All of the statements about sponges are correct except:
a. mesohyl is mostly noncellular and provides structural support.
b. sponges are among the most primitive organisms to have developed reproductive organs.
c. gas exchange of oxygen and carbon dioxide occurs through diffusion.
d. choanocytes have flagella that beat in a coordinated fashion.

The correct answer is b. Sponges are among the most primitive organisms to have developed reproductive organs.

Explanation:

Sponges are multi-cellular animals that are one of the members of Porifera phylum. These organisms are very primitive organisms so their body cells are not organized into a tissue so it lacks tissue or organ level of organization.

Developed reproductive organs are present in the organisms which have a higher level of body organization like mammals, reptiles. These organs produce and store gametes which helps in fertilization.

So as sponges lack tissue and organ level of organization it does not have reproductive organs and reproduce through budding or gamete fusion. They produce gametes through differentiation in their choanocytes.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: