Question 3
PART 2 — EXPERIMENT 2
Locate the main features on a valve of a freshwater clam. The 120-minute time limit is shared with all other experiment tasks. Handle sharp shell edges with care.
Material: One dry valve of freshwater clam *Sinanodonta* sp.
Procedure and description: A clam shell of *Sinanodonta* sp. consists of two equal valves connected by a hinge joint. Two adductor muscles contract to close the valves; they leave adductor muscle scars on a dry shell. The umbo is the oldest part. As the clam grows, the shell enlarges and forms growth lines on the outer surface. The shell has three layers, including nacre, which is widely used for decoration.
Question 3: Examine the valve, read the description, and identify the hinge joint, umbo, growth lines and nacre layer on Figure 4. Label the shell in the answer sheet. The adductor muscle scar is already labeled as an example.
Figure 4: Generalized bivalve shell exterior (A) and interior (B).
Label spaces: hinge joint ______; umbo ______; growth lines ______; nacre layer ______.
The source does not print points for this question; this package uses an editorial 4-point rubric.
Locate the main features on a valve of a freshwater clam. The 120-minute time limit is shared with all other experiment tasks. Handle sharp shell edges with care.
Material: One dry valve of freshwater clam *Sinanodonta* sp.
Procedure and description: A clam shell of *Sinanodonta* sp. consists of two equal valves connected by a hinge joint. Two adductor muscles contract to close the valves; they leave adductor muscle scars on a dry shell. The umbo is the oldest part. As the clam grows, the shell enlarges and forms growth lines on the outer surface. The shell has three layers, including nacre, which is widely used for decoration.
Question 3: Examine the valve, read the description, and identify the hinge joint, umbo, growth lines and nacre layer on Figure 4. Label the shell in the answer sheet. The adductor muscle scar is already labeled as an example.
Figure 4: Generalized bivalve shell exterior (A) and interior (B).
Label spaces: hinge joint ______; umbo ______; growth lines ______; nacre layer ______.
The source does not print points for this question; this package uses an editorial 4-point rubric.