Topic 7 : Genetics, Populations, Evolution and Ecosystems

• What is a genotype?

  The genetic constitution of an organism
• What does phenotype refer to?

  The expression of genes and environmental interaction
• What does homozygous mean?

  Same alleles for a single gene
• What does heterozygous mean?

  Different alleles for a single gene
• When is a recessive allele expressed?

  Only if no dominant allele is present
• What is a dominant allele?

  Always expressed in the phenotype
• What does codominant mean?

  Both alleles are equally dominant and expressed
• What is multiple alleles?

  More than two alleles for a single gene
• What is sex linkage?

  A gene located on the X chromosome
• What is autosomal linkage?

  Genes located on the same chromosome
• What is epistasis?

  One gene modifies or masks another gene's expression
• What is a monohybrid cross?

  Inheritance of one gene
• What is a dihybrid cross?

  Inheritance of two genes at a time
• What is the probability of a child having cystic fibrosis from two heterozygous parents?

  25% probability of having cystic fibrosis
• How do you calculate the probability of a girl with cystic fibrosis?

  Multiply 25% by 50%
• What is the probability of producing a red cow from two roan cows?

  25% probability of getting a red cow
• What are the possible blood groups from parents with blood group AB and O?

  50% probability of blood group A
• What is the inheritance pattern of color blindness?

  Recessive allele found on the X chromosome
• What is the probability of children being colorblind from a non-color blind male and a female carrier?

  25% probability of being colorblind
• What does epistasis influence in genetics?

  It masks the expression of another gene
• How does gene one affect pigment expression in Labradors?

  It controls whether pigment will be produced
• What is the outcome of crossing two homozygous dominant Labradors?

  All offspring will be heterozygous
• What is the expected offspring ratio from a dihybrid cross?

  9:3:3:1 ratio
• What is the effect of crossing over on gametes?

  It results in new combinations of alleles
• What is autosomal linkage in genetics?

  Two genes located on the same chromosome
• How are alleles inherited in autosomal linkage?

  They are inherited together on the same chromosome
• What happens to alleles during meiosis in autosomal linkage?

  The whole chromosome is pulled to create gametes
• What is the significance of parental phenotype in genetic crosses?

  It helps determine offspring traits
• What is the role of gametes in genetic crosses?

  They combine to form offspring genotypes
• What is the importance of matching offspring phenotype to genotype?

  It ensures accurate representation of traits
• What is the expected outcome of a dihybrid cross with heterozygous parents?

  All offspring will show dominant traits
• What is the effect of autosomal linkage on genetic crosses?

  It limits the variety of gametes produced
• How does the presence of dominant alleles affect offspring traits?

  They will be expressed in the phenotype
• What is the significance of recessive alleles in inheritance?

  They are only expressed when dominant alleles are absent
• What is the role of the Punnett square in genetic crosses?

  To predict offspring genotypes and phenotypes
• What is the expected ratio of offspring from a dihybrid cross?

  9:3:3:1 ratio
• What is the significance of genetic coding tables?

  They help represent different types of inheritance
• What is the importance of knowing key terms in inheritance?

  They are often asked as one-mark definitions
• How does the environment interact with phenotype?

  It influences the expression of genes
• What is the expected outcome of a genetic cross involving multiple alleles?

  It can produce various phenotypes