BIOLOGY NOTES - CHAPTER 1

Transcription

1 BIOLOGY NOTES - CHAPTER 1 SECTION 1 and 2 Biology is the study of life Bio = life Logy = study of The scientific study of all forms of life, or all types of organisms Science means to know Science is a body of knowledge about the natural world In class Activity = lets propose an explanation for why it rains without including any scientific thinking. Clouds are raining Invisible rivers are crying Rain god pours water on earth when angry Suppose someone doesn t believe your explanation, could you supply evidence to support your explanation? No why not can t gather evidence Scientist use science to propose explanations that can be tested by examining evidence Several features of science Science deals only with the natural world Scientists collect and organize information in a careful orderly way looking for patterns and connections between events Scientists propose explanations that can be tested by examining evidence Some explanations can be pseudoscience = fall outside the realm of scientific explanation, ex is astrology All living things and all the places they are found on Earth make up the biosphere. Every part of the biosphere is connected with every other part.

2 Hierarchy of Life Across the biosphere, the variety of life is called biological diversity or biodiversity. It generally increases from poles to the equator which means greater biodiversity is found in warmer areas. This is because more living things can survive in warmer temperatures and less temperature changes during the year.

3 Remember that an Organism = ANY individual living thing Characteristics of Living Organisms 1. Cellular structure and function a. All living things are made up of one or more cells b. The cell is the smallest unit capable of life c. Our bodies have 100 trillion cells, a paramecium has one cell 2. Reproduction a. It is the a process by which organisms make more of their own kind from one generation to the next b. The rate of reproduction changes based on organism; some bacteria reproduce every 15 minutes but the bristle cone pine tree reproduces after every 5000 years. c. Remember that just because an individual can t reproduce it doesn t mean a species won t survive. (species wouldn t survive if all organisms couldn t reproduce) 3. Metabolism a. The sum of all chemical reactions carried out by an organism 4. Homeostasis a. A constant stable internal condition despite the external environment. b. If an organism is unable to balance the internal and external conditions then it will die. 5. Heredity a. The passing of traits to their offspring through genes from parent to offspring. 6. Evolution a. A change in inherited characteristics of species over generations 7. Interdependence a. Organisms are dependent on one another and their environment. All living organisms must have all 7 of the above characteristics or they will not survive. Homeostasis Important because cells function best within a limited range of conditions. Temperature, blood sugar, acidity, and other conditions must be controlled. Breakdowns in homeostasis are often life threatening.

4 It is maintained through a process called negative feedback. This is a change in a system causes a response that tends to return that system to its original state. Behavior is also involved. Animals regulate temp through behavior. If you feel cold you put on a jacket, reptiles sit on a warm rock in the sun if cold move to the shade if hot. Polar bears hair is hollow to help store their body heat. o Polar bears hair is transparent but appears white because it reflects visible light like snow and ice do. There have been cases where polar bears have been green because the hollow hair took on the color from the algae infested water they were swimming in. case of their hair turning purple because of medicine treatment for dermatitis. Adaption in evolution are changes in a species that occur over many generations due to environmental pressures, not by choice. SECTION 3 Scientific Method The scientific method is a way to ask and answer scientific questions by making observations and doing experiments. The term is meant to capture the core logic of how science works aka process of science The scientific method can not Tell us what is morally right or wrong Speak to the existence of god or other supernatural being Tell if something is beautiful or ugly The scientific method can Seek natural causes to explain the workings of the world The steps of the scientific method are to:

5 Make an observation/ask a Question/state the problem has to be about the natural world Do Background Research using reliable sources Form a Hypothesis/make predictions o Hypothesis is an educated guess Conduct experiment/test Your Hypothesis o Test by observing and measuring or designing and running experiments o Data is given during experiment Non-significant data shows no effect, or an effect so small that the results could have happened by chance Statistically significant data shows an effect that is likely not due to chance Analyze Your Data Draw a Conclusion o Disprove or support your hypothesis Communicate Your Results Observation = a description, measurement, or record of any object or phenomenon, usually made with your senses Anecdotal evidence = informal observations that have not been systematically tested Example is to ask a class how coffee effects them to see if it s the same as you Inference = a conclusion reached on the basis of evidence and reasoning Experiments show factors that have a cause and effect relationship we call variables. 4 types of variables are as follows.

6 Independent variable - Condition that is manipulated, or changed by scientists and measured by changes in the dependent variable Dependent variable observed and measured during an experiment, they are the experimental data, aka responding Constants conditions that do not change during an experiment unchanging Controls conditions that mimic how things are found in the real world, comparison 2 groups in an experiment Experimental group = group in an experiment that experiences the experimental intervention or manipulation what is being tested Control group = group that experiences no experimental intervention or manipulations. Serves as the basis for comparison. o Receives a placebo or fake treatment that is given to mimic the experience of the experimental group o Placebo effect is an effect observed when members of a control group display a measureable response to a placebo because they think that they are receiving a real treatment Sample size strengthens results This is the number of individuals participating in a study or the number of times an experiment is repeated The larger the sample size the more likely the results will have statistical significance = real results, not random Theory is a proposed explanation for a wide range of observations and experimental results that is supported by a wide range of evidence. They can change based on new

7 evidence. They are a bunch of hypotheses that have not been disproven after being tested multiple times. SECTION 4 Microscope is a device that produce magnified images of structures that are too small to see with the unaided eye Types of microscopes Light microscopes (first type) o Most commonly used o Produce clear images of objects at a magnification of about 1000 times o Produces magnified images by focusing visible light rays o Study dead organisms and parts and observe tiny organisms while alive Light microscopes cannot produce clear images of objects smaller than 0.2 micrometers (1/5 diameter of a typical cell) Compound microscope o Allows light to pass through the specimen o Uses 2 lenses to form an image Biologist have developed techniques and procedures to make light microscopes more useful o Chemical stains dyes- show specific structures of a cell o Fluorescent dyes have been combined with video cameras and computer processing to produce moving 3d images of cell movement Electron microscope o Produce magnified images of focusing beams of electrons instead of light

8 o They require a vacuum to operate so you must use preserved and dehydrated specimen o NO living cells can be used 2 main types of electron microscopes TEM transmission electron microscope o Shine a beam of electrons through a thin specimen and gives details about the inside the cell SEM scanning electron microscope o Scan a narrow beam of electron back and forth across the surface of a specimen which produce realistic, dramatic, 3d images of the surface of the objects In class activity ask the students the following Which type of microscope would you use to do the following 1. Feeding habits of unicellular protozoa = light microscope 2. Surface of a red blood cell = SEM 3. Feeding habits of a house cat = none 4. Interior structures of a cell = TEM There will be a microscope lab where students learn the parts of the microscope and how to use it. They will look at premade slides and anything that they want to see.

9