The Needs of Living Things Notes 2.1d

The Needs of Living Things All living things must satisfy their basic needs for water, food, living space, and stable internal conditions.

Water All living things need water to survive. Most organisms can live for only a few days without water. Organisms need water to: –Obtain chemicals from their surroundings. –Break down food. –Grow. –Move substances within their bodies. –Reproduce.

Food Recall that organisms need a source of energy to live. They use food as their energy source. There are different ways to get energy.

How to get energy Autotrophs: auto- means “self”, and troph- means “feeder”. So these guys can feed themselves – usually by using the sun. –Example: all green plants and some bacteria

How to get energy Heterotrophs: hetero- means “other”, and troph- means “feeder”. So these guys need to get food from somewhere other than themselves. THEY EAT!! –Example: All animals are Heterotrophs as well as mushrooms and slime molds.

Living Space All organisms need a place to live and get food, water, and shelter. No matter where an organism lives, it must provide what it needs to survive. Because there is a limited amount of space on Earth, some organisms compete for space. Trees in a forest complete for sunlight above ground. Below ground, they compete for water and minerals.

Stable Internal Conditions Organisms must be able to keep the conditions inside their bodies stable, even when the conditions outside change. Homeostasis: homeo- means “the same”, stasis- means “to stay” or “to be”. Homeostasis keeps internal conditions just right for cells to function. Its like the Goldilocks position. Not too hot, not too cold, JUST RIGHT!

Homeostasis There are many things that cells need to keep the same, not just temperature. Barnacles need to stay wet, even when the tide goes out. They do this by closing their shells tightly – thereby conducting Homeostasis.