Introduction to Biology Chapter #1

Characteristics of Life Chapter 1.1

What is an organism? Organism= anything that has or once had all of the characteristics which define life

Characteristics of Life #1: Made of One or More Cells Unicellular= organisms consisting of a single cell –Examples: Prokaryotes (eubacteria & archaebacteria), protists & fungi

Characteristics of Life #1: Made of One or More Cells Multicellular = organisms that consist of more than one cell –Examples: animals, plants & fungi Which group of organisms can be either multicellular OR unicellular???

Characteristics of Life #2: Displays Organization Organization = living things are arranged in an orderly way Each organized structure in an organism has a specific function: –E.g. – an anteater’s snout holds the anteater’s long tongue

Characteristics of Life #2: Displays Organization The levels of biological organization from smallest to largest are: Atom < Molecule < Cell < Tissue < Organ < Organ System < Organism

Characteristics of Life #3: Grows and Develops Most organisms begin as one cell! Growth = results in the addition of mass to an organism, and in many organisms, the formation of new cells and new structures

Characteristic of Life #3: Grows and Develops Development = the process of natural changes that take place during the life of an organism

Characteristics of Life #4: Reproduces Reproduction = the production of offspring –Not an ESSENTIAL characteristic of living organisms Can you think of any situations in which a living organism would be incapable of reproducing? –Asexual vs. sexual reproduction

Characteristics of Life #4: Reproduces Species = a group of organisms that can breed with one another and produce fertile offspring What happens when reproductive barriers between different species are not complete? –Hybrids = offspring of two different species which interbreed

Characteristics of Life #5: Responds to Stimuli Organism’s Internal Environment = all things inside of an organism Organism’s External Environment = all things surrounding an organism –E.g. air, water, soil, rocks, and other organisms

Characteristics of Life #5: Responds to Stimuli A response is an organism’s reaction to a stimulus. Stimulus = anything that is part of either an organism’s external or an organism’s internal environment that causes a reaction Response = an organism’s reaction to a stimulus

Characteristics of Life #6: Requires Energy Autotrophs = organisms that produce their own energy using light from the sun through photosynthesis. Heterotrophs = organisms that get their energy requirements by consuming other organisms

Characteristics of Life #7: Maintains Homeostasis Homeostasis = regulation of an organism’s internal conditions to maintain life Athletes at high altitudes –Produce more red blood cells to carry oxygen to the tissues

Characteristics of Life #8: Adaptations Evolve Over Time Adaptation = any inherited characteristic that results from changes in a species over time The “Aye-Aye”

Characteristic of Life #9: Has a Genetic Code All organisms store the complex information they need to live, grow, and reproduce in a genetic code written in a molecule called DNA. What percentage of human DNA is shared with chimpanzees???

Which 2 characteristics of life is this list missing???

What is Science? Chapter 1.2

Goals of Science 1) To investigate and understand the natural world 2) To explain events in the natural world 3) To use these explanations to make useful predictions

How is Science Different? 1) Science deals only with the natural world 2) Scientists collect and organize information in a careful way, looking for patterns and connections between events 3) Scientists propose explanations that can be tested by examining evidence So… What is our definition of science?

Definition of Science Science = an organized way of using evidence to learn about the natural world AND Science = the body of knowledge scientists have built up over the years using this process

What is Science??? 1.Relies on evidence 2.Expands scientific knowledge 3.Challenges accepted theories 4.Questions results 5.Tests claims 6.Undergoes peer review –Peer review = a process by which the procedures used during an experiment and the results are evaluated by other scientists. 7. Uses the metric system (Meter, gram, liter, second)

Thinking Like a Scientist Observation = the process of gathering information about events or processes in a careful, orderly way….usually involves the senses (e.g., sight and hearing) Data = the information gathered from observations

Types of Data Quantitative: expressed in numbers, obtained by counting or measuring Example: there are 10 apples in that basket Qualitative: descriptive and involve traits that can’t usually be counted Example: the apples in that basket are a deep red

Observation vs. Inference Inference = a logical interpretation based on prior knowledge or experience; scientists use data to make inferences Example: 1)Observation: the horse is in line with the cart 2) Inference: the horse is PULLING the cart

Science is Always Changing: An Example from Astronomy Name that HOTTIE!

Copernicus and his heliocentric model Old Geocentric Model New Heliocentric Model

Science and Human Values We use science to inform decisions about health care, environmental policy, etc. Many of science’s major discoveries have been considered controversial b/c they call into question certain beliefs (ethics) Example: Cloning, stem cell research, evolution

The Scientific Method Chapter 1.3

Scientists make Observations What observations can you make about this image???

Observations vs. Inferences Observation = a direct method of gathering information in an orderly way –Recording information from the five senses Inference = combining what you know with what you have learned and beginning the process of making logical conclusions –Recording opinions

Step #1: Scientists Ask Questions/State the Problem Scientists base their questions upon: –Observations (after information has been collected) –Prior knowledge –Related research Why is this an important step???

Step #2: Scientists Form a Hypothesis Hypothesis= a testable explanation of a situation Dr. Ron Wiley hypothesized that the use of isometric exercise to raise blood pressure during maneuvers might increase tolerance to g- force and prevent blackouts How did he make this hypothesis?

Step #2: Scientists Form a Hypothesis Hypothesis= a testable explanation of a situation Theory = a well-tested explanation that unifies a broad range of observations

Step #3: Design an Experiment Experiment = an investigation of a phenomenon in a controlled setting to test a hypothesis Let’s look at a new experiment: –A scientist observes that grass does not grow in a certain part of a lawn. Hypothesis: The grass died because there was no water.

Step #3: Design an Experiment Control Group = a group used for comparison. –The plot of grass that was not given extra water. Experimental Group = the group exposed to the variable that is being tested. –The plot of grass that was given extra water.

Step #3: Design an Experiment Variable = any factor that can affect the outcome of an experiment –Water, sunlight, disease, etc. Independent Variable = the manipulated variable; what is changed by the experimenter. –Amount of water Dependent Variable = the variable that is measured; the results. –Grass growth

Step #3: Design an Experiment Constant = a factor/variable that doesn’t change during an experiment. What are some constants in our grass experiment???

Step #4: Perform an Experiment/Gather Data Data = Information gained from observations –Quantitative Data: numerical data (measurements of time, temperature, length, mass, area, etc.) Grass experiment = Area of healthy grass vs. area of dead grass –Qualitative Data: descriptions of what our senses detect Grass experiment = More healthy grass vs. less dead grass

Step #5: Analyze the Data Questions that scientists ask: –“Has my hypothesis been supported?” –“Is more data needed? –“Are different procedures needed?” Scientists work in groups to analyze data! Tables and graphs are good tools for data analysis

Step #6: Report Conclusions Scientists report their conclusions and findings in scientific journals (peer-reviewed journals) –What examples can you think of?

Step #6: Report Conclusions Conclusions may: –Confirm original hypothesis –Disprove original hypothesis –Indicate that further research is needed What other experiments could we do to test why the grass is not healthy?

A Historical Example of the Scientific Method: Spontaneous Generation Spontaneous Generation = the theory that life can arise from nonliving matter Biogenesis Generation = the theory that living things come only from other living things How are these two theories different???

Francesco Redi – Proposed Biogenesis Generation, Disproved Spontaneous Generation How would the presence of maggots be explained by spontaneous generation?

Louis Pasteur – Disproved Spontaneous Generation Louis Pasteur’s Experiment tent/chp03/ html