MINISTRY OF EDUCATION, HERITAGE AND ARTS YEAR 12 BIOLOGY REVISION WORKSHEET 4
Write the answers to the following questions in your exercise/activity books.
Genetics/Variability
Write definitions for the following terms giving examples where possible. Crossing over
Recombination of genes
Incomplete dominance
Codominance
Multiple alleles
Sex linked genes
Back or test cross (7 marks)
Solve the following mono-hybrid problems: (9 marks)
A pure black male cat mates with a white female. Black coat colour is the product of a dominant allele. Show the genotypes and phenotypes of the parental, F1 and F2 generations. Indicate the phenotypic and genotypic ratios of the F2 generation.
In humans, six fingers (F) is the dominant trait and five fingers (f) is the recessive trait. Both parents are heterozygous for six-fingers. Indicate the genotypes and phenotypes of the parents and their possible offspring. What is the probability of producing a five-fingered child?
In a certain species of plant, one purebred variety has hairy leaves and another purebred variety has smooth leaves. A cross of the two varieties produces offspring that all have smooth leaves. Predict the phenotypic and genotypic ratio of the F2 generation.
Solve the following di-hybrid problem:
In pea plants, seed shape is determined by two alleles: S is the allele for the dominant, spherical shape characteristic; s is the allele for the recessive, dented shape characteristic. Seed colour is also determined by two alleles: Y is the allele for the dominant, yellow colour characteristic; y is the allele for the recessive, green color characteristic.
A pure bred plant with green, spherical shaped seeds is crossed with a pure bred plant with yellow dented shaped seeds. a. State the phenotype and genotype for the parent plants, P1 and P2. b. Write the gametes produced by both parent plants. c. Give the genotype and phenotype of the F1 generation when P1 and
P2 are crossed. (2 marks)
Write the four types pf gametes that the F1 generation with produce. (2 marks)
Using a punnet square, show the cross between 2 F1 individuals. (4 marks)
In a population of 320 plants, calculate the number of plants that would have yellow, spherical shaped seeds. (2 marks) (2 marks) (1 mark)