Organisms' effects on the environment

4th grade

physical characteristic

a feature or trait that can be seen

weathering

the breakdown of rocks into very small particles by gravity, water, wind, and ice

runoff

the movement of water on a surface to areas of lower elevation

root

part of a plant that grows into the ground, absorbs water, and holds the plant in place

soil

a mixture of sand, silt, clay, rock, and humus (plant and animal remains)

flow

to move or travel in a certain direction

erosion

the removal and movement of sediment from one place to another by gravity, water, wind, or ice

habitat

the natural home where an organism lives

alter

to change something

obstruct

to block or get in the way of something

fungi

break down dead trees and leaves, returning nutrients to the soil

bacteria

this in soil helps break down dead material and change soil composition