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Unit 6 Reading Guide
Honors Biology
Chapter 6 – Meiosis and Mendel
Section 6.1 – Chromosomes and Meiosis
1. How do gametes differ from somatic cells?
2. The prefix homo- means “the same”. How does this relate to homologous chromosomes?
3. Are gametes haploid or diploid cells?
4. Is the cell that results from fertilization a haploid or a diploid cell? Explain.
Section 6.2 – Process of Meiosis
1. Describe the differences between mitosis and meiosis.
2. How are Meiosis I and Meiosis II the same? How are they different?
3. How many haploid daughter cells are formed at the end of Meiosis II?
Section 6.3 – Mendel and Heredity
1. List three examples of genetic traits.
2. In which generation of offspring did Mendel observe a 3:1 ratio in the appearance of the offspring?
3. Mendel saw purple flowers in the F1 generation, but both purple and white flowers in F2. How did this help him see
that traits are inherited as discrete units?
4. What is segregating in the law of segregation? When does this segregation occur?
Section 6.4 – Traits, Genes, and Alleles
1. Distinguish between the terms allele and locus.
2. Explain the difference between genotype and phenotype.
3. If you were to make an analogy and say that the genotype is like the blueprint, how would you complete the analogy
to describe phenotype?
4. Use the letters B and b to represent the following genotypes: heterozygous, homozygous recessive, and
homozygous dominant.
5. Explain why an organism’s genotype can be homozygous dominant, homozygous recessive, or heterozygous, but it
can never heterozygous recessive.
Section 6.5 – Traits and Probability
1. What do the letters on the axes of the Punnett square represent?
2. What do the grid boxes in a Punnett square represent? Why does each box have two alleles?
3. What would the phenotypic ratios of the offspring be from the following: Pp x pp? Is this a monohybrid or a dihybrid
cross?
4. If you are working with two tall pea plants and know that one is Tt, how could you determine the genotype of the
other plant?
5. When would you use a dihybrid cross?
6. What would the phenotypic ratio be of the offspring resulting from the following: YYRr x YyRr ?
Section 6.6 – Meiosis and Genetic Variation
1. Briefly explain how sexual reproduction generates new allele combinations in offspring.
2. What factors contribute to genetic diversity?
3. Suppose two genes are very close together on a chromosome. Are the genes likely to be separated by crossing
over? Explain.
4. You know that you get half your DNA from your mom and half from your dad. Does this mean you got one-quarter
of your DNA from each of your grandparents? Explain your reasoning.
5. Suppose you know that two genes exist on the same chromosome. How could you determine if they are located
close to each other?
Chapter 7 – Extending Mendelian Genetics
Section 7.1 – Chromosomes and Phenotype
1. What is a carrier?
2. What is the pattern of expression for autosomal genes? For sex-linked genes?
3. Why are males more likely than females to have sex-linked genetic disorders?
4. How might a scientist determine if a trait is sex-linked through observing the offspring of several genetic crosses?
Section 7.2 – Complex Patterns of Inheritance
1. How do multiple-allele traits differ from polygenic traits?
2. How can two people with type B blood have a child with type O blood? (Hint: You might want to use a Punnett
square.)
3. Sunlight can cause a person’s hair to become lighter in color. Is this an example of an interaction between genes
and the environment? Why or why not?
4. How is incomplete dominance expressed in a phenotype?
5. Why might polygenic traits vary more in phenotype than single gene traits?
Section 7.3 – Gene Linkage and Mapping
1. How was Mendel’s law of independent assortment inaccurate?
2. What is the relationship between the distance between two genes and the chance that they will be inherited
together?
3. How is a linkage map related to cross-overs that take place during meiosis?
Section 7.4 – Human Genetics and Pedigrees
1. Why can only females be carriers of sex-linked disorders?
2. What is a pedigree?
3. Is a person who is homozygous recessive for a recessive genetic disease a carrier? Explain.
4. Suppose a colorblind male and female with no recessive alleles for colorblindness have children. What is the
probability they will have a colorblind son? A colorblind daughter?
5. How do pedigrees for autosomal genes differ from pedigrees for sex-linked genes?
Chapter 9 – Frontiers of Biotechnology
Section 9.6 – Genetic Screening and Gene Therapy
1. What is genetic screening?
2. Why might genetic screening raise ethical concerns about privacy?
3. Briefly describe the goals and methods of genetic screening and counseling.