1 Ch.1: The Science of Biology

The Scientific Process Science is ultimately based on observation (perceiving objects or events using one of the five senses) Science is ultimately based on observation (perceiving objects or events using one of the five senses) Observations  lead to questions ---> which lead to experiments to answer the questions. Observations  lead to questions ---> which lead to experiments to answer the questions.

3 Scientific Method

When scientists want unbiased answers, they must devise a way to disprove any other ideas When scientists want unbiased answers, they must devise a way to disprove any other ideas In general, scientists… In general, scientists… 1.Collect observations and ask Questions 2.Form hypothesis and make predictions 3.Confirm predictions using experiments 4.Draw conclusions 5.Explain and construct a theory **REPEAT! REPEAT! REPEAT!**

5 STEP 1–Observation and Question Employing your five senses to perceive objects or events Employing your five senses to perceive objects or events

Asking a Question Based on observations; one or more questions are generated Based on observations; one or more questions are generated

Step 2-Hypothesis A hypothesis is a testable statement that can be shown to be true or false by observation or experimenting A hypothesis is a testable statement that can be shown to be true or false by observation or experimenting An educated guess An educated guess Must be measurable Must be measurable Sometimes written in “If, then …” format Sometimes written in “If, then …” format Example of Hypothesis Example of Hypothesis Good 1. Plants will grow taller when given Miracle Grow. 2. Girls will score higher on math tests than boys. 3. Hermit crabs choose colorful shells over drab shells. Bad 1. Plants will grow better when given Miracle Grow. 2. Girls are smarter than boys. 3. Hermit crabs like colorful shells.

Following the formation of a hypothesis, a researcher can then make a prediction. Following the formation of a hypothesis, a researcher can then make a prediction. A prediction is an expected outcome. If the statement is true, then you would expect a certain result. A prediction is an expected outcome. If the statement is true, then you would expect a certain result. A hypothesis is then tested by experimentation - a planned procedure designed to test the hypothesis. A hypothesis is then tested by experimentation - a planned procedure designed to test the hypothesis.

Step 3- Controlled Experiment A planned procedure used to test the hypothesis in which only one variable is tested—all other variables are unchanged; divided into 2 groups A planned procedure used to test the hypothesis in which only one variable is tested—all other variables are unchanged; divided into 2 groups Experimental Group: receives some kind of treatment or condition Experimental Group: receives some kind of treatment or condition Control Group: receives no treatment, used to compare Control Group: receives no treatment, used to compare **Everything about the two groups must stay the same, except for the factor you are testing (variable) WHY? --So you can tell if the factor that’s being tested has an effect

Example of an experimental design Hypothesis: Plants will grow taller when given Miracle Grow. Plants A & B are both given the same amount of light, water, and are stored at the same temperature. Plant A is given Miracle Grow. (All the variables are kept constant except the one you are testing. ) Which is the experimental group? Control group?

Independent Variable - the factor you apply to the experimental group, but not to the control group; the variable that is deliberately changed or manipulated = “I” know it ahead of time (Miracle Grow) Independent Variable - the factor you apply to the experimental group, but not to the control group; the variable that is deliberately changed or manipulated = “I” know it ahead of time (Miracle Grow) Dependent Variable – what happens as a result of the treatment—the factor that you are measuring; the variable in which you are observing changes or a response = the results of your experiment (height of plant) Dependent Variable – what happens as a result of the treatment—the factor that you are measuring; the variable in which you are observing changes or a response = the results of your experiment (height of plant) DRY MIX (for graphing your data): DRY MIX (for graphing your data): *Dependent/Responding variable on Y-axis (DRY) *Manipulated/Independent variable on X-axis (MIX)

Step 4-Collecting Data Vital to an experiment Vital to an experiment Collect and organize your results Collect and organize your results Usually presented in tables or graphs. Usually presented in tables or graphs.

Step 5- Drawing Conclusions Using the data collected, was the hypothesis supported or refuted? Using the data collected, was the hypothesis supported or refuted? Every conclusion must assume that the conclusion is only “to the best of our knowledge.” There are no absolutes in science. Every conclusion must assume that the conclusion is only “to the best of our knowledge.” There are no absolutes in science. Science is subject to change when new evidence is found. Science is subject to change when new evidence is found.

Theory Time-tested hypotheses that are accepted to be true, until shown to be false Time-tested hypotheses that are accepted to be true, until shown to be false They must explain a wide range of observations They must explain a wide range of observations Can be changed if new evidence presents itself Can be changed if new evidence presents itself

Questions Predictions & Hypotheses Experimentation Hypothesis supported Hypothesis refuted Related hypotheses are verified by many Theory

16 What is Biology? Bio = Life Bio = Life -logy = the study of -logy = the study of Biology is the study of all living things Biology is the study of all living things Living things are called organisms Living things are called organisms Organisms include bacteria, protists, fungi, plants, & animals Organisms include bacteria, protists, fungi, plants, & animals

17 Characteristics of Organisms

18 All Living Things Share Common Characteristics 1. Are composed of one or more Cells 2. They Reproduce (at some point) 3. Obtain & Use Materials & Energy to carry out life functions (metabolism) 4. Maintain A Stable Internal Environment (Homeostasis)

19 Common Characteristics 5. All Based On Universal Genetic Code (DNA) and pass on traits to offspring (Heredity) 6. AS A GROUP, Living Things Evolve, That Is They Change Over Time (Evolution) 7. Interdependence

20 All Organisms are made of Cells

21 Facts About Cells Cells are the smallest living unit of an organism that can carry out life’s function Cells are the smallest living unit of an organism that can carry out life’s function All cells contain living material called cytoplasm All cells contain living material called cytoplasm All cells are surrounded by a cell membrane that controls what enters & leaves the cell All cells are surrounded by a cell membrane that controls what enters & leaves the cell

22 More Cell Facts Cells are complex & highly organized Cells are complex & highly organized Cells have parts called organelles that do different jobs Cells have parts called organelles that do different jobs e.g. Chloroplasts in plants make sugars e.g. Chloroplasts in plants make sugars

23 Organisms are Grouped by their Number of Cells Unicellular Organisms Unicellular Organisms –Living Organism Made Up Of One Cell Multicellular Organisms Multicellular Organisms –Living Organism Made Up Of Many, Specialized Cells

24 Organisms Reproduce to Pass on their Genetic Traits

25 Two Types of Reproduction Sexual Reproduction Sexual Reproduction Involves 2 parents Involves 2 parents Egg fertilized by sperm to make a ZYGOTE Egg fertilized by sperm to make a ZYGOTE Offspring DIFFERENT from parents Offspring DIFFERENT from parents

26 Two Types of Reproduction Asexual Reproduction Asexual Reproduction Involves a single organism or cell Involves a single organism or cell Cell divides Cell divides Offspring IDENTICAL to parent Offspring IDENTICAL to parent

27 Metabolism Sum of all the chemical reactions in an organism Sum of all the chemical reactions in an organism All require energy All require energy Sunlight is the ultimate energy for life on Earth Sunlight is the ultimate energy for life on Earth

Ex: Humans eat plants and/or eat animals that have eaten plants Ex: Humans eat plants and/or eat animals that have eaten plants Energy flows from the sun to plants to plant-eating organisms to meat-eating organisms Energy flows from the sun to plants to plant-eating organisms to meat-eating organisms

29 Homeostasis Maintaining stable internal conditions in spite of changes in the environment Maintaining stable internal conditions in spite of changes in the environment Organisms unable to balance conditions will fall ill & die Organisms unable to balance conditions will fall ill & die Ex: Body temperature, pH, hydration, etc. Ex: Body temperature, pH, hydration, etc.

30 Cells Have a Genetic Code (DNA) copyright cmassengale

Heredity Pass traits to offspring via genes Pass traits to offspring via genes in each generation Genes are coded in DNA (deoxyribonucleic acid) Genes are coded in DNA (deoxyribonucleic acid) Mutation: changes in DNA sequence; most are neutral, some are helpful, some harmful Mutation: changes in DNA sequence; most are neutral, some are helpful, some harmful Ex: mutations in sex cells (gametes = sperm or egg) are passed on to other generations Ex: mutations in sex cells (gametes = sperm or egg) are passed on to other generations Ex: mutations in body cells (somatic cells) can disrupt normal fnx & cause cancer Ex: mutations in body cells (somatic cells) can disrupt normal fnx & cause cancer

Ex: Sickle cell anemia Ex: Sickle cell anemia --Red Blood Cells (RBCs) carry oxygen to body cells (they are made up of hemoglobin proteins) --In the diseased person: mutated hemoglobin causes the RBC to lose its shape---becomes crescent or sickle shaped reducing the oxygen carrying ability --Symptoms: extreme fatigue on the body & all major organs --Populations affected: U.S.: African-American pop. World: Africa

Malaria (an unrelated and extremely infectious disease) is very common in tropical areas & lead to many deaths ***People with the sickle cell disease are resistant to malaria b/c the organism the causes malaria cannot live without lots of oxygenated blood

Evolution The cause of diversity on Earth The cause of diversity on Earth Change in inherited characteristics of species over generations Change in inherited characteristics of species over generations --Species: genetically similar organisms that can produce fertile offspring Individuals of a species that have genetic traits that better enable them to meet nature’s challenges tend to survive & reproduce == Natural Selection ( those that don’t have the traits will die—survival of the fittest) Individuals of a species that have genetic traits that better enable them to meet nature’s challenges tend to survive & reproduce == Natural Selection ( those that don’t have the traits will die—survival of the fittest)

35 Living Things Evolve Groups Of Organisms (Not Individuals) Change Over Time In Order To Survive Within Changing Environments. Groups Of Organisms (Not Individuals) Change Over Time In Order To Survive Within Changing Environments. Fossil records show changes in groups of organisms Fossil records show changes in groups of organisms

Interdependence Organisms live & interact with other organisms and their environment Organisms live & interact with other organisms and their environment Ecology: the branch of biology that studies interdependence Ecology: the branch of biology that studies interdependence

37 Life is Organized on Several Levels

38 Levels Atoms Atoms Molecules Molecules Organelles Organelles Cells – life starts here Cells – life starts here Tissues Tissues Organs Organs System System Organism Organism

39 Levels Organism Organism Population Population Community Community Ecosystem Ecosystem Biosphere Biosphere

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