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 MENDEL'S LAW OF SEGREGATION - ANSWERSDuring meiosis, the factors that control each trait separate, and only one factor from each pair is/are passed to the offspring HETEROZYGOUS - ANSWERSwhen there are 2 different alleles for a trait (Rr) HOMOZYGOUS - ANSWERSwhen there are two identical alleles for a trait (RR or rr) GENOTYPE - ANSWERScombination of genes in an organism (allele combinations) PHENOTYPE - ANSWERSoutward appearance of an organism (physical appearance)• MITOSIS - ANSWERScell division where 2 identical cells are produced (2n → 2n) MEIOSIS - ANSWERScell division where one cell produces 4 haploid cells (2n → n) NOTE: this process ensures that the same diploid number as its parents after fertilization INCOMPLETE DOMINANCE - ANSWERSinheritance pattern where two dominant alleles produce a brand new trait when they are expressed together CO-DOMINANCE - ANSWERSinheritance pattern where two dominant alleles exist and are expressed together at the same time AUTOSOMAL CHROMOSOMES - ANSWERS22 pairs of chromosomes (excluding the sex chromosomes) → somatic cells SEX CHROMOSOMES - ANSWERS23rd pair of chromosomes in humans → determines sex of individual (XX - female, XY - male) DNA - ANSWERSdouble stranded, bases include: A,T,C,G and the sugar is deoxyribose RNA - ANSWERSsingle stranded, bases include: A,U,C,G and the sugar is ribose EXONS - ANSWERSpart of the DNA that actually codes for proteins primary structure INTRONS - ANSWERSpart of the DNA that does not code for proteins (removed during RNA splicing) CHROMOSOMAL MUTATION - ANSWERSorganism receives more or fewer chromosomes than normal GENE MUTATION - ANSWERSchange that affects a gene on a chromosome