Dams are barriers that prevent the flow of water. they are created to provide flood control, recreational areas, water for irrigation, and hydroelectric power. although dams serve many important purposes, they can also have a negative impact on the environment by a. serving as a place for people to have picnics. b. increasing fresh water sources for humans. c. providing new wildlife habitats. d. preventing fish from moving along a river.

As Dams act as Obstruction to the Natural Flow of the River, they Prevent fish from moving along the River (i.e.) either from Sea to River or From River to Sea.

So : Option D is the Answer

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

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.