Which of the following is correct about the flatworm's muscular system ?
a. it's muscles are attached to a center bone.
b. it consists of two layers of muscle.
c. its muscles are all involuntary.
d. it contains three types of muscle tissue.

The afrikaners are an example of a founder effect that occurs when a new colony is started by a few members of the original population and the random decrease in genetic variation is an example of

The phlogiston theory in the 17th century attempted to explain burning. the theory stated that combustable objects contained a material called phlogiston, a substance without mass, color, odor, etc. after objects burned, the objects were dephlogistonated and were then in their true form. the phlogiston theory was accepted until the 18th century, when lavoisier proved that combustion requires a gas that has mass. phlogiston is considered a) to be scientific knowledge b) not to be scientific knowledge c) to be proven by scientific method d) to be accepted in the modern scientific community

Which of the following is a common danger of commercial fishing?