1101 review for exam 3, Spring 2021

Question 1

The nucleotide sequence of a gene and the base sequence of the mRNA it codes for are not the same. Why?

Accepted Answer

Introns are present in the initial transcript but are then removed.

Question 2

Which of the following is the first event to take place in translation in eukaryotes?

Accepted Answer

the small subunit of the ribosome binds to the 5' cap of the mRNA.

Question 3

Each amino acid in a polypeptide is specified by a codon that consists of ________ nucleotide(s) in an RNA molecule.

Accepted Answer

3

Question 4

A cross between yellow and green peas has an F1 of all yellow peas. Crossing these F1 peas with green peas results in __

Accepted Answer

genotypic ratio of 1:1, phenotypic ratio of 1:1

Question 5

What is the best definition of a gene?

Accepted Answer

A DNA sequence that is expressed to form a protein or functional RNA

Question 6

Genetic differences between populations tend to be reduced by

Accepted Answer

gene flow

Question 7

In what ways does RNA synthesis differ from DNA synthesis?

Accepted Answer

All DNA is synthesized in S phase; not all DNA is transcribed to make RNA.

Question 8

Which of the following statements about nondisjunction is false?

Accepted Answer

In mammals, extra copies of the Y chromosome are typically inactivated.

Question 9

Nondisjunction occurs when

Accepted Answer

members of a chromosome pair fail to separate.

Question 10

Recessive X-linked traits are more likely to be expressed in a male fruit fly than a female fruit fly because

Accepted Answer

the male's phenotype resultsentirely from his single X-linked gene

Question 11

Mendel studied multiple traits in peas. What genetic term is used to describe an observable trait, such as seed color?

Accepted Answer

phenotype

Question 12

Which of the following statements about eukaryotic RNA is true?

Accepted Answer

Exons are spliced together

Question 13

Which of the following will tend to produce adaptive changes in populations?

Accepted Answer

natural selection

Question 14

Any change in the nucleotide sequence of DNA is called

Accepted Answer

a mutation

Question 15

Genetic drift resulting from a disaster that drastically reduces population size is called

Accepted Answer

the bottleneck effect

Question 16

Which of the following DNA mutations is most likely to damage the protein it specifies?

Accepted Answer

a base-pair deletion

Question 17

Which of the following mutations is most likely to cause a phenotypic change?

Accepted Answer

a single nucleotide deletion in an exon

Question 18

How do eukaryotic codons and prokaryotic codons compare?

Accepted Answer

Codons are a nearly universal language among all organisms.

Question 19

A 15-nucleotide sequence ending with a stop codon will direct the production of a polypeptide that consists of

Accepted Answer

4 amino acids

Question 20

Which of the following would most quickly be eliminated by natural selection?

Accepted Answer

a harmful allele in an asexual, haploid population

Question 21

Darwin found that many of the species on the Galápagos islands

Accepted Answer

resembled species on thenearest mainland

Question 22

A monohybrid cross is

Accepted Answer

matings between parents that differ in only one character.

Question 23

You cross an organism that is homozygous recessive with a heterozygote. How likely are homozygous recessive offspring?

Accepted Answer

50%

Question 24

If A is dominant to a and B is dominant to b, what is the expected phenotypic ratio of the cross: AaBb × AaBb?

Accepted Answer

9:3:3:1

Question 25

A frameshift mutation could NOT result from _____.

Accepted Answer

deletion of three consecutive bases

Question 26

What evidence is used to determine the branching sequence of an evolutionary tree?

Accepted Answer

anatomical or molecularhomologous structures

Question 27

Which of the following statements regarding Down syndrome is false?

Accepted Answer

It is least likely to be seen in the infants of mothers over 40.

Question 28

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This ratio suggests that _____.

Accepted Answer

the parents were both heterozygous for the particular trait

Question 29

Microevolution, or evolution at its smallest scale, occurs when

Accepted Answer

a population's allelefrequencies change over a span of generations

Question 30

The expression of both alleles for a trait in a heterozygous individual illustrates

Accepted Answer

codominance

Question 31

The frequency of homozygous dominant individuals in a population that is in Hardy-Weinberg equilibrium is equal to

Accepted Answer

p2

Question 32

The ultimate source of all new alleles is

Accepted Answer

mutation

Question 33

Both strands of the DNA are transcribed.

Accepted Answer

False

Question 34

Which one of the following statements about RNA processing is true? (select all correct)

Accepted Answer

A primary transcript is much longer than the final mRNA molecule., RNA processing can occur at the same time as transcription

Question 35

All offspring of a cross between black-eyed and orange-eyed mendelions have black eyes. Which is dominant?

Accepted Answer

black eyes

Question 36

If the codon is 5'-UUG-3', the anticodon on the tRNA that binds the codon is ________.

Accepted Answer

3'-AAC-5', 5'-CAA-3'

Question 37

Most people afflicted with recessive disorders are born to parents who were

Accepted Answer

not affected at all by the disease.

Question 38

In the genetic code,

Accepted Answer

many amino acids arespecified by more than one codon

Question 39

Where do transcription and translation occur in prokaryotic cells?

Accepted Answer

in the cytoplasm

Question 40

Ribosomes can attach to prokaryotic messenger RNA _____.

Accepted Answer

before transcription is complete

Question 41

Both strands of the DNA are replicated during S phase.

Accepted Answer

True

Question 42

A carrier of a genetic disorder who does not show symptoms is most likely to be ________ to transmit it to offspring.

Accepted Answer

heterozygous for the trait and able

Question 43

The first child of parents who are not albino (recessive trait) but have albino parents has a ___ chance of being albino

Accepted Answer

25%

Question 44

Which of the following statements would Darwin have disagreed with?

Accepted Answer

Speciation occurs through inheritance of acquired characteristics

Question 45

What amino acid sequence will be generated based on the following mRNA codon sequence? 5' AAC-AUG-UCU-UCG-UUA-UCC-UUG 3'

Accepted Answer

met-ser-ser-leu-ser-leu

Question 46

If tall is dominant to short, crossing a heterozygous plant with a homozygous tall plant will yield ____ short offspring

Accepted Answer

0%

Question 47

Which of the following best expresses the concept of natural selection?

Accepted Answer

differential reproductive success based on inherited characteristics

Question 48

A researcher inserts a mRNA into a eukaryotic cell after she has removed the 5' cap and 3' poly A tail. What happens?

Accepted Answer

The mRNA is digested by enzymes because it is not protected at the ends.

Question 49

The alleles of a gene are found at ________ chromosomes.

Accepted Answer

the same locus on homologous

Question 50

Which amino acid will be added to the 3' end of a tRNA with the anticodon 3'-AAG-5'?

Accepted Answer

phenylalanine

Question 51

Which of the following describes the central dogma of molecular biology?

Accepted Answer

DNA-->RNA-->protein

1101 review for exam 3, Spring 2021

Questions 51

1101 review for exam 3, Spring 2021

Questions 51