Choi 1 Wendy Choi Mr. Cook Ib Biology (period 3)

Choi 1 Wendy Choi Mr. Cook IB Biology (Period 3) 20 Oct 2008 Biology Syllabus 5.5.1- 5.5.5, D.5.1-D.5.10

5.5.1 Outline the binomial system of nomenclature. In Biology, we use binomial nomenclature to refer to an organism o Genus, then a species name o Genus – First letter capitalized o Species Name – First letter lower-case  Species names usually italicized o Examples: o Human beings are Homo sapiens o A Type of gray wolf = Canis lupus o Generally printed in a typeface (font) different from that used in the normal text o Handwritten— underlined individually; ex: Homo sapiens

5.5.2 List seven levels in the hierarchy of taxa— kingdom, phylum, class, order, family, genus, and species— using two examples for each level. •

Taxa- name assigned to an organism or a group of organisms o Kingdom – Newer: Plantae (green and red algae, and plants), Opisthokonts (amoebas, fungi, and animals), Excavata (free-living and parasitic protists)  6 in US: Animalia, Plantae, Fungi, Protista, Archaea, and Eubacteria  5 in UK and Australia textbooks: Animalia, Plantae, Fungi, Protista, and Prokaryota or Monera o Phylum - equivalent to the botanical term division  Animal Phyla •

Annelida – segmented worms, earthworms, leeches

Choi 2 •

Mollusca – soft bodies, not segmented o Snails, squid, scallops, mussels, clams, octopus

•

Anthropoda – Jointed Appendages o Exoskeleton – mostly insects o Includes the class crustae

 Plant Phyla •

Bryophytes – the mosses, very small, no vascular tissue (heartless)

• Filicinophyta – ferns; seedless, yes vascular tissues; brown spots make spores to reproduce ferns o Class  Mammalia: aka mammlas; vertebrate animals with the presence of sweat glands  Subclass Prototheria (egg-laying mammals) o Order  Primates – humans  Magnoliales – cucumber tree  Diptera – fruit fly o Family  Hominidae - humans  Drosophilidae – fruit fly  Magnoliaceae – cucumber tree o Genus  Homo – humans  Drosophila – fruit fly  Magnolia – cucumber tree o Species  sapiens – humans  melanogaster – fruit fly  acuminate – Cucumber Tree

Choi 3 5.5.3 Distinguish between the following phyla of plants, using simple external recognition features: bryophyte, filicinophyta, coniferophyta, and angiospermatophyta.

Plant Phyla

vascular tissue?

Seeds?

Flowers ?

Reproduce by?

info/ Specialty

Bryophytes

No

No

No

Via Spores

mosses, small, heartless

Filicinophyta

Yes, Complex

No

No

Brown Spots, spores like mosses

ferns; prefers dim environment with high humidity/ moisture

Coniferophyta

Yes, in bundles

Yes

No

Pollen or Seed

Largest + Oldest plants in this category

Angiospermophyta

Yes, in Bundles

Yes

Yes

By Seeds

250,0000+ species identified in this group

5.5.4 Distinguish between the following phyla of animals, using simple external recognition features: porifera, cnidaria, platyhelminthes, annelid, mollusca, and arthropoda.

Porifera – Sponges; Multicellular body with loose collection of cells; porous, canals & chambers for water passage; aquatic, mostly marine, either radial symmetry/ none; epidermis of flat pinocytes; interior surfaces lined with choanocytes creating water currents; area between gelatinous protein matrix called mesoglea; Skeletal structure of collagen and calcareous or siliceous spicules Cnidaria – two cellular layers, an outer epidermis and an inner gastrodermis; thin cell layers and the fragile animals; aquatic, mainly marine; symmetrical radially; one opening that serves as a mouth and anus; Special stinging cell organelles called nematocysts; No excretory or respiratory systems; No coelomic cavity. Platyhelminthes -- vermiform (wormlike shape); have third layer of cells (the mesoderm) instead of just the epidermis and gastrodermis as in cnidarians; bilateral symmetry; clustering of sensory structures and clumps of nerves (ganglia or "brains") in the head region; body cavities more complex through addition of specialized internal organs; fluid in the body cavity; an acoelomate body plan. Annelid – Body metamerically segmented; symmetry bilateral; outer circular and inner longitudinal muscle layers; outer transparent moist cuticle secreted by epithelium; Coelom well developed; Blood system closed and segmentally arranged; Digestive system complete and not metamerically arranged; respiratory gas exchange through skin, gills or parapodia; Excretory system typically a pair of nephridia for each metamere Mollusca – Body bilaterally symmetrical; unsegmented; definite head; ventral body wall specialized as muscular foot for locomotion; Dorsal body wall forms the mantle enclosing mantle; Surface epithelium usually ciliated, bearing mucous glands and sensory nerve endings; Coelom mainly limited to area around heart; Complex digestive system; rasping organ (radula) usually present; Open circulatory system of heart, blood vessels and sinuses; Gaseous exchange by gills, lung, mantle or body surface

Choi 4 Arthropoda – Bilateral symmetry; metameric body split into tagmata; Appendages jointed; Complex muscular system, with exoskeleton for attachment; Coelom reduced; most of body cavity consisting of haemocoel filled with blood; Open circulatory system, with dorsal heart, arteries and haemocoel.

5.5.5 Apply and Design a key for a group of up to eight organisms.

Choices: Human (Homo sapiens), Dog (Canis Lupus familiaris), Cat (Felis catus), Snail (Cyphoma gibbosum), Turtle (Agrionemys horsfieldii), Pine Tree (genus Pinus), Coffee Bean (Araecerus Schonherr), Green Bean (Phaseolus vulgaris) 1. The organism has an outer shell The organism has no shell 2. The organism can move The organism cannot move 3. The organism has four legs The organism has no legs 4. The organism is round The organism is rod-like 5. The organism has roots The organism has legs 6. The organism has two legs The organism has four legs 7. The organism has claws and whiskers The organism has no claws or whiskers

Go to # 2 Go to # 5 Go to # 3 Go to # 4 Agrionemys horsfieldii Cyphoma gibbosum Araecerus Schonherr Phaseolus vulgaris genus Pinus Go to #6 Homo Sapiens Go to #7 Felis Catus Canis Lupus familaris

Application: for example, if you see the following organism: 1. The organism has an outer shell --> #2 2. The organism can move --> #3 3. The organism has four legs --> Agrionemys horsfieldii

…Etc.

Choi 5

D.5.1 Outline the value of classifying living things. We develop systems to classify living things by grouping them together from external similarities to allow easy access for global communication on a particular species, keeping track of a variety that would be difficult to identify otherwise. It allows for universal communication of different species

D.5.2 Explain the biochemical evidence provided by the universality of DNA and protein structures for the common ancestry of living things. A. Universality of genetic code subsidizes the theory of evolution B. Similar chemistry and structure of chromosomes in eukaryotes 1. Analogous – similar use, different structure, different evolutionary origin 2. Homologous – similar structure, different usage, same evolutionary origin C. Chlorophyll is the same basic molecule in all photosynthetic organisms D. Cytochrome C is respiratory enzyme common to all eukaryotic organisms 1. Consists of a central ring structure with an iron atom in the center, and a protein chain about 100 amino acids long 2. The more closely related organisms are, the more similar their amino acids are 3. Comparisons of human and other organism's cytochrome 4. Cytochrome C may be used to construct a "tree of life" E. Enzymes - similar or identical enzymes are common to large groups of animals 1. trypsin - protein splitting enzyme - many animals from protozoans to mammals 2. amylase - starch-splitting enzyme found in everything from sponges to humans F. Nucleic Acid comparisons (DNA fingerprinting) - the more closely related two organisms are, the more similar is their DNA, e.g. identical twins 1. DNA fingerprinting a. now the preferred way to study the evolution of life b. it documents changes in genes, i.e. nucleotide sequences G. Orchid classification 1. Comparison of mitochondrial DNA sequences in primates - chimpanzees are the most closely related to humans, lemurs are the first primates

Choi 6 D.5.3 Explain how variations in specific molecules can indicate phylogeny. Phylogeny is the history of organismal lineages as they change through time. Proteins are genetically determined, so a close match in the amino acid sequence of two proteins from different species will indicate the genes in those proteins evolved from a common gene present in a shared ancestor.

D.5.4 Discuss how biochemical variations can be used as an evolutionary clock. Mutations are random changes in gene structure that occur at a roughly predictable rate. Therefore: 

more differences between the amino acid sequence of a common protein = further in the past two species had a common ancestor.



Example: hemoglobin of gorillas differs by one amino acid from human hemoglobin whereas elephant hemoglobin differs from human hemoglobin by 26 amino acids. Therefore elephants separated as a species from a common ancestor with humans longer ago then did gorillas. Information like this can help to group organisms in trees of descent and suggest how long ago they had a common gene pool.



Moves at a constant and invariable rate, so interpretation of data here must be very carefully done, with the uncertainties made clear



Check a specific protein and know that mutations occur at a certain rate. o

Count how many mutations there are in that specific protein and then calculate how many years the organism has evolved.

o

For example, if there are 10 mutations and mutations occur every 5,000 years in this protein - 10 times 5,000 = 50,000 years.

D.5.5 Define clade and cladistics. A clade is a taxonomic group which includes a single common ancestor and all the descendants of that ancestor; whereas cladistics is a the hierarchical classification of species which focuses on evolutionary ancestry (or classification according to clade). This can be shown with a tree-like diagram called the phylogenic tree.

D.5.6 Distinguish, with examples, between analogous and homologous characteristics. Similar structures due to the same evolutionary origin are known to be homologous, and structures that evolve separately to perform a similar function are known to be analogous. Analogous structures are also called convergent strutures which means that they serve the same function in different species but they evolved independently rather than from the same embrological constructs. Examples are wings of butterfles, bats, and birds. Homologous structures are shared by related species because they have been

Choi 7 inherited from the common ancestor. This can be demonstrated by bones of a human arm and the bones in a chimpanzee arm.

D.5.7 Outline the methods used to construct cladograms and the conclusions that can be drawn from them. 1. Begin with a list of taxa that can fit into the cladogram (the ingroup) and their derived characters 2. Choose an outgroup; a taxa that shares a primitive character with the ingroup, but exhibits none of the derived characters 3. Fill in a character table that will be used to make the cladogram. a. The taxon with the least number of derived characters should be the first row. b. The taxon with the greatest number of derived characters should be the last row. c. The character that is seen in the greatest number of taxa should be the first column. d. The character that is exhibited in the least number of taxa should be the last column. e. Use ones and zeroes to represent presence (1) or absence (0) of specific characters in specific species 4. Start with the first character (first column). The outgroup is the only taxon that doesn't exhibit the first character. Separate it from the other taxa on the cladogram. 5. Remember, the outgroup shares a common ancestor with the ingroup. Also, each split in the cladogram marks a separate evolutionary event.

D.5.8 Construct a simple cladogram.

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D.5.9 Analyze cladograms in terms of phylogenic relationships. For the cladograms above, one can see that whatever trait is shown, it is gained only once by each species. However these species all have a common ancestor and share only one trait.

D.5.10 Discuss the relationship between cladograms and the classification of living things. To classify living things based on ancestral relationships, cladograms pay an important role in evolutionary origin in order for scientists to categorize each organism into its kingdom, phylum, class, order, family, genus, and species.