Question

question 43
0.25 pts
why are the last two pairs of false ribs designated as floating ribs?
they are not attached to the vertebrae.
floating ribs do not attach even indirectly to the sternum.
there is no direct attachment of these ribs to the clavicle.
floating ribs are only attached indirectly to the sternum.
question 44
0.25 pts
which bone is the longest and heaviest bone in the body?
tibia
fibula
femur
humerus
question 45
0.25 pts
the extracellular components of bone matrix are
soft and calcified.
soft and decalcified.
hard and calcified.
hard and decalcified.

Explanation:

Question 43

To determine why the last two pairs of false ribs are floating ribs, we analyze each option:

• Option 1: False ribs (including floating ribs) are attached to the vertebrae, so this is incorrect.
• Option 2: Floating ribs (11th and 12th pairs) do not attach to the sternum directly or indirectly. This matches the definition.
• Option 3: Ribs are not attached to the clavicle, so this is irrelevant.
• Option 4: False ribs (not floating) attach indirectly to the sternum; floating ribs don't attach at all to the sternum, so this is incorrect.

We recall the characteristics of each bone:

• Tibia: A large leg bone but not the longest/heaviest.
• Fibula: A smaller leg bone, not the longest/heaviest.
• Femur: The thigh bone, which is the longest and heaviest bone in the human body.
• Humerus: The upper arm bone, not the longest/heaviest.

Bone matrix's extracellular components:

• Bone matrix is hard due to mineral (calcium phosphate) deposition, and it is calcified (has calcium salts).
• "Soft" is incorrect as bone matrix is hard. "Decalcified" would mean without calcium, which is not the case for normal bone matrix. So the correct description is hard and calcified.

Answer:

B. Floating ribs do not attach even indirectly to the sternum.

Question 44