18. Circle the letters of the sentences that are true about aquifers. a. They are permeable rock layers that are saturated with water.
b. They are recharged or refilled as rainwater seeps into them.
c. They are often made of shale and unbroken granite.
d. Many people rely on aquifers for drinking water.

"do a testcross with a homozygous recessive plant."

succession returns a disturbed

ecosystem to a more stable state. this is also classified into two (2) types:

primary succession and secondary succession. the primary succession arises when

a new land is transformed and a bare rock has been exposed providing an environment

that can be occupied for the first time. while, secondary succession occurs

when a previously occupied environment was disturbed that kills much of all its

community

explanation: