2024 Chapter 1 Lecture 2.pptx

The Tree of Life Chapter 1: Lecture 2 Lecturer Ms. Thabisa Mdlangu [email protected] BCB Department, Life Sciences Building Core 2, 5th Floor Tutorials: Mrs Dawn Faroe [email protected] Practicals: Mrs Lorne Geldebloem [email protected] Taxonomy Taxonomy: The science of branching and classifyin...

The Tree of Life Chapter 1: Lecture 2 Lecturer Ms. Thabisa Mdlangu [email protected] BCB Department, Life Sciences Building Core 2, 5th Floor Tutorials: Mrs Dawn Faroe [email protected] Practicals: Mrs Lorne Geldebloem [email protected] Taxonomy Taxonomy: The science of branching and classifying organisms Species: The basic unit of classification which designates a distinctive ‘type’ of organism Genus: Closely related species are grouped into the same genus Genus species: Together they denote the unique twoword scientific name of each species Homo sapiens, Musca domestica (Can either be italicized or underlined) Taxonomy involves more than simply naming things Taxonomists also strive to classify organisms according to what we know about evolutionary relationships i.e. : How recently one type of organism shared an ancestor with another type. The more recently diverged from a common ancestor, the more closely related they are presumed to be Broadest taxonomic category is the Domain: Domain Archaea Domain Bacteria Domain Eukarya Prokaryotes A prokaryote is a single-cell organism whose cell lacks a nucleus and other membranebounded organelles. An organism composed of one or more cells containing a nucleus and other membranebounded organelles Genetic evidence suggests that all species fall into one of these three domains Binomial nomenclature: the biological system of naming the organisms in which the name is composed of two terms, where, the first term indicates the genus and the second term indicates Domain Bacteria: Prokaryotic Most are unicellular Domain Archaea: Prokaryotic Mostly unicellular Domain Eukarya: Cell contains nuclei Unicellular or Multicellular Domain Eukarya (Kingdoms) Kingdom Protista Kingdom Animalia Kingdom Fungi Kingdom Plantae Example: Classifying an organism (Honey Bee) from Domain to species. Each classification category is based on certain characteristics in an organism. Scientists study the natural world Biology is a rapidly changing field Scientists use evidence to answer questions about the natural world The Scientific Method Scientific knowledge arises from the application of the Scientific method A scientific method is a general way of using evidence to answer questions and test ideas Science combines: Thinking, Detective work, Collaboration with other Scientists, learning from mistakes, and noticing connections How do scientists study the natural world? Observations and asking questions The Scientific method begins with these two May rely on what we can see, hear, touch, taste or smell or existing knowledge / experimental results Sometimes one can make connections between previously unrelated observations Hypothesis and Predictions Hypothesis: A tentative explanation for one or more observations : This is an essential unit of a scientific inquiry Must be testable: There must be a way to collect data that can support or reject it Becomes widely accepted when multiple lines of evidence support it, but interestingly cannot be proven true because future discoveries may contradict today’s results It is a general statement that should lead to a specific prediction Prediction: An anticipated outcome of the test of a hypothesis It is often written as an if statement:  Hypothesis: My lawnmower stopped working because it ran out of gas Prediction: If I put gas into the tank then it should start working Data Collection Conclusions are drawn based on the data collected Data may come from careful observation of the natural world Can also be done by carrying out an experiment to test the hypothesis under controlled conditions Discovery and experimentation work hand-in-hand Analysis and Peer review After collecting and interpreting data, investigators decide whether the evidence supports or falsifies the hypothesis Often the most interesting results are those that are unexpected because they provide new observations that force scientists to rethink their hypothesis Science advances as new information arises and explanations continue to improve Once a scientist has enough evidence to support or reject a hypothesis, they may write a paper and submit it for publication in a relevant journal The journal editors send the paper to anonymous reviewers who are knowledgeable about the topic – This process is called Peer review These scientists independently evaluate the validity of the methods, data and conclusions Peer review ensures that journal articles are of high quality An experiment design is a careful plan An experiment is an investigation carried out in controlled conditions Sample size: One of the most important decisions that an investigator makes in designing an experiment Variables: A changeable element of an experiment Independent variable: the factor that the investigator manipulates to determine whether it causes another variable to change Dependent variable: Any response that might depend on the value of the independent variable Standardized variable: Anything that the investigator holds constant for all subjects in the experiment, ensuring the best chances of detecting the effect of the independent variables Control: Provides the basis for comparison in measuring the effect of the independent variable Sometimes the experiment evidence may lead to multiple interpretations, and sometimes even the carefully planned experiment can fail to provide a definitive answer Even though scientists may make mistakes in the short term, science is self-correcting in the long run because it remains open to new data and new interpretations. Glossary of terms Domain Prokaryote Eukaryote Scientific method Hypothesis Prediction Variables Independent variable Dependent variable Standardized variable Control Binomial nomeclature: Experiment Peer review