Practice Questions
Identify the sex chromosomes present in human males and human females.
Propose a scenario where a newly arisen variation in an asexually reproducing species could be detrimental rather than advantageous.
Design a public awareness poster to explain that the father is responsible for the sex of the child. Your design concept should include a key visual, a simple slogan, and two bullet points explaining the science.
Evaluate the probability of a human couple having three sons in a row. Justify your calculation.
Contrast the number of sets of chromosomes found in a human somatic (body) cell with that found in a human germ (sex) cell.
Name the two types of earlobes found as variants in human populations.
Define the term 'heredity'.
Define a gene.
Name the plant that Gregor Mendel used for his experiments on inheritance.
Compare the chromosomal makeup of a normal human male and a normal human female, focusing on both autosomes and sex chromosomes.
Apply the concept of dominance to determine the flower color of a pea plant with the genotype Ww, if the allele for violet flowers (W) is dominant over the allele for white flowers (w).
List three examples of contrasting traits in pea plants studied by Mendel.
Justify the statement: 'Variations that confer a survival advantage are more likely to be preserved in a population.' Use the example of heat-resistant bacteria from the text.
Formulate a hypothesis to explain why, in a dihybrid cross between a plant with genotype RrYy, the traits for seed shape (R/r) and seed colour (Y/y) are inherited independently.
Formulate a simple rule for inheritance based on the evidence presented in Activity 8.1, where students correlate their earlobe type (free or attached) with their parents'.
Describe how variations arise during asexual reproduction.
Recall the phenotypic ratio of tall plants to short plants that Mendel found in the generation of his monohybrid cross.
Summarize the mechanism of sex determination in human beings.
Explain the difference between a dominant trait and a recessive trait, using an example from Mendel's experiments.
Explain what Mendel observed in the generation when he crossed a pure-bred tall pea plant with a pure-bred short pea plant.
Describe why sexually reproducing organisms have two copies of genes for each trait.
Analyze a scenario where trait 'X' is found in of an asexually reproducing bacterial population and trait 'Y' is found in of the same population. Which trait is likely to have arisen earlier, and why?
Analyze why in Mendel's experiments, the F1 progeny from a cross between a pure tall pea plant (TT) and a pure short pea plant (tt) were all tall, with no medium-height plants observed.
In humans, the allele for free earlobes (F) is dominant over the allele for attached earlobes (f). If two parents with free earlobes have a child with attached earlobes, analyze the genotypes of the parents and the child.
Design a project which aims to find the dominant coat colour in dogs, assuming black and brown are the two main colours controlled by a single gene. Your plan should outline the breeding crosses required, the expected observations over two generations, and the criteria to justify your conclusion.
Propose a genetic cross to determine the genotype of a tall pea plant from the F2 generation, which could be homozygous dominant (TT) or heterozygous (Tt).
Examine the genetic basis of sex determination in humans. Demonstrate with a Punnett square how sex is inherited and calculate the theoretical probability of having a boy or a girl.
Examine a situation where a population of brown beetles lives in a sandy environment. If a green color variation arises due to a mutation, analyze how this new trait could promote the survival of the species if the environment changes to a lush green forest.
A Mendelian cross was performed between a pure-breeding pea plant with round seeds (dominant) and a pure-breeding pea plant with wrinkled seeds (recessive). The F1 generation was then self-pollinated, producing a total of seeds in the F2 generation. Calculate the expected number of round seeds and wrinkled seeds in the F2 generation and demonstrate the cross.
In pea plants, tallness (T) is dominant over shortness (t). If a heterozygous tall plant (Tt) is crossed with another heterozygous tall plant (Tt), calculate the genotypic and phenotypic ratios of the offspring.
Analyze how the cellular mechanism involving genes and proteins explains the expression of dominant and recessive traits, using the example of tall (T) and short (t) pea plants.
Analyze the genetic contribution of each parent to determine the sex of a child in humans and justify the statement that the father is responsible for the sex of the offspring.
Justify why a single copy of the dominant allele 'T' is sufficient to make a pea plant tall, whereas two copies of the recessive allele 't' are required to make it short.
Critique the statement: 'The F1 progeny in Mendel's monohybrid cross are genetically identical to the dominant parent.'
Propose why a recessive allele that causes a genetic disorder might persist in a population's gene pool instead of being eliminated.
Critique the conclusion that 'a trait is dominant' based solely on the observation that children with light-coloured eyes are likely to have parents with light-coloured eyes. Why is this evidence insufficient?
Summarize the Law of Independent Assortment based on Mendel's dihybrid cross experiments.
In garden peas, round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). Solve a cross between a plant homozygous for round yellow seeds (RRYY) and a plant with wrinkled green seeds (rryy). Then, analyze the new combinations of traits that appear in the F2 generation after self-pollination of the F1 progeny.
Summarize how traits get expressed in an organism, starting from DNA.
Evaluate the statement: 'A man with blood group A marries a woman with blood group O, and their daughter has blood group O. This is enough to tell that blood group A is dominant.' Justify your reasoning.
Evaluate Mendel's decision to use pea plants (Pisum sativum) for his experiments. Justify why this choice was critical to his success in discovering the laws of inheritance.
Explain the importance of variation for the survival of a species.
Demonstrate how a plant breeder could use a test cross to determine the unknown genotype of a tall pea plant, which could be either homozygous dominant (TT) or heterozygous (Tt).
Compare and contrast the mechanisms that generate genetic variation in sexually reproducing organisms versus asexually reproducing organisms, and analyze how these differences impact the potential for species survival in a changing environment.
Evaluate the claim that asexual reproduction is always a disadvantage for a species in the long term compared to sexual reproduction. Is there any scenario where it might be advantageous?