Explain how Amoeba sp. can survive in hypotonic freshwater against the citoplasm of such organisms

To regulate osmotic pressure, most freshwater amoebae have a contractile vacuole (CV) that expels excess water from the cell. This organelle is necessary because the surrounding water is hypotonic with respect to the contents of the cell. Water is transferred across the amoeba's cell membrane by osmosis

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.

the answer is sex-linked recessive.