GLENDOWIE COLLEGE
YEAR 12 BIOLOGY
ACHIEVEMENT STANDARD: BIOLOGY 2.3 – DESCRIBE GENETIC VARIATION
AND CHANGE
UNIT: Genetic Variation
Credits: 3
Assessment: External
SPECIFIC LEARNING OUTCOMES:
(1)
To understand what variation is
 Explain what is meant by variation
 Explain the difference between discrete and continuous variation
 State the sources of variation
 Explain why variation is important
(2)
To understand how meiosis is a source of variation
 Explain the main steps in meiosis
 Explain what synapsis is
 Explain what crossing over is
 Explain what independent assortment is and how it contributes to variation
 Explain what recombination is and how it contributes to variation
 Explain what recombination is and how it contributes to variation
(3)
To understand how mutations are a source of variation
 Explain what a mutation is
 Explain what a mutagen is
 Explain the difference between induced and spontaneous mutations
 Explain the difference, in terms of inheritance, of a somatic and gametic mutation
 Explain the difference between harmful, beneficial and neutral mutations – give an example
of each
 Explain the evolutionary importance of neutral mutations
 Explain why mutations are described as the ultimate source of variation
(4)
To understand the difference between gene and chromosomal mutations
 Explain what a gene mutation is
 Draw diagrams to illustrate substitution, insertion, deletion and addition as gene mutations
 Describe the effects of substitution, insertion, deletion and addition gene mutations
 Explain what chromosomal mutations are
 Explain the difference between chromosomal block and number mutations
 Draw diagrams to illustrate inversion, duplications, translocations and deletions as
chromosomal block mutations
 Explain the difference between aneuploidy and polyploidy
 Give examples of aneuploidy and polyploidy
 Explain why chromosome number mutations occur
(5)
To understand Mendel’s contribution to genetics
 Explain who Mendel is and briefly outline his experiments
 Explain what a locus is
 Describe the relationship between a gene and an allele
 Describe the difference between genotype and phenotype
 Describe the difference between homozygous and heterozygous
 Explain what dominant and recessive alleles are
 Explain what is meant by true or pure breeding
 Explain what the first filial (F1) and second filial (F2) generation are
(6)
To learn how to use a Punnett square to carry out a monohybrid cross
 Explain what a monohybrid cross is
 Carry out a monohybrid cross
 State the phenotypic ratio expected when carrying out a monohybrid cross between two
heterozygotes
(7)
To learn how carry out a monohybrid test cross
 Explain what the testcross is used for
 State the phenotypic ratio expected for a heterozygote and homozygote
 Explain Mendel’s First Law (The Law of Segregation)
(8)
To understand the exceptions to the 3:1 ratio expected from a monohybrid
 Explain what incomplete dominance is
 State the phenotypic ratios expected in an incomplete dominance cross
 Explain what co-dominance is
 State the phenotypic ratios expected in a co-dominance cross
 Explain what over dominance is
 State the phenotypic ratios expected in an over dominance cross
 Explain what lethal genes are
 State the phenotypic ratios expected from a cross involving lethal genes
(9)
To understand what multiple alleles are
 Explain what multiple alleles are
 Describe an example where multiple alleles exist for a single gene (e.g. ABO blood groups
 Solve problems involving the inheritance of phenotypic traits involving multiple alleles
(10)
To understand how sex is determined
 Describe the basis of sex determination in humans and other mammals
(11)
To understand what sex linkage is
 Explain what is meant by sex linkage
 Explain why sex chromosomes are only partly homologous
 Describe examples of sex linked inheritance (e.g. red-green colour blindness, haemophilia)
 Solve problems involving sex linked inheritance
 Explain how Punnett squares involving sex linked genes differ from normal monohybrid
crosses
 Describe the difference in the pattern of inheritance for sex linked recessive traits and sex
linked dominant traits
(12)
To learn how to use a dihybrid cross to analyse inheritance
 Explain the difference between a monohybrid and dihybrid cross
 Describe the relationship between a monohybrid and dihybrid cross
 Use a dihybrid cross to solve problems involving inheritance
 State the phenotypic relationship expected when carrying out a dihybrid cross between two
heterozygotes
 Describe the effect of linkage on the inheritance of alleles