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.