During the process of endochondral ossification, chondrocytes in the cartilage model die. Why does this occur?
A. Blood supply to the cartilage is cut off by the developing periosteum.
B. Canaliculi connecting adjacent chondrocyte lacunae fuse.
C. Phagocytic osteoclasts in the new bone engulf and destroy the chondrocytes.
D. The developing bone collar secretes enzymes that destroy the chondrocytes.
E. Nutrients cannot diffuse to the chondrocytes through the calcified matrix.
Answer: E
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The text makes a distinction between positive and negative sexual rights. An example of a negative sexual right is the:
A. freedom to express one's sexuality with same-gender partners. B. freedom to experience sexual pleasure. C. freedom from sexual abuse and violence. D. right to reproductive self-determination.
Paracortical zone is typical for:
(a) thymus (b) lymph node (c) spleen (d) bone marrow
Comparing the left ventricle with the right ventricle, which of the following is true?
A) The left ventricle does more work than the right ventricle. B) The left ventricle pumps against less resistance than the right ventricle. C) The left ventricle produces a lower pressure than the right. D) The right ventricle is thicker than the left ventricle. E) The right ventricle pumps more blood than the left ventricle.
What is the main component of the A band of the myofibril?
A) Elastic filaments B) Actin filaments C) Thin filaments D) Thick filaments