The atrioventricular (av) valves of the human heart have "heart strings" attached to the ventricular side of the valve flaps. these strings, properly called chordae tendinae, reach downward from the underside of the valves and attach to the bottom of the ventricles. they are long enough to just allow the valve flaps to shut. what probably the biological role of the chordae tendinae?

The correct answer is - prevents the prolapse and hold them in the closed position so prevent from backflow of blood into atria.

Explanation:

The chordae tendineae also known as the heartstrings which are attached to the ventricular side of the bi capsid and tricuspid valve flaps. These are attached to the papillary muscles of the valves in the heart.

Blood flows to the ventricles from atria down the pressure gradient during systole. Heartstrings are relaxed due to the AV valves are forced open but during ventricular systole, these tendineae prevents backflow of the blood that in atria as they are tensed and prevent them to prolapse.

Thus, the correct answer is -  prevents the prolapse and hold them in the closed position so prevent from backflow of blood into atria.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

answer; the above answer to the above statement is (true)