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In human DNA, adenine (A) makes up approximately 30.9% of the bases, and guanine (G) makes up approximately 19.9% of the bases; therefore the percentage thymine (T) and cytosine (C) are

1. 29.4% T and 19.8% C
2. 29.8% T and 29.8% C
3. 19.8% T and 19.8% C
4. 19.8% T and 29.4% C

✅ Correct Answer: 1

If the chromosomes of a eukaryotic cell were lacking telomerase, the cell would

1. have a greater potential to become cancerous than one with telomerase
2. become increasingly shorter with each cycle of replication
3. not produce okazaki fragments
4. be unable to take up extraneous DNA from the surrounding solution

✅ Correct Answer: 2

Which of the following statements concerning transcription and translation in eukaryotic cells is NOT correct?

1. Transcription results in the production of mRNA, whereas translation results in the production of polypeptides
2. Transcription occurs in the nucleus, whereas translation occurs in the cytoplasm
3. Transcription uses DNA as a template, whereas translation uses mRNA as a template
4. Transcription results in the production of polypeptides, whereas translation results in the production of mRNA

✅ Correct Answer: 4

The open, less compacted form of DNA that is available for transcription is known as the

1. chromatin
2. heterochromatin
3. promotor
4. euchromatin

✅ Correct Answer: 4

A sequence on a DNA molecule that recognizes specific transcription factors that can stimulate transcription of nearby genes is known as the

1. promotor
2. operator
3. enhancer
4. euchromatin

✅ Correct Answer: 3

During the stage in which insertion of eukaryotic DNA into the plasmid vector occurs, the sticky ends formed by digestion of both DNA types with the same restriction enzyme may join in a recombinant molecule because

1. the eukaryotic DNA and plasmid DNA will have the same sequence
2. the eukaryotic DNA and plasmid DNA will have complementary sequences
3. the plasmid DNA can join with any eukaryotic DNA, regardless of sequence
4. the plasmid DNA and the eukaryotic DNA cannot join together due to differences in the structure of their DNA molecules

✅ Correct Answer: 2

Which of the following statements is NOT true of restriction enzymes?

1. Restriction enzymes protect their bacterial host against intruding foreign DNA from viruses or other bacterial cells
2. Most restriction enzymes are named after the bacterial organism from which they were first isolated
3. Each restriction enzyme recognizes a specific sequence of bases on the DNA molecule
4. Each restriction enzyme cuts at random locations along the DNA molecule

✅ Correct Answer: 4

The uptake of naked DNA from solution by bacterial cells is known as

1. transcription
2. electroporation
3. transduction
4. transformation

✅ Correct Answer: 4

The classification of organisms into kingdoms has come under debate in recent years, with most of the debate focused on the

1. algae and fungi
2. prokaryotes and simple eukaryotes
3. algae and plants
4. fungi and plants

✅ Correct Answer: 2

n the steps leading up to the origin of life on earth, early protobionts could not have evolved into living cells without both

1. competition for resources and the development of hereditary mechanisms
2. a semipermeable membrane and a nucleus
3. a semipermeable membrane and the ability to catalyze chemical reactions
4. a nucleus and the ability to catalyze chemical reactions

✅ Correct Answer: 1

Which of the following statements about the lac operon is NOT true?

1. RNA polymerase can be blocked by an active repressor protein attached to the operator
2. RNA polymerase attaches at a site on the DNA strand, known as the promoter
3. There is a regulatory gene that is downstream from the structural genes that can inhibit transcription
4. The regulatory gene produces the active repressor

✅ Correct Answer: 3

Which of the following statements about the HIV virus is NOT true?

1. The viral nucleotides contain ribose
2. HIV contains uracil, not thymine
3. HIV infection begins with the entrance of the virus into the host when the gp 120 and gp 41 function to pull the virus across the plasma membrane
4. HIV makes the host cell produce reverse transcriptase

✅ Correct Answer: 4

All of the following are means of posttranscriptional control in eukaryotes EXCEPT

1. the capping of the 58 end with a modified guanosine triphosphate
2. the addition of a poly-A tail to the 38 end
3. the cutting out of introns by a spliceosome
4. the ligation of exons by DNA polymerase

✅ Correct Answer: 4

Which of the following statements is NOT true concerning restriction fragment length polymorphisms (RFLPs)?

1. Suspects whose fragments do not match any other fragments at a crime scene can be vindicated
2. The polymerase chain reaction can be used to produce more copies of DNA obtained at a crime scene before RFLP analysis
3. Most RFLPs use radioactive probes
4. With the advent of PCR technology, restriction enzymes are no longer needed to perform RFLP analysis

✅ Correct Answer: 4

The number of tRNA molecules required by eukaryotic organisms to ferry around the amino acids is

1. 64
2. 63
3. 45
4. 23

✅ Correct Answer: 3

A student using a compound microscope with a 10X ocular lens and a 4X objective lens measured his field of view with a plastic ruler and found it to be 4 mm. He then placed some of his cheek cells on a slide, found them using the 4X objective lens and switched to the 40X objective lens. He counted twelve cells, side by side, that stretched from one side of the field of view to the other. What is the best estimate for the diameter of a cheek cell?

1. 0.033 mm
2. 0.132 mm
3. 0.0132 mm
4. 0.0033 mm

✅ Correct Answer: 1

In fruit flies, the gray body color is dominant to the black, and long wings are dominant to short. If you crossed a gray, short-winged fly to a black, long-winged fly and got 25 percent gray, long wing; 25 percent gray, short wing; 25 percent black, short wing; and 25 percent black, long wing, what were the genotypes of the parental flies?

1. Ggll and GgLl
2. Ggll and ggLl
3. GGll and ggLl
4. GGll and GgLl

✅ Correct Answer: 2

Which of the following statements about mitochondria is (are) true?

1. Mitochondria exist in all eukaryotes
2. Mitochondria exist in bacteria and plants
3. Mitochondria exist in animals, plants, and fungi
4. Both (A) and (C) are true

✅ Correct Answer: 4

The flowing cytoplasm of an active amoeba is

1. propelled by microfilaments for lipid synthesis
2. an adaptation for extracellular digestion
3. composed of microtubules and extracellular matrix
4. dependent on microfilaments for intracellular circulation

✅ Correct Answer: 4

In the earthworm, the efficiency of food absorption is increased by the presence of

1. the liver, which stores extra food in addition to making metabolic enzymes
2. the cecum, which stores unsuitable intake for excretion
3. infolds, which add surface area to the intestine
4. malphigian tubules, which increase the density of the food

✅ Correct Answer: 3

A consensus sequence is associated with __________, while a signal sequence is part of __________.

1. translation, hnRNAs
2. DNA, translation
3. transcription, a snurp
4. spliceosomes, translation

✅ Correct Answer: 4

One would expect to find steroid hormone receptors in the

1. plasma membrane
2. endoplasmic reticulum
3. nucleus
4. cytosol

✅ Correct Answer: 3

Select the correct order of events in a persons response to a bacterial infection:

1. macrophage ingestion – Helper T cell activation – B cell activation – clonal formation
2. clonal formation – Helper T cell activation – B cell activation – macrophage ingestion
3. macrophage ingestion – B cell activation – T helper cell activation – clonal formation
4. Helper T cell activation – B cell activation – macrophage ingestion – clonal formation

✅ Correct Answer: 1

People who have an extra X chromosome could have gotten it through

1. non-disjunction
2. transposition
3. transduction
4. crossing over

✅ Correct Answer: 1

The HIV virus infects mostly

1. complement cells
2. red blood cells
3. T-killer cells
4. T-helper cells

✅ Correct Answer: 4

Which of the following functions can be attributed to DNA polymerase?

1. It replaces RNA nucleotides with DNA nucleotides
2. It fixes errors in the replication of DNA
3. It ads nucleotides to the growing chain at the 3? end
4. All of the above are true

✅ Correct Answer: 4

During translation, the first amino acid

1. occupies the aminyl site first, then the peptidyl site
2. occupies the aminyl site before the attachment of the large portion of the ribosome
3. of the polypeptide chain is methionine
4. all of the above

✅ Correct Answer: 3

A signal sequence

1. is a sequence of DNA that begins transcription
2. is a sequence of RNA that is spliced out in the nucleus
3. is a sequence of DNA that directs a protein to certain organelles
4. is a sequence of DNA that attracts transcription factors

✅ Correct Answer: 3

Northern blotting is used with

1. DNA
2. RNA
3. hnRNA
4. ssDNA

✅ Correct Answer: 2

One would expect to find reverse transcriptase in

1. the plasmids of competent cells
2. retrovisuses
3. purple sulfur bacteria
4. archaebacteria

✅ Correct Answer: 4

The target tissue for parathyroid hormone is (are) the

1. kidneys
2. bones
3. small intestine
4. all of the above

✅ Correct Answer: 4

The products of oxidative phosphorylation are

1. oxygen and water
2. NADH and ATP
3. water and ATP
4. pyruvate and NADPH

✅ Correct Answer: 3

A major difference between gram positive and gram negative bacteria is that the former has

1. a liposaccharide outer covering with a small peptidoglycan component in the cell wall
2. a small peptidoglycan component covering a large liposaccharide base
3. a large peptidoglycan component in the cell wall
4. a cell wall composed of liposaccharide and chitin

✅ Correct Answer: 3

Let X represent an atom and X* its radioactive isotope. Assume both are taken up by living organisms. If the half-life of X* is 4,000 years, how much X* will be present in the remains of an organism that is 16,000 years old

1. as much as a living organism
2. 4 times as much
3. one-fourth as much
4. one-sixteenth

✅ Correct Answer: 4

All of our cells contain protooncogenes that may turn into oncogenes, which are cancer genes. The best explanation for protooncogenes is that they

1. came into our cells from a viral infection of our ancestors
2. arose from plasmids that have been inserted into bacteria and now reside in us
3. are DNA junk with no known function
4. help regulate cell division

✅ Correct Answer: 4

In genetic engineering, it is necessary to cut DNA out of bacteria and eukaryotes. To insert the human insulin gene into a bacteria, one should use

1. two different restriction enzymes so that the pieces would not reanneal
2. the same restriction enzyme so that both pieces will have the same sticky ends
3. methylated bacterial DNA so that only some of it will be spliced
4. two different ligases to reanneal the DNA

✅ Correct Answer: 2

Watson and Crick used all of the following information in elucidating the physical structure of DNA EXCEPT

1. the Meselson-Stahl experiment
2. X-ray crystallography
3. Chargoffs rules
4. the different sizes of purines and pyrimidines

✅ Correct Answer: 1

Which of the following organelles is out of order from an endomembrane point of view?

1. nucleus
2. vesicles
3. golgi apparatus
4. endoplasmic reticulum

✅ Correct Answer: 4

The products of the light reactions, or photophosphorylation, in photosynthesis are

1. oxygen and water
2. oxygen and ATP
3. oxygen, ATP, and NADPH
4. water, ATP, and NADPH

✅ Correct Answer: 3

__________ refers to one gene affecting many traits.

1. Polygenesis
2. Pleiotropy
3. Linkage
4. Epistasis

✅ Correct Answer: 2

Which of the following blood types are possible if the parents are A and O blood types?

1. A and O
2. B and O
3. AB only
4. O only

✅ Correct Answer: 1

The portion of the DNA molecule that can vary is its

1. sugar
2. base
3. deoxyribose
4. ribose

✅ Correct Answer: 2

An mRNA is 429 nucleotides long. The number of amino acids in the polypeptide chain formed from this mRNA is

1. 143
2. 142
3. 141
4. 429

✅ Correct Answer: 2

Which of the following is NOT consistent with Griffith�s experiments?

1. injected mixture of R-strain and live S-strain: mouse dies
2. injected S-strain: mouse dies
3. injected heat-killed S-strain: mouse lives
4. injected mixture of heat-killed S-strain and live R-strain: mouse lives

✅ Correct Answer: 4

Which of the following is a semi-conservative process?

1. DNA replication
2. non-disjunction
3. translation
4. transcription

✅ Correct Answer: 1

Which of the following is true about enzymes?

1. They always work alone
2. They are consumed in a reaction
3. They are amino acid polymers
4. They always require a coenzyme

✅ Correct Answer: 3

Which of the following has a vitamin as a building block?

1. apoenzyme
2. alloenzyme
3. metallic ion
4. coenzyme

✅ Correct Answer: 4

Which enzyme would the microbes in the gut of a termite need to have in order to metabolize the cell walls of the wood that termites eat?

1. cellulase
2. esterase
3. protease
4. pepsin

✅ Correct Answer: 1

The reds, oranges, and yellows of the leaves of deciduous trees that become evident in the fall are from

1. carotenoids
2. ATP
3. leaf decay
4. chlorophylls

✅ Correct Answer: 1

Which of the following base substitution mutations in the mRNA above would have the least effect on the resulting polypeptide?

1. substitution of UCC for UUC in Phe
2. substitution of CAA for CCA in Pro
3. substitution of CAC for CAG in Gln
4. substitution of GGA for GGU in Gly

✅ Correct Answer: 4

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SAT BIOLOGY MCQ SET 3