7th Grade Chapter19 Studyguide
GPS: S7L4 – Students will examine the dependence of organisms on one another and their environments.
Chapter 19 Cycles in Our Ecosystems
Anything that has mass and occupies space is matter. This matter must be used over and over again in our closed ecosystem, we call this recycling. We will discuss a few of the very important cycles life depends on.
The Water Cycle
The movement of water among the oceans and our atmosphere, and the movement of fresh water (lakes, rivers, and streams) and our atmosphere make up the water cycle. There are several parts we will consider of the water cycle.
Precipitation
Water moves from the atmosphere to the land or bodies of water as precipitation (rain, snow, sleet, and hail). About 91 % of the water falls into our oceans, the rest falls on lakes, rivers, ponds, streams and the land as fresh water. Remember: fresh water does not necessarily mean it is clean water, it simply means it is low in salt content. Think of ocean water as salt-water.
Evaporation
When water goes from the bodies of water on the Earth back into the atmosphere, evaporation has occurred. This cycle is driven by the energy from the sun. When water vapor cools as it undergoes the process of condensation. Condensation is the process of water going from the gas phase into the liquid phase. In order for water to condensate, the moisture must have some form of particulate to attach to. This particulate can be in the form of dust, smoke, or other forms of pollution as well as solid surfaces. When condensation occurs in the atmosphere and falls back to Earth we again have precipitation. This is why it is called the water cycle.
Ground Water
As the water falls to the Earth, some of it falls onto the land. Some of the water seeps into the ground and enters underground caves, rocks with small pores and is often stored there. This water in under ground is called ground water. Ground water may stay in the Earth for hundreds to thousands of
Chapter 19 Cycles in Our Ecosystems
Anything that has mass and occupies space is matter. This matter must be used over and over again in our closed ecosystem, we call this recycling. We will discuss a few of the very important cycles life depends on.
The Water Cycle
The movement of water among the oceans and our atmosphere, and the movement of fresh water (lakes, rivers, and streams) and our atmosphere make up the water cycle. There are several parts we will consider of the water cycle.
Precipitation
Water moves from the atmosphere to the land or bodies of water as precipitation (rain, snow, sleet, and hail). About 91 % of the water falls into our oceans, the rest falls on lakes, rivers, ponds, streams and the land as fresh water. Remember: fresh water does not necessarily mean it is clean water, it simply means it is low in salt content. Think of ocean water as salt-water.
Evaporation
When water goes from the bodies of water on the Earth back into the atmosphere, evaporation has occurred. This cycle is driven by the energy from the sun. When water vapor cools as it undergoes the process of condensation. Condensation is the process of water going from the gas phase into the liquid phase. In order for water to condensate, the moisture must have some form of particulate to attach to. This particulate can be in the form of dust, smoke, or other forms of pollution as well as solid surfaces. When condensation occurs in the atmosphere and falls back to Earth we again have precipitation. This is why it is called the water cycle.
Ground Water
As the water falls to the Earth, some of it falls onto the land. Some of the water seeps into the ground and enters underground caves, rocks with small pores and is often stored there. This water in under ground is called ground water. Ground water may stay in the Earth for hundreds to thousands of