How Do We Know When Something is Alive? The world around you is made up of many different things. Some things, such as plants and animals are considered to be living. Other things, such as cars and rocks, are considered to be nonliving. Living things are called organisms. You know that plants and animals are living things.

Characteristics of Living Things 1. Living things are highly organized and contain many complex tissues

Characteristics of Living Things 2. Living things use energy. They get this energy from food! 3. Living things have a definite shape and a limited size.

Characteristics of Living Things 4. Living things have a limited life span.

Characteristics of Living Things 5. Living things grow 6. Living things respond to changes in their environment.

Characteristics of Living Things 7. Living things reproduce

Characteristics of Living Things 8. Living things are made up of one or more cells Cells are the “building blocks” of life!

Life Functions Biology is the study of living things, or once living things All living things carry out certain activities that are necessary to stay alive These are called life functions

1. Nutrition Nutrition includes the activities by which living things obtain food and break it down into nutrients These nutrients supply the energy and materials necessary for the growth and repair of their bodies

Types of Nutrition Autotrophic: These organisms make their own food, typically through photosynthesis (“self-feeders”) Example: Plants Heterotrophic: These organisms must obtain their own food from the environment (“other-feeders”) Example: Animals

Three Steps of Nutrition 1. Ingestion: Taking in of food 2. Digestion: Breaking down food into simpler forms that an organism can use 3. Egestion: Removal of undigested food from the digestive tract (this is NOT excretion)

2. Transport Transport can be separated into two parts: Absorption: Usable materials (food, water, oxygen) are taken in by the organism Circulation: These materials are distributed throughout the organism

3. Respiration Respiration is the release of energy by the chemical breakdown of food It is NOT the same thing as breathing! Two types of respiration: Aerobic: Requires oxygen (plants, animals) Anaerobic: Does not require oxygen (bacteria, yeast)

4. Synthesis Chemical activities by which an organism uses small molecules to build larger molecules These small molecules become available through the process of digestion The large molecules become part of the structure of an organisms through assimilation

Food gets broken down into smaller pieces through digestion. These smaller pieces are then used to build your body structures (muscles, bones).

5. Growth An increase in the size or number of cells This is aided by the process of synthesis Example: You started off as one single cell, and now you are made up of over 30 trillion cells!

6. Excretion The removal of “metabolic wastes” produced by cells as a result of their life functions These wastes include urine, sweat, tears, and carbon dioxide (liquid wastes) This is NOT the same thing as egestion (solid wastes)

7. Regulation Involves the coordination and control of all activities of an organism In animals, regulation is accomplished by two specialized body systems. Can you name them?

8. Reproduction Organisms producing more of their own kind NOT essential for the survival of the organism, but it is crucial for the continued existence of that organism as a species

Two Types of Reproduction Asexual Sexual One only parent is necessary All offspring are identical to the parent Examples: Bacteria, some plants and fungi Two parents are required Offspring are NOT identical to either parent Examples: Animals

Metabolism The sum total of all of the life functions Includes all of the chemical reactions in your body and the release of energy Preconception is that it has to do with food, but this is actually true because almost all of the life functions have to do with food!

Homeostasis Maintaining a constant, stable, internal environment regardless of an organisms external environment This is the goal of all life functions! What are some ways your body maintains a constant and stable internal environment?

rowth espiration omeostasis ynthesis ransport egulation ssimilation utrition etabolism xcretion eproduction