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Directed Reading B
Section: Traits and Inheritance
A GREAT IDEA
Circle the letter of the best answer for each question.
1. What is the ratio that Mendel found for dominant to recessive
traits?
a. 1 to 1
c. 3 to 1
b. 2 to 1
d. 4 to 1
2. What do scientists call instructions for an inherited trait?
a. alleles
c. albinism
b. phenotype
d. genes
3. What are the two forms of a gene called?
a. alleles
c. albinism
b. phenotype
d. genes
Phenotype
4. What is a phenotype?
a. an inherited problem
c. a recessive gene
b. a group of 10 alleles
d. the way an organism looks
5. What prevents hair, skin, and eyes from having any color?
a. alleles
c. ratio
b. albinism
d. probability
Genotype
6. What are both inherited alleles together called?
a. an organism
c. homozygous
b. a genotype
d. heterozygous
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Directed Reading B continued
Circle the letter of the best answer for each question.
7. What kind of plant has two dominant genes OR two recessive
genes?
a. an organism
c. homozygous
b. a genotype
d. heterozygous
8. What kind of plant has one dominant gene AND one recessive gene?
a. an organism
c. homozygous
b. a genotype
d. heterozygous
Punnett Squares
Use the table below to answer questions 9 through 12. For each
question, circle the letter of the best answer for each question.
p
p
P
Pp
Pp
P
Pp
Pp
9. Look at the table above. What is this table called?
a. P-grid
c. heredity map
b. dominance chart
d. Punnett square
10. What is a Punnett square used for?
a. to show recessive traits
c. to show dominant traits
b. to show possible offspring
d. to show homozygous alleles
11. Look at the table above. If purple flower color (P) is dominant,
what color will most of the offspring be?
a. purple
c. same number of purple and white
b. white
d. lavender (white and purple mix)
12. Look at the table above. What is the probability that the offspring
will be Pp?
a. 25%
c. 75%
b. 50%
d. 100%
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Directed Reading B continued
More Evidence for Inheritance
Circle the letter of the best answer for each question.
13. Which two combinations of genotypes are exactly the same?
a. PP and Pp
c. pp and Pp
b. Pp and pP
d. pP and pp
WHAT ARE THE CHANCES?
Probability
14. What is the chance of a parent with one green allele and one blue
allele giving a blue allele to an offspring?
a. 100% chance
b. 25% chance
c. 50% chance
d. 75% chance
Read the description. Then, draw a line from the dot next to each
description to the matching word.
•
•
•
•
15. the chance that something
will happen
16. how probability is usually
written
17. how to find probability
18. reason traits in pea plants
are easy to predict
a. multiply
b. only two choices
c. fraction or percent
d. probability
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Directed Reading B continued
MORE ABOUT TRAITS
Incomplete Dominance
Circle the letter of the best answer for each question.
19. What is it called when each allele has its own degree of influence?
a. incomplete dominance
b. complete dominance
c. cross-breeding
d. probability
One Gene, Many Traits
20. A white tiger’s blue eyes are an example of what?
a. first-generation characteristic
b. dominant trait
c. many genes influencing one trait
d. one gene influencing more than one trait
Many Genes, One Trait
21. How many genes determine human eye color?
a. none
b. at least two
c. 1,000
d. one
The Importance of Environment
22. What can influence traits besides genes?
a. height
b. albinism
c. environment
d. phenotype
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TEACHER RESOURCE
25. half the number of chromosomes that
26.
27.
28.
29.
30.
31.
32.
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34.
35.
36.
37.
38.
4.
5.
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25.
were present in the original cell
meiosis
genotype
sex chromosomes
two X chromosomes
one X and one Y chromosome
the X chromosome
the Y chromosome
They are more likely to have a
sex-linked disorder.
Answers will vary. Sample answer:
color blindness and hemophilia
pedigree
carrier
recessive
selective breeding
Directed Reading B
SECTION: MENDEL AND HIS PEAS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
B
B
D
C
A
C
B
B
C
A
dominant
recessive
D
B
A
Vocabulary and Section
Summary
SECTION: MENDEL AND HIS PEAS
1. heredity: the passing of genetic traits
from parent to offspring
2. dominant trait: the trait observed in
the second generation when parents
with different traits are bred
3. recessive trait: a trait that reappears in
the third generation after disappearing
in the second generation when parents
with different traits are bred.
SECTION: TRAITS AND INHERITANCE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
C
D
A
D
B
B
C
B
D
B
A
C
B
B
B
B
D
C
D
B
A
C
B
A
D
meiosis
X chromosomes
Y chromosome
hemophilia
pedigree
carriers
recessive
selective breeding
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
SECTION: TRAITS AND INHERITANCE
A
B
C
D
C
A
B
A
D
B
C
1. gene: one set of instructions for an
inherited trait
2. allele: one of the alternative forms of a
gene that governs a characteristic,
such as hair color
3. phenotype: an organism’s appearance
or other detectable characteristic
4. genotype: the entire genetic makeup of
an organism; also, the combination of
genes for one or more specific traits
5. probability: the likelihood that a
possible future event will occur in any
given instance of the event
SECTION: MEIOSIS
1. C
2. B
3. A
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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