| Date | November 2021 | Marks available | 1 | Reference code | 21N.1.HL:.tz0.14 |
| Level | Higher Level | Paper | Paper 1 | Time zone | time zone 0 |
| Command term | Question number | 14 | Adapted from | N/A |
Question
When the forearm acts as a first-class lever to extend the elbow, which muscle acts as the effort to lift a load?
A. Biceps brachii
B. Deltoid
C. Trapezius
D. Triceps brachii
Markscheme
D
Examiners report
The elbow joint is a useful and complex joint in terms of movement as a lever because it depends on which muscle is acting to cause the movement. If the triceps is used to extend the elbow as in a punch or press up then it is operating as a 3rd class lever. However, if the biceps brachii is used to extend the elbow, as in lowering a dumbbell down during a bicep curl exercise then it is operating as a 1st class lever. The insertion points for the muscular force are the key to understanding this.
Syllabus sections
-
19M.2.SL.tz0.3e:
The diagram shows the lower leg.
Identify the elements A, B and C of the lever system.
-
22M.1.SL.tz0.19:
Levers are working throughout the body when a basketball player performs a jump shot. Where is the effort applied in the lower right leg?
-
22M.1.HL:.tz0.15:
The diagram shows a volleyball player serving right-handed. Which is an example of a first-class lever during the acceleration phase of the serve?
[Source: 4x6/DigitalVision Vectors via Getty Images.]
A. Extension of the right elbow
B. Flexion of the left elbow
C. Plantar flexion of the right ankle
D. Extension of the left knee
-
19N.1.SL.tz0.20:
The diagram shows elbow extension. Which type of lever is used?
[Source: © International Baccalaureate Organization 2019]
A. First
B. Second
C. Third
D. No lever is used during elbow extension
-
21M.1.SL.tz0.18:
What is an example of a first-class lever?
A. Triceps contracting, moving the elbow
B. Biceps contracting, moving the elbow
C. Quadriceps contracting, moving the knee
D. Hamstrings contracting, moving the knee
