Biology homework help

Biology homework help. Instructions
Select the correct answer for the 70 multiple choice questions by highlighting the correct answer
 

1. Item 1

Enzymes:

1. increase the energy of activation for a reaction, thus increasing the reaction rate.
2. decrease the energy of activation for a reaction, thus decreasing the reaction rate.
3. increase ΔG for a reaction, thus increasing the reaction rate.
4. decrease the energy of activation for a reaction, thus increasing the reaction rate.
5. decrease ΔG for a reaction, thus increasing the reaction rate.

 

1. Item 2

Hemophilia is an X-linked recessive disorder involving blood clotting. If a Mr. Y, who is a hemophiliac, marries Mrs. Z, who is a carrier for hemophilia, and one of their daughters (Miss A, who is not a hemophiliac) marries a normal man (Mr. B), what is the probability that a grandson of Mr. Y and Mrs. Z is a hemophiliac?

1. 25% B. 50%  C. 75%  D. 100%  E. Cannot be determined from the information given

 

1. Item 3

All of the following could cause increases in resting blood pressure EXCEPT:

1. increased Na+ reabsorption by the kidney.
2. increased heart rate.
3. decreased dehydration.
4. caffeine.
5. None of the above.

 

1. Item 4

The functions of the liver include all of the following EXCEPT:

1. formation of blood proteins.
2. regulation of glycogen metabolism.
3. secretion of bile.
4. storage of vitamins.
5. secretion of bicarbonate.

 

1. Item 5

Osteoblasts, osteoclasts, and osteocytes are the three cell types found in bone tissue. Osteoclasts are activated by:

1. low blood Ca2+ levels and high parathyroid hormone levels.
2. low blood Ca2+ levels and high calcitonin levels.
3. high blood Ca2+ levels and high calcitonin levels.
4. high blood Ca2+ levels and high vitamin D levels.
5. low blood Ca2+ levels and low parathyroid hormone levels.

 

1. Item 6

Which hormone binds to a receptor on the cell surface?

1. Aldosterone
2. Progesterone
3. Cortisol
4. Adrenaline
5. Testosterone

 

1. Item 7

Which of the following RNA sequences would be transcribed if the sequence of the DNA coding strand were TATTGCATCAA?

1. UAUUGCAUCAA
2. AUAACGUAGUU
3. TTGUTGCUUTU
4. AUAAGCAUCAA
5. UUGAUCGUUAU

 

1. Item 8

The pentose phosphate pathway is involved in all of the following EXCEPT:

1. eliminating reactive oxygen species.
2. producing nucleotides.
3. facilitating fatty acid synthesis.
4. forming NADH.
5. generating ribose-5-phosphate.

 

1. Item 9

When blood pressure is low, the rate of blood filtration drops. The kidney secretes renin to help compensate. The direct effect that renin has in the body is to:

1. generally constrict arterioles to increase peripheral resistance.
2. convert the blood protein angiotensinogen into angiotensin I.
3. convert angiotensin I into angiotensin II, a powerful vasoconstrictor.
4. dilate the renal artery.
5. dilate the glomerular capillaries.

 

1. Item 10

In designing antibiotics to treat infections caused by facultative anaerobic bacteria in humans, the targets which would be most attractive are inhibitors of bacterial:

1. mRNA splicing.
2. electron transport.
3. poly-A addition for mRNAs.
4. transcription.
5. None of the above.

 

1. Item 11

A double homozygous dominant rabbit with bent ears and big feet is crossed with a double homozygous recessive rabbit with straight ears and small feet. One of the F1s is backcrossed to the double homozygous recessive parent producing an F2 generation with the following ratios of phenotypes: 15 rabbits with bent ears and big feet, 15 rabbits with straight ears and small feet, 5 rabbits with bent ears and small feet, and 5 rabbits with straight ears and big feet. What is the recombination frequency between the gene for ear position and the gene for foot size?

12. 12.5%
13. 25%
14. 33.3%
15. 50%
16. 66.7%

 

1. Item 12

During muscle contraction, which regions of the sarcomere shorten?

1. A band II. I band III. H band
2. II only
3. I and II only
4. II and III only
5. I and III only
6. I, II, and III

 

1. Item 13

Which cells in the testes are responsible for secretion of testosterone?

1. Sustentacular (Sertoli) cells
2. Spermatogonia
3. Supporting cells
4. Interstitial (Leydig) cells
5. None of the above secrete testosterone.

 

1. Item 14

What is the primary effect of transposons?

1. Generate mutations and chromosomal rearrangements
2. Facilitate recombination during meiosis
3. Provide protection against integration of lysogenic viruses
4. Increase the affinity of RNA polymerase binding to a promoter
5. Conduct DNA replication proofreading

 

1. Item 15

The volume of air that remains in the lungs after a complete expiration is called the:

1. residual volume.
2. expiratory reserve volume.
3. functional residual capacity.
4. vital capacity.
5. tidal volume.

 

1. Item 16

All of the following are methods by which bacteria can achieve genetic diversity EXCEPT:

1. conjugation.
2. binary fission.
3. transformation.
4. transduction.
5. recombination.

 

1. Item 17

The dendrites of a single postsynaptic neuron often form synapses with axons of many different presynaptic neurons. The combined input of all the presynaptic neurons ultimately determines whether the postsynaptic neuron will fire an action potential or not. This is known as:

1. facilitation.
2. integration.
3. cooperativity.
4. temporal summation.
5. spatial summation.

 

1. Item 18

A hospital has possibly switched the babies of Couples X and Y. Their blood types are as follows:
Couple X: type A and type A Baby 1: type O
Couple Y: type AB and type O Baby 2: type B
Which baby belongs to which couple?

1. Both babies belong to Couple Y.
2. Baby 1 belongs to Couple Y and Baby 2 belongs to Couple X.
3. Baby 1 belongs to Couple X, but Baby 2 could belong to either couple.
4. Baby 1 belongs to Couple X and Baby 2 belongs to Couple Y.
5. Baby 2 belongs to Couple Y, but Baby 1 does not belong to either couple.

 

1. Item 19

If red blood cells are placed in pure water, which of the following would occur?

1. The cells would swell due to the high osmotic pressure of the water.
2. The cells would shrink due to the high osmotic pressure of the cells.
3. The cells would neither shrink nor swell because red blood cells are isotonic to water.
4. The cells would swell because they are hypotonic to the water.
5. None of the above would occur.

 

1. Item 20

The net products of glycolysis per glucose molecule are:

1. 4 ATP, 2 NADH, 2 pyruvate
2. 2 ATP, 2 NADH, 2 pyruvate
3. 2 ATP, 4 NADH, 2 lactate
4. 4 ATP, 4 NADH, 4 pyruvate
5. 2 ATP, 2 NADH, 2 lactate

 

1. Item 21

The hair cells on the basilar membrane represent which of the following receptor types?

1. Baroreceptor
2. Thermoreceptor
3. Mechanoreceptor
4. Chemoreceptor
5. Nociceptor

 

1. Item 22

Which of the following cells are produced by the first meiotic division of oogenesis?

1. Oogonium
2. Primary oocyte and first polar body
3. Secondary oocyte and first polar body
4. Secondary oocyte and second polar body
5. Mature ovum and second polar body

 

1. Item 23

Potassium moving down its concentration gradient through K+channels in the plasma membrane is an example of:

1. simple diffusion.
2. active transport.
3. exocytosis.
4. osmosis.
5. facilitated diffusion.

 

1. Item 24

All of the following can be observed during both meiosis and mitosis EXCEPT:

1. alignment of chromosomes on the metaphase plate.
2. separation of sister chromatids.
3. synapsis of homologous chromosomes.
4. cytokinesis.
5. dissolution of the nuclear membrane.

 

1. Item 25

The opening of which type of ion channel initiates an action potential?

1. Voltage-gated Na+
2. K+ leak
3. Voltage-gated K+
4. Voltage-gated Ca2+
5. Na+/K+ pump

 

1. Item 26

All of the following are true about Gram– bacteria EXCEPT:

1. they have thin cell walls.
2. they have an inner plasma membrane.
3. they stain a dark purple in Gram stain.
4. they are more resistant to antibiotics than Gram+ bacteria.
5. they have a layer of plasma membrane outside the cell wall.

 

1. Item 27

When measuring reaction velocity as a function of substrate concentration, a researcher usually keeps the concentration of enzyme at a constant level. What would happen if the enzyme concentration were NOT kept constant?

1. Vmax would remain constant, but V would change.
2. Vmax would remain constant, but Km would change.
3. Vmax would change, but Km would remain constant.
4. both Vmax and Km would change.
5. None of the above would necessarily occur.

 

1. Item 28

What role does p53, a typical product of a tumor suppressor gene, play in the cell?

1. Signal CD4 T cells to destroy a cell infected with a cancer-causing virus
2. Upregulate transcription of protooncogenes
3. Promote chemotaxis and diapedesis of the cell
4. Trigger apoptosis if abnormal cell growth cannot be halted
5. Stimulate production of additional mitochondria

 

1. Item 29

Which of the following correctly lists functions of the sympathetic nervous system?

1. Dilate pupils, reduce heart rate, increase blood pressure, inhibit GI tract
2. Increase heart rate, constrict pupils, decrease blood pressure, inhibit GI tract
3. Increase blood pressure, dilate pupils, dilate bronchial tubes, increase heart rate
4. Inhibit GI tract, increase heart rate, constrict bronchial tubes, increase blood pressure
5. Dilate bronchial tubes, stimulate GI tract, increase heart rate, constrict pupils

 

1. Item 30

All of the following statements about DNA replication are true EXCEPT:

1. it occurs in the 5′ to 3′ direction.
2. both new strands are replicated continuously along the parent strands.
3. prokaryotes use five different DNA polymerases.
4. it requires an RNA primer.
5. it is semiconservative.

 

1. Item 31

A virus infects a cell and immediately induces the cellular machinery to produce new viral particles. These new viruses exit the cell by budding through the cell membrane. Which of the following is true about this virus?

1. It is a plant virus involved in a lytic cycle.
2. It is a bacterial virus involved in a lysogenic cycle.
3. It is a plant virus involved in a productive cycle.
4. It is an animal virus involved in a lytic cycle.
5. It is an animal virus involved in a productive cycle.

 

1. Item 32

The structure that secretes progesterone during the menstrual cycle is the:

1. oocyte.
2. ovary.
3. developing follicle.
4. corpus luteum.
5. uterus.

 

1. Item 33

Which of the following lists organelles that have only a single membrane?

1. Nucleus, rough ER, mitochondria
2. Mitochondria, Golgi apparatus, rough ER C. Lysosome, Golgi apparatus, nucleus
3. Golgi apparatus, rough ER, lysosome
4. Mitochondria, lysosome, rough ER
5. Item 34

Which intermediate of cellular respiration is NOT part of gluconeogenesis?

1. Oxaloacetate
2. Phosphoenolpyruvate
3. Dihydroxyacetone-phosphate
4. Fructose-6-phosphate
5. Acetyl-CoA

 

1. Item 35

Which of the following sensory receptors are NOT mechanoreceptors?

1. Aortic baroreceptors
2. Hearing receptors in the Organ of Corti
3. Rods and cones
4. Pacinian corpuscles
5. Golgi tendon organs

 

1. Item 36

The hormone responsible for raising blood glucose levels between meals is:

1. glucagon.
2. insulin.
3. epinephrine.
4. ACTH.
5. none of the above.

 

1. Item 37

A woman who is heterozygous for brown eyes (blue is recessive) and heterozygous for brown hair (blond is recessive) marries a man who has blond hair and is heterozygous for brown eyes. What is the probability they will have a son who has brown hair and brown eyes, and who is capable of fathering children with blue eyes?

1. 1/4
2. 1/2
3. 1/8
4. 1/16
5. This cannot be determined from the information given.

 

1. Item 38

The ion channel responsible for the plateau of the cardiac muscle cell action potential is the:

1. Na+ leak.
2. K+ leak.
3. voltage-gated Na+.
4. voltage-gated K+.
5. voltage-gated Ca2+.

 

1. Item 39

The functions of the large intestine include all of the following EXCEPT:

1. fecal storage.
2. reabsorption of water.
3. production of vitamin K by intestinal bacteria.
4. digestion and absorption of nutrients not fully digested in the small intestine.
5. reabsorption of electrolytes.

 

1. Item 40

During which phase of the ovarian cycle are increasing levels of estrogen secreted?

1. Secretory phase
2. Follicular phase
3. Ovulatory phase
4. Menstrual phase
5. Proliferative phase

 

1. Item 41

Telomerases are important in the replication of eukaryotic DNA because they:

1. connect leading and lagging strand fragments to create a contiguous linear chromosome.
2. remove methyl groups from protected sequences to allow replication.
3. generate the repetitious DNA sequences at the end of linear chromosomes.
4. provide primers for leading strand synthesis.
5. unwind the double helix for replication to begin.

 

1. Item 42

In the absence of ATP, which step(s) of the sliding filament theory CANNOT occur?

1. Myosin head groups attach to actin. II. Myosin “power stroke” pulls actin toward center of sarcomere. III. Myosin releases actin. IV. Myosin head groups are cocked back to “reset” to original position.
2. II only
3. II and III only
4. III and IV only
5. I and II only
6. II, III, and IV only

 

1. Item 43

Which of the following structures are NOT made of microtubules?

1. Microvilli
2. Mitotic spindle
3. Flagella
4. Cilia E. Centrioles

 

1. Item 44

Which blood vessel carries oxygenated blood to the left atrium of the heart?

1. Aorta
2. Pulmonary artery
3. Pulmonary vein
4. Superior vena cava
5. Coronary artery

 

1. Item 45

Blood filtration by the kidney takes place at the:

1. vasa recta.
2. proximal tubule.
3. renal artery.
4. glomerular capillaries.
5. distal tubule.

 

1. Item 46

A competitive inhibitor causes:

1. Vmax to decrease and Km to remain unchanged.
2. Vmax to remain unchanged and Km to decrease.
3. Vmax to remain unchanged and Km to increase.
4. Vmax to increase and Km to remain unchanged.
5. neither Vmax nor Km to be affected.

 

1. Item 47

Which of the following is a characteristic of prokaryotic protein synthesis?

1. Prokaryotic mRNA is monocistronic.
2. The first amino acid translated is formyl-methionine.
3. Prokaryotic transcription requires three separate RNA polymerases.
4. The mRNA must be polyadenylated at the 3’ end.
5. Introns must be spliced out before translation can occur.

 

1. Item 48

What attributes of prions makes them difficult to destroy?

1. Tough outer cell wall
2. Resistance to heat and chemical treatment
3. Ability to mutate quickly
4. Resemblance to human cell surface receptors
5. Integration into the host cell genome

 

1. Item 49

The role of surfactant in the respiratory system is to:

1. stimulate the diaphragm.
2. increase the lipid solubility of oxygen, allowing it to diffuse more easily into the blood.
3. dilate the bronchial tubes.
4. reduce surface tension in the alveoli.
5. trap inhaled dirt and dust particles.

 

1. Item 50

Which of the following contributes the most to maintenance of the normal resting membrane potential of cells?

1. K+ leak channels
2. Na+ leak channels
3. Na+/K+ ATPase
4. Opening of voltage-gated Na+ and K+ channels
5. Establishment of a strong Na+ concentration gradient

 

1. Item 51

Including the ATP used for amino acid activation/tRNA loading, approximately how many ATP equivalents are required to synthesize a 200 amino acid protein?

1. 200
2. 400
3. 600
4. 800
5. 1000

 

1. Item 52

Which best described the process by which rod cells are activated?

1. light strikes a depolarized rod cell → Na+ channels close → hyperpolarization of rod stops release of an inhibitory neurotransmitter
2. light strikes a depolarized rod cell → Na+ channels open → hyperpolarization of rod stops release of an inhibitory neurotransmitter
3. light strikes a rod cell at resting membrane potential → Na+channels open → depolarization of rod leads to an action potential
4. light strikes a rod cell at resting membrane potential → K+channels open → hyperpolarization of rod stops release of an inhibitory neurotransmitter
5. light strikes a depolarized rod cell → K+ channels open → hyperpolarization of rod stops release of an inhibitory neurotransmitter

 

1. Item 53

Which of the following bacterial auxotrophs should be grown in a lactose-based medium containing arginine and threonine but lacking histidine?

1. Arg– Lac+ Thr– His+
2. Arg– Lac– Thr+ His–
3. Arg+ Lac– Thr+ His–
4. Arg+ Lac+ Thr+ His–
5. Arg– Lac– Thr– His+

 

1. Item 54

The area of the cerebral cortex which controls voluntary motor function and complex reasoning is the:

1. parietal lobe.
2. frontal lobe.
3. temporal lobe.
4. occipital lobe.
5. olfactory lobe.

 
 

1. Item 55

In an operon, which of the following best describes the promoter?

1. It is the binding site for the repressor.
2. It is a molecule that inactivates the repressor and permits transcription.
3. It activates the repressor-inducer complex to permit transcription.
4. It is the binding site for met-tRNAmet to initiate translation.
5. It is the binding site for RNA polymerase.

 

1. Item 56

In muscle cells undergoing anaerobic respiration (i.e., fermentation):

1. pyruvate is reduced to ethanol.
2. pyruvate is oxidized to ethanol.
3. pyruvate is reduced to lactic acid.
4. pyruvate is oxidized to lactic acid.
5. none of the above. Muscle cells cannot undergo fermentation.

 

1. Item 57

Spermatogenesis occurs in the:

1. vas deferens.
2. epididymis.
3. scrotum.
4. seminiferous tubules.
5. none of the above.

 
 

1. Item 58

Cholecystokinin functions in digestion to cause the release of:

1. trypsinogen. II. bile. III. pepsinogen.
2. II only
3. I and II only
4. I and III only
5. II and III only
6. I, II, and III

 

1. Item 59

Alcohol inhibits the production of antidiuretic hormone. A person who has consumed alcohol would have:

1. increased urine output and increased urine osmolarity.
2. decreased urine output and increased urine osmolarity.
3. increased urine output and increased blood osmolarity.
4. decreased urine output and decreased blood osmolarity.
5. increased urine output and decreased blood osmolarity.

 

1. Item 60

Which of the following muscle fiber types uses oxidative metabolism?

1. Type I II. Type IIa III. Type IIb
2. I only
3. I and II only
4. III only
5. II and III only
6. I, II, and III

 

1. Item 61

Cell surface proteins, such as receptors, begin synthesis on cytoplasmic ribosomes, but are targeted by signal sequences (particular amino acid sequences within the protein) to the rough ER to complete their synthesis. Which of the following statements concerning signal sequences is/are true?

1. They are hydrophobic. II. They can be found at the beginning of the protein’s amino acid sequence. III. They are always cleaved from the mature protein upon completion of translation. IV. They can be found in the middle of the protein’s amino acid sequence.
2. I and II only
3. II and III only
4. I, II, and III only
5. III only
6. I, II, and IV only

 

1. Item 62

Carbon dioxide is a small hydrophobic molecule that can freely diffuse across plasma membranes. In the bloodstream, it combines with water to form carbonic acid. Excess carbon dioxide provides the primary drive for respiration, primarily as dissociated carbonic acid. Low arterial PCO2 would cause all of the following physiological changes EXCEPT:

1. decreased HCO3– reabsorption by the kidney.
2. increased HCO3– transport out of the cerebrospinal fluid.
3. faster ventilation rate.
4. decreased PCO2 in the cerebrospinal fluid.
5. increased plasma pH.

 

1. Item 63

Aerobic respiration in eukaryotes produces less ATP per glucose molecule than aerobic respiration in prokaryotes. This is because:

1. prokaryotes can produce a larger proton gradient across the inner mitochondrial membrane, thus causing a greater driving force for ATP synthesis.
2. eukaryotes must actively transport glucose into the mitochondria where respiration occurs.
3. prokaryotes can generate 2.5 ATP per FADH2 molecule, whereas eukaryotes can only generate 1.5 per FADH2.
4. the electrons from cytoplasmic NADH in eukaryotes are shuttled to ubiquinone instead of NADH dehydrogenase.
5. fermentation and the tricarboxylic acid cycle can run simultaneously in prokaryotes, generating two additional ATP per glucose molecule.

 

1. Item 64

The autonomic nervous system uses several different neurotransmitters in several different locations with several different receptor types. Which of the following receptors binds ACh at parasympathetic target organs?

1. Muscarinic receptors
2. Nicotinic receptors
3. α receptors
4. β receptors
5. Adrenergic receptors

 

1. Item 65

All of the following statements about stem cells are true EXCEPT:

1. adult stem cells can be collected from the bone marrow and are multipotent. II. the zygote and early cells of the embryo are totipotent. III. embryonic stem cells are pluripotent and can become any of the embryonic germ layers or the trophoblast.
2. I only
3. II only
4. I and III only
5. II and III only
6. I, II, and III

 

1. Item 66

HIV, the virus that causes AIDS, is a (+)RNA retrovirus. A significant concern in the treatment of HIV infection with drugs is the development of drug-resistant virus. Which of the following is most likely to contribute to the development of drug-resistant HIV?

1. Mutation of the virus after insertion into the host-cell genome
2. Frequent random errors in transcription of the viral genome by host-cell enzymes
3. Viral proteins folding differently in the presence of drug than in its absence
4. Covalent modification of viral nucleic acids by the drug
5. Mutation of viral reverse transcriptase after infection of the host cell

 

1. Item 67

A portion of prokaryotic mRNA has the following base sequence: 5’ACAUCUAUGCCACGA3’. Which of the following could result from a mutation that changes the underlined base to A?

1. Inhibition of initiation of translation II. Truncation of the polypeptide III. A shift in the reading frame for translation
2. I only
3. II only
4. II and III only
5. I and II only
6. I, II, and III

 

1. Item 68

During systole, the left ventricle of the heart pumps about 60% of its blood out to the body. This amount is referred to as the ejection fraction. The blood that remains in the ventricles at the end of ejection is called the residual volume, and is typically about 50 mL. Congestive heart failure is caused by a reduced pumping efficiency of the left ventricle. This could result in all of the following EXCEPT:

1. congestion of blood in the pulmonary artery.
2. residual volume less than 50 mL.
3. decreased aortic pressures and blood flow.
4. right ventricular failure.
5. pulmonary edema.

 
 
 

1. Item 69

Polydactyly is a disorder caused by a dominant allele that results in extra fingers. If the allele causing polydactyly is present at a frequency of 0.2 in a certain large, isolated, randomlymating population, what is the frequency of affected individuals in this population?

1. 0.04
2. 0.32
3. 0.36
4. 0.64
5. 0.96

 

1. Item 70

Epidural block is a form of anesthesia commonly used to prevent the pain of childbirth. It involves the injection of a somewhat lipid-soluble anesthetic into the epidural space (a fat filled region outside the dura mater of the spinal cord). This successfully blocks the pain of uterine contractions during labor without blocking the contractions themselves. This is because:

1. the somatic motor neurons innervating the uterus are not affected by the anesthetic.
2. injection of the anesthetic occurs too low on the spinal column to affect the uterus.
3. the anesthetic does not cross the dura mater and thus does not affect the spinal cord.
4. the blood vessels that pick up and transport the anesthetic do not travel to the uterus.
5. the contractions are stimulated by hormonal stimuli that are not affected by the anesthetic.

Biology homework help