9.1 Energy flow in ecosystems *** Every living thing needs energy. Energy in an ecosystem ispassed from one organism to another.Energy in Plants and AnimalsSunlight is the main energy source for life on Earth.Energy...

Environments naturally change over time. These changes can occur veryslowly or very quickly. Changes to an environment can affect ecosystems andthe species that inhabit them. The Process of Change This process of gradual change...

Human activities change environments. Whenecosystems change, some organisms die or leave the area.Other organisms adapt to the changes and survive. Like all organisms, humans interact with theirenvironment. We get our food, shelter, and waterfrom...

Complex organisms are made of many organ systems.The skeletal and muscular systems work together to supportand move your body. A group of organs that work together makes up an organsystem. The heart and blood...

The respiratory and circulatory systems work together to deliveroxygen and nutrients to cells throughout the body. The Respiratory SystemYour body cells need a constant supply of oxygen to use thenutrients in the food you...

The digestive system makes nutrients available to all body cells.The nervous system controls all other systems in the body.The Digestive SystemOne of your favorite foods might be pizza. It contains manynutrients your body needs....

The human body has many ways to preventdisease-causing organisms from getting into tissues.Microorganisms in Your BodyWhen you get a cut or scrape, you should clean it andcover it with a bandage so the wound...

Earth’s Landforms Viewed from space, Earth’s land might seemflat. From close up, you can see many naturalfeatures on Earth’s surface. These features arecalled landforms. Tallest and FlattestThe tallest and most visible landforms aremountains. Most...

You have learned that Earth is made up oflayers. The crust is the thin outer layer. Themantle lies beneath the crust. PlatesEarth’s surface is broken into several hugeplates of rock. Plates are made of...

What is weathering?Every day, rocks move and change shape asthe wind blows and rain falls. Look at the rockbelow. What happened to it?Even the largest boulder can break apart overtime. Weathering is the slow...