Unit 2: BiodiversityChapter 4, 5, 6

p. 100Biology 2201

Classifying Living Things

Scientific knowledge is constantly evolving ( changing ):• new evidence is discovered• laws and theories are tested and possibly restricted, revised or even

replaced• paradigm shifts can occur Why is this happening?• because of the wide variety of living things on Earth

Bio diversity / \ Life Variety

• new species are constantly being discovered • VIDEO on Biodiversity (David Suzuki)

https://www.youtube.com/watch?v=N5ssjM2Fjuc

• How do we distinguish between things that are ‘living’ and those that are ‘non-living’?

• Video: Classifying ‘Living’ vs ‘Non-Living’

https://www.youtube.com/watch?v=1Tlx8xhs888&safety_mode=true&persist_safety_mode=1&safe=active - warning – corny video ☺

How Biologists Describe Living Things: (Objective 1 - page 104)

1. Living things are organized systems made up of one or more cells:

• unicellular ( one cell )• multicellular ( more than one cell )• in multicellular organisms cells can be organized into

tissues, organs and organ systems 2. Living things metabolize matter and energy:• chemical reactions used to digest and use food• release energy to be used by cells• build molecules to help cells work properly

3. Living things interact with their environment and are homeostatic:

• homeostasis ( staying the same )• even though organisms interact with their environment,

they maintain a constant internal environment that is different from their surroundings ( eg. Your body temp. )

4. Living things grow and develop:• unicellular organisms grow and split (reproduce )• multicellular living things grow and develop• ( sperm + egg -> organism )

5. Living things reproduce themselves:• biogenesis (make other living things like themselves) 6. Living things are adapted to their surroundings:• physical features and abilities that make them well-suited

for the way they live in a certain environment• eg. obtain food

– transport nutrients– excrete wastes– move ( those that do move )– reproduce– communicate

Objective 2

• How can all this information about living things be organized in such a way that it can be best understood and used?

• development of ‘scientific classification systems’

• classify? - to put things in groups based on certain characteristics

Using your own classification system – put all of these items into groups – they all have to be grouped ☺

Obj 2 Why classify?• 1.5 million different kinds (species) of organisms have been

identified• maybe 20 million (?) more that are waiting to be discovered• To organize all this information, we have developed

classification systems:• can be as simple as you classifying your CDs• or can be as complicated as trying to classify all the living

organisms on this Earth• early biologists like Aristotle, didn’t have as many organisms

to classify

• Aristotle had only named two kingdoms – plant and animals… why?

• Aristotle classified all organisms into Kingdom Plantae or Kingdom Animalia (These are still part of the classification system used today)

• around the 1850’s, the invention of the microscope led to the discovery of other organisms that were not plants or animals

• (Eg. some organisms moved like animals but were photosynthetic like plants - called euglena)

thus, scientists had to revise their original ideas

• Ernst Haeckel put these ‘new organisms’ into a new Kingdom called Protista

• as more organisms were discovered, Kingdom Fungi and Kingdom Monera were added

• just recently, new discoveries about Kingdom Monera have led Scientists to split this group into Kingdom Bacteria and Kingdom Archaea (more later)

Naming and Classifying Organisms

• biologists need specific details to identify organisms • classification systems allow the accurate identification

of a particular organism • Taxonomy - the science of naming organisms and

assigning them to groups. / \Taxon Taxa

(Singular) (Plural)

https://www.youtube.com/watch?v=F38BmgPcZ_I&safety_mode=true&persist_safety_mode=1&safe=active

• Why do the scientific names have to be ‘so complicated’ like Canis lupus(gray wolf) or Homo sapiens (humans)?

• originally, common names in local languages were used around the 18th century.

• This practise was discontinued and then Latin was used everywhere

• however, these names were very long and descriptive ( Bee example on video! )

• then, a Swedish botanist, named Carolus Linnaeus developed a system for naming plants and animals called

• binomial nomenclature/ \

two names a system for naming things

Bee video

Obj 4 - Naming and Classifying Organisms

• this is still the system we use today • in his system of binomial nomenclature, Linnaeus gave

each organism a two-part scientific name • eg. red maple -> Acer rubrum Or Acer rubrum

/ \genus

specific epithet

|

species name

Naming and Classifying Organisms

• a ‘genus’ name refers to the relatively small group of organisms to which a particular organism belongs

• eg. all maples trees carry the genus name Acer

• ‘specific epithet’ - a Latin description of an important characteristic of the organism

• eg. rubrum is Latin for ‘red’• this system is used by scientists

everywhere• organisms that share important

characteristics, are classified in the same taxon (group)

https://www.youtube.com/watch?v=aJUB4R5j0dI – binomial nomenclature

• the taxa used are as follows: Classification VideoKingdom

Phylum Class Order Family Genus Species

Objective 3 - Naming and Classifying Organisms

https://www.youtube.com/watch?v=KPtAuojPQVQ - good

https://www.youtube.com/watch?v=6jAGOibTMuU&safety_mode=true&persist_safety_mode=1&safe=active - classification rap

https://www.youtube.com/watch?v=dnF_UdPbJZ0 - neon trees remake

• These are in order from the most general taxon (Kingdom) to the most specific taxon (Species)

• Refer to page 109 Table 4.1 - • ‘kingdom’ contains the greatest number of organisms• as you move down to ‘species’, you have narrowed the

number of organisms in the taxon down to one particular species.

• Eg. All animals belong to Kingdom Animalia, BUT, only some of them belong to Phylum Chordata (the rest belong in another phyla) and only some of Phylum Chordata belong to Class Mammalia and so on until you have only one species.

Naming and Classifying Organisms

Obj. 6 Common Names• Why isn’t it practical for scientists to use common

names for organisms ( ie. cat, dog, daisy) when they want to talk to other scientists about organisms?

• when you say ‘cat’, not everyone calls what you think of as a ‘cat’ that particular name ( ie. French -chat )

• also, there are many different species of ‘cats’ (ie. lions, tigers, house cat) - which one are you referring to?

• also, within the same language people may use different names for the same organism (ie. puma, cougar or mountain lion are all the same animal)

• also, common names can be misleading - look at Figure 4.7 on page 112

• this confusion would make it very difficult for scientists to communicate with one another

Objective 5 - Dichotomous Keys• (Also called Identification Keys or Taxonomic Keys) • people use these keys as to name organisms

already identified by taxonomists• such keys move from general to specific

descriptions• the keys usually consists of a series of paired

statements that describe alternative (opposite) characteristics of an organism

• these paired statements usually deal with the presence or absence of some characteristic or structure that is easily seen

Dichotomous Keys

• as each pair of statements gets more specific, a smaller grouping of organisms is produced until the species is finally identified

• you can also create a dichotomous key of your own to identify organisms (or anything)

• Complete the worksheet – ‘Fun With Fictitious Animals’

• LAB - Creating a Dichotomous Key page 110-111

Obj 7 Viruses - Where do they fit? P. 122

• bacteria and viruses cause many diseases for all kingdoms• bacteria are classified as living but viruses are not• viruses have no cellular structure - no cytoplasm, no organelles, no cell

membrane and they do not carry out respiration or other life processes - therefore, they are not classified in any of the kingdoms

• they consist of strands of DNA surrounded by a protective protein coat called a capsid

• they infect other cells• there are 160 major groups which differ in size and shape ( Fig. 4.20 page

122 )• list the 4 shapes and give an example of each:• viruses do multiply but not on their own• they depend on the metabolism of prokaryotic and eukaryotic cells to

multiply• refer to the Life Cycle of the T4 virus ( Fig.4.21 page 123 )

Lifecycle of a Virus

Obj 8 Problems with categorizing…

Difficulties with Categorizing (Obj 8-9)• problems that can arise when we try to put organisms into groups• scientists must look at all the characteristics of organisms and

decide which group they should be placed in• no classification system is carved in stone• why not?

– newly discovered organisms– new things discovered about organisms that are already known

• classification systems need to be adaptable• as mentioned earlier, there were 5 Kingdoms but recently that was

changed to 6• this happened when new information was discovered about

bacteria that determined they should be put into two separate groups ( more later )

What are some of the things we can look at in different species to

determine if they are closely related?

Modern Classification Techniques• scientists compare characteristics of different species living

today with each other and with extinct species• taxonomy also involves other sciences such as evolution• there are different criteria that scientists can use to classify

organisms and determine evolutionary relationships• they include:

– (i) radioactive dating– (ii) comparative anatomy (structural information )– (iii) comparative embryology– (iv) biochemical information ( DNA / Proteins ) – (v) cellular structure– (vi) behavior

Obj. 10

(i) Radioactive Dating (video first) • Archaeopteryx - an extinct dinosaur that was a cross

between a bird and a reptile, showing that they may have a common ancestor. It was determined to be 150 million years old - how do we know this?

• when we try to determine fossils ages, either relative age or absolute age is used

https://www.youtube.com/watch?v=2Ipa9uhyRoU&feature=related&safety_mode=true&persist_safety_mode=1&safe=active - 5 mins

•relative age - because of the way sedimentary rock forms ( ie. in layers ), the age of the layers can be determined in relation to each other - the oldest layers are laid down first and are found at the bottom. Thus, the younger layers are on top because they were recently added. •the relative age of the fossils

found in these rocks can then be determined.

Radioactive Dating

• NOTE: relative age does not determine the absolute (actual) age of the fossil, only the age of the fossil relative to the layers of sediment it is in.

• absolute age - Pin-points the exact age of a fossil using radioactive dating techniques.

• radioactive isotopes break down into new elements at a known rate called a half-life. (Page 113)

• a half-life is the time it takes for ½ of a radioactive sample to break down.

Tearing paper illustration

Carbon Dating Half - life Useful range

C14 ----------> N14 5730 yrs 60 000 yrs

Sample Problem: If you had a fossil with 25% of C14 left in it and you

know that in the living organism there is 100% C14, you could use the following method to find the absolute age of the fossil:

Radioactive Dating

Number of half lives % of C14 % of N14

0 100 0

1 50 50

2 25 75

•Calculate the number of half-lives needed to reduce the C14 in the living organism to the amount that is left in the fossil (in this case: 2)•Multiply by the half - life (in this case, 5730 years)

to determine the age of the fossil.•5730 * 2 = 11,460. Because only 25% of the

original C14 remains, we know it has been decaying for 11, 460 years

Number of half lives % of C14 % of N14

0 100 0

1 50 50

2 25 75

Radioactive Dating - You try :)

If Carbon 14, which has a half-life of 5730 years has been decaying for 28650 years, how much C14 is left?

28650/5730 = 5 half lives

# of Half lives % of C14 % of N14

0 100 0

1 50 50

2 25 75

3 12.5 87.5

4 6.25 93.75

5 3.125 96.875

ii) Comparative Anatomy - Comparing the anatomy of organisms indicates a common ancestry because of:

• homologous structures - structures having a common ancestry but with different uses in various species.

• Eg. Similar bone structure of the forelimb of a bat, whale, horse and human suggests these different species have a common evolutionary origin . Page 113,114 & 664

• analogous structures - body parts of organisms that do not have a common evolutionary origin but perform similar functions. Eg. insect wings and bird wings are similar in function but not in structure. Page 665

• vestigial organs - small or incomplete organs (or bones) that have no apparent function in one organism but do have a function in another species. This indicates evolutionary origin from a common ancestor. Page 665

Eg. Human ear musclesHuman appendixHip bones in whalesHuman tail boneLeg bones in snakesForelimbs in the flightless ostrich

3 mins -

https://www.youtube.com/watch?v=4dBfWkN4m74

iii) Comparative Embryology

• Organisms with a common ancestor sometimes have embryos that look the same early in their development (eg. gill slits and tail in human embryos indicates humans share common ancestry with birds, reptiles and fish) Page 665

iv) Comparative Biochemistry

• Comparing the molecules of one species with another can indicate a common ancestry. An organism’s DNA determine the proteins that form the body of the organism. Page 115

• human proteins (amino acid sequences) have more in common with chimpanzee proteins than frog proteins & pig or beef.

• can be used to determine which animal would be best to extract insulin to treat human diabetes

v) Cellular Structure (p. 106 -107)

• Studying the structure of cells can give clues to their evolutionary history

• you have studied the two basic types of cells - prokaryotic and eukaryotic (review Fig.4.4 on p. 106)

• the first life forms were prokaryotic (similar in appearance to bacteria) and existed approximately 3.5 billion years ago

• eukaryotes appeared later (approximately 1.5 billion years ago )• multicellular organisms appeared only 700 million years ago

Cell structure cont’d...•prokaryotes which were once classified into one kingdom

(Monera) have been discovered to be very diverse•Bacteria and Archaea, have been seen to be different from

each other (in fact, Archaea and Eukarya are more closely linked), and therefore have been put into different Kingdoms (thus, the 6 Kingdoms instead of 5)•Also, biologists have created a new level of classification,

above Kingdoms, called domains•there are three domains - Domain Bacteria, Domain

Archaea, and Domain Eukarya•( Fig. 4.5, page 107 - Important )

vi) Behavior (p. 706)

• how organisms are adapted in how they respond to their environment is called behavioral adaptations

• eg. include migration, courtship displays, food-collecting behavior

• it is believed that these adaptations have evolved in response to changes in environmental conditions as continents formed and moved millions of years ago

• the favorable adaptations were passed on to the offspring• note: Biofact p.706

Review – possible m.c.Which of the two organisms are most closely related?

A. Deerus octagis & Deerus deafusB. Deerus octagis & Deerus postisC. Deerus magnus & Deerus humpisD. Deerus purplinis & Deerus deafus

https://ww

w.polleveryw

here.com/m

y/polls

Objective 4 – Advantages of Binomial Nomenclature

• Initially species were given a long strong of latin names

• Linneaus – 2 words for each species (simpler)• First – genus; Second – species• No two species have the same name• Latin – universal language used around World

for naming species

Objective 11

• Classification systems improved with modern techniques:

• Discovered that organisms once thought to be closely related were found not to be related and vice versa

• Ex. Echinodermata (sea star) are more closely related to chordates than to any other invert.

Why are Angiosperms considered to be the most diverse (most successful) group of plants?

( page 175 - 181 )• the assistance of animals (eg. bees) and wind in pollination• Has structures that attract animal pollinators - whom the

plants supply with food (ie. flowers - different color and shape flowers attract different types of pollinators)

• the way seeds are protected (eg. inside fruit)• the function of fruit in seed dispersal (eg. animals eat the

fruit, which get passed undigested through the digestive system of the animal and dispersed away from the original plant)

• the presence of specialized tissues in plants to help them survive heat, cold and drought (eg. specialized leaf tissue)

The Six KingdomsWhat are the general characteristics that distinguish the six Kingdoms from each other?

You will use the information on p. 132 - 167 to complete Table 1: Kingdom Worksheet. As you fill in the chart, these are the things you will be looking for:

• cell type - prokaryotic or eukaryotic?• cell wall - present or not?

– If present what is it composed of?• body form

– unicellular (made up of one cell)– multicellular (made up of more than one cell)– colonial (unicellular but live in colonies)

• nutrition - how does the organism obtain its nutrition?– photosynthesis, chemosynthesis, absorption, ingestion, heterotroph, autotroph

• nervous system - present or absent?• reproduction - asexual, sexual or both?• locomotion - able to move or not?• examples for each Kingdom

Each kingdom starts on page…

• Bacteria – p. 132• Archaea – p. 138• Protista – p. 140• Fungi – p. 152• Plants – p. 164• Animals – p. 182