Lecture Outline - Chapter 1

1.1. The Characteristics of Life (Fig. 1.1) (p. 5)

1. Life Has Organization
   • a. Life processes maintain this organization but upon death, an organism breaks apart and its structure disappears. Living organisms are organized at various levels from the simplest to the most complex and include: atoms, molecules, cell organelles, cells (smallest unit of life), tissues, organs, organ systems, and the organism. (Fig. 1.2)
2. Life Acquires Materials and Energy (Fig. 1.3)
   • a. Living things acquire nutrient molecules that can be used as building blocks or for the organism's structures.
   • b. Molecular bond energy is also used in cell metabolism, the chemical reactions in a cell. Energy is the capacity to do work.
3. Homeostasis Means "Staying the Same"
   • a. The internal environment of an organism stays relatively constant compared to external environment; for example, body temperature fluctuates only slightly during a variable day.
4. Life Responds to Stimuli
   • a. Living things often respond to external stimuli by moving, whether an animal detects an enemy and runs or plant leaves track the movements of the sun.
   • b. Behaviors are directed toward minimizing injury, acquiring food, and reproducing.
5. Life Reproduces (Fig. 1.4)
   • a. During reproduction, a copy of its hereditary information (genes) is passed on.
   • b. Unicellular organisms may reproduce asexually by dividing into two cells, each of which has the same genes and structure as the single parent.
   • c. Multicellular organisms may reproduce sexually. Each parent contributes one-half of the total number of genes to an offspring, which then has characteristics of both parents and may not resemble either one exactly.
6. Life Grows and Develops (Fig. 1.5)
   • a. Growth is recognized by an increase in size and often the number of cells, is a part of development.
   • b. Human development includes all changes that take place between conception and death.
7. Life Adapts
   • a. Adaptations are modifications that make an organism suited to its way of life; for example, hollow bones in birds reduce weight and permit flight.
   • b. Adaptations are selected by evolution, the process where characteristics of species change through time. When new variations arise that allow certain members of the species to capture more resources, survive in higher numbers and have more offspring than poorly adapted members. Evolution explains the diversity and unity of life.

1. Population-all the members of one species (e.g., cabbage butterflies, poison ivy, crabgrass, etc.).
2. Community-a group of populations of both plants and animals that live together (e.g., a pond, backyard, forest stream, etc.).
3. Ecosystem- consists of the various interactions among populations and with the physical environment.
4. Biosphere-the surface of the earth where life can exist.
   • a. Upper boundary is higher atmosphere.
   • b. Lower boundary extends into soil and ocean bottoms.
5. Humans Threaten the Biosphere
   • a. Humans modify existing ecosystems for our own purposes.
   • b. Increases in human populations threaten more ecosystem stability and diversity.
   • c. Loss of stable and diverse ecosystems in turn threatens human populations; for example, destruction of the world's rain forests may lead to increased carbon dioxide in the atmosphere, which in turn may increase average daily temperature.
6. Biodiversity
   • a. From perhaps 80 million species, fewer than 2 million have been described.
   • b. Extinction, which occurs naturally, has increased from human's alteration of the environment, development, pollution, and overfishing.
   • c. Modern extinction rates from human activities could exceed the five natural mass extinctions in geological history.
   • d. Even if you do not believe in a species existing for its own sake, the extinction of species reduces resources available to humans for food, clothing, medicines and other raw materials.
     FOCUS: Tropical Rain Forest Destruction

     • i. Rain forests constitute an area similar in size to the 48 contiguous states.
     • ii. Each year an area of rain forest the size of Oklahoma is lost.
     • iii. Social, economic and political forces encourage poor people to convert rain forest to small farms, followed by logging, mining and cattle ranching.
     • iv. Harvest of natural forest products might be an economic alternative that would save this ecosystem.

1.3. The Classification of Living Things

1. Taxonomists are biologists who name, describe, and group organisms.
2. A scientific name is a binomial ("two names"); the scientific name of humans is:
   Homo sapiens
   (name of genus is capitalized, specific epithet is lower case; both are in Latin and italic)

   Similar species share detailed characteristics; organisms in different kingdoms share fewer general characteristics and are distantly related.

   Five kingdoms are commonly recognized: Monera, Protista, Fungi, Plantae, and Animalia. (Fig. 1.7)

1. Science only observes and tests the natural world.
2. Science attempts to be objective or free of personal bias; it is difficult to eliminate all subjective influences.
3. Conclusions of science are subject to change or refinement whenever new findings arise.
4. Theories, such as theory of evolution, are concepts based on conclusions of experiments and observations not yet found lacking. (Fig. 1.8)
5. The Scientific Method
   • a. Accumulate data (new and old observations). (Fig. 1.9)
   • b. Formulate a hypothesis (a tentative explanation of observed phenomena); inductive reasoning may be used to generalize from selected facts.
   • c. Test the hypothesis; an experiment may be conducted using deductive reasoning (Òif...thenÓ statement) in order for scientists to decide which data to collect.
   • d. Formulate a conclusion.
   • e. Report the findings in a scientific journal-detailed enough so that the experiment can be repeated-and suggesting other experiments.
6. Controlled Experiments
   • a. An experimental variable is the element being tested (amount of sweetener).
   • b. The dependent variable is the result or change observed (presence or absence of bladder cancer).
   • c. A control is not subjected to the experimental variable.
7. Designing Experiments-all conditions of an experiment remain the same for all groups except for the control, which goes through all the steps of the experiment except for the one part being tested; for example, identical mice fed with or without a food sweetener. (Fig. 1.10)
8. Continuing Experiments (Fig. 1.11)
   • a. Scientists use mathematical analyses of results to be objective.
   • b. Results often suggest additional new research or need to repeat experiments.

   1.5. Science and Social Responsibility

   1. Everyone-including non-scientists-can use science.
      • a. Natural events and laws are universal.
      • b. Science theories and principles apply to past, present and future events.
      • c. Doctrines based on faith or not subject to observation or experiment are not part of science; scientific creationism is not science.
   2. Science has improved our life.
      • a. More and better food from new strains of agricultural plants.
      • b. Better medicine (antibiotics, vaccines, surgery, genetic research, etc.).
   3. Science also fosters technology that is potentially dangerous. Science is impartial and attempts to study natural phenomena without making ethical or moral decisions.
   4. The responsibility for best use the scientific knowledge rests with all men and women.
   
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