Worksheet:
Exam 3 Review
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Kelly
Biol 211 (4)
Holscher
11/8/15
1.) What is a chromatid?
A) a chromosome in the G1 stage of mitosis
B) a replicate chromosome
C) a region that holds 2 chromosomes together
D) a structure in the cell composed of centrioles
E) extra-nuclear DNA
2.) If there are 20 chromatids in the cell, how many centromeres are there
A) 10
B) 20
C) 40
D) 60
E) 80
3.) Asexual reproduction results in the production of identical offspring unless which of the following
occurs
A) natural selection
B) cloning
C) crossing over
D) mutation
E) environmental change
4.) If a species has a 2n number of chromosomes = 16 then which of the following is true?
A) The species is diploid with 32 chromosomes per cell
B) A gamete from this species contains 4 chromosomes
C) Each cell has 8 homologous pairs
D) The species has 16 sets of chromosomes per cell
E) None of the above
5.) Which of the following occurs in meiosis but not mitosis?
A) chromosome replication
B) synapsis of chromosomes
C) production of daughter cells
D) alignment of chromosomes at the center of cell
E) condensation of chromatin
6.) A human cell containing 22 autosomes and a Y chromosome is a
A) egg
B) zygote
C) sperm
D) a male somatic cell
E) a female somatic cell
7.) Which of the following happens at the conclusion of meiosis I?
A) homologous chromosomes are separated
B) the chromosome number per cell is conserved
C) sister chromatids are separated
D) four daughter cells are formed
E) the sperm cell fertilizes the egg
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8.) A cross between a homozygous purple flowered and a homozygous white flowered pea plants results
in offspring with purple flowers. This demonstrates
A) blending inheritance
B) true breeding traits
C) dominance of one trait over another
D) a di-hybrid cross
E) a mistake by Mendel
9.) When you cross an organism that is homozygous recessive for a trait with one that is a heterozygote
for the same trait, what is the chance of producing homozygous recessive offspring?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
10.) The rare llama-rabbit is known to have 2 traits: head shape (H) and tail length (T) that are controlled
by un-linked genes. The genotype of a stud-male llama-rabbit is HhTt. Which of the following is a
possible genotype found in his gametes?
A) HT
B) Hh
C) HhTt
D) Tt
E) H
11.) An organisms appearance or observable traits are referred to as its
A) genotype
B) phenotype
C) character
D) trait
E) dominant allele
12.) Which of the following statements is true?
A) The closer two genes are on a chromosome, the lower the probability of a crossing over event will
occur between them,
B) The observed frequency of recombination of two genes that are on the same chromosome has a
maximum value of 100%
C) All of the traits that Mendel studied are due to linked genes
D) Linked genes are found on different chromosomes
E) Crossing over occurs during prophase II of meiosis
Figure 2
A
W
3
E
5
G
12
13.) Figure 2, is a map of 4 genes (A, W, E, and G) and their relative distances on a chromosome.
Between which 2 genes would you expect the highest frequency of recombination?
A) A and W
B) A and E
C) A and G
D) E and G
E) W and E
14.) Using Figure 2, between which two genes would you expect the lowest frequency of recombination?
A) W and E
B) A and W
C) A and G
D) E and G
E) W and G
15.) Mendel’ s law of independent assortment refers to
A) mitosis
B) alleles segregating during gamete production
C) the independent orientation of homologous chromosome pairs relative to each other
D) fertilization of the egg by an independent sperm
16). Which of the following statements is false about genetic drift?
a) Genetic drift is one cause of microevolution
b) Genetic drift is the random change in allele frequencies in a population
c) Genetic drift has a stronger affect on really small populations
d) Genetic drift can predict allelic frequencies of each generation
e) All statements are false
17). __________ isolation is an example of a prezygotic barrier where two species of trout
breed at different seasons.
a) Gametic
b) Temporal
c) Behavioral
d) Habitat
e) Mechanical
18.) If the allele frequencies in a population are A: 0.6 and a: 0.4. what is the frequency of the Aa
genotype if the population is in Hardy-Weinberg equilibrium?
A) 1.0
B) 0.52
C) 0.36
D) 0.48
19.) Using the same data what is the frequency of the AA genotype?
A) 1.0
B) 0.52
C) 0.36
D) 0.48
20.) Individuals from two lizard species can mate but the offspring are sterile. This is an example of a
A) pre-zygotic reproductive barrier
B) anatomical incompatibility
C) geographic isolation) post-zygotic reproductive barrier
Label all of the parts and
E) behavioral isolation
explain their importance.
How many chromosomes
does it have?
How many chromatids does it
have?
How many centromeres does
it have?
The Mitotic Cell Cycle:


H


Label each letter
What letters =
Interphase?
Mitosis?
What is G0, and
how would it fit
in?
How would a
circular
representation of
meiosis differ?
Compare and Contrast:
Mitosis:
Meiosis:
What stage do they both start out in?
How many divisions does a mitotic cell undergo?
How many division does a meiotic cell undergo?
What stages are unique to this type of cell division?
What stages are unique to this type of cell division?
Final Product: (Number cells? Ploidy? Relation to original
cell?)
Final Product: (Number? Ploidy? Relation to original cell?)
What human cells does this process produce? How
many autosomes/sex chromosomes?
What human cells does this process produce? How
many autosomes/ sex chromosomes?
What problems can arise?
What problems can arise?
Is genetic variation introduced? How?
Is genetic variation introduced? How?
How many combinations of daughter cells could
result from this meiotic division?
For a good animated overview of Mitosis and Meiosis visit: vcell.ndsu.nodak.edu/animations
Genetics:
Explain locus vs. gene vs. allele. Give an example.
What do the following letter combinations represent?
Are the following homozygous or heterozygous? How many gametes could each produce?
HH
Rr
EeGG
TtAa
RrHHTT
Punnett Square practice:
Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. Persons who are
heterozygous for albinism are carriers. Persons who are homozygous recessive have the disease.
If a person who does not have the disease and is not a carrier marries a carrier for the disease, what
is the chance they will have a child with the disease? What is the chance they will have a child
who is a carrier? Show the Punnett square to support your answer.
What are the parental genotypes: Are they hetero/homozygous?
How many different gametes can each parent produce?
Parent 1:
Parent 2:
Linkage vs. unlinked?
What causes two genes to be linked?
Given 2000 offspring, that would mean 500 of each of these phenotypic classes.
Say you make this mating, and your actual results look like this:
Long Green - 850
Long Blue - 150
Short Green - 150
Short Blue - 850
How does sex linkage differ from the linkage discussed above?
Fathers
Mothers
Evolution:
Explain what a theory is? How does it differ from a hypothesis?
Darwin's Theory: Who else proposed a similar theory?
Explain the two components of Darwin’s Theory.
Idea 1:
Idea 2:
Define a population in under 10 words. How does it integrate into Darwin’s ideas?
Hardy-Weinberg (Measuring Evolution):

What equations are helpful for measurement? What does each term stand for?

What are the 5 assumptions for Hardy Weinberg?
-How do we know when evolution is occurring? What may cause evolution to occur?
-What type of population is most likely to be in Hardy Weinberg Equilibrium?
Practice Problem:
Sickle-cell anemia is an interesting genetic disease. Normal homozygous individuals (SS) have normal
blood cells that are easily infected with the malaria parasite. Thus, many of these individuals become very
ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood
cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells,
individuals often die because of the genetic defect. However, individuals with the heterozygous condition
(Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition,
malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to
survive better than either of the homozygous conditions. If the sickle-cell allele (s) is present in the
population with a frequency of 0.3 what percentage of the population will be more resistant to malaria
because they are heterozygous (Ss) for the sickle-cell gene?
Macroevolution:
Speciation: What are the 3 steps?
Step 1:
Step 2:
Step 3:
How do allopatric and sympatric speciation differ?
What could be the result (there are a few) if you brought two populations back together?
BRIEFLY explain the Biological Species Concept? Morphological Species Concept? Phylogenetic Species
Concept?
Pre-zygotic barriers
Post-zygotic barriers
What is the primary difference between these two categories?
What is it?
Incomplete Dominance
Multiple Alleles
Pleiotropy
Examples?