Match each description of the types of mechanical weathering to the correct term. 1.rocks tumble and collide with one another in a flowing stream1

2.water gets into cracks of rocks and expands as it freezes

3.the release of pressure causes sheets of rock to peel away

a.
exfoliation

b.
ice wedging

c.
abrasion

a #3

b#2

c#1

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation: