QUESTION 11 There is evidence that invertebrates possess the required enzymes to produce calcitriol, but it is thought that they do not because regulation of calcium ions is less critical in invertebrates. • True • False QUESTION 12 The hormonal control of blood calcium and phosphate • Is centered on body phosphate, body calcium changes in concert with changes in body phosphate. • Is dependent on CRGP (calcitonin-related gene peptide) in invertebrates but not vertebrates. • Is dependent on PTH and calcitriol in vertebrates and invertebrates. • Is dependent on stanniocalcin in terrestrial animals. QUESTION 13 Why do terrestrial animals express calcium sibling proteins? • The terrestrial environment has far less available calcium than aquatic environments. • Only aquatic animals produce calcitriol. • Terrestrial animals have lost the gene for FGF23. • The terrestrial environment has far more available calcium than aquatic environments. QUESTION 14 Cell signaling through the VDR requires .... • heterodimerization with the retinoic x receptor (RR) in the cell nucleus after binding of calcitriol. • homodimerization after binding calcitriol within the nucleus. • homodimerization in the cell cytoplasm after binding calcitriol and then translation of the complex into the nucleus. • heterodimerization with the liver x Receptor (LxR) in the cell nucleus after binding of calcitriol. QUESTION 15 Calcitriol and the VDR control blood calcium levels in bony fish. • This is not true, bony fish have no need for a hypercalcemic hormone. • This is true but only in bony fish that do not express stanniocalcin. • This is true, bony fish have a need for a hypercalcemic hormone. QUESTION 16 VDR • Upregulates the expression of the enzyme that degrades calcitriol. • Downregulates the expression of TRP channels in the gut. • Is only expressed in the bone cells of vertebrates. • Is found in invertebrates and vertebrates but is under the control of calcitriol only in vertebrates. QUESTION 17 What is the likely reason for the evolution for calcitriol synthesis? • It is thought to have evolved when aquatic animals became terrestrial. • It is thought to have evolved as a means to ensure the use of calcium ion as part of cell effector pathways. • It is thought to have evolved when animals moved from seawater to freshwater sources. • It is thought to have evolved as a molecular trap for UV-B in aquatic animals. QUESTION 18 Mineralocorticoids ... • includes aldosterone, which accelerates calcium gain in the body. • include corticosterone, which prevents calcium loss from the body. • include cortisol, which as a natriuretic effect. • include aldosterone, which has an anti-natriuretic effect. QUESTION 19 Calcitriol • Is produced by the proximal convoluted tubule of the vertebrate kidney. • Is under the regulation of parathyroid hormone (PTH). • Signals through the VDR that heterodimerizes with the RxR transcription factor. • Has all the properties listed above. QUESTION 20 Which statement about the hormonal evolution of sodium ion control is correct? • In hagfish, both aldosterone and deoxycorticosterone regulate blood sodium ion. • In elasmobranchs, because they are osmoconformers, there is no need for hormonal control of sodium ions. • Fish produce atrial natriuretic peptide, but it plays no role in the control of sodium ion. • In amphibians, angiotensin Il doesn't act to stimulate aldosterone synthesis. • All of the above statements accurately describe the evolution of sodium ion in vertebrates. Answer all for my homework please

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