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Genetics

Modified True/False
Indicate whether the statement is true or false.  If false, change the identified word or phrase to make the statement true.
 

 1. 
Mendel discovered predictable patterns in the inheritance of traits. _________________________

 

 2. 
Garden peas are difficult to grow because they mature slowly. _________________________

 

 3. 
When Mendel cross-pollinated two varieties from the P generation that exhibited contrasting traits, he called the offspring the second filial, or F2, generation. _________________________

 

 4. 
The contrasting forms of each character studied by Mendel appeared in a 3:1 ratio in the F2 generation. _________________________

 

 5. 
A dominant allele masks the effect of a recessive allele. _________________________

 

 6. 
The allele for a recessive trait is usually represented by a capital letter. _________________________

 

 7. 
Heterozygous individuals have two of the same alleles for a particular gene. _________________________

 

 8. 
The inheritance of sex-linked traits can be studied by making a pedigree of several generations of a family. _________________________

 
 
nar001-1.jpg
 

 9. 
Refer to the illustration above. The father listed in the pedigree is most likely heterozygous for the trait. _________________________

 

 10. 
Refer to the illustration above. Child #3 probably has the dominant phenotype. _________________________

 

 11. 
Albinism is caused by a recessive allele. _________________________

 

 12. 
The phenotype that results from an inherited pair of alleles depends on the instructions in the genes only. _________________________

 

 13. 
Traits for different characters that are usually inherited together are said to be combined. _________________________

 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 14. 
The passing of traits from parents to offspring is called
a.
genetics.
c.
development.
b.
heredity.
d.
maturation.
 

 15. 
The difference between Mendel’s experiments in the area of heredity and those done by earlier researchers was that
a.
earlier researchers did not have microscopes.
b.
earlier researchers used detailed and numerical procedures.
c.
Mendel expressed the results of his experiments in terms of numbers.
d.
Mendel used pea plants with both purple and white flowers.
 

 16. 
The scientific study of heredity is called
a.
meiosis.
c.
genetics.
b.
crossing-over.
d.
pollination.
 

 17. 
The “father” of genetics was
a.
A. Knight.
c.
Gregor Mendel.
b.
Hans Krebs.
d.
Charles Darwin.
 

 18. 
Garden peas are good subjects for studying heredity because they
a.
are difficult to grow.
c.
produce few offspring.
b.
mature quickly.
d.
have few traits.
 

 19. 
Mendel obtained his P generation by allowing the plants to
a.
self-pollinate.
c.
assort independently.
b.
cross-pollinate.
d.
segregate.
 

 20. 
Step 1 of Mendel’s garden pea experiment, allowing each variety of garden pea to self-pollinate for several generations, produced the
a.
F1 generation.
c.
P generation.
b.
F2 generation.
d.
P1 generation.
 

 21. 
F2 : F1 ::
a.
P : F1
c.
F1 : P
b.
F1 : F2
d.
P : F2
 

 22. 
An allele that is always expressed whenever it is present is called
a.
dominant.
c.
recessive.
b.
phenotypic.
d.
superior.
 

 23. 
The discovery of chromosomes provided a link between the first law of heredity that stemmed from Mendel’s work and
a.
pollination.
c.
mitosis.
b.
inheritance.
d.
meiosis.
 

 24. 
The law of segregation states that
a.
alleles of a gene separate from each other during meiosis.
b.
different alleles of a gene can never be found in the same organism.
c.
each gene of an organism ends up in a different gamete.
d.
each gene is found on a different molecule of DNA.
 

 25. 
Mendel’s law of segregation states that
a.
pairs of alleles are dependent on one another when separation occurs during gamete formation.
b.
pairs of alleles separate independently of one another after gamete formation.
c.
each pair of alleles remains together when gametes are formed.
d.
the two alleles for a trait segregate independently when gametes are formed.
 

 26. 
The phenotype of an organism
a.
is used to represent its genetic composition.
b.
is the physical appearance of a trait.
c.
occurs only in dominant individuals.
d.
cannot be seen.
 

 27. 
If an individual possesses two recessive alleles for the same trait, the individual is said to be
a.
homozygous for the trait.
c.
heterozygous for the trait.
b.
haploid for the trait.
d.
mutated.
 

 28. 
When an individual heterozygous for a trait is crossed with an individual homozygous recessive for the trait, the offspring produced will
a.
all have the same genotype.
b.
show two different phenotypes.
c.
show three different phenotypes.
d.
all have the same phenotype.
 

 29. 
Tallness (T) is dominant to shortness (t) in pea plants. Which of the following represents a genotype of a pea plant that is heterozygous for tallness?
a.
T
c.
Tt
b.
TT
d.
tt
 

 30. 
homozygous : heterozygous ::
a.
heterozygous : Bb
c.
probability : chance
b.
gg : Gg
d.
factor : gene
 

 31. 
Mendel’s finding that the inheritance of one trait had no effect on the inheritance of another became known as the
a.
law of dominance.
b.
law of universal inheritance.
c.
law of separate convenience.
d.
law of independent assortment.
 
 
In humans, having freckles (F) is dominant to not having freckles (f). The inheritance of these traits can be studied using a Punnett square similar to the one shown below.
nar002-1.jpg
 

 32. 
Refer to the illustration above. The child represented in box 1 in the Punnett square would
a.
be homozygous for freckles.
b.
have an extra freckles chromosome.
c.
be heterozygous for freckles.
d.
not have freckles.
 

 33. 
Refer to the illustration above. The parents shown in the Punnett square could have children with a phenotype ratio of
a.
1:2:1.
c.
3:1.
b.
4:0.
d.
2:2.
 

 34. 
Refer to the illustration above. Which box in the Punnett square represents a child who does not have freckles?
a.
box 1
c.
box 3
b.
box 2
d.
box 4
 

 35. 
Refer to the illustration above. The child in box 3 of the Punnett square has the genotype
a.
FF.
c.
ff.
b.
Ff.
d.
FfFf.
 
 
In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.

nar003-1.jpg
 

 36. 
Refer to the illustration above. The device shown, which is used to determine the probable outcome of genetic crosses, is called a
a.
Mendelian box.
c.
genetic graph.
b.
Punnett square.
d.
phenotypic paradox.
 

 37. 
Refer to the illustration above. Both of the parents in the cross are
a.
black.
c.
homozygous dominant.
b.
brown.
d.
homozygous recessive.
 

 38. 
Refer to the illustration above. The phenotype of the offspring indicated by box 3 would be
a.
brown.
c.
a mixture of brown and black.
b.
black.
d.
white.
 

 39. 
Refer to the illustration above. The genotypic ratio of the F1 generation would be
a.
1:1.
c.
1:3.
b.
3:1.
d.
1:2:1.
 

 40. 
What is the expected genotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?
a.
1:0
c.
1:2:1
b.
1:1
d.
1:3:1
 

 41. 
What is the expected genotypic ratio resulting from a heterozygous ´ heterozygous monohybrid cross?
a.
1:2:1
c.
1:2
b.
1:3:1
d.
1:0
 

 42. 
What is the expected phenotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?
a.
1:3:1
c.
2:1
b.
1:2:1
d.
1:0
 

 43. 
The unknown genotype of an individual with a dominant phenotype can be determined using a
a.
ratio.
c.
probability formula.
b.
dihybrid cross.
d.
test cross.
 

 44. 
What is the probability that the offspring of a homozygous dominant individual and a homozygous recessive individual will exhibit the dominant phenotype?
a.
0.25
c.
0.66
b.
0.5
d.
1.0
 

 45. 
Probability is calculated by dividing the number of one kind of possible outcome by the
a.
number of other kinds of outcomes.
b.
total number of all possible outcomes.
c.
number of genes being considered.
d.
total number of offspring produced.
 

 46. 
If a characteristic is sex-linked, the gene for it is found on
a.
a sex chromosome.
c.
a linked chromosome.
b.
an autosome.
d.
an allele.
 

 47. 
Since the allele for colorblindness is located on the X chromosome, colorblindness
a.
cannot be inherited.
c.
is sex-linked.
b.
occurs only in adults.
d.
occurs only in females.
 

 48. 
A diagram in which several generations of a family and the occurrence of certain genetic characteristics are shown is called a
a.
Punnett square.
c.
pedigree.
b.
monohybrid cross.
d.
family karyotype.
 

 49. 
In humans, eye color and height are controlled by
a.
simple dominance.
c.
polygenic inheritance.
b.
multiple alleles.
d.
incomplete dominance.
 

 50. 
Which of the following traits is controlled by multiple alleles in humans?
a.
eye color
c.
colorblindness
b.
blood type
d.
albinism
 

 51. 
What would be the blood type of a person who inherited an A allele from one parent and an O allele from the other?
a.
type A
c.
type AB
b.
type B
d.
type O
 

 52. 
Which of the following is not an outcome of the environment modifying a phenotype?
a.
the changing of the color of an animal’s fur as the temperature changes
b.
the increased intelligence of a person who attended school for many years
c.
the very short stature of a kind of tree that grows at a high altitude in comparison with the same kind of tree growing at a lower altitude
d.
the pink-flowered snapdragons that result from crosses between red-flowered and white-flowered snapdragon plants
 

 53. 
Genes that are close together on a single chromosome are considered to be
a.
alleles.
c.
independent.
b.
homozygous.
d.
linked.
 



 
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