Question 1

Which structure is directly responsible for the striated appearance of skeletal muscle fibers?

Accepted Answer

The repeating pattern of sarcomeres within myofibrils

Question 2

During muscle contraction, which event occurs first in the sliding-filament model?

Accepted Answer

ATP binds to the myosin head, releasing it from actin

Question 3

What is the primary function of calcium ions ($$\mathrm{Ca$$^{2+}$$}) in $$muscle contraction?

Accepted Answer

To bind to troponin, causing the troponin-tropomyosin complex to expose myosin binding sites on actin

Question 4

Which equation best describes the relationship between muscle force ($$F) $$and cross-sectional area ($$A) of a $$muscle?

Accepted Answer

$$F \propto A$$

Question 5

A marathon runner’s leg muscles are likely to have a high abundance of which type of muscle fiber?

Accepted Answer

Slow fibers

Question 6

Which of the following statements about the sarcomere is correct?

Accepted Answer

Thin filaments are composed of coiled chains of actin

Question 7

In the regulation of muscle activity, what role do tropomyosin and troponin play when the muscle is relaxed?

Accepted Answer

They block the myosin binding sites on actin, inhibiting sliding

Question 8

Which sequence correctly describes the steps in the actin-myosin interaction during muscle contraction?

Accepted Answer

ATP binds to myosin head → Myosin head releases from actin → Myosin head binds to new actin subunit → Pi released → Head bends → ADP released

Question 9

Which type of skeletal muscle fiber is most abundant in muscles used for rapid, short bursts of activity, such as a chicken’s breast muscle?

Accepted Answer

Fast fibers

Question 10

What is the main disadvantage of the pennate arrangement of muscle fibers in exoskeletons?

Accepted Answer

It limits the range of movement due to small width and length change

Question 11

Which of the following best explains why animals with hydrostatic skeletons, such as earthworms, use antagonistic muscle groups for movement?

Accepted Answer

To alternate relaxation and contraction, causing shape change and movement via peristalsis

Question 12

Which of the following is NOT a function of the skeletal system?

Accepted Answer

Producing ATP for muscle contraction

Question 13

Which element of the vertebrate endoskeleton is responsible for connecting skeletal muscles to bones?

Accepted Answer

Tendons

Question 14

In the context of animal locomotion, which environment presents the greatest cost of locomotion per unit mass?

Accepted Answer

Running

Question 15

Which of the following best describes the relationship between body mass ($$m) $$and cost of locomotion ($$C) $$for running, flying, and swimming animals?

Accepted Answer

$$C$$ decreases with $$m$$

Question 16

Which of the following is a real-world consequence of molting in arthropods with exoskeletons?

Accepted Answer

Temporary vulnerability to predators due to shedding of the exoskeleton

Question 17

Which muscle tissue type is involved in involuntary movement and lacks striations?

Accepted Answer

Smooth muscle

Question 18

What is the effect of an action potential arriving at the axon terminal of a motor neuron in muscle contraction?

Accepted Answer

Release of acetylcholine (ACh) from the motor neuron

Question 19

Which of the following best explains why larger animals tend to locomote more gently and straight-legged compared to smaller animals?

Accepted Answer

Larger animals have a lower cost of locomotion per unit mass

Question 20

Which of the following is a correct statement about antagonistic muscle groups in vertebrates?

Accepted Answer

They coordinate movement by pairs of muscles working together to move a bone back and forth

Animal Movement: Muscle and Skeletal Systems

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