Genetics Review
The following are concepts from the unit that you should be able to describe and explain. This document is to
guide you in studying for the test. Please make sure that you review ALL of your material from class in order to
study most effectively.
Part 1: Vocab
Define the following vocab terms:
1. Gene – contains information for a specific trait
7. P generation – parental generation
2. Allele – an alternate form of a gene (height is a trait;
the alleles for that trait can either be tall or short)
3. Homozygous
8. F1 generation – offspring of the parental generation
4. Heterozygous – one dominant allele, one recessive
allele
10. Genotype – the alleles present in an organism (GG,
Gg, or gg)
5. Dominant – when present this trait is always
expressed
11. Phenotype – the physical trait that the genotype
codes for ( blond hair, brown eyes, white fur, etc.)
9. F2 generation – offspring of the F1 generation
6. Recessive – only expressed when the dominant
allele is not present
Part 2: Questions
1. Who is the father of modern genetics? Give a brief description of his “occupation” and what he experimented
on. Mendel – Monk, experimented with pea plants
2. What is the difference between cross-pollination and self-pollination?
Cross pollination- oneplant pollinates another
Self-pollination – one plant pollinates itself
3. What is a hybrid? Cross between a homozygous dominant individual and a homozygous recessive individual. A
hybrid is a heterozygous individual
4. What does the law of independent assortment state? Alleles for different traits separate independently of
one another during meiosis – they do not depend on one another to divide.
5. What does the law of segregation of alleles state? Alleles separate into different gametes during meiosis
6. What is the difference between a monohybrid cross and a dihybrid cross? Monohybrid studies one trait,
dihybrid studies two traits inherited together
7. Describe the difference between complete dominance, incomplete dominance and co-dominance.
Complete dominance – when the dominant allele is present, the phenotype for that allele is expressed (shows
up) in the organism
Incomplete dominance – the heterozygous individual is a mix of the two alleles (red +white = pink)
Complete dominance – the heterozygous individual show BOTH phenotypes at the same time (red + white = red
and white spotted
8. list and describe 2 human diseases that are inherited on an autosomal dominant allele.
Huntington’s – late onset, causes rapid deterioration of nervous system
Neurofibromatosis – causes tumors on nervous system organs and skin
9. List and describe 2 human diseases that are inherited on an autosomal recessive allele.
Cystic fibrosis – affects lungs and oxygen exchange
Pku – do not have enzyme to break down phenylalanine (amino acid) – it builds up in body and causes toxicity
Sickle cell – causes red blood cells to be sickle shaped – do not carry oxygen efficiently
10. List and describe 2 human disorders/ diseases that are x-linked and describe why they are called x-linked.
Red-green colorblindness – lack the ability to distinguish between certain colors
Hemophilia – lack clotting factor in blood – can bleed easily, accidental internal bleeding is a concern
11. What inheritance pattern does blood typing follow? List the three possible alleles.
Codominance, multiple alleles. Possible alleles: IA, IB, i
12. What is a test cross and when is it used? Crossing a known homozygous recessive individual with an
individual of an unknown genotype to determine what its genotype is.
Part 3: Genetics Practice Problems
1. Tongue rolling is dominant to non tongue rolling. One parent is heterozygous for tongue rolling and one
parent who can’t roll their tongue. What would be the possible phenotypes and genotypes of their offspring?
What percent of their offspring could possibly be able to roll their tongue?
2. Two parents seem normally healthy and are surprised when they find out their newborn son has PKU. What
are the genotypes of the parents and what was the chance that their son could inherit the disease?
3. One parent has Huntington’s disease and the other does not. Luckily, none of their children have inherited the
disorder. If this is true, what is the genotype of the parent with Huntington’s? What are the chances that their
children would or would not have the disease?
4. As their daughter grows up, a husband and wife discover that she is colorblind. What does this mean about
the genotypes and phenotypes of the mom and dad? What chance did the daughter have of being colorblind?
5. A couple with type A and type B blood are surprised to find out their son is type O. What are the genotypes of
the parents? What is the chance they will have offspring with other blood types?
6. A red flowered plant known to display incomplete dominance is cross pollinated by a bee with another plant
of the same type with white flowers. What color flower will the plants from their seeds produce?
7. Seed color and seed shape are inherited together. Yellow color is dominant to green and round seed shape is
dominant to wrinkled. One plant that is homozygous dominant for Yellow color and heterozygous for seed
shape is crossed with an individual who is heterozygous for both. Draw the punnett square to show the possible
outcome of their offspring. Give all possible genotypes and phenotypes.