Biology confusion! 10 points to best answer!?

[Rose L]

Which of the following is correct about the flatworm’s muscular system?
It contains three types of muscle tissue.
It consists of two layers of muscle.
Its muscles are attached to a center bone.
Its muscles are all involuntary.


Which of the following is correct about the human muscular system?
Smooth and cardiac muscles operate involuntarily.
Skeletal muscles often form in hollow internal structures.
Each bone is attached to one muscle.
Muscles of the body can pull and push.


When a person bends an arm, a different muscle is used to bring it back to the original position. Why can’t the same muscle be used to both bend and unbend the arm?
Muscles are not long enough.
Each muscle wraps around only one bone.
Muscles can only pull, not push.
The first muscle needs time to make more ATP.

[Yaybob]

Which of the following is correct about the flatworm’s muscular system?
It consists of two layers of muscle. From http://userwww.sfsu.edu/~biol240/labs/lab_17hydrostaticsk/pages/flatworms.html "Obtain a slide showing a cross section of the flatworm Planaria and you'll see a ciliated epithelium followed by a layer of circular muscles and finally a longitudinal muscle layer."

Which of the following is correct about the human muscular system?
Smooth and cardiac muscles operate involuntarily.
From http://biology.about.com/library/organs/blcircsystem4.htm "Unlike most of the other hollow organs, whose muscle layers are composed of smooth muscle, the heart is composed of cardiac muscle. The smooth muscle surrounding the other hollow organs is involuntary, meaning it does not need to be told to contract. Cardiac muscle is also involuntary."

When a person bends an arm, a different muscle is used to bring it back to the original position. Why can’t the same muscle be used to both bend and unbend the arm?
Muscles can only pull, not push.
From http://biology.clc.uc.edu/courses/bio105/muscles.htm "It is important to remember that muscles can only pull or contract, not push