Life & Classification Notes

Introduction• This class is not just a “science”

class.

• We will study living things.

• The branch of science that studies all the living things on Earth is called Biology.

Introduction continuedIn order to be considered living, an object must have or being able to do the following 6 things:

1. Have highly organized bodies with at least 1 cell

2. Can reproduce

3. Have genetic material

4. Can grow & develop

5. Have a metabolism

6. Can adapt & evolve

Cells• A cell is a collection of molecules that

are able to perform the functions of life

Reproduction

• Reproduction is the process where organisms create new, genetically similar, organisms to themselves

Genetic material

• Genetic material is a molecule that holds the information for making the traits of an organism

Grow & develop

• Growth is the process where living things increase in size

• Development is the process where living things get new body parts or abilities

Metabolism

• Metabolism is the set of chemical reactions in a living thing that either use or release energy

Adapt & Evolve

• Adapting is the process where organisms change their bodies or behavior based on their environment

• Evolution is the change in the genetics and characteristics of a species over time

Living or Non-living Test

• If an object has all 6characteristics, then it is considered an organism– An organism is a living thing– The term “biotic” is used to describe

living things

• If an object is missing 1 or more characteristics, then it is considered non-living– The term “abiotic” is used to describe

non-living things

Example 1 – Rye Grass

Has a cell Can reproduce Has genetic material Grows & develops Has a metabolism Can adapt & evolve

Example 2 – Flu Virus

Has a cell Can reproduce Has genetic material Grows & develops Has a metabolism Can adapt & evolve

Example 3 – Bread Mold

Has a cell Can reproduce Has genetic material Grows & develops Has a metabolism Can adapt & evolve

Example 4 – Water

Has a cell Can reproduce Has genetic material Grows & develops Has a metabolism Can adapt & evolve

Classification• Classification is the process of grouping

living things based on their similarities and differences

• The branch of science that deals with naming and classifying organisms is known as taxonomy

• Taxon (taxa-plural) is the generic term for any of the groups organisms are put into at any of the levels

Classification• Which taxa

an organism is placed into depends on its adaptations

• An adaptation is a body part or behavior that helps an organism live or reproduce

Taxa

• There is a hierarchy (series of levels) of groups (taxa) from broadest to most specific

– The higher a taxon is on the list, the more organisms are in it

– The lower a taxon is on the list, the fewer organisms are in it

– The more taxa two organisms share, the more adaptations they have in common

Level of Classification

Definition

Domain A group kingdoms that have similar characteristics

Kingdom A group of phyla that have similar characteristics

Phylum A group of classes that have similar characteristics

Class A group of orders that have similar characteristics

Order A group of families that have similar characteristics

Family A group of genera that have similar characteristics

Genus A group of species that have similar characteristics

Species

A group of organisms that have many characteristics in common and are able to reproduce with each other and make fertile

offspring

Facts about our system• There are 3 taxa at the domain level

• There are 6 taxa at the kingdom level

• There are around 100 taxa at the phylum level• There are thousands of taxa at the class level• There are tens of thousands of taxa at the order level• There are hundreds of thousands of taxa at the family level• There are a few million taxa at the genus level• There are between 8 & 10 million taxa at the species level

(not including the ones for bacteria and archaea)

Full Classification• Organisms get classified into a taxon (group) at each level of

classification based on their adaptations

• Here’s how humans are classified…

Level of Classification

TaxonCharacteristics members of that

taxon shareOther members of the taxon

Domain Eukarya Cells have a nucleus & other organized parts Algae, fungus, & plants

Kingdom Animalia Bodies have more than one cell & ingest food Clams, starfish, insects, & worms

Phylum Chordata Have a spinal cord Fish, frogs, snakes, & birds

Class Mammalia Have fur, feed milk to babies, control their own body temperature Whales, bats, mice, & elephants

Order Primates 5 fingers/toes per hand/foot, opposable thumbs, large cerebellum (brain) Lemurs, monkeys, & baboons

Family Hominidae 32 teeth, limbs and hands/feet built for terrestrial life Chimps, gorillas, & orangutans

Genus Homo Throat and brain built for complex language

Homo neanderthalensisHomo erectus

Species sapiens Complex logical and abstract thought NONE

Problem with naming organisms #1

People in different countries speak different languages so their names for organisms are all different

Could lead to confusion for

scientists trying to share

information

Solution to naming problem #1

Scientific names for organisms are all in Latin

It’s fair because

Latin is not spoken

anywhere as a first

language

Problem with naming organisms #2

• The animal in the picture below is called all of the following names in the US:– cougar, – mountain lion, – puma, – Nittany lion, – Florida panther– catamount

• Different regions within the same country give the same organism different names.

Solution to naming problem #2

• The animal in the picture below has the scientific name:

Puma concolor

• Scientific names are unique to the organism.• All organisms have 1 name & names are not

used more than once

Problem with naming organisms #3

• Some common names don’t accurately describe what the organism actually is

• Starfish, silverfish & jellyfish are not fish.

Solution to naming problem #3

• Scientific names are usually descriptions of the characteristics of the organism

• Felis = cat • silvestris = woodlands

• Felis silvestris = cat of the woodlands

Some people don’t follow the rules

• The scientist who discovers and describes a new organism gets to name it.

– Some are named after themselves

– Some are named after famous people

– Some are named as a joke

Binomial Nomenclature• Binomial nomenclature gives every organism a

standard, 2-word, scientific name

• Rules for writing a scientific name:– First word is the genus name– Second word is the species name– First letter of the genus gets capitalized– First letter of the species is lower case– Whole name gets italicized when it is typed

(or underlined when it is handwritten)

• Example for humans:

Identification and Classification

• There are 2 types of tools that can help scientists identify and classify organisms:– Dichotomous keys

(also called taxonomic keys)– Field Guides

• They both have benefits and problems

Dichotomous (taxonomic) Key

• Characteristics given in pairs– Organism will either have one characteristic or the

other

• Read both characteristics and either go to another set of characteristics OR identify the organism

• GOOD = organized and can be used forward and backwards

• BAD = can get pretty technical (need to know a lot about the organism’s characteristics)

Example Dichotomous Key

• 1a Tentacles present – Go to 2• 1b Tentacles absent – Go to 6

• 2a Eight Tentacles – Octopus• 2b More than 8 tentacles – Go to 3

• 3a Tentacles hang down – Go to 4• 3b Tentacles upright – Sea Anemone

• 4a Balloon-shaped body – Jellyfish• 4b Body NOT balloon-shaped – Go to 5

Field Guide

• Book of pictures of different organisms

• Match the characteristics of the organism you are trying to identify to the characteristics of the organisms in the pictures

• GOOD = don’t have to know anything other than what the organism looks like

• BAD = takes a long time and easy to miss small differences between organisms

Example Field Guide