Biology - The Unity and Diversity of Life | Biology

Preview (6 of 18 Pages)

100%

Biology - The Unity and Diversity of Life - Page 1 preview image

Loading page ...

Study GuideBiology–The Unity and Diversity of Life1. Basics of Classification (Taxonomy)1.1 Why Do We Classify Living Things?Earth is home tomore than 8 million different species. This number keeps changing as scientistsdiscover newspecies every year. With so many living things, biologists need a clear way to organizethem.The branch of biology that does this is calledtaxonomy, and scientists who work in this field areknown astaxonomists. Taxonomy helps us understand how living things are related and how life onEarth is bothdiverse and connected.1.2 The Beginning of Modern TaxonomyIn the mid-1700s, a Swedish scientist namedCarolus Linnaeusmade a major contribution tobiology. He studied plants and animals and grouped them based on theirreproductive parts.Linnaeus also introduced a naming system calledbinomial taxonomy, which gives every organism atwo-part scientific name. His system was so well designed that it is still used today.Later, Linnaeus’s work was combined withCharles Darwin’s theory of evolution. Darwin explainedthat:•All modern species evolved from earlier species.•All living organisms share acommon ancestry.Because of this,evolutionbecame the organizing principle of modern taxonomy. Today, organismsare classified in ways that reflect theirevolutionary relationships.1.3 What Is Classification?The wordclassificationmeans the same thing astaxonomy. It refers to the process of organizingand naming organisms based on shared characteristics and ancestry.

Biology - The Unity and Diversity of Life - Page 2 preview image

Loading page ...

Study GuideBecause evolutionary relationships can be complex, classification systems can also be complex.Scientists often revise them as new evidence is discovered. Even so, classification gives us valuableinsight into how life on Earth is organized.1.4 Rules for Naming OrganismsAll living organisms are named and classified using aninternational system of rulesdeveloped inthe early twentieth century. These rules:•Apply only toscientific names, not common names.•Provide a standard method for namingnew species.This ensures that scientists around the world can communicate clearly and avoid confusion.1.5 Scientific Names: Binomial NomenclatureEach organism has abinomial name, which means it hastwo parts:1.Genus name2.Species modifierFor example, the scientific name of humans isHomo sapiens:•Homois thegenus•sapiensis thespecies modifierThe genus name is usually anoun, and the species modifier is often anadjective. Together,Homosapiensroughly means“knowing human”or“intelligent human.”1.6 What Is a Species?Aspeciesis generally defined as a group of organisms that:•Caninterbreed naturally•Producefertile offspringOrganisms from different species usually do not mate. If they do, one of two things happens:

Biology - The Unity and Diversity of Life - Page 3 preview image

Loading page ...

Study Guide•The mating is unsuccessful, or•The offspring issterile(cannot reproduce)Example:•Ahorse(Equus caballus) and adonkey(Equus assinus) can mate and produce amule.•However, mules are sterile, so horses and donkeys are considereddifferent species.In contrast, different breeds of horses (like quarter horses and thoroughbreds) can produce fertileoffspring, so they all belong to thesame species.1.7 Human Species, Past and PresentToday, there is onlyone living human species:Homo sapiens.In the past, other human species existed, such asHomo erectus. These are considered separatespecies because they likelycould not interbreedwithHomo sapiens.1.8 Levels of ClassificationClassification groups organisms intolarger and larger categoriesbased on shared traits.Here is the general order, from smallest to largest:•Species•Genus(plural: genera)•Family•Order•Class•Phylum(used for animals) orDivision(used for plants and fungi)•Kingdom•DomainThedomainis the largest and most inclusive category and has replaced kingdom as the highestlevel.

Biology - The Unity and Diversity of Life - Page 4 preview image

Loading page ...

Study Guide1.9 Human Classification: An ExampleLet’s see how humans fit into this system, starting from the broadest category:•Domain:Eukarya (made of eukaryotic cells)•Kingdom:Animalia (has animal characteristics)•Phylum:Chordata (has a backbone at some stage of life)•Class:Mammalia (has mammary glands and nurses young)•Order:Primata (includes primates like monkeys and gorillas)•Family:Hominidae (human-like creatures)•Genus:Homo•Species:Homo sapiensThis step-by-step system shows how classification helps us understand bothwhat makes humansuniqueandhow we are related to other living organisms.2. Quiz Basics of Classification Taxonomy1. QuestionTaxonomy is best described as:Answer Choices•a method of scientifically naming species that once created, never changes•classifying organisms that reflect their biological ancestry, and is often the subject ofrevision•the art of preparing, stuffing, and mounting the skins of animals with lifelike effectCorrect Answerclassifying organisms that reflect their biological ancestry, and is often the subject of revision

Biology - The Unity and Diversity of Life - Page 5 preview image

Loading page ...

Study GuideWhy This Is CorrectTaxonomy is the science of classifying living organisms based on shared characteristics andevolutionary (biological) relationships. As new evidence—such as genetic data—is discovered,classifications can change. This is why taxonomy is often revised overtime.2. QuestionEarth today is home to about how many different species?Answer Choices•8 million•80,000•800,000Correct Answer8 millionWhy This Is CorrectScientists estimate that Earth is home to around8 milliondifferent species of plants, animals, fungi,and microorganisms. Many of these species have not yet been discovered or formally described,especially those living in oceans and tropical regions.3. QuestionWhich characteristic doesNOTdefine a species?Answer Choices•ability to interbreed•ability to produce fertile offspring•ability to produce offspring that may or may not be fertile

Biology - The Unity and Diversity of Life - Page 6 preview image

Loading page ...

Study GuideCorrect Answerability to produce offspring that may or may not be fertileWhy This Is CorrectA species is defined as a group of organisms that caninterbreed naturally and produce fertileoffspring. If offspring may be infertile (like a mule, which comes from a horse and a donkey), theparents are considered different species.4. QuestionWhich of the following pairs areNOTconsidered the same species?Answer Choices•Chihuahua and Dalmatian•donkey and horse•quarter horse and thoroughbredCorrect Answerdonkey and horseWhy This Is CorrectDonkeys and horses can mate, but their offspring (a mule or hinny) is usuallyinfertile, which meansthey arenot the same species.In contrast, different dog breeds (like Chihuahuas and Dalmatians) and different horse breeds (likeQuarter Horses and Thoroughbreds) can interbreed and producefertile offspring, so they areconsidered the same species.5. QuestionWhat is the correct order of classification, frombroadesttomost specific?

Preview Mode

This document has 18 pages. Sign in to access the full document!

Report

Biology - The Unity and Diversity of Life

Study Now!

Document Details

Related Documents

Biology - Vascular Plants Structure and Function

Biology - The Science of Biology

Biology - The Origin and Evolution of Life

Biology - The Chemical Basis of Life

Biology - The Biology of Cells

Biology - Support and Movement in Animals

Biology - Reproduction

Biology - Recombinant DNA and Biotechnology

Biology - Protista

Biology - Principles of Evolution

Company

Explore

Study Tools