Atoms are electrically neutral because they contain equal quantities of positively charged protons and negatively charged electrons. Electrons and protons have equal but opposite charges, so the result is no net charge.
Answer:
D. contains fluid that becomes more concentrated as it moves down into the medulla
Explanation:
In kidney, loop of Henle is portion of the nephron which leads from proximal convoluted tubule to distal convoluted tubule.
Liquid entering loop is solution of the salt, urea, and also other substances which are passed along by proximal convoluted tubule. It is the tubule from which most of dissolved components which are needed by body are reabsorbed into blood. <u>First segment of loop,descending limb, is permeable to the water, and liquid reaching bend of loop is much richer than blood plasma in the salt and the urea.</u> As liquid returns through ascending limb, NaCl diffuses out of tubule into surrounding tissue, where concentration is lower. In third segment of loop, tubule wall effect further removal of the salt.
D) long chains of amino acids used for building, repair, and maintenance
