Inheritance

Question 1

What influences variation in phenotype? (2)

Answer 1

• Environment (1)
• Variation in genotype (1)

Question 2

What is the different of genotype and phenotypes (2)

Answer 2

• Genotype is combination of alleles (E.G. Tt, TT, tt) (1)
• Phenotype is the visible characteristic the genotype produces (1)

Question 3

What are codominant alleles? (2)

Answer 3

• Both alleles contributing to the phenotype (1)
• Cats having both black and white fur (1)

Question 4

What is monohybrid inheritance? (2)

Answer 4

• Inheritance controlled by single gene (1)
• Offspring 3:1 ratio (1)

Question 5

What is dihybrid cross? (2)

Answer 5

• Shows 2 inheritance (1)
• Offspring 9:3:3:1 (1)

Question 6

When would dihybrid cross be different? (3)

Answer 6

• loci of 2 different genes on the same chromosome (1)
• Inherited together known as autosomal linkage (1)
• Prevented by crossing over in meiosis (1)

Question 7

How do male and female chromosomes work? (3)

Answer 7

• Male has XY while Female has XX (1)
• Male only needs one recessive allele to have disease (1)
• Chance of recessive phenotype is larger (1)

Question 8

What is epistasis? (3)

Answer 8

• Allele of one gene masks the expression of alleles of other genes (1)
• E.G. Allele to code for pigment synthesis is required for plant to be a colour (1)
• Affects dihybrid and monohybrid ratios (1)

Question 9

What is the food chain? (2)