Deck 41: Action and Support: the Muscles and Skeleton

Question 1

The thick filaments of a myofibril are composed of

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

Answer 1

B

Question 2

How does an action potential enter a skeletal muscle cell?

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

Answer 2

A

Question 3

Skeletal muscle appears striped because of the

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

Answer 3

C

Question 4

The term motor unit refers to

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

Question 5

Skeletal muscle

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

Question 6

What is the function of the sarcoplasmic reticulum?

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

Question 7

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

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

Question 8

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

Question 9

Protein bands that connect sarcomeres are called

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

Question 10

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

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

Question 11

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

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

Question 12

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

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

Question 13

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

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

Question 14

The connective tissue cords that connect muscles to bones are called

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

Question 15

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

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

Question 16

Calcium binding to ___________initiates skeletal muscle contraction.

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

Question 17

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

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

Question 18

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

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

Question 19

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

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

Question 20

Which of these muscle components is the smallest?

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

Question 21

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) Ventricles of the heart
D) Quadriceps (leg muscle)

Question 22

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

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

Question 23

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

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

Question 24

What is the major disadvantage of an exoskeleton?

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

Question 25

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

Question 26

Earthworms and slugs move by

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

Question 27

In cardiac muscle

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

Question 28

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

Question 29

Where are the largest motor units in human muscles located?

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

Question 30

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

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

Question 31

Smooth muscle

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

Question 32

____________muscle constricts arteries when blood pressure drops suddenly.

A) Cardiac
B) Striated
C) Smooth

Question 33

A muscle fiber generates maximum contractile force when

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

Question 34

Which of the following is TRUE of cardiac muscle?

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

Question 35

Both smooth and cardiac muscle fibers

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

Question 36

Skeletal muscle produces force as the___________ ?walk? along the ___________.

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

Question 37

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

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

Question 38

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

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

Question 39

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

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

Question 40

Cnidarians have what type of skeleton?

A) Hydrostatic skeleton
B) They donʹt have a skeleton
C) Exoskeleton
D) Endoskeleton

Question 41

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

Question 42

Bones store calcium and

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

Question 43

Bone-forming cells are known as

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

Question 44

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

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

Question 45

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

Question 46

Which of the following increases bone mass?

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

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

Question 48

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

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

Question 49

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

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

Question 50

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

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

Question 51

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

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

Question 52

Cartilage primarily consists of

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

Question 53

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

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

Question 54

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

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

Question 55

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) The cells enable bone to lengthen and shorten as needed.
C) The cells allow bone to get stronger as physical demands are placed on it.
D) Bone growth never finishes; it continues at a slow pace throughout life.

Question 56

The living cells of cartilage are called

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

Question 57

A callus is a mass of bone and cartilage that

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

Question 58

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

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

Question 59

Osteoporosis is the

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

Question 60

The hard, outer shell of vertebrate bone

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

Question 61

Cartilage is composed of specialized cells called

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

Question 62

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

Question 63

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

Question 64

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

Question 65

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

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

Question 68

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

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

Question 69

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

Question 70

The sternum is part of the axial skeleton.

Question 71

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

Question 72

What are tendons?

Question 73

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

Question 74

In a hinge joint

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

Question 75

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

Question 76

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

Question 77

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

Question 78

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

Question 79

Cartilage is well supplied with blood vessels.

Question 80

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