1.2 U NIFYING T HEMES OF B IOLOGY

S YSTEMS 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…)

E COSYSTEM We are part of a biological system---ecosystem

H OMEOSTASIS 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 S CIENTIFIC T HINKING AND P ROCESSES 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

O BSERVING Using senses to study the world Using computers to gather information Observations help scientists form a hypothesis

E XPERIMENTS 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

T HEORY 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.

1.4 B IOLOGISTS ’ T OOLS AND T ECHNOLOGY

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.