Name _____________________________
Unit Genetics Test Review
1. Gregor Mendel used pea plants to study the inheritance of traits
2. Heterozygous – 2 different alleles for a trait. Homozygous – 2 identical alleles for a trait
3. What are hybrids? The offspring from crosses between parents with different traits are hybrids
4. What are the offspring of the F1 generation called? F2
5. Genes are chemical factors that determine traits. The different forms of a gene are called Alleles
6. The physical appearance of an organism is its phenotype
7. Define each:
a) Principle of Dominance - some alleles are dominant and some are recessive
b) Principle of Independent Assortment - the alleles for different genes usually segregated
independently of one another (i.e. hair color and eye color are not linked together)
c) Principle of Segregation - in most sexually reproducing organisms, each adult has two copies of
each gene. These genes are segregated from each other when gametes are formed.
8. When Mendel crossed true-breeding tall plants with true-breeding short plants, all the offspring of the F1
generation were tall and the alleles for tall plants are dominant (heterozygous)
9. If blue eyes are recessive, how many alleles for that trait does a person have to have in order to have blue
eyes? 2
10. What is the relation between principles of probability and genetics?
probability – the likelihood that a certain event will occur
The principles of probability can be used to predict the traits of the offspring produced by genetic crosses.
11. What is the probability of getting tails 4 times in a row when you flip a coin?1/16
12. What is the probability it will tails on the 5th flip ½.
13. What is incomplete dominance? Give an example. where one allele is not completely dominant over
another; the heterozygous phenotype is in between the two homozygous (parents) phenotypes. Mirabilis
plants (red flower X white flower = pink flower)
14. What is codominance? Give an example both alleles are expressed. Roan colored cattle.
15. Give an example of a polygenic trait Wide range of skin color in humans and multiple alleles human genes
for blood type
16. Cells that contain only one set of chromosomes (i.e. sex cells/gametes) are said to be haploid.
17. Cells that contain two sets of chromosomes (i.e. somatic cells) are said to be diploid
18. Male diploid cell = 46XY Sperm = 23X or 23Y
Sperm are haploid. 50 % of sperm carry X chromososme and 50 % of sperm carry Y chromosome.
19. If an organism’s diploid number is 90, what is its haploid number?45
20. What process cuts chromosome number in ½ and produces gametes? meiosis
21. List four differences between mitosis and meiosis.
Mitosis
Meiosis
All somatic cells
Only sex cells
2 daughter cells – exactly identical to each other
and parent cell
4 daughter cells – genetically different from each
other and parent cell
# of chromosomes remains same
Diploid Diploid
4 phases
# of chromosomes is cut in half
Diploidhaploid
8 phases
22. Radiation can cause mutations in genes/chromosomes. Only those mutations that occur in sex cells pass
on to offspring.
23. How many chromosomes are shown in a normal human karyotype 46
24. The “matching” or “corresponding” chromosomes from each parent in a human karyotype are called
homologous chromosomes.
25. What are all the chromosomes EXCEPT the sex chromosomes called? Autosomes
26. What is the gender of the person in the karyotype in the picture above male
27. What are the sex chromosomes for males? XYAnd Females? XX
28. What chromosomal disorder is present in the karyotype above - Trisomy 21 (Down syndrome)
Explain what causes it. Nondisjunction - failure of one or more homologous chromosomes (pairs) to
separate during meiosis.
29. In a pedigree, what does a shaded circle represent? Female with a trait or disorder
This pedigree shows inheritance of the hemophilia (a sex linked trait) XH = normal Xh = hemophiliac
30. How many males in this pedigree are hemophiliac? 10
31. Carrier female(s) are not shaded in the diagram. Is queen Victoria a carrier? Yes
32. What is a genotype of Beatrice - XH Xh or XH XH
33. What is shown in following figure?
Chromosomes exchange portion of chromatids (alleles)  “crossing over”
34. Between what genes will crossing over most likely occur on a gene map?
Genes that are farther apart are more likely to be separated by a crossover in
meiosis.
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Study your notes, labs, and assignments and read chapter 11 & 14 from the
book.
Study from the genetics problems packet.
Be able to do Punnett sq - monohybrid, dihybrid, incomplete, codominance,
sex linked and give the genotypes and phenotypes of offspring.