With the help of Figure 17.8, indicate whether the ring system in each of the following heterocyclic amines is (1) saturated (2) unsaturated or (3) fused. More than one choice may be correct for a given heterocyclic amine.

a. Pyrrole

b. Indole

c. Pyrimidine

d. Purine

Winter wheat is planted in the early fall, grows over the winter when the weather is colder, and is harvested in the spring. As the temperature drops, the makeup of the plasma membrane of winter wheat changes. Unsaturated fatty acids replace saturated fatty acids in the phospholipids of the membrane. Why is this a suitable adaptation?

Potassium chloride has a solubility of 43 g of $\mathrm{KCl}$ in 100 g of $\mathrm{H_2O}$ at 50 $\dedgree$C. Determine if adding 25 g of $\mathrm{KCl}$ to 100. g of $\mathrm{H_2O}$ forms an unsaturated or saturated solution at 50 $\dedgree$C.

Potassium nitrate has a solubility of 32 g of $\mathrm{KNO_3}$ in 100 g of $\mathrm{H_2O}$ at 20 $\degree$C. Determine if aadding 68 g of $\mathrm{KNO_3}$ to 150. g ofv$\mathrm{H_2O}$ forms an unsaturated or saturated solution at 20 $\degree$C.

What products would result after hydrolysis from reaction of the enamine prepared from cyclopentanone and pyrrolidine with the following $\alpha$, $\beta$-unsaturated acceptors? (a) H$_2$C=CHCOOEt (b) H$_2$C=CHCHO (c) CH$_3$CH=CHCOCH$_3$

Which condensed structural formula represents an unsaturated compound?

(1) $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_3$

(2) $\mathrm{CH}_3 \mathrm{CHCHCH}_3$

(3) $\mathrm{CH}_4$

(4) $\mathrm{CH}_3 \mathrm{CH}_3$

Identify which of the following statements applies to tristearin: (a) It is a solid at room temperature. (b) It is unreactive toward molecular hydrogen in the presence of Ni. (c) It undergoes hydrolysis to produce unsaturated fatty acids. (d) It is a complex lipid. (e) It is a wax. (f) It has a phosphate group.

Potassium fluoride has a solubility of 92 g of KF in 100 g of $\mathrm{H_2O}$ at 18 $\degree$C. Determine if adding 42 g of KF to 50. g of $\mathrm{H_2O}$ mixtures forms an unsaturated or saturated solution at 18$\degree$C.

Identify each of the following reactions in the $\beta$ oxidation of palmitic acid, a $\mathrm{C}_{16}$ fatty acid, as activation, transport into mitochondria, first oxidation, hydration, second oxidation, or cleavage (thiolysis):

a. $\alpha, \beta$-Unsaturated palmitoyl CoA and $\mathrm{H}_2 \mathrm{O}$ form 3-hydroxypalmitoyl CoA.

Which statement about unsaturated fats is true?

(A) They are more common in animals than in plants.

(B) They have double bonds in their fatty acid chains.

(C) They generally solidify at room temperature.

(D) They contain more hydrogen than do saturated fats having the same number of carbon atoms.

Which formula represents an unsaturated hydrocarbon?

(1) $\mathrm{C}_5 \mathrm{H}_{12}$

(2) $\mathrm{C}_4 \mathrm{H}_{10}$

(3) $\mathrm{C}_3 \mathrm{H}_{\mathrm{8}}$

(4) $\mathrm{C}_2 \mathrm{H}_4$

Which of the following pictures best represents an unsaturated solution of sodium chloride, $\mathrm{NaCl}$ ? In these pictures, the dark gray spheres represent $\mathrm{Na}^{+}$ions and the green spheres represent chloride ions. For clarity, water molecules are not shown.

Potassium nitrate has a solubility of 32 g of $\mathrm{KNO_3}$ in 100 g of $\mathrm{H_2O}$ at 20 $\degree$C. Determine if adding 19 g of $\mathrm{KNO_3}$ to 50. g of $\mathrm{H_2O}$ forms an unsaturated or saturated solution at 20 $\degree$C.

During a heavy rainstorm, runoff is most likely to occur if the surface of the soil is (1) firmly packed clay-sized particles (2) loosely packed sand-sized particles (3) covered by trees, shrubs, and grasses (4) unsaturated and has a gentle slope