproduction)
• The parent’s genetic material (DNA) is passed on to offspring, creating continuity of
life
• Diversity of life occurs because the genetic materials of offspring are slightly different
The Capacity to Evolve
• The genetic composition of a whole species changes over many generations
• Mutations and variable offspring allow a species to evolve
• The evolutionary theory suggests that the genetic makeup of a population will change
over time as result of natural selection (organisms with certain adaptations survive and
reproduce more successfully than others)
2. How Do Sciences Study Life?
How do Scientists Study Life?
• All matter is formed of elects
• An atom is the smallest particle of an element retaining the properties of an element
• Molecules provide the building blocks for cells, the smallest unit of life
• In multicellular forms, cells combine to form tissues
• Tissues combine to form organs, which can be united as organ systems
• Multicellular organisms are composed of multiple organ systems
• Organisms of the same type that are capable of interbreeding are called a species
• A group of organisms of the same species living in a given area is a population
• Interacting populations make up a community
• A community and its nonliving environment is an ecosystem
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