bio sample exam

Question 1

From the perspective of the cell receiving the message, the three stages of cell
signaling are
a) the endocrine, local, and synaptic stages
b) signal reception, signal transduction, and cellular response
c) signal reception, nucleus disintegration, and new cell generation
d) the alpha, beta, and gamma stages
e) signal reception, cellular response, and cell division

Answer 1

b) signal reception, signal transduction, and cellular response

Question 2

In order to respond to a signal molecule, a target cell must have specific receptor
proteins for that chemical signal. Which of the following statements regarding
signal molecules and their receptors is correct?
a) Signal molecules that are hydrophobic have intracellular receptors
b) Signal molecules that are hydrophilic have intracellular receptors
c) Signal molecules that are hydrophobic have cell membrane receptors
d) Signal molecules that are hydrophilic have cell membrane receptors
e) Both a and d are correct

Answer 2

e) Both a and d are correct

Question 3

The signal-transduction pathway in animals that use epinephrine
a) involves activation of glycogen breakdown in liver and skeletal muscle cells
b) is a classic example of synaptic signaling
c) is a classic example of paracrine signaling
d) operates independently of hormone receptors on target cells

Answer 3

a) involves activation of glycogen breakdown in liver and skeletal muscle cells

Question 4

Arachidonic acid is the precursor of prostaglandins, a hormone-like substance that
intensify the sensation of pain. Non-steroidal anti-inflammatory drugs, such as
aspirin and ibuprofen reduce the production of prostaglandins by which of the
following mechanisms?
a) Inhibiting the enzyme cyclooxygenase
b) Preventing arachidonic release which limits prostaglandin production
c) Stabilizing membrane phospholipids and make them less accessible to
activated phospholipase
d) All of the above are true
e) All of the above are false

Answer 4

d) All of the above are true

Question 5

5) There is an increase in protein synthesis during this phase

Answer 5

G1 phase

Question 6

6) The shortest part of the cycle

Answer 6

Mitosis

Question 7

7) DNA is duplicated during this phase.

Answer 7

S phase

Question 8

8) Chromatin is phosphorylated

Answer 8

G2 phase

Question 9

9) Homologous chromosomes
a) may exchange parts during meiosis.
b) have alleles for the same characteristics even though the gene expression may
not be the same.
c) are in pairs, one chromosome of each pair from the father and one from the
mother.
d) pair up during metaphase I meiosis.
e) all of the above.

Answer 9

e) all of the above.

Question 10

10) During which phase of somatic cell cycle are two-chromatid chromosomes found?
a) from interphase through anaphase.
b) from G1 of interphase through metaphase.
c) from metaphase through telophase.
d) from anaphase through telophase.
e) from prophase through late metaphase.

Answer 10

e) from prophase through late metaphase.

Question 11

11) The phase in meiosis that cause the most variation in the four resulting daughter
cells is
a) metaphase II
b) telophase I
c) prophase I
d) anaphase II
e) Interphase

Answer 11

c) prophase I

Question 12

12) If there are 46 centromeres in a cell, how many chromosomes are there?
a) 10 b) 20 c) 30 d) 46 e) 80

Answer 12

d) 46

Question 13

13) If the haploid number for a species is 3, each dividing diploid cell will have how
many chromatids at metaphase I?
a) 3 b) 6 c) 9 d) 12 e) 18

Answer 13

d) 12

Question 14

14) How do cells at the completion of meiosis compare with the cell from which they
were derived?
a) They have twice the amount of cytoplasm and half the amount of DNA.
b) They have half the amount of chromosomes and half the amount of DNA.
c) They have the same number of chromosomes and half the amount of DNA.
d) They have the same number of chromosomes and the same amount of DNA.
e) They have half the amount of cytoplasm and twice the amount of DNA.

Answer 14

b) They have half the amount of chromosomes and half the amount of DNA.

Question 15

15) What is a human cell that contains 22 pairs of autosomes and two X
chromosomes?
a) an unfertilized egg cell b) a sperm cell c) a male somatic cell
d) a female somatic cell e) Both a and d are correct

Answer 15

d) a female somatic cell

Question 16

20) Mendel’s law of dominance could be represented by
3
a) TT X tt b) Tt X Tt c) Tt X tt d) tt X tt e) TT X TT

Answer 16

a) TT X tt

Question 17

21) Mendel’s law of segregation could be represented by
a) NN X nn b) Nn X Nn c) Nn X nn d) nn X nn e) NN X NN

Answer 17

b) Nn X Nn

Question 18

22) The F2 phenotypic ratio of a monohybrid cross is
a) 1:1 b) 2:1 c) 9:3:3:1 d) 1:2:1 e) 3:1

Answer 18

e) 3:1

Question 19

3) The usual F2 phenotypic categories of a dihybrid cross yields a ratio of
a) 1:1:1:1 b) 2:1 c) 9:3:3:1 d) 1:2:1 e) 1:1

Answer 19

c) 9:3:3:1

Question 20

24) Catalyzes synthesis of a new strand of DNA

Answer 20

d) DNA polymerase

Question 21

25) Unwinds the two strands of DNA during replication.

Answer 21

a) helicase

Question 22

26) Covalently connects segments of DNA

Answer 22

c) DNA ligase

Question 23

27) Synthesizes short segments of RNA primer.

Answer 23

e) primase

Question 24

28) The lagging strand of DNA is synthesized through the use of
a) base-paring b) replication is synthesized enzyme, helicase
c) Okazaki fragments d) topoisomerases

Answer 24

c) Okazaki fragments

Question 25

29) All of the following elements are present in DNA except a) oxygen b) nitrogen c) carbon d) sulfur e) phosphorus

Answer 25

d) sulfur

Question 26

30) What kind of chemical bonds are found between paired bases of the DNA double helix? a) hydrogen b) ionic c) covalent d) sulfhydryl e) phosphate

Answer 26

a) hydrogen

Question 27

31) Which of the following descriptions best fits the class of molecules known as nucleotides? a) a nitrogen base and a phosphate group only. b) a nitrogen base and a five-carbon sugar only. c) a nitrogen base, a phosphate group, and a five-carbon sugar. d) a five-carbon sugar, a phosphate group, and a purine. e) a pyrimidine, a purine, and a six-carbon sugar

Answer 27

c) a nitrogen base, a phosphate group, and a five-carbon sugar.

Question 28

32) What is the relationship among DNA, a gene, and a chromosome? a) A chromosome contains hundreds of genes which are composed of protein. b) A chromosome contains hundreds of genes which are composed of DNA c) A gene contains hundreds of chromosomes which are composed of proteins. d) A gene is composed of DNA, but there is no relationship to a chromosome. e) A gene contains hundreds of chromosomes which are composed of DNA

Answer 28

b) A chromosome contains hundreds of genes which are composed of DNA

Question 29

33) Which of the following gene products, if absent or defective, would prevent the functioning of the others? a) transfer RNA b) ribosomal RNA c) messenger RNA d) RNA polymerase e) aminoacyl-tRNA synthetase

Answer 29

d) RNA polymerase

Question 30

34) The designations 3' and 5' indicates that the a) 3' hydroxyl group of the sugar on one nucleotide is joined to the 5' hydroxyl group of the adjacent sugar by a phosphodiester bond. b) nitrogen atoms exist on the rings of purine or pyrimidine bases. c) cross-linking of the third and fifth carbon atoms of deoxyribose exist. d) bonding between purines and deoxyribose and between pyrimidines and deoxyribose. e) bonds that form between adenine and thymine and between guanine and cytosine are weak.

Answer 30

a) 3' hydroxyl group of the sugar on one nucleotide is joined to the 5' hydroxyl group of the adjacent sugar by a phosphodiester bond.

Question 31

35) Where is the attachment site of RNA polymerase? a) structural gene region b) initiation region c) promoter region d) operator region e) regulator region

Answer 31

c) promoter region

Question 32

36) What are the coding segments of a stretch of DNA called? a) introns b) exons c) codons d) replicon e) transposons

Answer 32

b) exons

Question 33

37) A particular eukaryotic protein is 300 amino acids long. If we disregard the introns, which of the following could be the number of nucleotides in the DNA that codes for this protein? a) 3 b) 100 c) 300 d) 900 e) 1800

Answer 33

d) 900

Question 34

38) If a fragmented sample of DNA is found to have the base composition of adenine, 40; thymine, 22; guanine, 19; and cytosine, 19, what conclusion can be drawn? a) The DNA is linear and double-stranded b) The DNA is single-stranded c) The DNA has highly repetitive sequences d) The DNA has a high melting point

Answer 34

b) The DNA is single-stranded

Question 35

39) All of the following are directly involved in translation except a) mRNA b) tRNA c) ribosomes d) DNA

Answer 35

d) DNA

Question 36

40) Once transcribed, eukaryotic hnRNA (or pre-mRNA) typically undergoes substantial alteration that includes a) excision of introns b) fusion into circular forms known as plasmids. c) linkage to histone molecules d) union with ribosomes. e) fusion with other newly transcribed mRNA

Answer 36

a) excision of introns

Question 37

41) The nitrogenous base adenine is found in which three of the following? a) proteins, triglycerides, and testosterone b) proteins, ATP, and DNA c) ATP, RNA, and genes d) alpha glucose, ATP, and DNA e) proteins, carbohydrates

Answer 37

c) ATP, RNA, and genes

Question 38

42) When a ribosome first attaches to a mRNA molecule, one tRNA binds to the ribosome. The tRNA that recognizes the initiation codon binds to the a) amino acid site (A site) of the ribosome only. b) peptide site (P site) of the ribosome only. c) large ribosomal subunit only. d) second tRNA before attaching to the ribosome. e) Both a and c are correct

Answer 38

b) peptide site (P site) of the ribosome only.

Question 39

43) As a ribosome translocates along a mRNA molecule by one codon, which of the following occurs? a) The transfer RNA that was in the A site moves into the P site. b) The tRNA that was in the P site moves into the A site. c) The tRNA that was in the P site departs from the ribosome. d) The tRNA that was in the A site departs from the ribosome. e) Both a and c are correct

Answer 39

e) Both a and c are correct

Question 40

44) Aminoacyl-tRNA synthetase catalyzes the attachment of a(n) a) amino acid to a tRNA b) amino acids to DNA c) amino acid to a ribosome d) ribosome to a mRNA

Answer 40

a) amino acid to a tRNA

Question 41

45) Choose the answer that has these events of protein synthesis in the proper sequence. 1) tRNA binds to the P site and the large ribosomal subunit binds the small one. 2) A peptide bond forms. 3) tRNA binds to the A site. 4) Small ribosomal subunit associates with mRNA. 5) Translocation and the ribosome advances three nucleotides. a) 1, 3, 2, 4, 5 b) 4, 1, 2, 5, 3 c) 5, 4, 3, 2, 1 d) 4, 1, 3, 2, 5 e) 2, 4, 5, 1, 3

Answer 41

d) 4, 1, 3, 2, 5

Question 42

46) A frameshift mutation could result from a) a base insertion only. b) a base deletion only. c) a base substitution only. d) deletion of three consecutive bases. e) either an insertion or deletion of a base

Answer 42

e) either an insertion or deletion of a base

Question 43

47) If an individual has an extra chromosome 21, they have a) Jacobs syndrome b) Downs syndrome c) Turner syndrome d) Klinefelter syndrome

Answer 43

b) Downs syndrome

Question 44

48) A permanent change in the structure of a chromosome that can be detected microscopically is termed a a) chromosome mutation b) chromosome deletion c) gene mutation d) gene addition e) nondisjunction

Answer 44

a) chromosome mutation

Question 45

49) If an individual has a XXY genotype, they are classified as having a) Down’s Syndrome b) Jacobs Syndrome c) Turners Syndrome d) Klinefelter Syndrome

Answer 45

d) Klinefelter Syndrome

Question 46

50) A person with an XO genotype is classified as having a) Down’s Syndrome b) Jacobs Syndrome c) Turners Syndrome d) Klinefelter Syndrome

Answer 46

c) Turners Syndrome

Question 47

51) A DNA molecule contains 30% adenine. How much cytosine does it have? (4 pts.)

Answer 47

20%

Question 48

52) a) How many hydrogen bonds link adenine and thymine? (2 pts.)

Answer 48

2

Question 49

b) How many hydrogen bonds link cytosine and guanine? (2 pts.)

Answer 49

3

Question 50

53) A mutation may be caused by a change in the base sequence of DNA. Some mutations are silent. Describe two types of mutations that might be silent. (4 pts.)

Answer 50

silent point mutation- A change in one DNA base that does not change the amino acid in the protein.This happens because some different codons can still code for the same amino acid. mutations in non-coding regions- A mutation that occurs in an intron does not affect gene expression or protein function.

Question 51

56) Correctly respond to the following questions on protein synthesis, by recording the phrase that describes each stage. a) Which stage in protein synthesis is the enzyme peptidyl transferase utilized? (2 pts.)

Answer 51

translation

Question 52

b) Which stage in protein synthesis is the protein modified? e.g., acquisition of carbohydrates, coenzymes, etc. (2 pts.)

Answer 52

folding and processing

Question 53

c) Which stage in protein synthesis is the enzyme aminoacyl-tRNA synthetase utilized? (2 pts.)

Answer 53

elongation

Question 54

d) Which stage in protein synthesis is the protein "release factor" utilized? (2 pts.)

Answer 54

termination and release

Question 55

e) Which stage in protein synthesis is the reading frame established? (2 pts.)

Answer 55

initiation

Question 56

EXTRA CREDIT QUESTIONS (6 pts.) 1) If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle fibers, at which stage will mitosis be arrested? a) Anaphase b) Prophase c) Telophase d) Metaphase e) Interphase

Answer 56

d) Metaphase

Question 57

EXTRA CREDIT QUESTIONS (6 pts.) 2) Which of the following is defined incorrectly? a) structural gene--codes for an amino acid sequence b) operator gene--acts as on/off switch c) eukaryotic gene--introns and exons d) ribosomes--rRNA and protein e) hnRNA--cytoplasm

Answer 57

e) hnRNA--cytoplasm

Question 58

3) The inability of homologous chromosomes to separate during meiosis is termed ____. a) linked genes b) disjunction c) nondisjunction d) cross-over 10

Answer 58

c) nondisjunction