Q: A plant breeder wants to produce only offspring with the recessive phenotype. Which parental genotypes should be crossed?

Homozygous recessive $$\times$$ homozygous recessive

Question 1

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype consists of the alleles an organism carries, while phenotype is the physical manifestation of those alleles.

Question 2

A pea plant with genotype $$Rr is $$crossed with another plant with genotype $$Rr. $$What is the expected phenotypic ratio of the offspring if $$R is $$dominant to $$r$$?

Accepted Answer

$$3:1 ($$three dominant, one recessive)

Question 3

Which principle states that alleles separate during the formation of gametes, ensuring offspring inherit one allele from each parent?

Accepted Answer

Principle of Segregation

Question 4

In a dihybrid cross between two individuals heterozygous for both traits ($$RrYy 	imes RrYy$$), what is the expected phenotypic ratio if the genes assort independently?

Accepted Answer

$$9:3:3:1$$

Question 5

Which of the following scenarios best illustrates the concept of particulate inheritance?

Accepted Answer

A trait that disappears in one generation and reappears unchanged in the next.

Question 6

If a monohybrid cross is performed between two homozygous individuals ($$AA 	imes aa$$), what will be the genotype of the F1 generation?

Accepted Answer

All $$Aa$$

Question 7

Which of the following best explains why meiosis is essential for the principle of segregation?

Accepted Answer

Meiosis allows homologous chromosomes to pair and then separate, so each gamete receives only one allele of each gene.

Question 8

A geneticist observes that two traits are inherited together more often than not. Which principle is likely being violated?

Accepted Answer

Principle of Independent Assortment

Question 9

In a real-world scenario, a genetic disorder is only expressed when an individual has two copies of a recessive allele. What is the probability that two heterozygous parents ($$Aa 	imes Aa) $$will have an affected child?

Accepted Answer

$$1/4$$

Question 10

Which of the following is an example of cross-fertilization?

Accepted Answer

A plant receives pollen from a different plant and produces seeds.

Question 11

A researcher performs a test cross between a plant with an unknown genotype and a homozygous recessive plant. If all offspring display the dominant phenotype, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant

Question 12

Which of the following best describes the Law of Independent Assortment?

Accepted Answer

Alleles for different genes separate independently during gamete formation.

Question 13

If a monohybrid cross produces a $$3:1$$ phenotypic ratio, which of the following must be true about the alleles involved?

Accepted Answer

One allele is completely dominant over the other.

Question 14

A scientist is studying a gene with two alleles, $$A$$ and $$a. If $$the frequency of $$A in a $$population is $$0.6$$, what is the expected frequency of heterozygotes ($$Aa) $$under Hardy-Weinberg equilibrium?

Accepted Answer

$$0.48$$

Question 15

Which of the following is NOT a feature of Mendel's particulate inheritance theory?

Accepted Answer

Genes blend together in offspring.

Question 16

A plant breeder wants to produce only offspring with the recessive phenotype. Which parental genotypes should be crossed?

Accepted Answer

Homozygous recessive $$	imes$$ homozygous recessive

Question 17

Which of the following best explains why a heterozygous individual ($$Aa) $$expresses the dominant phenotype?

Accepted Answer

The dominant allele masks the effect of the recessive allele.

Question 18

In a real-world medical case, a child inherits cystic fibrosis, a recessive disorder, even though neither parent has the disease. What are the most likely genotypes of the parents?

Accepted Answer

Both parents are heterozygous carriers.

Question 19

Which of the following best describes a monohybrid cross?

Accepted Answer

A cross between individuals that are heterozygous for a single gene.

Question 20

Which of the following is a direct consequence of the chromosome theory of inheritance?

Accepted Answer

Genes are located on chromosomes and are inherited together if they are close to each other.

Mendelian Genetics: Principles of Inheritance

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