Download Grade 12 Biology Exam Questions with Correct Answers. and more Exams Nursing in PDF only on Docsity!
Grade 12 Biology Exam Questions
with Correct Answers
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:
- DENATURATION - (94°C) DNA separates
- ANNEALING - (54°C) Primers bind to single DNA strands
- EXTENSION - (72°C) DNA polymerase (Taq polymerase) adds bases to the primer segments to build up complementary strands of DNA DARWINS VOYAGE - ANSWERSSpent 5 years sailing on the H.M.S Beagle - observations were that the species of organisms on the Galapagos islands differed from those organisms on the mainland. Published "On the Origin of Species by Means of Natural Selection"
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:
- DNA replicates
- Cell elongates
- Divides into 2 genetically identical cells •allows for lots of bacteria, little genetic diversity (except for any random mutations that may occur) CYANOBACTERIA - ANSWERSIn the group Eubacteria MAIN GROUPS OF PROTISTS - ANSWERS•Animal-like (amoeba, paramecium) •Plant-like (algae) •Fungus-like (watermolds - feed on decaying matter) PSEUDOPODS - ANSWERShow an amoeba obtains food CONTACTILE VACUOLE - ANSWERShow a paramecium gets rid of excess water
•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
NORMAL KARYOTYPE - ANSWERS
MONOSOMY KARYOTYPE - ANSWERS
TRISOMY KARYOTYPE - ANSWERS
