Question

the skeleton of cartilaginous fish requires phosphorus and calcium to be built
true
false
the skeleton of cartilaginous fish is beneficial as it’s lightweight and very flexible
true
false
the gills are the site of gas exchange for respiration, and all sharks have 5 gills
true
false
cartilaginous fish have an operculum that guards the sensitive gill tissues
true
false

Explanation:

First Question:

Cartilaginous fish (like sharks) have skeletons made of cartilage. Cartilage does not require significant amounts of phosphorus and calcium for its structure (unlike bony fish with calcified skeletons). So the statement is false.

The skeleton of cartilaginous fish is made of cartilage, which is lightweight and flexible. This is beneficial for their movement (e.g., swimming) as it allows agility and reduces weight for buoyancy - related advantages. So the statement is true.

Gills are the site of gas exchange in cartilaginous fish. Most sharks do have 5 - 7 gill slits, but saying "all sharks have 5 gills" is incorrect as some species have more (e.g., 6 or 7). So the statement is false.

Answer:

False

Second Question: