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Cells and Heredity Chapter 3 Study Guide



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

1. 

When Mendel crossed purebred short plants with purebred tall plants, all of the offspring were short. _________________________

 

2. 

A pea plant that is heterozygous for tall stems has the alleles Tt. _________________________

 

3. 

An organism’s physical appearance is its phenotype. _________________________

 

4. 

The sex cells produced by meiosis have twice the number of chromosomes as the parent cells. _________________________

 

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

5. 

What did Gregor Mendel do to study different characteristics in his genetics experiments?
a.
He studied only asexual animals.
b.
He studied only self-pollinating plants.
c.
He cross-pollinated plants.
d.
He cross-pollinated animals.
 

6. 

In Mendel’s experiments, what proportion of the plants in the F2 generation had a trait that had been absent in the F1 generation?
a.
none
b.
one fourth
c.
half
d.
three fourths
 

7. 

Factors that control traits are called
a.
genes.
b.
purebreds.
c.
recessives.
d.
parents.
 

8. 

Scientists call an organism that has two different alleles for a trait a
a.
hybrid.
b.
trait.
c.
purebred.
d.
factor.
 

9. 

What does the notation TT mean to geneticists?
a.
two dominant alleles
b.
two recessive alleles
c.
at least one dominant allele
d.
one dominant and one recessive allelle
 

10. 

What does the notation Tt mean to geneticists?
a.
two dominant alleles
b.
two recessive alleles
c.
at least one recessive allele
d.
one dominant allele and one recessive allelle
 

11. 

What is probability?
a.
the actual results from a series of events
b.
the likelihood that a particular event will occur
c.
the way the results of one event affect the next event
d.
the number of times a coin lands heads up
 

12. 

What did Mendel predict was the probability of producing a tall plant from a genetic cross of two hybrid tall plants?
a.
one in four
b.
two in four
c.
three in four
d.
four in four
 

13. 

What does a Punnett square show?
a.
all the possible outcomes of a genetic cross
b.
only the dominant alleles in a genetic cross
c.
only the recessive alleles in a genetic cross
d.
all of Mendel’s discoveries about genetic crosses
 

14. 

If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that an offspring will have black fur?
a.
25 percent
b.
50 percent
c.
75 percent
d.
100 percent
 

15. 

An organism’s physical appearance is its
a.
genotype.
b.
phenotype.
c.
codominance.
d.
heterozygous.
 

16. 

What does codominance mean in genetics?
a.
Both alleles are dominant.
b.
Both alleles are recessive.
c.
The alleles are neither dominant nor recessive.
d.
Each allele is both dominant and recessive.
 

17. 

What happens during meiosis?
a.
Each sex cell loses half of its chromosomes.
b.
Chromosome pairs separate to form new sex cells.
c.
Each sex cell copies itself to form four new chromosomes.
d.
Chromosome pairs remain together when new sex cells are formed.
 

18. 

When sex cells combine to produce offspring, each sex cell will contribute
a.
one fourth of the normal number of chromosomes.
b.
half the normal number of chromosomes.
c.
the normal number of chromosomes.
d.
twice the normal number of chromosomes.
 

19. 

What is the genetic code?
a.
the order of nitrogen bases along a gene
b.
the number of nitrogen bases in a DNA molecule
c.
the order of amino acids in a protein
d.
the number of guanine and cytosine bases in a chromosome
 

20. 

What does messenger RNA do during protein synthesis?
a.
copies the coded message from the DNA and carries it into the cytoplasm
b.
copies the coded message from the DNA and carries it into the nucleus
c.
carries amino acids and adds them to the growing protein
d.
copies the coded message from the protein and carries it into the nucleus
 

21. 

What do transfer RNA molecules do during protein synthesis?
a.
copy the coded message from the protein and carry it into the nucleus
b.
copy the coded message from the DNA and carry it into the nucleus
c.
carry amino acids and add them to the growing protein
d.
copy the coded message from the DNA and carry it into the cytoplasm
 

22. 

What is a mutation?
a.
any change that is harmful to an organism
b.
any change in a gene or chromosome
c.
any change that is helpful to an organism
d.
any change in the phenotype of a cell
 

23. 

A mutation is harmful to an organism if it
a.
changes the DNA of the organism.
b.
changes the phenotype of the organism.
c.
reduces the organism’s chances for survival and reproduction.
d.
makes the organism better able to avoid predators.
 

24. 

The different forms of a gene are called
a.
alleles.
b.
factors.
c.
masks.
d.
traits.
 

25. 

Where does protein synthesis take place?
a.
in the ribosomes in the nucleus of the cell
b.
on the ribosomes in the cytoplasm of the cell
c.
in the chromosomes in the nucleus of the cell
d.
on the chromosomes in the cytoplasm of the cell
 

26. 

What does the notation tt mean to geneticists?
a.
two dominant alleles
b.
two recessive alleles
c.
at least one dominant allele
d.
one dominant and one recessive allelle
 

27. 

An organism’s genotype is its
a.
genetic makeup
b.
feather color
c.
physical appearance
d.
stem height
 

28. 

Which nitrogen base in RNA is NOT part of DNA?
a.
adenine
b.
guanine
c.
cytosine
d.
uracil
 

29. 

An organism that has two identical alleles for a trait is
a.
codominant.
b.
tall.
c.
homozygous.
d.
heterozygous.
 

30. 

A heterozygous organism has
a.
three different alleles for a trait.
b.
two identical alleles for a trait.
c.
only one allele for a trait.
d.
two different alleles for a trait.
 

Completion
Complete each sentence or statement.
 

31. 

The offspring of a ____________________ plant will always have the same alleles for a trait as the parent.
 

 

32. 

If D represents the dominant allele of a gene, then ____________________ represents the recessive allele.
 

 

33. 

A chart used to predict results of genetic crosses is known as a(n) ____________________.
 

 

34. 

In a cross between two hybrid Tt pea plants, ____________________ percent of the offspring will be Tt.
 

 

Short Answer
 
 
Use the diagram to answer each question.

cell_hered_ch_3_stu_files/i0390000.jpg
 

35. 

Identify structure A and state what it is made of.
 

36. 

Identify structures B and C.
 

37. 

Identify structure D and state where it is made.
 

38. 

Identify structure E and describe its function.
 

39. 

What are the three nitrogen bases in transfer RNA that pair with bases A-G-U in messenger RNA?
 

40. 

If one of the nitrogen bases on structure D were replaced by a different base, what effect might that have on protein synthesis?
 



 
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