GRADE 12 BIOLOGY EXAM REVIEW QUESTIONS AND ANSWERS 2025
CLONES - (ANSWER)genetically identical organisms derived from a single genetic source
POLYGENIC TRAITS - (ANSWER)traits such as skin color, height which are controlled by many (poly)
genes
ASEXUAL REPRODUCTION - (ANSWER)mode of reproduction where offspring arise from a single parent
and inherits the genes of that parent only (2n → 2n)
TELOMERES - (ANSWER)the protective caps at the end of chromosomes
SEX-LINKED TRAITS - (ANSWER)traits that are carried on the X chromosome
GAMETES - (ANSWER)reproductive cells (i.e. egg and sperm) formed during meiosis (2n → n)
GENES - (ANSWER)controls the traits in an organism
CARRIERS - (ANSWER)they can pass a gene for a recessive disorder; they are heterozygous for a
recessive disorder; they have one dominant allele
PYRIMIDINES - (ANSWER)nitrogen bases in DNA; include thymine and cytosine
ALLELES - (ANSWER)an alternative form of a single gene passed from generation to generation
ZYGOTE - (ANSWER)part of sexual reproduction; result of the union of egg and sperm (2n)
PURINES - (ANSWER)nitrogen bases in DNA; include adenine and guanine
CROSS POLLINATION - (ANSWER)process Mendel used to pollinate flowers of short plants with pollen
from tall plants (when pollen is delivered to a flower from a different plant)
,GRADE 12 BIOLOGY EXAM REVIEW QUESTIONS AND ANSWERS 2025
FERTILIZATION - (ANSWER)the process by which haploid gametes combine → result is the formation of a
zygote
CROSSING OVER - (ANSWER)exchange of genetic material between homologous chromosomes → results
in genetic recombination (occurs in meiosis during prophase I)
DIHYBRID - (ANSWER)individual differing in two traits (i.e. BbEe)
MUTAGEN - (ANSWER)physical/chemical agent that can change genetic material (i.e. asbestos, UV light
from the sun)
GEL ELECTROPHORESIS - (ANSWER)an electric current is used to separate DNA fragments according to
the size of the fragments
HOMOLOGOUS CHROMOSOMES - (ANSWER)a pair of chromosomes of the same kind (i.e. sex
chromosomes)
SOMATIC CELLS - (ANSWER)body cells; contain 46 chromosomes (2n - diploid)
RECOMBINANT DNA - (ANSWER)made by inserting a segment of DNA from one organism into a
chromosome of another
SEXUAL REPRODUCTION - (ANSWER)when 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 - (ANSWER)series of 3 or more alleles that can code for a trait (i.e. human blood
groups)
, GRADE 12 BIOLOGY EXAM REVIEW QUESTIONS AND ANSWERS 2025
GENETICS - (ANSWER)study of how traits are inherited through the interactions of alleles
GENE THERAPY - (ANSWER)treating genetic disorders by inserting normal alleles into cells
THEORY - (ANSWER)series of statements that can explain multiple hypotheses; provides explanations
and predictions that can be tested
HAPLOID - (ANSWER)cell with one of each kind of chromosome (sex cells) → n
DIPLOID - (ANSWER)two of each kind of chromosome (somatic cells ) → 2n•
MENDEL'S LAW OF INDEPENDENT ASSORTMENT - (ANSWER)In meiosis, the way in which a chromosome
pair separates does not affect the way other pairs separate
MENDEL'S LAW OF SEGREGATION - (ANSWER)During meiosis, the factors that control each trait
separate, and only one factor from each pair is/are passed to the offspring
HETEROZYGOUS - (ANSWER)when there are 2 different alleles for a trait (Rr)
HOMOZYGOUS - (ANSWER)when there are two identical alleles for a trait (RR or rr)
GENOTYPE - (ANSWER)combination of genes in an organism (allele combinations)
PHENOTYPE - (ANSWER)outward appearance of an organism (physical appearance)•
MITOSIS - (ANSWER)cell division where 2 identical cells are produced (2n → 2n)
MEIOSIS - (ANSWER)cell division where one cell produces 4 haploid cells (2n → n) NOTE: this process
ensures that the same diploid number as its parents after fertilization
CLONES - (ANSWER)genetically identical organisms derived from a single genetic source
POLYGENIC TRAITS - (ANSWER)traits such as skin color, height which are controlled by many (poly)
genes
ASEXUAL REPRODUCTION - (ANSWER)mode of reproduction where offspring arise from a single parent
and inherits the genes of that parent only (2n → 2n)
TELOMERES - (ANSWER)the protective caps at the end of chromosomes
SEX-LINKED TRAITS - (ANSWER)traits that are carried on the X chromosome
GAMETES - (ANSWER)reproductive cells (i.e. egg and sperm) formed during meiosis (2n → n)
GENES - (ANSWER)controls the traits in an organism
CARRIERS - (ANSWER)they can pass a gene for a recessive disorder; they are heterozygous for a
recessive disorder; they have one dominant allele
PYRIMIDINES - (ANSWER)nitrogen bases in DNA; include thymine and cytosine
ALLELES - (ANSWER)an alternative form of a single gene passed from generation to generation
ZYGOTE - (ANSWER)part of sexual reproduction; result of the union of egg and sperm (2n)
PURINES - (ANSWER)nitrogen bases in DNA; include adenine and guanine
CROSS POLLINATION - (ANSWER)process Mendel used to pollinate flowers of short plants with pollen
from tall plants (when pollen is delivered to a flower from a different plant)
,GRADE 12 BIOLOGY EXAM REVIEW QUESTIONS AND ANSWERS 2025
FERTILIZATION - (ANSWER)the process by which haploid gametes combine → result is the formation of a
zygote
CROSSING OVER - (ANSWER)exchange of genetic material between homologous chromosomes → results
in genetic recombination (occurs in meiosis during prophase I)
DIHYBRID - (ANSWER)individual differing in two traits (i.e. BbEe)
MUTAGEN - (ANSWER)physical/chemical agent that can change genetic material (i.e. asbestos, UV light
from the sun)
GEL ELECTROPHORESIS - (ANSWER)an electric current is used to separate DNA fragments according to
the size of the fragments
HOMOLOGOUS CHROMOSOMES - (ANSWER)a pair of chromosomes of the same kind (i.e. sex
chromosomes)
SOMATIC CELLS - (ANSWER)body cells; contain 46 chromosomes (2n - diploid)
RECOMBINANT DNA - (ANSWER)made by inserting a segment of DNA from one organism into a
chromosome of another
SEXUAL REPRODUCTION - (ANSWER)when 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 - (ANSWER)series of 3 or more alleles that can code for a trait (i.e. human blood
groups)
, GRADE 12 BIOLOGY EXAM REVIEW QUESTIONS AND ANSWERS 2025
GENETICS - (ANSWER)study of how traits are inherited through the interactions of alleles
GENE THERAPY - (ANSWER)treating genetic disorders by inserting normal alleles into cells
THEORY - (ANSWER)series of statements that can explain multiple hypotheses; provides explanations
and predictions that can be tested
HAPLOID - (ANSWER)cell with one of each kind of chromosome (sex cells) → n
DIPLOID - (ANSWER)two of each kind of chromosome (somatic cells ) → 2n•
MENDEL'S LAW OF INDEPENDENT ASSORTMENT - (ANSWER)In meiosis, the way in which a chromosome
pair separates does not affect the way other pairs separate
MENDEL'S LAW OF SEGREGATION - (ANSWER)During meiosis, the factors that control each trait
separate, and only one factor from each pair is/are passed to the offspring
HETEROZYGOUS - (ANSWER)when there are 2 different alleles for a trait (Rr)
HOMOZYGOUS - (ANSWER)when there are two identical alleles for a trait (RR or rr)
GENOTYPE - (ANSWER)combination of genes in an organism (allele combinations)
PHENOTYPE - (ANSWER)outward appearance of an organism (physical appearance)•
MITOSIS - (ANSWER)cell division where 2 identical cells are produced (2n → 2n)
MEIOSIS - (ANSWER)cell division where one cell produces 4 haploid cells (2n → n) NOTE: this process
ensures that the same diploid number as its parents after fertilization
