Question 1: Define a Punnett Square and explain its purpose in genetics.

Answer: A Punnett Square is a diagram used to predict the probability of offspring inheriting particular combinations of alleles from parents. It helps visualize genetic inheritance patterns.

Question 2: What is the difference between genotype and phenotype?

Answer: Genotype refers to the genetic makeup of an individual (the alleles they carry), while phenotype is the observable physical or biological traits resulting from the genotype.

Question 3: Describe how a heterozygous individual for a dominant trait expresses the trait.

Answer: A heterozygous individual with one dominant and one recessive allele will express the dominant trait because the dominant allele masks the recessive one.

Question 1: A cross between two heterozygous parents (Aa x Aa) is performed. Calculate the probability of their offspring being homozygous recessive (aa).

Answer: The probability is 25% or 1 in 4. Using a Punnett Square: AA, Aa, Aa, aa; thus one out of four offspring is aa.

Question 2: If a tall plant (Tt) is crossed with a short plant (tt), what is the expected phenotypic ratio of the offspring?

Answer: The expected phenotypic ratio is 1 tall : 1 short. The Punnett Square shows 2 tall (Tt, Tt) and 2 short (tt) offspring.

Question 1: Design a simple experiment to determine whether a plant's height is controlled by a dominant or recessive allele, describing the steps and variables involved.

Answer: Students should select a tall plant with a known genotype, cross it with a short plant, and observe the offspring. The independent variable is the parent plant's height; the dependent variable is the height of the offspring. Control variables include environmental conditions, and safety precautions involve handling plants carefully and disposing of plant material properly.

Question 2: Explain how understanding Punnett Squares can help in agriculture, such as breeding for desirable traits.

Answer: Punnett Squares allow breeders to predict the likelihood of offspring inheriting desirable traits like disease resistance or higher yield, enabling more efficient selection and breeding programs.

Question 3: Describe a scenario where Punnett Squares might not accurately predict inheritance outcomes.

Answer: Punnett Squares may not be accurate in cases of incomplete dominance, codominance, polygenic traits, or when environmental factors influence gene expression, as these scenarios involve more complex inheritance patterns.

Question 1: In a study, 200 offspring from a cross between two heterozygous parents (Aa x Aa) were observed. The phenotypic ratio was approximately 75% tall and 25% short. Does this data support the predicted Mendelian ratio? Explain your reasoning.

Answer: Yes, the data supports the predicted 3:1 phenotypic ratio. Out of 200, about 150 are tall and 50 are short, consistent with Mendelian inheritance for a single gene with dominant and recessive alleles.