grade 11 biology

biodiversity unit

how many species are there to be estimated on Earth?

over 10 million

what is an example of the significance of biodiversity?

fishing provides livelihood and food security for over 200 million people; one in five people depend on seafood as their primary source of protein

what is the main threat for biodiversity?

human activities and environmental changes

what is taxonomy?

the science of classifying organisms

what is a dichotomous key?

a tool used to classify unknown organisms (classification tool)

why is taxonomy so important?

genetics and medical research (if an animal is related to us, then drugs tested on the animal might work similarly); agriculture (a close relative to a crop plant could help improve crop yields by borrowing genes); environment (key for ecologists who need to know the identity of species in an ecosystem, so predictions can be made about the ecosystem if environmental changes occur)

what is an easy way to remember the order of classification?

Dumb King Philip Came Over From German Soil (DKPCOFGS)

what is the main problem of using common names?

the potential for confusion regarding which species is being discussed, since they sometimes give the wrong impression of an organism (ladybugs are actually beatles); usually aren’t the same from one language to anther; may describe several different organisms (dozens of insect species around the world)

who invented binomial nomenclature?

Carl Linnaeus in the mid-1700s; every species has a two-part name; the first word is the genus, and the second is the species

what is a genus?

a relatively small group of closely related species; can be many species in a genus

what is a species within binomial nomenclature?

only used once within a genus

how can ancestral relations be determined using this naming system?

search for animals of the same genus

why does Linnaeus’s system of binomial names help us understand the relationships among species?

based on similarities among species, so the name tells us which species may be related

what are the categories in the classification system?

species; genus; family; order; class; phylum; kingdom

what are the six kingdoms of life?

archaea; bacteria; protista; fungi; plantae; animalia

what are the six levels of classification into which organisms are arranged?

kingdom, phylum, class, order, family, genus, species

what is the kingdom archaea?

the most ancient types of organisms; unicellular; found in harsh environments that are extremely salty and have low oxygen concentrations; found in salt pools, sulphur springs, volcanoes, and in oxygen-free environments

what is the kingdom bacteria?

found everywhere, classification has just begun; prokaryotic and unicellular; some bacteria can cause disease in humans

what is the kingdom protista?

unicellular and eukaryotic; obtain their nutrition via absorption, ingestion, and photosynthesis; evolved from prokaryotic bacteria; not very diverse in nature, contains all the eukaryotes that are not in fungi, plants, or animals

what is the kingdom fungi?

multicellular eukaryotes that build cell walls similar to plants

what is the kingdom plantae?

multicellular, autotrophic organisms that produce their food via photosynthesis; they have cell walls that contain cellulose; examples include molasses, ferns, and seed plants

what is the kingdom animalia?

multicellular, heterotrophic organisms have cell membranes without walls; they can be complex, with their cells organized into tissues, organs, and organ systems; two main divisions of the kingdom are vertebrates and invertebrates

what is a species?

all members of the same species must be able to breed with each other to produce normal, fertile offspring

what is the level of classification above kingdoms?

led by Carl Woese in the 1970s, a cladogram was proposed (a branching diagram) sorting the kingdoms into three domains (bacteria, archaea, eukarya)

what kingdoms are grouped in eukarya?

protista, fungi, plantae, and animalia; believed to have developed from archaea

what are the qualities of bacteria and archaea as domains?

they are the least well-known, mostly because they are all microscopic in size

what are the characteristics of archaea?

the oldest of organisms found on Earth; are unicellular and prokaryotic, lacking a true nucleus; are usually found in areas with extreme conditions (probably because they appeared when Earth was full of threats, like poisonous gases and unbearable heat, in which they still live in these conditions today); membrane lipids with branched hydrocarbons; chromosomes are circular; lacks nuclear envelopes; lacks membrane bound organelles; methionine is the initiator amino acid for protein synthesis; lacks peptidoglycan in the cell wall; growth not inhibited by streptomycin and chloramphenicol; histones are associated with DNA; contains several types of RNA polymerase

what are the characteristics of bacteria?

more widespread than archaea; more complex in structure, and can live in all but the most extreme conditions; found everywhere, including in food and your body; approximately 2% of your body mass is bacteria; chromosomes are circular; lacks nuclear envelopes; lacks membrane bound organelles

what are the qualities of eukarya?

methionine is the initiator amino acid for protein synthesis; lacks peptidoglycan in the cell wall; growth not inhibited by streptomycin and chloramphenicol; histones are associated with DNA; contains several types of RNA polymerase

in what ways are archaea different from bacteria?

archaea are simpler in structure than bacteria; they are found mainly in extreme environments (for example, highly saline or very hot), whereas bacteria are found in less extreme environments

what are bacteria?

extremely small, rangng from 0.2 - 10 microns (a typical eukaryotic cell is about 10 times larger); they are all single-celled; all are prokaryotes; their DNA is not surrounded by a membrane; cell organelles in bacteria are not surrounded by membranes; the DNA of bacteria is made of a single chromosome; all reproduce asexually by binary fission

why are bacteria hard to classify?

many species can exchange genes with one another; one way to classify bacteria is based on whether they can make their own food (autotrophs) or not (heterotrophs)

what are the current methods of classifying bacteria?

using genetic analysis (they have been grouped into 15 phyla); biologists organize bacteria based on attributes that are important to us; classified by shape

what are bacilli (bacillus)?

rod-shaped bacteria

what are cocci (coccus)?

spherical shaped bacteria

what are spirilli (spirillus)?

spiral-shaped bacteria

what are the types of bacteria?

aerobic (those that can or must live in the presence of oxygen); anaerobic (those that can or must live without the presence of oxygen); some can be both, but most are one or the other

what is the structure of bacteria?

cell wall; capsule; cytoplasm; plasmids; flagella; pili; colonies

what is a cell wall?

provides support and protection for the contents of the cell

what is a capsule?

a layer of sticky material outside the cell wall that allows the cell to cling to surfaces

what is a cytoplasm?

a liquid that contains ribosomes, responsible for the formation of proteins and DNA

what are plasmids?

small rings of DNA outside of the chromosomes; plasmids contain far fewer genes than the bacterial chromosomes, but they code for enzymes to break down antibiotics

what are flagella?

rotating tails that allow for some bacteria to move around

what are pili?

short hair-like strands of protein that enable bacteria to stick to a surface or obtain foodh

how do bacteria asexually reproduce?

binary fission; similar to mitosis, but much simpler

how do bacteria sexually reproduce?

in less favorable conditions, some bacteria are able to reproduce sexually, allowing cells with new genetic combinations, and offering a chance that they may be better adapted to changing conditions

what are the three ways bacterial cells can create new genotypes?

transduction, transformation, and conjugation

what is transduction?

bacteriophages (bacteria-attacking viruses) can change the DNA of bacteria by inserting some of their own DNA into the bacterial genome; they may also carry DNA from one bacterium to another

what is transformation?

free pieces of DNA move from a donor cell to a recipient cell; bacteria can “take up” this DNA and incorporate it into their genomes, changing their DNA

what is conjugation?

bacterial cells become linked to one another through a bridge called a pilus; one bacterium transfers all or part of its chromosome to the other across the pilus; it then undergoes binary fission to produce daughter cells with the same genetic makeup

what are some harmful diseases caused by bacteria?

clostridia causes botulism, tetanus, and gangrene; streptococci causes strep throat, scarlet fever, and pneumonia; staphylococci causes boils, food poisoning, and skin infection

how are soil bacteria beneficial?

plants require nitrogen to make proteins, but most can’t absorb it in the pure form; soil bacteria, after eating dead organic matter, put pure nitrogen back into the soil, while others make nitrates which is also absorbable by plants; cyanobacteria are able to take nitrogen from the air and change it into nitrates for plant use; it is essential to the cycling of matter and the functioning of ecosystems; can’t be accomplished without the help of bacteria

how are decay bacteria beneficial?

they help break down biological wastes inside septic tanks and sewage disposal systems; almost all sewage treatment uses decay bacteria at some point in the process

how are bacteria beneficial in the manufacturing of food products?

used in the production of many dairy products such as cheeses, butter, buttermilk, and yogurt; anaerobic bacteria decompose the sugars present in cabbage leaves stored in an air-tight container into lactic acid and ethyl alcohol , giving pickled foods their distinctive flavors; bacteria found in the air can change the ethyl alcohol produced by yeast into vinegar (acetic acid) by using the alcohol as food for metabolism

how are bacteria beneficial for the manufacturing of drugs and industrial products?

bacteria are used to make drugs such as insulin as well as industrial products; bacteria can be used to produce specific proteins; to accomplish this, large containers of specially-chosen bacteria are provided with nutrients and ideal growing conditions, and the products are then collected; they are also used to prepare animal skins for making leather goods, and genetically engineered bacteria are used to break down oil spills

what did Louis Pasteur discover?

majority of diseases were caused by bacteria, but not all diseases could be traced to bacteria

what did Martinus Beijerinck hypothesize?

there must be something smaller than bacteria that causes diseases, calling it a “virus”

what are viruses?

they are so simple that they lack most components of a cell, and thus cannot eat or reproduce unless inside a cell; many biologists consider them mobile genes that live off cells, and they fall somewhere between living and non-living things

what are traits that viruses share with living things?

they possess genetic material that is capable of mutation or genetic recombination; they can adapt to changing environments through replication and mutation within their host cells

what are traits that viruses share with non-living things?

they have no cell organelles. and are unable to produce their own cellular energy or proteins; they must rely on their host for all cellular functions; they can only replicate within living cells; they do not grow; they can be crystallized, which is common for non-living things

what is the structure of viruses?

they can only be viewed with an electron microscope; they are much smaller than the smallest bacterium; they have a chain of nucleic acids that may consist of a single strand of RNA or a double strand of DNA; the amount of genetic information in any virus is very small; most viruses have fewer than 10 genes - far fewer than bacteria

what are some virus structures?

capsids and bacteriophage

what’s a capsid?

consists of viral nucleic acids surrounded by a protein coat called the capsid; made up of several hundred protein molecules packed together in a geometric pattern; some larger viruses have a complex envelope surrounding the capsid, helping the virus recognize and attach to a host cell

what is a bacteriophage?

consists of three main parts (head, sheath, and tail); the head contains the DNA; the sheath is the body of the virus; the tail is where the phage attaches to the cell wall of bacteria, and can be designed to attach specific types of bacteria

how can viruses replicate?

through the lytic cycle and lysogenic cycle

what is the lytic cycle?

the phage attaches itself to the cell by its tail; the phage releases an enzyme that breaks down the cell membrane; the viral nucleic acid is then injected into the cell; the viral nucleic acid takes over, making the host cell’s DNA inactive, and normal cellular metabolism stops, with the host cell being directed to make copies of the viral nucleic acid and proteins; the viral protein and nucleic acid are assembled into new viruses; the host cell then makes an enzyme that digests the cell membrane from the inside, causing the cell to burst open and releasing hundreds of new viruses

what is the lysogenic cycle?

the DNA combines with the host DNA in a way that doesn’t interfere with activity, and so when the host cell copies its own DNA, the viral DNA is also copied; external stimuli can cause the viral DNA to become active, and the host cell will be directed by the viral DNA to manufacture new viruses using the lytic cycle

what are plants, bacteria, and fungi vulnerable to?

changes to biodiversity, such as climate change, since they can’t migrate as fast as animals and insects

what are fungus-like protists?

heterotrophs that absorb nutrients from dead or decaying organic matter; they reproduce by forming spores; all are able to move at some point in their lives

what is the result of fungus-like protista breaking down organic material?

dark, rich topsoil

what is oomycota?

includes water molds, white rust, and downy mildews; most water molds are decomposers that grow as cottony masses; white rust and downy mildews live as parasites of plants

what is slime mold?

occurs all over the world and has over 900 species; appear as “slime”

what are characteristics of protists with flagella?

move by swinging their whip-like structures; called zooflagellates; some feed on protists, others live in the bodies of other organisms; some beneficial, some harmful; the primary component in the marine food chain

what are Giardia lamblia?

flagellated parasite that colonizes and reproduces in the small intestine of humans, causing giardiasis or beaver fever; usually associated with contaminated water supplies

what are protists with pseudopods?

they move by cytoplasmic streaming, creating finger-like projections of cytoplasm called pseudopods; amoebas are an example

what are two amoebas that cause human disease?

naegleria and entamoeba; found in tropics and countries with poor sanitation

what are amoebas?

major consumers of bacteria in soil ecosystems, ensuring nutrient regeneration and continued functioning of the ecosystem

what are protests with cilia?

often called cilates, and move through beating hair-like structures called cilia; can reproduce sexually or asexually; they have a skeleton-like covering called a pellicle, made of polysaccharides; contains one macronucleus and one or more micronuclei (macro for operations, micro for reproduction); they have an oral groove in which food is swept into; only one member can cause disease, which causes massive diarrhea if consuming contaminated water with pig/human waste