Themes in the study of Life

Themes in the study of Life • Biologist study life in many different scales of size and time. • I am showing you this because it is beautiful. Thousand hand dance by mdsign -- Revver Online Video Sharing Network The hierarchy of biological organization • All organisms are composed of cells--the fundamental unit of life. Most organisms are single cells; other organisms, including humans, are multicellular. Cells to tissues • Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle Tissues to organs • Different tissues are in turn grouped together to form larger functional units, called organs. Organs/Systems • Cells, tissue and organs form systems. • Such as the nervous system. Organs to system/systems to organism topic 1.1.12 page 43 sg • Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole. • Organisms belong to a species – a group of organism which can interbreed and produce viable young. Species form populations • Species in a particular area constitute a population Populations make communities • Population inhabiting an area at the same time make up a community Communities make ecosystems • A community plus its physical environment constitutes an ecosystem. Living things are classified. Topic 5.5 page 34-35 study guide • Taxonomy – the discipline of identifying and classifying organisms. • Basic group is species: similar characteristics which can interbreed and produce fertile offspring. • Every species is classified into a genus: group of similar organisms. Rules: page 34 sg binomial system • • • • 1st name is genus – upper case first letter 2nd name is species- lower case first letter Italics are used when the name is printed The name is underlined if hand written Why classify • Organization of data allows identification • Shows evolutionary links • Prediction of characteristics shared by group of organisms. • A group of organisms such as a species or genus is called a taxon • Hierarchy of taxa - Hierarchy of taxa • • • • • • Kingdom phylum Class Order Family genus For IB • Follow one plant and one animal through the taxonomic classification. • You will find this information on Page 35study guide. • I recommend that you use humans for the animals as it is also required for your higher level topic on Evolution • Human Taxonomy Option D 4.1 Kingdom Phylum Class Order Family Genus Species Animalia Chordata Mammalia Primata Hominidae Homo sapien TOK • Binomial nomenclature was developed by Carolus Linnaueus. He also defined four groups of humans and the divisions were based on both physical and social traits. • Think about social context of scientific work and how it affects findings • Linnaeus proposed that inside of Homo sapiens, there were four subcategories. These categories, Americanus, Asiaticus, Africanus, and Europeanus were based on place of origin at first, and later skin color. Each race had certain characteristics that members supposedly had. • Native Americans were reddish, stubborn, and angered easily. • Africans were black, relaxed and negligent. • Asians were sallow, avaricious, and easily distracted. • Europeans were white, gentle, and inventive. linnaeus's races were clearly skewed in favour of Europeans. • Over time, this classification led to a racial hierarchy, in which Europeans were at the top. • You are to read the following link and be prepared to discuss. • http://www.geocities.com/ginkgo100/racis m.html Classification 5.5.4 phyla of animals page 35 study guide • You will need to be able to list the simple characteristics of each phyla Poriferans are commonly referred to as sponges • • • • No clear symmetry Attached to a surface Pores through body No mouth or anus Platyhelminthes/planaria, tapeworms, liver flukes • • • • Bilateral symmetry Flat bodies Unsegmented Mouth but no anus Mollusca slugs/snails/clams/squids • Muscular foot and mantle • Shell usually present • Segmentation not visible • Mouth and anus Cnidarua – jellyfish/corals/sea anemones • • • • Radially symmetric Tentacles Stinging cells Mouth but no anus • coral Annelida – earthworms, leeches, ragworms • • • • Bilateral symmetry Bristles often present Segmented Mouth and anus • ragworm Arthropoda – insects, spiders, crabs, millipedes • • • • • Bilateral symmetry Exoskeleton Segmented Jointed appendages http://trc.ucdavis.edu/ biosci10v/bis10v/wee k9/millipedeucd.mov Classification using a dichotomy key page 34 sg A dichotomous key contains a series of choices that lead the user to the correct name of an item. "Dichotomous" means "divided into two parts.“ Therefore, a dichotomous key will always give two choices in each step. • first step is to look at the group of objects or organisms and separate them into two groups based on a single distinguishing characteristic.