Question

1. during a bicep curl, which muscle acts as the antagonist? *

a. biceps
b. triceps
c. deltoid
d. pectoralis major

1. what movement occurs when you lift your leg straight forward at the hip joint? *

a. extension in the frontal plane
b. rotation in the sagittal plane
c. abduction in the transverse plane
d. flexion in the sagittal plane

1. which of the following pairs correctly identifies an agonist - antagonist relationship? *

a. hamstrings and gluteus maximus
b. quadriceps and hamstrings
c. biceps and deltoids
d. pectorals and latissimus dorsi

Explanation:

Question 3

In a bicep curl, the biceps (agonist) contract to flex the elbow. The triceps, which extend the elbow, act as the antagonist (opposing the biceps' action). Biceps are the agonist, deltoid and pectoralis major are not involved in elbow flexion/extension for this exercise.

Lifting the leg straight forward at the hip is hip flexion (decreasing the angle at the hip joint). Flexion occurs in the sagittal plane (divides body into left/right). Extension increases angle, rotation is turning, abduction is moving away from midline (frontal plane). So the correct movement is flexion in the sagittal plane.

Agonist-antagonist pairs have opposing actions. Quadriceps (extend knee) and hamstrings (flex knee) are a classic agonist-antagonist pair for knee movement. Hamstrings & gluteus maximus (both involved in hip extension), biceps & deltoids (different actions), pectorals & latissimus dorsi (horizontal adduction/abduction but not a direct agonist-antagonist for a single joint action like quad-hamstrings) don't fit as well.

Answer:

B. Triceps

Question 4