Question 1: Define a genetic diagram and explain its purpose in genetics.

Answer: A genetic diagram is a visual representation of how genes are inherited, showing parental and offspring genotypes or phenotypes, used to predict inheritance patterns.

Question 2: Describe the difference between a genotype and a phenotype with reference to genetic diagrams.

Answer: Genotype refers to the genetic makeup (alleles), while phenotype is the observable trait expressed; genetic diagrams illustrate both.

Question 3: Explain why Punnett squares are used in genetic diagrams.

Answer: Punnett squares are used to predict the probability of offspring inheriting particular genotypes and phenotypes from parental alleles.

Question 1: A heterozygous tall plant (Tt) is crossed with a homozygous dwarf (tt) plant. What is the probability that an offspring will be tall? (Use a Punnett square)

Answer: 50%

Question 2: In a genetic diagram, if the frequency of a dominant allele (A) is 0.6 in a population, what is the expected frequency of heterozygous individuals (Aa) according to Hardy-Weinberg principle? (Use p + q = 1 and 2pq) Show your calculation.

Answer: q = 1 - p = 0.4; 2pq = 2 × 0.6 × 0.4 = 0.48 or 48%

Question 1: Describe a theoretical experiment to determine the inheritance pattern of a genetic trait using genetic diagrams, including variables and safety precautions.

Answer: The experiment involves crossing individuals with known genotypes, recording offspring phenotypes, and analysing inheritance patterns. Variables include parental genotypes, environmental factors, and sample size. Safety precautions involve handling genetic materials carefully, avoiding contamination, and following laboratory protocols.

Question 1: In a sample of 200 plants, 90 display a dominant trait, and 110 display a recessive trait. Using genetic principles, estimate the allele frequencies in the population and interpret what this suggests about the population's genetic diversity.

Answer: Let p = frequency of dominant allele, q = recessive allele. Since 110 are recessive (aa), q² = 110/200 = 0.55, so q ≈ √0.55 ≈ 0.74. Then p = 1 - q ≈ 0.26. The high q indicates a high frequency of the recessive allele, suggesting limited genetic diversity for this trait.

Question 1: Explain how genetic diagrams are used in plant breeding programmes to develop new crop varieties with desirable traits. Include considerations of inheritance, selection, and genetic diversity.

Answer: Genetic diagrams help breeders predict inheritance of traits, select parent plants with desirable genotypes, and manage genetic diversity to ensure beneficial traits are passed on while maintaining population health.