Chapter 1-A View of Life

1.1 How to Define Life

• cells are the basic unit of life
• energy-capacity to do work
• energy is needed to maintain the organization of the cell and the organism
• metabolism-the chemical reactions occurring in a cell
• the sun is the ultimate source of energy for life on earth
• photosynthesis-process that transforms solar energy into chemical energy in the bonds of organic nutrient molecules
• homeostasis-the maintenance of internal conditions within certain boundaries
• homeostasis is needed for metabolic processes to continue
• some organisms depend on behavior to regulate internal environment, while others have control mechanisms
• living things find energy/nutrients by interacting with their surroundings
• the ability to respond results in movement, which ensures survival and allows organisms to carry on daily activities
• behavior-daily activities
• reproduce-make another organism like itself
• genes-specific information for how the organism is to be ordered
• genes are made of long molecules of DNA (deoxyribonucleic acid)
• adaptations-modifications that make organisms suited to their way of life
• organisms become modified over time by natural selection
• natural selection-groups that inherit favorable characteristics increase their and their offspring's chances for survival, so the attributes of the species' members change over time
• living things have similar cell organization, their genes are composed of DNA, and carry out the same metabolic reactions to acquire energy and maintain organization
• evolution-descent with modification

1.2 How the Biosphere is organized

• individual organisms belong to a population, the members of a species belong to a community, communities make up the biosphere-a thin layer of life that encircles the earth
• communities are highly dynamic
• ecologists study the movemtn of energy and nutrients though communities
• ecosystem-populations with a community interacting within themselves and with the physical environment
• food chain
• plants take in inorganic nutrients, plants and animals return carbon dioxide to the atmosphere when they respire, when organisms decay, inorganic nutrients are absorbed by plants again
• plants use solar energy to produce organic nutrients, which is also converted to heat
• ecosystems are either terrestrial or aquatic
• tropical rain forests have the greatest diversity (central and west Africa, South America, Southeast Asia)
  
• most populations live in the canopy and interact
• rain forests act as giant sponges and absorb carbon dioxide, a pollutant
• an increased amount of CO₂ would cause a temperature and acid rain increase
• biodiversity-number and size of populations within a community

1.3 How Living Things are Classified

• taxonomy-the discipline of identifying and classifying organisms according to certain rules
• biologists give living things a binomial, a two-part name
• species, genera, families, orders, class, phyla, kingdoms, domains
• 5 kingdoms (Monera, Protista-unicellular to multicellular organisms and include algae and protozoans, Fungi-molds and mushrooms, Plantae-multicellular photosynthesizers, Animalia-multicellular and ingest food), 3 domains (Bacteria-unicellular prokaryotes, Archea-unicellular prokaryotes, Eukarya)
  

1.4 The Process of Science

• biology-the scientific study of life
• science-only what is observable by the senses or by instruments that extend the ability of the senses as a way to understand the natural world
• observations can be made by any of the 5 senses and help scientists conduct investigations
• phenomenon-observable event
• inductive reasoning-when a person uses isolated facts and creative thinking to come up with a possible explanation
• hypothesis-a possible explanation
• experiments-artificial situations devised to test hypotheses
• deductive reasoning-a general statement that infers a specific conclusion (if, then)
• David P. Barash tested the hypothesis that aggression of the male mountain bluebirds varies during the reproductive cycle
• control group-a group that experiences all the steps but does not contain the experiment variable
• data-results of an experiment
• conclusion-whether the results support or falsify the hypothesis
• falsify-show to be untrue
• variable-a factor that can cause an observable change during the experiment
• experimental variable-the deliberately manipulated step of the experiment; component of the experiment being tested
• dependent variable-the effects of the experiment; results or change that occurs due to the experimental variable
• scientific method-process of science

1. observations
2. previous data
3. formulation of hypothesis
4. observations and/or experimentation
5. new data
6. conclusion
7. theory

• scientific theories-concepts that join together well-supported and related hypotheses
• cell theory-all organisms are composed of cells
• biogenesis theory-life comes only from life
• evolution theory-all living things have a common acnestor and are adapted to a particular way of life
• gene-organisms contain coded information that dictates their form, function, and behavior
• principle/law-theories that are generally accepted by an overwhelming number of scientists