Archive for June 2017

Two amino acids are linked by a peptide bond when -

14:24

Two amino acids are linked by a peptide bond when -




a. two ribosomes attach simultaneously to the same mRNA transcript
b. two tRNAs pair with neighboring codons on an mRNA transcript
c. two codons on an mRNA transcript bind to each other
d. a ribosome attaches to two codons on an mRNA transcript





Answer: B

The genetic code specifies the correlation between -

14:24

The genetic code specifies the correlation between -



a. a DNA-nucleotide sequence and an RNA-nucleotide sequence
b. an mRNA-nucleotide sequence and a tRNA-nucleotide sequence
c. an mRNA-nucleotide sequence and an rRNA-nucleotide sequence
d. an RNA-nucleotide sequence and an amino acid sequence




Answer: D

A mutation is a -

14:23

A mutation is a -





a. change in the direction of a replication fork
b. form of cancer
c. kind of DNA replication
d. change in the nucleotide sequence of DNA





Answer: D

In replication in prokaryotes, -

14:21

In replication in prokaryotes, -



a. there are two origins
b. two replication forks move in opposite directions
c. replication proceeds in one direction
d. there are no replication forks




Answer: B

Replication of the two DNA strands takes place -

14:21

Replication of the two DNA strands takes place - 



a. in two different directions
b. in the same direction of the replication fork
c. in a direction opposite to that of the replication fork
d. at right angles to the direction of the replication fork




Answer: A

Before replication can take place, -

14:21

Before replication can take place, -



a. DNA polymerases must add complementary nucleotides to the DNA
b. the two strands of DNA must separate
c. the covalent bonds in DNA must break
d. helices must break the bonds in the nucleotides




Answer: B

The percentage of adenine in DNA is -

14:21

The percentage of adenine in DNA is - 



a. equal to the percentage of cytosine
b. equal to the percentage of thymine
c. not related to the percentage of thymine
d. equal to the percentage of guanine





Answer: B

The primary function of DNA in cells is to -

14:20

The primary function of DNA in cells is to -



a. serve as a storage form for unsaved nucleotides
b. occupy space in the nucleus to keep the nucleus from collapsing
c. store information that tells the cells which proteins to make
d. serve as a template for making long, spiral carbohydrates




Answer: C

A cross between true-breeding green-podded pea plants and true-breeding yellow-podded pea plants produces only green-podded plants. When the F1 generation is allowed to self-pollinate, the F2 generation consists of

14:17

A cross between true-breeding green-podded pea plants and true-breeding yellow-podded pea plants produces only green-podded plants. When the F1 generation is allowed to self-pollinate, the F2 generation consists of 



a. only green-podded plants
b. only yellow-podded plants
c. about three-quarters yellow-podded plants and one-quarter green-podded plants
d. about three-quarters green-podded plants and one-quarter yellow-podded plants



Answer: D

When Mendel crossed a strain of tall pea plants with a strain of short pea plants, he observed that all of the plants in the F1 generation were tall. This suggests that

14:16

When Mendel crossed a strain of tall pea plants with a strain of short pea plants, he observed that all of the plants in the F1 generation were tall. This suggests that 



a. the tall trait was controlled by a dominant factor
b. the short trait was controlled by a dominant factor
c. both traits were controlled by a recessive factor
d. allowing plants to cross-pollinate for one generation




Answer: A

Mendel obtained plants that were true-breeding for particular traits by

14:16

Mendel obtained plants that were true-breeding for particular traits by 




a. growing plants from the seeds of other plants that showed that trait
b. discarding plants that showed other traits
c. allowing plants to self-pollinate for several generations
d. allowing plants to cross-pollinate for one generation

Answer: C

Which of the following statements is false or incorrect?

14:13

Which of the following statements is false or incorrect? 




A) Cardiac muscle contracts when stimulated by its own autorhythmic muscle cells.
B) Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute.
C) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.
D) Cardiac muscle fibers can use lactic acid to make ATP.



Answer: C

What part of the sarcolemma contains acetylcholine receptors?

14:13

What part of the sarcolemma contains acetylcholine receptors? 



A) motor end plate
B) end of the muscle fiber
C) part adjacent to another muscle cell
D) any part of the sarcolemma




Answer: A

The part of the sarcolemma that contains acetylcholine receptors is the motor end plate.

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________.

14:12

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________. 



A) cross bridge attachment would be optimum because of all the free binding sites on actin
B) no muscle tension could be generated
C) maximum force production would result because the muscle has a maximum range of travel
D) ATP consumption would increase because the sarcomere is "trying" to contract



Answer: B

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?

14:12

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers? 




A) a sprint by an Olympic runner
B) a long, relaxing swim
C) playing baseball or basketball
D) gym climbing




Answer: B

What is the most distinguishing characteristic of muscle tissue?

14:12

What is the most distinguishing characteristic of muscle tissue? 




A) the design of the fibers
B) the ability to respond to nervous stimulation
C) the diversity of activity of muscle tissue
D) the ability to transform chemical energy into mechanical energy


Answer: D

Which of the following statements is most accurate?

14:11

Which of the following statements is most accurate? 



A) Muscle tension remains relatively constant during isotonic contraction.
B) T tubules may be sliding during isotonic contraction.
C) The I band lengthens during isotonic contraction.
D) Myofilaments slide during isometric contractions.





Answer: A

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

14:11

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? 




A) calcium ions returning to the terminal cisternae
B) the tropomyosin blocking the myosin once full contraction is achieved
C) acetylcholinesterase destroying the ACh
D) the action potential stops going down the overloaded T tubules



Answer: C

The sliding filament model of contraction involves ________.

14:11

The sliding filament model of contraction involves ________. 





A) actin and myosin sliding past each other and partially overlapping
B) the shortening of thick filaments so that thin filaments slide past
C) actin and myosin lengthening in order to slide past each other
D) the Z discs sliding over the myofilaments



Answer: A

Muscle tone is ________.

14:11

Muscle tone is ________. 




A) the ability of a muscle to efficiently cause skeletal movements
B) the feeling of well-being following exercise
C) a state of sustained partial contraction
D) the condition of athletes after intensive training




Answer: C

Which of the following statements is true?

14:10

Which of the following statements is true? 



A) Cardiac muscle cells have many nuclei.
B) Smooth muscle cells have T tubules.
C) Striated muscle cells are long and cylindrical with many nuclei.
D) Cardiac muscle cells are found in the heart and large blood vessels.




Answer: C

Smooth muscle is characterized by all of the following except ________.

14:09

Smooth muscle is characterized by all of the following except ________. 



A) it appears to lack troponin
B) there are more thick filaments than thin filaments
C) there are no sarcomeres
D) there are noncontractile intermediate filaments that attach to dense bodies within the cell




Answer: B

Which of the following is true about smooth muscle?

14:09

Which of the following is true about smooth muscle? 





A) Certain smooth muscle cells can actually divide to increase their numbers.
B) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements.
C) Smooth muscle cannot stretch as much as skeletal muscle.
D) Smooth muscle has well-developed T tubules at the site of invagination.



Answer: A

Which of the following describes the cells of unitary smooth muscle?

14:09

Which of the following describes the cells of unitary smooth muscle? 




A) They depend upon recruitment using the autonomic nervous system.
B) They are used for vision and hair raising.
C) They exhibit spontaneous action potentials.
D) They consist of muscle fibers that are structurally independent of each other.





Answer: C

Which of the following is the correct sequence of events for muscle contractions?

14:08

Which of the following is the correct sequence of events for muscle contractions? 




A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
B) neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke
C) muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments
D) neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke





Answer: A

In an isotonic contraction, the muscle ________.

14:07

In an isotonic contraction, the muscle ________. 





A) changes in length and moves the "load"
B) does not change in length but increases tension
C) never converts pyruvate to lactate
D) rapidly resynthesizes creatine phosphate and ATP



Answer: A

What is the role of calcium ions in muscle contraction?

14:06

What is the role of calcium ions in muscle contraction? 



A) form hydroxyapatite crystals
B) reestablish glycogen stores
C) bind to regulatory sites on troponin to remove contraction inhibition
D) increase levels of myoglobin




Answer: C

What is the functional role of the T tubules?

14:06

What is the functional role of the T tubules? 




A) stabilize the G and F actin
B) enhance cellular communication during muscle contraction
C) hold cross bridges in place in a resting muscle
D) synthesize ATP to provide energy for muscle contraction



Answer: B

The term aponeurosis refers to ________.

14:03

The term aponeurosis refers to ________. 



A) the bands of myofibrils
B) a sheetlike indirect attachment to a skeletal element
C) the rough endoplasmic reticulum
D) the tropomyosin-troponin complex



Answer: B

Which of the choices below does not describe how excess postexercise oxygen consumption (oxygen deficit) restores metabolic conditions?

14:03

Which of the choices below does not describe how excess postexercise oxygen consumption (oxygen deficit) restores metabolic conditions? 





A) converts lactic acid back into glycogen stores in the liver
B) re-synthesizes creatine phosphate and ATP in muscle fibers
C) increases the level of lactic acid in the muscle
D) replaces the oxygen removed from myoglobin



Answer: C

Rigor mortis occurs because ________.

14:02

Rigor mortis occurs because ________. 



A) the cells are dead
B) sodium ions leak into the muscle causing continued contractions
C) no ATP is available to release attached actin and myosin molecules
D) proteins are beginning to break down, thus preventing a flow of calcium ions



Answer: C

What is the primary function of wave summation?

14:01

What is the primary function of wave summation? 





A) produce smooth, continuous muscle contraction
B) increase muscle tension
C) prevent muscle relaxation
D) prevent muscle fatigue



Answer: A

Creatine phosphate functions in the muscle cell by ________.

14:01

Creatine phosphate functions in the muscle cell by ________. 



A) forming a temporary chemical compound with myosin
B) forming a chemical compound with actin
C) inducing a conformational change in the myofilaments
D) storing energy that will be transferred to ADP to resynthesize ATP




Answer: D

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

14:00

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.




A) contraction
B) relaxation
C) latent
D) refractory



Answer: C

What does excess postexercise oxygen consumption represent?

14:00

What does excess postexercise oxygen consumption represent? 



A) amount of oxygen needed for aerobic activity to accomplish the same amount of work
B) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used
C) the amount of oxygen equal to the oxygen already used
D) the amount of oxygen taken into the body immediately after the exertion




Answer: B

Myoglobin ________.

14:00

Myoglobin ________. 




A) breaks down glycogen
B) is a protein involved in the direct phosphorylation of ADP
C) stores oxygen in muscle cells
D) produces the end plate potential


Answer: C

Which of the following would be recruited later in muscle stimulation when contractile strength increases?

13:59

Which of the following would be recruited later in muscle stimulation when contractile strength increases? 



A) motor units with the longest muscle fibers
B) many small motor units with the ability to stimulate other motor units
C) large motor units with small, highly excitable neurons
D) motor units with larger, less excitable neurons



Answer: D

The strongest muscle contractions are normally achieved by ________.

13:58

The strongest muscle contractions are normally achieved by ________. 



A) increasing stimulus above the threshold
B) increasing stimulus above the treppe stimulus
C) increasing the stimulation up to the maximal stimulus
D) recruiting small and medium muscle fibers





Answer: C

Most skeletal muscles contain ________.

13:58

Most skeletal muscles contain ________. 




A) muscle fibers of the same type
B) a mixture of fiber types
C) a predominance of slow oxidative fibers
D) a predominance of fast oxidative fibers



Answer: B

What is the role of tropomyosin in skeletal muscles?

13:57

What is the role of tropomyosin in skeletal muscles? 




A) Tropomyosin is the chemical that activates the myosin heads.
B) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.
C) Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.
D) Tropomyosin is the receptor for the motor neuron neurotransmitter.



Answer: B
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