Download Study Guide - ANSWERS Unit 4 Part 1 Test

Study Guide - ANSWERS
Unit 4 Part 1 Test
Meiosis
1. What are two similar chromosomes that you will inherit from your parents are called?
homologous chromosomes
2. Explain the difference between the terms diploid and haploid. Give an example of each cell.
Diploid cells have a pair of each of the homologous chromosomes. Haploid cells only have
one of the pair (thus it needs the other half to “work”). Diploid cells are somatic / body
cells like skin, hair, eye, liver, heart, etc. Haploid cells are gametes / sex cells like sperm
and egg.
3. Using the picture below, answer the following questions.
a. The top 2N cell on meiosis drawing is called a (diploid / haploid) cell.
b. Mitosis produces genetically identical daughter cells.
c. Meiosis produces 4 genetically different haploid cells.
d. Mitosis produces more somatic cells.
e. Meiosis is taking a diploid germ cell and creating 4 haploid sperm or egg (gametes).
f. What phase do sister chromatids pull
apart? Anaphase II of Meiosis II
g. What phase does a tetrad form?
Interphase (into Prophase I)
h. What phase does crossing over occur?
Prophase I
i. What does crossing over ensure?
Genetic variation in the gametes
j. What phase does homologous duplicated
chromosomes line up in the middle of the
cell? Metaphase I of Meiosis I
k. During meiosis I homologous
chromosomes are separated, and during meiosis II, sister chromatids are separated.
l. When does DNA replication occur? Interphase How many times does it occur? Just once
4. What would happen if our gametes were created using mitosis? Our chromosome number
would continue to increase, making it very hard for DNA to work. We essentially would
continue to have more and more traits. Meiosis keeps the chromosome number in organisms
consistent.
5. What type of cell would contain 22 autosomes and an x or y? Gamete / Sex Cell
6. What is the name for a specific location on a chromosome, consisting of a segment of DNA,
that codes for a specific protein? gene
7. Genes code for proteins that determine inheritable traits.
Mendelian Genetics
1. Cross Aa x Aa (A Adams apple, a no Adams apple)
2.
3.
4.
5.
6.
7.
8.
a. What does the outcome of the Punnett Square show us?
The possible genotypes and phenotypes of the offspring.
b. What term best represents the parents : homozygous or heterozygous
Explain.
It is heterozygous because the two alleles are different (in this case, one is
dominant and one is recessive).
c. What would the phenotypic ratio of the offspring be? 4:0
d. What is the letter “a” considered? an allele (one form of a gene)
The Law of SEGREGATION states that organisms inherit 2 copies of each gene, but
separate those copies before donating only one copy to each of their offspring.
Recessive alleles may not be expressed because they are masked by dominant alleles.
The Law of INDEPENDENT ASSORTMENT, is one explanation of the genetic variation within
species.
In cats, Pulvaria is a recessive genetic disorder that affects its eye sight. If the parents
of a cat are homozygous recessive and homozygous dominant for Pulvaria, what are the
chances that the cat (offspring) has the disorder? 0% because all the offspring would be
heterozygous. In order for the genetic disorder to show up, there must be two recessive
alleles present.
In Mendel’s monohybrid cross of a purebred white-flowered plant (pp) and a purebred
purple-flowered (PP) he got plants that were all purple.(phenotype)
How did Mendel get purebred plants? He allowed plants to self-pollinate only. What does
the term purebred mean? It means the alleles stay consistent - they aren’t mixed with
alleles from another organism.
A female cow Bb (black spots) and LL (long tongue) mates with a bull BBll.
a. What are the possible gametes the father can pass down? Bl only
b. How many of their offspring will potentially be black spotted with a long tongue.
100%....50% BBLl and 50% BbLl
Exceptions to Mendelian Genetics
1. If a red beta fish mates with a blue beta fish and the offspring is purple, this would be
Incomplete Dominance.
2. If a red beta fish mates with a blue beta fish and the offspring is red and blue polka
dotted, this would be Codominance.
3. Hair color, eye color, and height are all examples of polygenic traits. This means that
multiple genes are used to express this trait.
4. If genes are close to each other on a chromosome, they are considered to be linked. This
simply refers to the notion that during crossing over, if they are close together, they have
a chance of crossing over together.
5. Color-blindness, hemophilia, and male pattered baldness are all sex-linked traits. This
means that they are located on a sex chromosome like an X or Y. Females are normally
carriers while males express the trait.
6. Blood typing is an example of codominance and multiple alleles.