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Question #47404
The Question
The evolutionary increase in hominid cranial capacity exerted a strong selection pressure on the female pelvic girdle, which was already constrained by the biomechanical requirements of bipedalism. Which of the following statements INCORRECTLY describes the anatomical relationship between these evolutionary pressures and the human pelvic structure?
Options
- A.
Efficient bipedalism favored a narrower pelvis to optimize the weight-bearing biomechanics of the ball-and-socket joint at the acetabulum.
- B.
The evolutionary increase in fetal brain size necessitated a wider pelvic inlet, creating an evolutionary trade-off known as the obstetrical dilemma.
- C.
To accommodate the parturition of large-brained infants, the pubic symphysis evolved as a highly mobile synovial joint to allow maximum separation of the coxal bones.
- D.
The acetabulum, which articulates with the head of the femur, is formed by the fusion of the ilium, ischium, and pubis to ensure stability during locomotion.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Synovial_Joint_Varieties|Hominid_Cranial_Capacity|Natural_Selection_Directionality
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the functional yielding of the pubic symphysis during childbirth (facilitated by relaxin) with its structural classification.
Because it 'moves' to solve the evolutionary constraint of a large cranial capacity, students might fall for the trap that it is a 'synovial joint', forgetting the strict NCERT classification of the pubic symphysis as a cartilaginous joint with limited movement.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Synovial Joint Varieties |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |