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1.2 Unifying Themes of Biology. Systems. All levels of life have systems of related parts What is a system? Group of parts that work together to make a whole Digestive system (mouth, esophagus, stomach, intestines, colon…) Sound System in a car (amp, stereo, speakers, bass…). Ecosystem.
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Systems • All levels of life have systems of related parts • What is a system? • Group of parts that work together to make a whole • Digestive system (mouth, esophagus, stomach, intestines, colon…) • Sound System in a car (amp, stereo, speakers, bass…)
Ecosystem • We are part of a biological system---ecosystem
Homeostasis • With changing temp and environment conditions, our bodies need a way to regulate with internally. • Sweating when it’s hot • Shivering when it’s cold • Feeling thirsty when dehydrated • Homeostasis is maintained through negative feedback and behavior
1.3 Scientific Thinking and Processes • There are many methods used by scientists to study and understand life. • Scientific Process: • Observation • Forming Hypothesis • Experimenting (testing the hypothesis) • Analyzing data • Evaluate results • Form a conclusion
Observing • Using senses to study the world • Using computers to gather information • Observations help scientists form a hypothesis
Experiments • Used to test a hypothesis • Independent and dependent variables are used to find cause and effect relationships • The dependent variable relies on the independent variable. • Dependent is what is observed and measured, independent is what is manipulated by the experimenter. • Only one independent should be manipulated at a time, all other conditions should remain constant
Theory • Theories are proposed explanations for observations based on scientific evidence. • Theories are hypothesis that have been tested and supported by a wide range of evidence.
Different rose bushes are grown in a greenhouse for two months. The number of flowers on each bush is counted at the end of the experiment. • You water three sunflower plants with salt water. Each plant receives a different concentration of salt solutions. A fourth plant receives regular water. After a two-week period, the height is measured. • Three redwood trees are kept at different humidity levels inside a greenhouse for 12 weeks. One tree is left outside in normal conditions. Height of the tree is measured once a week.
Pea plant clones are given different amounts of water for a three-week period. The first pea plant receives 400 mL a day. The second pea plant receives 300 mL a day. The third 200 mL a day and the fourth does not receive any extra water; the palnt only receives natural ways of receiving water. The height of pea plants are recorded daily.