Download Chapter 14 Study Qs

Chapter 14 Study Questions: Mendel and the Gene Idea
1) Define the following terms:
 monohybrid cross:
 dihybrid cross:
 pedigree:
 gene:
 allele:
 genome:
 locus:
2) What is a test cross? Give an example of a testcross that might be performed on a pea plant of unknown
genotype that has purple flowers (purple, P, is dominant to white, p).
3) Two-Gene Cross Problem: In pea plants, purple flowers (P) are dominant to white flowers (p), and round
seeds (R) are dominant to wrinkled seeds (r). A plant that is heterozygous for both traits is crossed with a
plant that is heterozygous for flower color and has wrinkled seeds. Draw a Punnett Square illustrating this
cross and list the genotype and phenotype ratios expected in the offspring.
4) What is meant by “incomplete dominance”? Give an example of a trait that illustrates this.
5) Distinguish between complete dominance and codominance. Give an example of a human trait that
illustrates codominance.
6) Describe and give an example of a trait (in humans or another animal) that illustrates the following
inheritance patterns:
 multiple alleles:
 pleiotropy:
 epistasis:
 polygenic inheritance:
7) Complete the table below:
Disease / Condition
Cause
Cystic fibrosis
Tay-Sachs
Symptoms
Treatment /
Prevention /
Testing possible?
-gentle pounding,
Antibiotics
-can’t prevent
-testing possible
-1/25000 Caucasians
have
-1/25 Caucasians
carriers
-most common lethal
genetic disease in US
-No treatment or
prevention
-Testing possible
-High number of Jews
from central Europe
-1/3600 births
-Testing possible
-Most common
recessive inherit.
diease in Blacks
(1/400)
-Advantage to Ss in
Africa (malaria resist)
-Test avail.
-Once deterioration
begins, can’t stop it
-No obvious phenotypic
effect until 35-45 yrs
-everyone is screened
for @ birth before
leave hospital
-treatment: Avoid
amino acid
phenylalanine in diet
- 1/10000 births in US
Sickle-cell anemia
Huntington Disease
Phenylketonuria
(pku)
Other info (which
populations
affected?, etc.)
8) Distinguish between the following methods of fetal testing. Indicate in your answers what kinds of
information are provided with each test. Which tests have risks associated with them? Which tests are
safest?
 amniocentesis:
 chorionic villus sampling:
 ultrasound:
 fetoscopy: