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Grade 12 Biology Exam Questions with Correct Answers.
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CLONES - ANSWERSgenetically identical organisms derived from a single genetic source POLYGENIC TRAITS - ANSWERStraits such as skin color, height which are controlled by many (poly) genes ASEXUAL REPRODUCTION - ANSWERSmode of reproduction where offspring arise from a single parent and inherits the genes of that parent only (2n → 2n) TELOMERES - ANSWERSthe protective caps at the end of chromosomes SEX-LINKED TRAITS - ANSWERStraits that are carried on the X chromosome GAMETES - ANSWERSreproductive cells (i.e. egg and sperm) formed during meiosis (2n → n) GENES - ANSWERScontrols the traits in an organism CARRIERS - ANSWERSthey can pass a gene for a recessive disorder; they are heterozygous for a recessive disorder; they have one dominant allele PYRIMIDINES - ANSWERSnitrogen bases in DNA; include thymine and cytosine ALLELES - ANSWERSan alternative form of a single gene passed from generation to generation ZYGOTE - ANSWERSpart of sexual reproduction; result of the union of egg and sperm (2n) PURINES - ANSWERSnitrogen bases in DNA; include adenine and guanine CROSS POLLINATION - ANSWERSprocess Mendel used to pollinate flowers of short plants with pollen from tall plants (when pollen is delivered to a flower from a different plant)
FERTILIZATION - ANSWERSthe process by which haploid gametes combine → result is the formation of a zygote CROSSING OVER - ANSWERSexchange of genetic material between homologous chromosomes → results in genetic recombination (occurs in meiosis during prophase I) DIHYBRID - ANSWERSindividual differing in two traits (i.e. BbEe) MUTAGEN - ANSWERSphysical/chemical agent that can change genetic material (i.e. asbestos, UV light from the sun) GEL ELECTROPHORESIS - ANSWERSan electric current is used to separate DNA fragments according to the size of the fragments HOMOLOGOUS CHROMOSOMES - ANSWERSa pair of chromosomes of the same kind (i.e. sex chromosomes) SOMATIC CELLS - ANSWERSbody cells; contain 46 chromosomes (2n - diploid) RECOMBINANT DNA - ANSWERSmade by inserting a segment of DNA from one organism into a chromosome of another SEXUAL REPRODUCTION - ANSWERSwhen genetic material of two organisms combine (egg and sperm) to create a new organism; process that starts with meiosis that ensures that organisms will have the same diploid number of chromosomes as its parents when fertilization is successful; sometimes referred to as reduction division MULTIPLE ALLELES - ANSWERSseries of 3 or more alleles that can code for a trait (i.e. human blood groups) GENETICS - ANSWERSstudy of how traits are inherited through the interactions of alleles GENE THERAPY - ANSWERStreating genetic disorders by inserting normal alleles into cells THEORY - ANSWERSseries of statements that can explain multiple hypotheses; provides explanations and predictions that can be tested HAPLOID - ANSWERScell with one of each kind of chromosome (sex cells) → n DIPLOID - ANSWERStwo of each kind of chromosome (somatic cells ) → 2n• MENDEL'S LAW OF INDEPENDENT ASSORTMENT - ANSWERSIn meiosis, the way in which a chromosome pair separates does not affect the way other pairs separate
NONDISJUNCTION - ANSWERScell division in which sister chromatids fail to separate properly and the presence of an extra chromosome results (i.e. Downs syndrome - extra chromosome #21; Edwards syndrome - extra chromosome #18) MONOSOMY - ANSWERShaving only one of a particular type of chromosome instead of the normal 2 (i.e. Turner syndrome - X_) TRISOMY - ANSWERSchromosomal disorder characterized by an additional chromosome (i.e. Klinefelter syndrome - XXY) FUNCTION OF DNA LIGASE - ANSWERSa sealing enzyme PROMOTER - ANSWERSbinds with RNA polymerase to initiate transcription MET-TRNA - ANSWERScalled the initiation complex and is the start of polypeptide assembly RNA SPLICING - ANSWERSwhen introns from the primary transcript and the final "processed" mRNA is produced mRNA (messenger RNA) - ANSWERScarries genetic information from DNA in the nucleus to direct protein synthesis in the cytoplasm tRNA (transfer RNA) - ANSWERStransports amino acids to the ribosome rRNA (ribosomal RNA) - ANSWERSassociates with protein to form the ribosome NONSENSE - ANSWERSmay cause a premature termination of the mRNA because of the substitution, deletion, or addition or nucleotides that code for a "stop" codon MISSENSE - ANSWERSsubstitution of nucleotides that alters only one amino acid sequence (little or no effect on the polypeptide formation) SILENT MUTATION - ANSWERSsubstitution of a nucleotide that codes for the same amino acid → no change in the formation of the polypeptide. TRANSLOCATION - ANSWERSone chromosome breaks off & is added to a different chromosome INVERSION - ANSWERSchromosome breaks off & is reinserted ADDITION - ANSWERSduplication of genes on the same chromosome (also called addition) DELETION - ANSWERSpart of a chromosome is left out
FRAMESHIFT MUTATION - ANSWERSsingle base is added/deleted. One of the most severe types ofmutations POINT MUTATION - ANSWERSchange in a single base pair of DNA EVOLUTION - ANSWERSchanges over many generations FITNESS - ANSWERSis a measure of the contribution of a genotype to the gene pool of the next generation MICROEVOLUTION - ANSWERSchanges in gene frequencies within a population GENETIC DRIFT - ANSWERSa random change in the frequency of alleles in a population FOSSILS - ANSWERSpreserved remains of organisms; can show speciation, successive changes in structures, and extinction of organisms ADAPTATION - ANSWERShelpful variations of species that provides improved functions in populations SPECIES - ANSWERSorganisms that share similar characteristics and can reproduce among themselves to produce a fertile offspring; usually a Latin name REPRODUCTIVE ISOLATION - ANSWERSinability of a species to breed successfully (geographical, behavioural, physiological, genetic barriers) → usually leads to speciation BINOMIAL NOMENCLATURE - ANSWERSdeveloped by Carolus Linnaeus → two word naming system (genus=1st word, species=2nd word) MACROEVOLUTION - ANSWERSchange in the look of a species over time (phenotype) CLASSIFICATION - ANSWERSgrouping of objects or information based on similarities SPECIATION - ANSWERSevolution that results in a new biological species PROKARYOTE - ANSWERSunicellular organism that lacks a nucleus EXTREMOPHILE - ANSWERSform of archaebacterial; can live in extreme environments ENDOSYMBIONT THEORY - ANSWERStheory that suggests the important relationship between ancestral eukaryotic and prokaryotic cells
CONVERGENT EVOLUTION - ANSWERSevolution in which distantly related organisms evolve (i.e. many forms of aquatic animals look alike even though they had diverse ancestors) POSTZYGOTIC ISOLATION - ANSWERSoccurring after the formation of a zygote (i.e. sterile hybrid offspring) PREZYGOTIC ISOLATION - ANSWERSoccurs before the formation of a zygote (i.e. prevention of gamete fusion, temporal isolation, geographical isolation) BEHAVIOURAL ISOLATING MECHANISM - ANSWERSi.e different mating calls TEMPORAL ISOLATING MECHANISM - ANSWERSi.e. two species of wild lettuce grow in the same areas, but one flowers in the early spring and the other flowers in the summer GRADUALISM - ANSWERSmodel of evolution that states that evolution occurs as a slow process PUNCTUATED EQUILIBRIUM - ANSWERSmodel of evolution that states that evolution occurs rapidly ANGIOSPERMS - ANSWERSflowering plants GYMNOSPERMS - ANSWERSreferred to as "naked-seed" plants VESTIGIAL ORGAN - ANSWERSreduced form of a functional structure that indicates shared ancestry (i.e. appendix in humans) MIGRATION - ANSWERSthe movement of genes into and out of a gene pool (most likely to contribute to gene flow between populations) STABILIZING SELECTION - ANSWERSthe average individuals of a population are favored. i.e. Human babies born with below-normal and above-normal weights have a lower chances of survival than babies born with average weights (birth weights don't vary much in human populations) DIRECTIONAL SELECTION - ANSWERSselection that favors one extreme form of a trait in a population. i.e. Dark colored peppered moths favored on the bark of oak trees after industrial pollution DISRUPTIVE SELECTION - ANSWERSfavors both extreme forms of a trait. i.e. A plant with three varying heights have their own pollinators - when the pollinator that prefers the plant of medium height leaves an area, medium height plants would be selected against and their populations would decline
OVER-EXPLOITATION - ANSWERSthe excessive use of species that have economic value (i.e. Bison - hunted for meat and hide that could be sold commercially - hunted for sport to the brink of extinction) EDGE EFFECTS - ANSWERSconditions near the boundary between two habitats SUSTAINABLE USE - ANSWERSusing resources at a rate in which they can be replaced ECOLOGICAL SUCCESSION - ANSWERSThe change in one ecosystem that happens when one community replaces another as a result of changing abiotic and biotic factors BIOTIC - ANSWERSliving factors (i.e. plants, animals) PUBLIC EDUCATION - ANSWERSmaking all members of society aware of possible impacts of their actions and decisions BIOREMEDIATION - ANSWERSaddition of living organisms (natural predators) to a degraded ecosystem ABIOTIC - ANSWERSnon-living factors (i.e. sunlight, water) RENEWABLE RESOURCE - ANSWERSresources that can regenerate (i.e. solar energy, wind) QUADRANTS - ANSWERScan be used in small areas of habitat (typically 1 square meter), selected at random to act as samples for assessing the distribution of plants and animals KEYSTONE SPECIES - ANSWERSwhen one species plays a key role in an ecosystem NON-RENEWABLE RESOURCE - ANSWERSresources that can't be replaced by natural processes (i.e. fossil fuels, coal, oil, natural gas) BIODIVERSITY - ANSWERSa variety of species in an ecosystem GENETIC DIVERSITY - ANSWERSthe variety of genes or inheritable characteristics that are present in a population (i.e. different color of beetles in a given area) SPECIES DIVERSITY - ANSWERSthe number of different species and the relative abundance of each species in a biological community ECOSYSTEM DIVERSITY - ANSWERSthe variety of ecosystems that are present in the biosphere (factors such as populations and abiotic factors can affect the diversity) EDGE EFFECTS - ANSWERScaused by Fragmentation of habitat
INTERPHASE - ANSWERScells grows, DNA synthesized & replicated, cell prepares for division PROPHASE - ANSWERSchromatin coils to form visible chromosomes METAPHASE - ANSWERSchromosomes move to the equator ANAPHASE - ANSWERScentromeres split and sister chromatids are pulled apart to opposite poles of the cell TELOPHASE - ANSWERStwo distinct daughter cells are formed → the cells separate as the cell cycle proceeds into the next interphase DNA REPLICATION - ANSWERSoccurs once in meiosis (meiosis is a reduction division so replication of chromosomes must occur once) MUTATION - ANSWERSpermanent change in DNA sequence (can occur in somatic cells or gametes); most likely the ultimate source of genetic variability. Might have no effect on an organism, may be harmful to an organism, may be beneficial to an organism GENETIC CODE - ANSWERS•Composed of mRNA base triplets called codons •There are 64 different codons - each codes for the addition of amino acids to a growing polypeptide chain during the process of translation •The genetic code is degenerate (more than one codon can code for a particular amino acid) •AUG will always code for a "start" codon and begins the assembly of the polypeptide •Nonsense codons code for a "stop" codon that ends the process of translation RIBOSOME STRUCTURE - ANSWERS•Composed of a large subunit and small subunit •The mRNA binding site is on the small subunit •There are three tRNA binding sites: A site, P site, and E site •Site where polypeptide chain is created and released PCR (Polymerase Chain Reaction) - ANSWERSfunction is to copy gene sequences (amplify DNA) STEPS:
HARDY WEINBERG CONDITIONS - ANSWERS•Large population •No immigration or emigration (migration= movement in an out) •No mutation in the gene of interest •No natural selection occurs (individuals reproduce at equal rates) •Mating is random HARDY WEINBERG FORMULA - ANSWERSp^2 (homozygous dominant individuals) +2pq (heterozygous dominant individuals)+ q^2 (homozygous recessive individuals)=1(total population) CLASSIFOCATION SYSTEM - ANSWERSKingdom (least specific - broadest category) Phylum Class Order Family Genus Species (most specific - smallest category) DOMAIN - ANSWERScreated because of great differences among bacteria EUBACTERIA VS ARCHAEBACTERIA - ANSWERSEubacteria have peptidoglycan in their cell walls BACTERIA SHAPES - ANSWERS•Bacilli - rod •Cocci - spherical •Spirochetes - spiral BINARY FISSION - ANSWERS•Asexual •Steps:
•CLOTHING: cotton, silk, and wool and dyes from plants and animals (i.e. wool from sheep) •MEDICINES: mostly from plants and bacteria, but also fungi, and animal (insect) toxins (i.e. Asprin from Willow trees) •BUILDING PRODUCTS: lumber and finishing products from plants (i.e. pine, cedar, maple - build homes, fences, hardwood floors, etc.) •AIR QUALITY MAINTENANCE: mostly plants taking in CO2 and releasing O2 (i.e. process of photosynthesis) •WASTE RECYCLING: by decomposers - mostly fungi and bacteria - i.e. Bacteria and other microbes are useful in breaking down the garbage in our landfills MARK AND RECAPTURE - ANSWERSM/N=R/C: M = marked initially R = Marked recaptures C = Total in second sample N = Total population size CORRIDORS BETWEEN HABITATS - ANSWERS•ADVANTAGES - creates a larger piece of land that can sustain greater biodiversity •DISADVANTAGE - diseases can pass from one area to another Eubacteria - ANSWERSProkaryotic (Lack a nucleus), Autotrophic and heterotrophic, Asexual, Unicellular, cell wall made of Peptidoglycan Protists - ANSWERSEukaryotic (Nucleus), Autotrophic and heterotrophic, asexual/sexual, Uni/multicellular, No cell wall Fungi - ANSWERSEukaryotic (Nucleus), Heterotrophic (Decomposers), Asexual and Sexual, Uni/multicellular, cell wall made of Chitin Plantae - ANSWERSEukaryotic (Nucleus), Autotrophic, Asexual and Sexual(Alternation of Generations), Multicellular, cell wall made of Cellulose Animalia - ANSWERSEukaryotic (Nucleus), Heterotrophic, Asecual and Sexual, Multicellular, No cell wall SEX LINKED (PEDIGREE) - ANSWERStrait that affects more males then females AUTSOMAL (PEDIGREE) - ANSWERStrait that affects and equal amount of females as males, or more females than males RECESSIVE (PEDIGREE) - ANSWERStrait that skips a generation DOMINANT (PEDIGREE) - ANSWERStrait that appears in every generation SHAPES (PEDIGREE) - ANSWERS