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What is Biology? An Invitation to Biology. Are there places on Earth that we haven’t yet explored? YES!!!! Inaccessible Indonesian cloud forest “The more.

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Presentation on theme: "What is Biology? An Invitation to Biology. Are there places on Earth that we haven’t yet explored? YES!!!! Inaccessible Indonesian cloud forest “The more."— Presentation transcript:

1 What is Biology? An Invitation to Biology

2 Are there places on Earth that we haven’t yet explored? YES!!!! Inaccessible Indonesian cloud forest “The more we learn about nature, the more we realize we have yet to learn.”

3 What is Biology? The scientific study of life Why study it? Where do you fit in? About 20 species become extinct every minute in rainforests alone. The current rate of extinctions is about 1,00 times faster that normal. Human activities are responsible for this accelerated rate of extinction. We, as human, are intimately connected to the world around us. When we change the Earth, we change life on Earth.

4 Biology and Scientific Inquiry If you accept information without question, you allow someone else to think for you. Critical thinking means judging information before accepting it. This allows you to move beyond the content of information and to look for underlying assumptions, evaluate supporting statements, and think of possible alternatives.

5 How can you begin to think critically? Be aware of what you intend to learn from new information. Be conscious of bias or underlying agendas in books, lectures, or online. Decide whether ideas are based upon opinion or evidence. Question authority figures respectfully. Consider what you want to believe and realize that those biases influence your learning.

6 The Scope and Limits of Science: What Science Does There are many ways to think about the natural world. Science, the systematic study of nature, is one way. It helps us to be objective about our observations of nature, in art because of its limitations. We limit science to a subset of the world: only that which is observable.

7 The Scope and Limits of Science: What Science Does Not Do Science does not answer questions like “Why do I exist?” Answers to questions such as this are subjective. They depend upon personal experiences and mental connections that shape our consciousness. This is not to say that subjective answers are not valuable, but just that they can vary from one person to the next or one society to the next. Science also does not address the supernatural (anything beyond nature).These things are not directly observable and so are not considered science. In fact, scientists may cause controversy when they discover a natural explanation for something that was thought to be supernatural. Copernicus and the center of the universe In addition, exploring a traditional view of the natural world from a scientific perspective might be misinterpreted as questioning morality even though the two are not the same. As a group, scientists are no less moral, less lawful, or less spiritual than anyone else. However, their work follows a particular standard: Their explanations must be testable in ways that others can repeat.

8 How Science Works Science helps us to communicate our experiences without bias, similar to a universal language. Consider this list of common research practices: Observe some aspect of nature. Frame a question about your observation. Read what others have discovered concerning the subject then propose a hypothesis (a testable answer) to your question. Using your hypothesis as a guide, make a prediction ( a condition that should exist if the hypothesis is not wrong). (“If” is the hypothesis, “then” is the prediction.) Devise ways to test the accuracy of the prediction by conducting experiments or gathering information. Tests may be performed on a model (similar system) is testing an object or event directly is not possible. Assess the results of the experiments. Data that confirm the prediction are evidence in support of the hypothesis. Data that disprove the prediction are evidence that they hypothesis may be flawed. Report all the steps of your work, along with any conclusions you drew, to the scientific community.

9 How Science Works These steps are commonly referred to as The Scientific Method. These are common practices that scientists may use, but every scientist does not always follow every single step in this list, especially in Biology. There are different ways to do research. No matter which steps a scientist does use and which ones he or she leaves for others to do, scientists do NOT accept information simply because someone says it is true. They evaluate supporting evidence and find alternative explanations. They think CRITICALLY.

10 Theory vs. Law When a hypothesis has not been disproven even after years of tests, if it is consistent with all of the evidence gathered to date, and if it has helped us to make successful predictions about other phenomena, it is considered a scientific theory. A law of nature describes a phenomenon that has been observed to occur in every circumstance without fail, but for which we currently do not have a complete scientific explanation. It refers to the fact that we know that something happens and how it happens, but we don’t know why it happens.

11 The Power of Experiments Experiments are used to test predictions that flow from a hypothesis. Experiments are usually designed to determine the effects of a single variable. Since biological systems are complex, with many interacting variables, it can be difficult to study one variable separately from others. Therefore biology researchers often test two groups of individuals sisde by side. An experimental group is a group of individuals that have a certain characterisitic or receive a special treatment. This group is tested alongside a control group. A control group is identical to the experimental group except for one variable, the variable being tested (the independent variable). Any differences between these two groups indicates the effect of changing the variable ( the independent variable).

12 Olestra Experiment Group 1: 500 individuals who ate 13 oz. of regular potato chips during a movie Group 2: 500 individuals who ate 13 oz of potato chips containing Olestra (a fat replacement used for flavoring) during a movie Results: 89% of people eating Olestra chips reported having cramps after the movie. 93% of people eating regular chips reported having cramps after the movie.

13 Olestra Experiment: Homework Answer: What question were the researchers trying to answer? What was their independent variable? What was their dependent variable? What were some of their constant variables? Which group was their control group? Which group was their experimental group?

14 Butterflies and Birds Experiment Researchers made two observations When a peacock butterfly rests, it folds its wings so that only the dark underside shows. When the butterfly sees a predator approaching, it repeatedly flicks its paired forewings and hind wings open and closed. As the forewing slides over the hind wing, a hissing sound and a series of clicks are produced.

15 Birds and Butterflies Experiment The researchers asked a question: “Why does a peacock butterfly flick its wings?” “Why does a peacock butterfly flick its wings?” They then came up with two hypotheses: Although wing-flicking probably attracts predatory birds, it also exposes brilliant spots that resemble owl eyes. Anything that resembles owl eyes is known to startle small, butterfly-eating birds, so exposing the wing spots might scare off the predators. The hissing and clicking sounds produced when the the peacock butterfly rubs the sections of its wings together may deter predatory birds.

16 Birds and Butterflies Experiment The researchers then made two predictions: IF brilliant wing spots of peacock butterflies deter predatory birds, THEN individuals with no wing spots will be more likely to get eaten by predatory birds than individuals with wing spots. IF the sounds that peacock butterflies produce deter predatory birds, THEN individuals that do not make the sounds will be more likely to be eaten by predatory birds than individuals that make the sounds.

17 Birds and Butterflies Experiment To test their predictions, the researchers conducted an experiment. They painted the wing spots of some butterflies black, cut off the sound making part of the hindwing of other butterflies, and did both to a third group. They then put each butterfly into a large cage with a hungry predator and watched the pair for thirty minutes.

18 Birds and Butterflies Experiment Results of the experiment: Wing SpotsWing SoundTotal Number of Butterflies Number EatenNumber survived SpotsSound909 (100%) No spotsSound1055 (50%) SpotsNo sound808 (100%) No spotsNo sound1082 (20%)

19 Birds and Butterflies Experiment: Homework Answer: What conclusion did the researchers come to?

20 Sampling Error Because researchers can rarely observe all individuals of a group, they often have to look at subsets of an area, a population, event, or some other aspect of nature. They test the subset, then use their results to make generalizations to the entire population. However, generalizing results from a subset to an entire population is risky since that subset may not represent the whole population. Therefore, scientists have to consider sampling error when reporting their results. Sampling size is represented on a graph with error bars. Sampling error is the difference between the results from a subset and results from the whole. It is used most often when sample size is small. Beginning an experiment with a large sample size or repeating an experiment many times can minimize sampling error.

21 Sampling error

22 Probability Sample size is also important in probability. For example, if you flip a coin, there is a 50% chance that it will land on heads and a 50% chance that it will land on tails. If you flip the coin ten times only (small sample size) and get that is landed on heads only 3 times (30% probability of landing on heads), this isn’t representative of the true probability of the coin landing on heads. However, if you flipped the coin 1,000 times (large sample size), you would most probably find that your results would more accurately reflect the true probability of the coin landing on heads (50%) or on tails (50%) Scientists will refer to their experimental results as statistically significant. This simply means that the results that they observed and recorded were unlikely to have happened just by chance. It means that the results have been rigorously statistically analyzed and that there is a very low probability (< 5%) that the results have been skewed by sampling error.

23 Levels of Organization of Life

24 ATOMS: the basic building blocks of all matter MOLECULES: Atoms join to form molecules. The molucules of lfie are made only by living cells. These are carbohydrates, lipids, proteins, and nucleic acids. The same atoms make up both living and non-living things. The unique properties of life emerge as certain kinds of molecules become organized into cells. CELL: The smallest unit of life that can survive and reproduce on its own, given information in its DNA, energy, and raw materials. ORGANISM: An individual that consists of one or more cells. In larger organisms, these cells may be organized into tissues (groups of similar cells that have the same function), organs, and organ systems. POPULATION: A group of the same type of individuals (or species) living in a given area. COMMUNITY: Consists of all population of all species in a given area. ECOSYSTEM: Communities interacting with their environment. BIOSPHERE: Most inclusive level- includes all regions of Earth’s crust, waters, and atmosphere in which organisms live.

25 Life is more than just the sum of its parts. Some emergent property occurs at each successive level of life’s organization. An emergent property is a characteristic of a system that does not appear in any of a system’s component parts. For example, the emergent property- life- appears first at the level of the cell.

26 So, what is life, really? Even though life is not easy to define since it has always been and always is changing, we can determine if something is alive by considering the characteristics of life.

27 The Characteristics of Life Living things require energy to sustain life’s organization All organisms spend a lot of time acquiring energy and nutrients. However, how they go about this task is different. All organisms spend a lot of time acquiring energy and nutrients. However, how they go about this task is different. Producers make their own food using energy and simple raw materials they get directly from their environment. (ie. plants) Producers make their own food using energy and simple raw materials they get directly from their environment. (ie. plants) Consumers cannot make their own food; they get energy and nutrients indirectly by feeding on other organisms. (ie. Animals, decomposers, etc.) Consumers cannot make their own food; they get energy and nutrients indirectly by feeding on other organisms. (ie. Animals, decomposers, etc.)

28 Energy is not recycled. It flows through the world of life in one direction, from the environment to living organisms. The flow of energy is one way because, with each energy transfer, some energy escapes as heat. Cells can not use heat to do work. Thus the energy that enters the world of life eventually leaves it. One Way Flow of Energy in Living Things

29 The Characteristics of Life Living things sense and respond to change. Living organisms sense and respond to changes both inside and outside of its body using receptors ( a molecule or cellular structure that responds to a specific form of stimulation). Unless the internal environment is kept within certain ranges of composition, temperature, etc., your body cells will die. By sensing and adjusting to change, you an all other organisms keep conditions in the internal environment within a range that favors cells survival. This condition that favors cell survival is called homeostasis (“staying the same”) and is a defining feature of life.

30 The Characteristics of Life Living things grow and reproduce. Individuals of every natural population are alike in certain aspects of their body form, function, and behavior but the details of such traits can take different forms from one individual to the next. This is due to the outcome of information encoded in DNA (deoxyribonucleic acid). DNA is the signature molecule of life. DNA carries information that guides growth (increases in cell size, number, and volume) and development ( process by which the first cell of a new individual becomes a multi-celled adult. Only multi-celled species undergo development, but all organisms inherit DNA from parents. Inheritance refers to the transmission of DNA from parents to offspring. Inheritance occurs by the process of reproduction. Both inheritance and reproduction are hallmark features of life.

31 Life’s Diversity Living organisms differ in their details; they show tremendous variation in traits. Each time a new species (kind of organism) is discovered, it is given a two-part name. The first part of the name specifies the genus, which is a group of species that share a unique set of features. The second part of the name is the species name. Individuals of a species share one or more heritable traits and they can interbreed successfully (producing fertile offspring) if the species is sexually reproducing The genus and species names are always italicized and the genus name is always capitalized.

32 Classification of Life’s Diversity Classification Systems are used to organize and retrieve information about species. Most classification systems sort species into groups on the basis of their traits. There are different classification systems. A very popular system that has been used is the Five Kingdom classification system. The five kingdoms in this system are Monera, Protista, Fungi, Plantae, and Animalia. A common classification system that is currently used classifies all living things into three domains: Bacteria, Archae, and Eukarya. Protista, Plantae, Fungi, and Animalia kingdoms are included in the Eukarya domain, while the Monera kingdom is subdivided into two domains: Archae and Bacteria.

33 Life’s Diversity: Prokaryotes All Bacteria and Archaeans are single-celled organisms. All are also prokaryotes, meaning that their DNA is not contained within a nucleus ( membrane-enclosed sac that protects a cell’s DNA). Prokaryotes are the most numerous and diverse organisms. Different kinds are producers or consumers and they inhabit nearly all of the biosphere, including extreme environments such as frozen desert rocks, boiling sulfur-clogged lakes, and nuclear reactor waste.

34 Life’s Diversity: Eukaryotes All organisms in the domain Eukarya are eukaryotes. These organisms are those that contain a true, well- defined nucleus. Protists are the simplest eukaryotes. Some protists are rpoducers while others are consumers. Many are single cells that are larger and more complex than prokaryotes. Some are unicellular while others are multicellular. Fungi, plants, and animals are also eukaryotes.

35 Eukaryotes: Fungi Most fungi are multicellular. Many are decomposers, and all secrete enzymes that digest food outside the body and then absorb the released nutrients. Examples include yeast, mushroom

36 Eukaryotes: Plants All plants are multicellular and live on land or in freshwater. (Ex. Trees) Most produce their own food using a process called photosynthesis, in which the energy of the sun is used to drive the production of sugars from carbon dioxide and water. Most produce their own food using a process called photosynthesis, in which the energy of the sun is used to drive the production of sugars from carbon dioxide and water. Plants serve as food for most other organisms in the biosphere.

37 Eukaryotes: Animals Animals are multicellular consumers that ingest the tissues and/or juices of other organisms. Herbivores eat plant material. (Ex. Rabbits) Carnivores eat meat. (Ex. Lions) Scavengers (or detritivores) eat the remains of other organisms. (Ex. Vultures) Parasites withdraw nutrients from the tissues of a host. (Ex. Mosquitoes) Animals grow and develop through a series of stages that lead to the adult form. Most animals actively move about for at least part of their lives.

38 Homework: Complete the Venn diagram on my website to compare and contrast the two classification systems discussed in the PowerPoint.

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