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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.
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