Which of the following statements about prescribed burns is true? a. Prescribed burns will always have detrimental effects on ecosystems, but should be used to protect homes. b. Prescribed burns are necessary for preventing natural wildfires. c. Prescribed burns can help maintain healthy ecosystems. d. None of the above

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

Anita thinks that she has heterozygous alleles for red hair. if she is correct, which of these diagrams best illustrates anitas alleles pf red hair

Which of the following is not a symptom of desertification? a) decrease in salt content of the soil b) lowering of the water table c) reduced surface water d) increased soil erosion e) loss of native vegetation