I NVITATION TO B IOLOGY Chapter 1 Biology is the study of life

T HE S CIENCE OF N ATURE All living organisms are alike in key aspects Organization of living organisms occurs in successive levels

T HE S CIENCE OF N ATURE Levels of organization Atoms Molecules Carbohydrates, lipids, proteins, and nucleic acids CELLS Smallest unit of life able to survive and reproduce

T HE S CIENCE OF N ATURE Levels of organization Organism An individual that consists of one or more cells Tissues Specialized cells which work together to perform a collective function ( only in multi-cellular organisms ) Organs Groups of tissues engaged in a collective task ( only in multi-cellular organisms ) Organ Systems Set of organs engaged in a collective task ( only in multi- cellular organisms )

T HE S CIENCE OF N ATURE Levels of organization Population Group of the same species ( uni- or multi- cellular ) living in the same area Community All of the populations in the same area Ecosystem Community interacting with the physical and chemical environment Biosphere All regions of the Earth where organisms live

Fig. 1-3a, p. 4 atom moleculecelltissueorganorgan system

Fig. 1-3b, p. 4 multicelled organismpopulationcommunityecosystem biosphere

T HE S CIENCE OF N ATURE Levels of organization Characteristics of a level that do not appear in any of the previous levels are referred to as emergent properties Cell  tissue  organ  organ system … Each level shows emergent properties

H OW L IVING T HINGS A RE A LIKE All living organisms are alike in key aspects Organization Energy Sense and respond to change DNA guides cell functions

H OW L IVING T HINGS A RE A LIKE Energy Organisms must acquire and use energy Producers make their own food (autotrophs) Photosynthesis or chemosynthesis Consumers can not make their own food (heterotrophs) Eat producers or other consumers Cellular respiration is the metabolic pathway that releases energy for the consumers

H OW L IVING T HINGS A RE A LIKE Sensing and responding to change Organisms sense and respond to changes in conditions inside and outside the body Receptors sense the change This triggers a change in activity of the organism Homeostasis Organisms keep their internal conditions within a range that favors survival

H OW L IVING T HINGS A RE A LIKE DNA guides cell functions DNA is the basis of growth, development, reproduction, and genetic traits The instructions in DNA are used to make proteins Each protein has a different function

Q UESTIONS Biology is the study of ______ Atoms make bonds to form _________ What are the four types of molecules found in living organisms? What is the smallest unit of life? What is one way that organisms can acquire and use energy? What molecules guide growth, development, and reproduction?

Q UESTIONS If you understand that all living organisms share the above traits… You should be able to determine if a virus is considered a living organism Viruses: Are composed of proteins and nucleic acids, but do not form cells Infect living cells Can not reproduce or acquire energy on their own

C RITICAL T HINKING AND S CIENCE Critical thinking Judging the quality of information before accepting it Discerning judgment Be an open-minded skeptic Be conscious of Bias: your own and others Opinion versus evidence What do you intend to learn

H OW S CIENCE W ORKS Observations From nature From other scientists reports

H OW S CIENCE W ORKS Ask a question about the observations Form a hypothesis A testable answer to your question Predict the results of the experiment If…, then…

H OW S CIENCE W ORKS Design an experimental test Experimental Design Experimental group Manipulated or treated Control group A standard for comparison Variables Independent: treatment under study ( the variable that is manipulated or changed ) Dependent: event that is measured or observed Controlled: all other factors (should be kept the same)

H OW S CIENCE W ORKS Analyze and Report the findings Data (test results) that are consistent with the prediction are evidence in support of the hypothesis Data that are inconsistent with the prediction are evidence that the hypothesis is flawed and should be revised Report the results to allow other scientists to check and confirm the work

Table 1-3, p. 12

Fig. 1-11, p. 14 Hypothesis Olestra® causes intestinal cramps. Prediction People who eat potato chips made with Olestra will be more likely to get intestinal cramps than those who eat potato chips made without Olestra. ExperimentControl GroupExperimental Group Percentages are about equal. People who eat potato chips made with Olestra are just as likely to get intestinal cramps as those who eat potato chips made without Olestra. These results do not support the hypothesis. Conclusion Eats regular potato chips Eats Olestra potato chips 93 of 529 people get cramps later (17.6%) 89 of 563 people get cramps later (15.8%) Results

L IMITS OF S CIENCE Science is the systematic study of nature Objective about our observations Limited to only that which is observable Explanations must be testable in the natural world in ways that others can repeat

L IMITS OF S CIENCE Pitfalls of science Studying subsets Subset might not reflect the whole Sampling error Difference between results obtained from a subset and results from the whole Statistical significance Results that are statistically unlikely to have occurred by chance Bias Interpreting results based on what the researcher wants to find out

P HILOSOPHY OF S CIENCE Theory A theory is a hypothesis supported by a great deal of evidence The hypothesis becomes accepted as theory because Consistent with all of the evidence gathered Helps in making predictions about other observations Predictive power has been tested many times Close to the “truth”, but always open to revision Not used in science to mean a speculative idea, opinion, or belief “I have this theory about why my dog eats the roses.”

Table 1-4, p. 13

Q UESTIONS What is wrong with the following experiment? Jim wanted to know if larger snails could move faster than small snails. He found one large snail and put it on his gravel driveway and measured how long it took the snail to move 3 inches. He found one small snail and tested how long it took the snail to move 3 inches on the sidewalk. After testing Jim concluded that the large snail was slower than the small snail.

Q UESTIONS What is wrong with the following experiment? Edna has heard that gingko extracts can improve memory. Edna gives 8 little old ladies a memory test (they all did poorly) The 8 little old ladies use gingko for 6 weeks Edna tests the ladies each week with the memory test By the end of 6 weeks all of the little old ladies have shown memory improvement

S UMMARY Life’s levels of organization Cells Life’s unity Critical Thinking Scientific Inquiry