Deck 41: Action and Support: the Muscles and Skeleton

Question 1

What is the function of troponin and tropomyosin during skeletal muscle contraction?

A) To increase the amount of calcium entering the muscle fiber
B) To regulate bonding between actin and myosin
C) To remove calcium from the muscle fiber
D) To prevent over- contraction of muscle fibers
E) To generate an action potential

Answer 1

B

Question 2

The fluid in the sarcoplasmic reticulum contains a high concentration of ions, which are released by the stimulation of an action potential.

A) iron
B) phosphorus
C) potassium
D) sodium
E) calcium

Answer 2

E

Question 3

Skeletal muscle

A) contracts the large blood vessels.
B) moves the body.
C) expands the large blood vessels.
D) propels food through the digestive tract.
E) is the muscle tissue of the heart.

Answer 3

B

Question 4

The thick filaments of a myofibril are composed of

A) actin.
B) T tubules.
C) myoglobin.
D) myosin.
E) sarcoplasm.

Question 5

Which molecule contains a binding site for the attachment of myosin heads?

A) Troponin
B) Tropomyosin
C) Actin
D) Myoglobin

Question 6

When lifting a heavy object, the strength of leg muscle contractions is determined by the

A) number of calcium ions released by the sarcoplasmic reticulum.
B) number of thick and thin filaments involved in each sarcomere during contraction.
C) amount of ATP used by each active sarcomere during muscle contraction.
D) frequency of action potentials and number of muscle fibers stimulated.

Question 7

Protein bands that connect sarcomeres are called

A) myofibrils.
B) troponins.
C) T tubules.
D) Z discs.

Question 8

When a muscle fiber receives an action potential from a neuron, how many sarcomeres in the fiber contract?

A) All of the sarcomeres in the fiber contract.
B) The number that contracts is inversely proportional to the strength of the action potential.
C) The number that contracts is directly proportional to the strength of the action potential.
D) Approximately one half of the sarcomeres in the fiber contract.

Question 9

How does an action potential enter a skeletal muscle cell?

A) Through a T tubule
B) By diffusion
C) As a result of the interaction between actin and myosin
D) In response to the release of calcium ions

Question 10

What is the function of the sarcoplasmic reticulum?

A) Provides support
B) Storage of calcium ions
C) Contraction
D) Storage of ATP

Question 11

Muscles used for activities that require fine motor control, such as holding and writing with a pencil, have

A) motor units consisting of many muscle cells.
B) motor units consisting of only a few muscle cells.
C) access to large amounts of ATP.
D) many neuromuscular junctions.

Question 12

The myofibrils of skeletal muscle are made up of repeating units called

A) T tubules.
B) motor units.
C) Z lines.
D) fibers.
E) sarcomeres.

Question 13

The site of communication between a neuron and a muscle fiber is called a

A) myofibril.
B) Z disc.
C) sarcomere.
D) neuromuscular junction.

Question 14

Skeletal muscle appears striped because of the

A) way the sarcoplasmic reticulum wraps around the myofibril.
B) arrangement of ions across the sarcoplasmic reticulum membrane.
C) orientation of T tubules.
D) arrangement of thick and thin filaments.
E) accessory proteins in thin filaments.

Question 15

Calcium binding to initiates skeletal muscle contraction.

A) tropomyosin
B) troponin
C) myosin
D) actin

Question 16

The T tubules that tunnel deep into a muscle fiber are formed from

A) osteocytes.
B) plasma membrane.
C) blood proteins.
D) neurons.

Question 17

The connective tissue cords that connect muscles to bones are called

A) thick filaments.
B) tendons.
C) thin filaments.
D) ligaments.

Question 18

Which of these muscle components is the smallest?

A) Myosin filament
B) Myofibril
C) Skeletal muscle
D) Muscle fiber

Question 19

The term motor unit refers to

A) all the motor neurons stimulating a skeletal muscle.
B) all the skeletal muscles in one region of the body.
C) all the muscle fibers that synapse with one motor neuron.
D) an entire skeletal muscle.
E) all sarcomeres within a single muscle fiber.

Question 20

Which of the following is TRUE with regard to the sliding filament mechanism of muscle contraction?

A) When a muscle fiber is contracting, the thin fibers are connected to the thick fibers.
B) When actin pushes the Z discs farther apart, the muscle contracts.
C) The muscle relaxes when calcium ions are released into the fluid surrounding the thick and thin filaments.
D) The energy for contraction comes from the breakdown of actin into myosin.

Question 21

How would a calcium deficiency affect the process of skeletal muscle contraction?

A) Myosin heads would not bind to actin efficiently.
B) Skeletal muscles would not be able to utilize ATP as a source of fuel.
C) The myosin heads would remain attached to actin molecules.
D) The action potential would be blocked from entering the muscle fiber.

Question 22

Cnidarians have what type of skeleton?

A) Exoskeleton
B) Hydrostatic skeleton
C) They don't have a skeleton
D) Endoskeleton

Question 23

Which of the following would be composed of smooth muscle?

A) Muscles that allow you to cross your eyes
B) Muscles of the uterus
C) Quadriceps (leg muscle)
D) Ventricles of the heart

Question 24

Fast- twitch muscle fibers, such as those that predominate in the legs of sprinters, _ than slow- twitch fibers, which predominate in the legs of marathon runners.

A) contain fewer mitochondria
B) contain higher levels of myoglobin
C) have a greater blood supply
D) produce more ATP

Question 25

What is the major disadvantage of an exoskeleton?

A) It does not protect the internal organs.
B) It does not provide effective support for muscles.
C) It hardens only after an extended exposure to air.
D) It must be periodically shed for growth to occur.

Question 26

muscle constricts arteries when blood pressure drops suddenly.

A) Cardiac
B) Smooth
C) Striated

Question 27

Both smooth and cardiac muscle fibers

A) possess intercalated discs.
B) contain a single nucleus.
C) have multiple nuclei.
D) are striated.

Question 28

Smooth muscle

A) is under voluntary control.
B) contracts when stretched.
C) produces rapid contractions.
D) does not contain actin or myosin.

Question 29

Which of these animals is correctly matched with its type of skeleton?

A) Mayfly/hydroskeleton
B) Bird/exoskeleton
C) Shark/hydroskeleton
D) Lobster/exoskeleton
E) Earthworm/endoskeleton

Question 30

In skeletal and cardiac muscles, relaxation occurs as ions are pumped back into the sarcoplasmic reticulum.

A) calcium
B) sodium
C) potassium
D) chloride

Question 31

An exoskeleton is characteristic of , whereas an endoskeleton is a characteristic of .

A) reptiles; insects
B) insects; reptiles
C) mammals; spiders
D) sea anemones; humans

Question 32

In cardiac muscle

A) potassium is released from the sarcoplasmic reticulum.
B) an action potential spreads throughout the Z discs.
C) intercalated discs connect the muscle fibers together.
D) calcium enters the cell from storage chambers called intercalated discs.

Question 33

Which of the following is TRUE of cardiac muscle?

A) It is under voluntary control.
B) Its cells contain large numbers of mitochondria.
C) Its cells are tapered at each end.
D) It is not striated, like skeletal muscle.

Question 34

Skeletal muscle produces force as the "walk" along the .

A) actin heads; myosin
B) ATP molecules; myofibrils
C) myosin heads; actin
D) creatine phosphate molecules; sarcomere

Question 35

A muscle fiber generates maximum contractile force when

A) it has been exposed to creatine phosphate.
B) it receives repeated action potentials from a motor neuron.
C) some of the myofibrils contract and then relax at the same time.
D) it has been stretched excessively.

Question 36

Earthworms and slugs move by

A) contracting their cilia.
B) alternating contractions of longitudinal and circular muscles.
C) contracting extensor and flexor muscles attached to their endoskeleton.
D) stretching their longitudinal muscles and contracting their circular muscles.

Question 37

Thick filaments are composed primarily of , whereas thin filaments consist of .

A) T tubules; Z discs
B) myosin; actin
C) actin; myosin
D) Z discs; T tubules

Question 38

What would happen to a person who was poisoned with a chemical that blocks the production of neurotransmitters at neuromuscular junctions?

A) The muscles would swell.
B) The sarcoplasmic reticulum would release sodium ions instead of calcium ions.
C) The muscles would be unable to contract.
D) The person's muscles would contract uncontrollably.

Question 39

In a muscle that is resistant to fatigue, such as that of a marathon runner, you would expect

A) a nonstriated appearance.
B) elevated levels of ATP.
C) a limited (or decreased) blood supply.
D) very few mitochondria.

Question 40

Where are the largest motor units in human muscles located?

A) Leg muscles
B) Arm muscles
C) Muscles of the face
D) Muscles in the hand

Question 41

It is possible to remove calcium from compact bone by soaking the bone in vinegar for an extended period of time. Once the calcium is gone, the bone should be

A) more rigid and inflexible.
B) completely dissolved.
C) extremely flexible.
D) about half the size as before soaking.

Question 42

The muscles of your lower leg are arranged in antagonistic pairs so that you

A) can stand upright.
B) have a backup when one muscle is not strong enough.
C) can both flex and extend your leg.
D) obtain a stronger contraction than you would with a single muscle.

Question 43

What advantage does the activity of osteoblasts and osteoclasts impart to vertebrates, even after growth has finished?

A) As old bones are dissolved, new bones can be formed.
B) Bone growth never finishes; it continues at a slow pace throughout life.
C) The cells allow bone to get stronger as physical demands are placed on it.
D) The cells enable bone to lengthen and shorten as needed.

Question 44

The hard, outer shell of vertebrate bone

A) does not contain osteons.
B) is compact bone.
C) is made of glucosamine.
D) is spongy bone.

Question 45

If a doctor tells a patient that he has broken an axial bone, to which of these bones would the doctor be referring?

A) Radius
B) Ilium
C) Clavicle
D) Vertebra
E) Fibula

Question 46

Which of the following increases bone mass?

A) Dietary nitrogen supplements
B) Moderate stress from weight- bearing exercises
C) Increased osteoclast activity
D) Increasing the action potentials that directly stimulate bones

Question 47

After falling down a flight of stairs, it feels like you broke your ankle; however the emergency room doctor says you tore a ligament. This means you tore the

A) insertion of a muscle.
B) the cartilage in your ankle joint.
C) connective tissue band that joins two bones.
D) delicate membrane that covers the surface of the bone.
E) connective tissue band that attaches muscle to bone.

Question 48

Which of the following attaches one bone to another bone at a joint?

A) Cartilage
B) Callus
C) Ligament
D) Tendon

Question 49

Bones store calcium and

A) glycogen.
B) amino acids.
C) phosphorus.
D) manganese.
E) magnesium.

Question 50

When you break your leg, a thickened area forms around the outside of the bone. Over a period of time, this thickened area

A) becomes a permanent part of the spongy bone.
B) is dissolved by osteoclasts as osteoblasts add new bone.
C) forms new tendons, ligaments, and/or muscles.
D) moves to the skin surface and is shed as dead skin.
E) is digested by enzymes secreted by the muscles.

Question 51

A callus is a mass of bone and cartilage that

A) forms after a bone breaks.
B) is involved in bone formation in the vertebrate embryo.
C) is a form of bone cancer.
D) thickens the fibrous structure of a muscle.

Question 52

If an athlete damages the cartilage in her knee, it tends to heal very slowly because cartilage

A) is dead tissue.
B) lacks a blood supply.
C) hardens with age.
D) cannot be replaced or repaired by the body.
E) is rejected by the body as it is formed.

Question 53

The living cells of cartilage are called

A) osteoblasts.
B) osteoclasts.
C) chondrocytes.
D) osteocytes.

Question 54

Which of the following individuals is most likely to have the greatest bone density?

A) An astronaut who has been in space for an extended time
B) A computer programmer
C) A person who walks 30 minutes a day
D) A person who has been chronically ill and in bed

Question 55

Red bone marrow, which produces red blood cells, white blood cells, and platelets, is located in

A) compact bone.
B) spongy bone.
C) ligaments.
D) cartilage.

Question 56

Osteoporosis may occur when the activity of exceeds the activity of .

A) osteoclasts; osteocytes
B) osteocytes; osteoclasts
C) osteoclasts; osteoblasts
D) osteoblasts; osteoclasts

Question 57

Cartilage primarily consists of

A) magnesium and manganese.
B) actin.
C) glycoproteins and collagen.
D) myosin.
E) calcium and phosphate.

Question 58

What happens to an astronaut who spends 2 months in the weightless environment of a space capsule?

A) Bone density increases and muscle mass increases.
B) Bone density decreases and muscle mass decreases.
C) Bone density increases and muscle mass decreases.
D) Bone density decreases and muscle mass increases.

Question 59

Osteoporosis is the

A) conversion of cartilage to bone in the developing embryo.
B) painful swelling of joints.
C) loss of calcium from hard bone.
D) detachment of a ligament from a bone.

Question 60

Bone- forming cells are known as

A) osteoclasts.
B) osteoblasts.
C) osteocytes.
D) chondrocytes.

Question 61

In the human skeleton, the is a ball- and- socket joint.

Question 62

The end of a skeletal muscle that is attached to a stationary, fixed bone is the origin. The end of a skeletal muscle that is attached to a movable bone is called the

A) insertion.
B) hinge.
C) flexor.
D) extensor.
E) joint.

Question 63

Cartilage is composed of specialized cells called

A) erythrocytes.
B) chondrocytes.
C) platelets.
D) osteoblasts.
E) osteoclasts.

Question 64

A joint that is movable in only two dimensions, such as the elbow, is called a joint.

Question 65

What might be a major disadvantage of having a ball- and- socket joint, rather than a hinge joint, in the human knee?

A) Decreased muscle strength
B) Reduced ability to move the lower leg
C) Decreased joint flexibility
D) Decreased joint stability

Question 66

Some joints, such as those joining the bones of the skull, are immobile and do not allow the two bones involved to move.

Question 67

In a hinge joint

A) movement can occur only in two dimensions.
B) an extensor muscle rotates the bones.
C) motion occurs when gravity pulls on the insertion.
D) the flexor and the extensor must contract at the same time.
E) movement in three dimensions is possible.

Question 68

At a joint, the end of a skeletal muscle that is attached to the bone that moves is known as the origin.

Question 69

Action potentials stimulate the sarcoplasmic reticulum to release chloride ions into the muscle cell.

Question 70

Cartilage is well supplied with blood vessels.

Question 71

How does a muscle return to its extended condition after contracting?

Question 72

The sternum is part of the axial skeleton.

Question 73

Arrange these muscle tissue groupings in order, from most inclusive to least inclusive: sarcomere, motor unit, thick and thin filaments, myofibril, muscle fiber.

Question 74

What are tendons?

Question 75

In light of the role of calcium ions in muscle contraction, what happens to a person who is deficient in dietary calcium?

Question 76

The type of ion found in high concentrations in the sarcoplasmic reticulum is .

Question 77

Motor units are all of the sarcomeres that make up a muscle fiber.

Question 78

The vertebrate skeleton is made up of _ , ligaments, and bones.

Question 79

During embryonic development, the skeleton is initially made of _ , which is later replaced by bone.

Question 80

Describe the differences between fast- twitch and slow- twitch muscle fibers.