AnswersPMHS Biology I Q2Asexual and Sexual Reproduction

Asexual and Sexual Reproduction — Unit test Answers

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1
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Consider the diagram.Which process is represented?

Question illustration
A
nondisjunction
B
translocation
C
inversion
D
insertion
2
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Which diagram correctly shows how homozygous alleles are found on homologous chromosomes?

A
A chromosome is labeled Upper A a.
Option A
B
A chromosome is labeled a a.
Option B
C
2 chromosomes are labeled Upper A and a.
Option C
D
2 chromosomes are labeled a and a.
Option D
3

A mutation causes a sequence of DNA that has the nucleotides TTG to be changed to TCG. The resulting protein has a different sequence of amino acids. Which type of mutation is this?

A
missense
B
nonsense
C
silent
D
frameshift
4

What does a karyotype show?

A
genetic abnormalities
B
relationships among family members
C
carriers of a genetic disorder in a family
D
alleles on each chromosome
5

A strand of DNA contains the bases adenine, cytosine, cytosine, and guanine, in that order. Which would be the order of the bases on the opposite strand of DNA?

A
cytosine, adenine, adenine, and thymine
B
cytosine, thymine, thymine, and adenine
C
thymine, guanine, guanine, and cytosine
D
thymine, adenine, adenine, and cytosine
6

Francois Jacob and Jacques Monod studied Escherichia coli (E. coli) bacteria by using lab experimentation. What revision to their initial hypothesis did they come up with?

A
The lac operon is repressed by allolactose.
B
E. coli are unable to process lactose sugar.
C
All E. coli operons are always turned on.
D
Two operons regulate gene control in E. coli.
7

What does DNA provide the code for?

A
nitrogenous base pairing
B
protein synthesis
C
deoxyribose formation
D
nucleotide synthesis
8

Fragile X syndrome, characterized by mental retardation, is caused by which chromosomal change?

A
deletion
B
translocation
C
inversion
D
insertion
9

Missense, nonsense, and silent mutations are examples of which type of mutation?

A
substitution
B
insertion
C
deletion
D
replication
10

Which agent would cause the least damage to a chromosome?

A
radiation
B
X-rays
C
chemicals
D
ultrasound
11

Which is an agent that causes a mutation in DNA or chromosomes?

A
nondisjunction
B
karyotype
C
mutagen
D
phenotype
12

Which does not occur during translation?

A
tRNA pairs with complementary mRNA.
B
Met-tRNA binds to the start codon.
C
DNA is transcribed into a complementary strand of mRNA.
D
A chain of amino acids, linked by peptide bonds, is formed.
13

Which best describes a gene?

A
the short arm of a chromosome
B
tightly coiled strands of DNA
C
the center of a chromosome
D
a segment of chromosomal DNA
14

The structure of DNA resembles a twisted ladder. Which structural components form the rungs of the ladder?

A
deoxyribose sugars
B
phosphate groups
C
nitrogenous base pairs
D
ribosomes
15

Which base is found only in DNA?

A
adenine
B
guanine
C
cytosine
D
thymine
16

Which accurately describes the relationship between cancer risk and exposure to mutagens?

A
Cancer risk decreases when a person is exposed to mutagens because the risk of DNA mutation decreases as well.
B
Cancer risk increases when a person is exposed to mutagens because the risk of DNA mutations increases as well.
C
Cancer risk increases when a person is exposed to mutagens because the risk of DNA mutations decreases considerably.
D
Cancer risk decreases when a person is exposed to mutagens because the risk of DNA mutations increases considerably.
17

Which step in transcription occurs first?

A
mRNA moves the code from the nucleus to the ribosome for protein production.
B
A gene is expressed through protein production.
C
RNA polymerase attaches to the promoter.
D
A repressor protein must attach to the operator.
18

Photo 51 is a picture of the structure of DNA that was used to create a model of DNA. Who created the photo?

A
James Watson and Francis Crick
B
Erwin Chargaff
C
Rosalind Franklin
D
Friedrich Miescher
19

A scientist observes a pair of separate chromosomes that have genes for the same trait arranged in the same order. However, some of the alleles for the genes are different. What is the scientist most likely observing?

A
homologous chromosomes with heterozygous alleles
B
homologous chromosomes with homozygous alleles
C
heterozygous chromosomes with heterozygous alleles
D
heterozygous chromosomes with homozygous alleles
20

Which of the following difference between DNA and RNA allows them to perform their unique functions?

A
DNA contains ribose, while RNA contains deoxyribose.
B
DNA is single-stranded, whereas RNA is double-stranded.
C
DNA contains thymine, while RNA contains uracil.
D
RNA is found only in the nucleus, while DNA is found only in the cytoplasm.

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