18. over time, how do sand dunes tend to migrate? a. perpendicular to the movement of the wind b. in the same direction as the wind blows c. toward the wind d. in random directions

in the same direction as the wind blows

Explanation:

The dunes are hills formed by grains of sand held together by the action of wind or water. Over time, as sand dunes tend to migrate in the same direction as the wind blows.

They have a larger side that is eroded (windward) and a smaller, steeper side (leeward) where deposition of eroded material occurs. Through this mechanism of erosion and deposition the dunes are considered highly dynamic, "moving" over time.

economic impact of malaria is estimated to cost africa $12 billion every year. this figure factors in costs of health care, absenteeism, days lost in education, decreased productivity due to brain damage from cerebral malaria, and loss of investment and tourism.

answers are:

lysogenic     viral dna merges with host cell dna

lysogenic     no symptoms

lytic               viral dna takes over

lysogenic     virus does not destroy host cell

lytic               virus destroys host cell

lytic               induces symptoms of viral infection

lysogenic       cell reproduces and spreads provirus