Char of lv things & necess of life

Is It Alive?

Characteristics of Living Things

&Necessities of

Life

Characteristics of Living Things

What makes something living or nonliving?

Is a rock living? What about a piece of grass? Or an icicle?

There are 6 characteristics of

living things

#1: Living Things Have Cells

All living things are composed of one or more cells

What is a cell? A cell is a membrane-covered structure that contains all the material necessary for life

Unicellular = one cell; multicellular = more than one cell

#2: Living Things Sense and Respond to Change

A stimulus is a change that affects the activity of an organism.

-Examples: chemicals, gravity, light, sound, hunger, or anything else that activates a response

Homeostasis is the maintenance of a stable internal environment Allows us to keep our internal environment in check when

external environment is changing Example: When it gets cold outside, our internal temp still

stay 98.6 degrees

Homeostasis is kind of like a see-saw, which your body wants to keep balanced.

-Outside temp is cold, but our bodies don’t plunge into a low body temp—it works hard to balance our temp at 98.6 degrees, no

matter what the outside weather!

#3: Living Things Reproduce Sexual reproduction:

two parents produce offspring that is similar to both parents

Asexual reproduction: single parent produces offspring that is identical to the parent

#4: Living Things Have DNA The cells of ALL living

things contain the molecule “deoxyribonucleic acid, or DNA

DNA controls structure and function of the cells

Heredity: passing copies of DNA from parent to offspring

#5: Living Things Use Energy

Organisms need and use energy to carry out activities in life

Metabolism: the total of all the chemical activities that the organism performs

#6: Living Things Grow and Develop

We all GROW! It doesn’t matter if you are a multicellular or unicellular organism

We all develop! As we grow, we go through different stages in our lives. Example: US! Baby->child->teen-

>adult Acorn seedling sapling

tree

Necessities of Life

Organisms need 4 things to live: Water

Your body is made up of 70 % water

Most of the chemical reactions involved in metabolism require water

AirA mixture of gases (oxygen and

carbon dioxide)Organisms on land get oxygen

from the airMarine animals get dissolved

oxygen from the water or by coming up for air

Green plants, algae, and some bacteria need carbon dioxide in addition to oxygen to undergo their food making process called photosynthesis

Food Gives us energy and raw materials

needed to carry on life processes such as replacing cells

Producers: make their own food Consumers: get food by eating other

organisms Decomposers: break down nutrients

of dead organisms or animal wastes

5 Building Blocks of Cells 1) Proteins:

Molecule made up of amino acids; helps build and repair body structures. Example: protein hemoglobin is in red blood cells and binds to oxygen to deliver it throughout the body

2) Carbohydrates: molecules made up of sugar A) Simple

carbohydrates: one sugar molecule, like table sugar

B) Complex carbohydrates: hundreds of sugar molecules, such as plants (potato, whole wheat)

3) Lipids: do not dissolve in water; include fats and steroids

A) phospholipids are the molecules that form much of the cell membrane; the head is attracted to water but the tail is not—the tails attract to form two layers

4) ATP: “Adenosine Triphosphate”; major energy-carrying molecule in the cell; provides energy for the cell

5) Nucleic Acids: have all the information a cell needs to make proteins; DNA is a nucleic acid

Shelter (a place to live) All living

things need a place to live that has all of the necessities of life (enough space, food, water, etc)