Life Functions
A. CHARACTERISTICS OF LIFE Biology is the STUDY OF LIVING THINGS All living things have ALL (not just some) of the characteristics of life. All living things show a great deal of DIVERSITY (DIFFERENCES) but also have many characteristics in common. In other words, they show UNITY (SIMILARITIES). Each living thing is called an ORGANISM.
There are eight things that all living things (ORGANSIMS have in common: 1. LIVING THINGS ARE HIGHLY ORGANIZED AND CONTAIN MANY COMPLEX SUBSTANCES 2. LIVING THINGS ARE MADE UP OF ONE (UNICELLULAR) OR MORE (MULTICELLULAR) CELLS. A CELL IS THE SMALLEST UNIT OF LIFE 3. LIVING THINGS USE ENERGY 4. LIVING THINGS HAVE A LIMITED LIFE SPAN 5. LIVING THINGS GROW 6. LIVING THINGS RESPOND TO CHANGES IN THE ENVIRONMENT 7. LIVING THINGS ARE ABLE TO REPRODUCE
ALL LIVING THINGS POSSESS ALL OF THESE CHARACTERISTICS. NON LIVING THINGS ARE CLASSIFIED AS NON LIVING BECAUSE THEY DO NOT POSSESS ALL OF THEM… ALTHOUGH IT IS POSSIBLE FOR THEM TO POSSESS SOME!
B. THE LIFE FUNCTIONS Scientists have been unable to agree on a single definition of life, but do agree on what the signs of life are. Thus, we will now discuss the 8 life functions. What are they? R= RESPIRATION R= REGULATION R= REPRODUCTION E= EXCRETION G= GROWTH N= NUTRITION T= TRANSPORT S= SYNTHESIS R-R-R-E-G-N-T-S
1. RESPIRATION INVOLVES RELEASING CHEMICAL ENERGY FOUND IN NUTRIENTS. Organisms need materials and energy to stay ALIVE. An organism uses energy and a constant supply of materials to PERFORM ALL LIFE FUNCTIONS. The two types of respiration are: Aerobic Respiration- USES O2 Anaerobic Respiration- DOES NOT USE O2
2. REGULATION INVOLVES CONTROLLING AND COORDINATING VARIOUS ACTIVITIES Animals have: Nervous system- CARRIES NERVE MESSAGES (IMPULSES) Endocrine system- CARRIES CHEMICAL MESSAGES (HORMONES) Plants have PARTS THAT PRODUCE HORMONES, BUT NO NERVOUS SYSTEMS
3. REPRODUCTION INVOLVES AN ORGANISM PRODUCING NEW ORGANISMS OF THE SAME KIND Is reproduction necessary for the continued existence of an organism? NO. Is reproduction necessary for the continued existence of a species? YES- THE SPECIES WILL DIE OUT (EXTINCT) IF IT STOPS PRODUCING The two types of reproduction: ASEXUAL- ONE PARENT; ALL OFFSPRING IDENTICAL TO THE PARENT SEXUAL- TWO PARENTS; OFFSPRING NOT IDENTICAL TO EITHER PARENT
4. EXCRETION INVOLVES THE REMOVAL OF WASTES FROM AN ORANISM’S BODY
5. GROWTH INVOLVES AN INCREASE IN SIZE There is a difference between growth and development: GROWTH DEVELOPMENT INCREASE IN SIZE UNICELLULAR AND MULTICELLULAR ORGANISMS UNDERGO THIS CELLS IN AN ORGANISM INCREASE IN NUMBER AND DIFFERENTIATE (BECOME DIFFERENT) ONLY MULTICELLULAR ORGANISMS UNDERGO THIS
6. NUTRITION INVOLVES TAKING MATERIAL FROM THE ENVIRONMENT AND PUTTING IT INTO USABLE FORMS There are two types of nutrition: Autotrophic Nutrition- MAKE THEIR OWN FOOD (EXAMPLE: PLANTS) Heterotrophic Nutrition- CANNOT MAKE THEIR OWN FOOD Heterotrophic nutrition involves: Ingestion TAKING IN FOOD Digestion BREAKING DOWN FOOD Egestion DISCHARGING FOOD
7. TRANSPORT INVOLVES SUBSTANCES ENTERING AND LEAVING CELLS AND BECOMING DISTRIBUTED WITHIN CELLS Transport involves: Absorption DIRECT EXCHANGE WITH THE ENVIRONMENT Circulation DISTRIBUTES MATERIALS AMONG CELLS
8. SYNETHESIS SIMPLE SUBSTANCES ARE COMBINED TO MAKE COMPLEX SUBSTANCES EXAMPLE: Dehydration Synthesis
C. METABOLISM ALL THE CHEMICAL REACTIONS OCCURRING WITHIN THE CELL(S) OF AN ORGANISM R+R+R+E+G+N+T+S= METABOLISM !
D. HOMEOSTASIS THE CONDITION OF A CONSTANT, STABLE INTERNAL ENVIRONMENT Organisms need to keep their internal conditions relatively stable to survive (Examples: fever, diabetes). The process of maintaining a stable internal environment is called HOMEOSTASIS If homeostasis is disrupted in a major way, an organism cannot survive!
E. EVOLUTION AS A GROUP (not individually), species change, or EVOLVE over time. F. BRANCHES OF BIOLOGY The many levels at which life can be studied include (from smallest to largest): CELLS TISSUES ORGANS ORGAN SYSTEMS ORGANISM POPULATION COMMUNITY ECOSYSTEM BIOSPHERE