Life Functions A CHARACTERISTICS OF LIFE Biology is
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 O 2 – Anaerobic Respiration- DOES NOT USE O 2
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 - INCREASE IN SIZE - UNICELLULAR AND MULTICELLULAR ORGANISMS UNDERGO THIS DEVELOPMENT - 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 ORGAN SYSTEMS ORGANISM POPULATION COMMUNITY ECOSYSTEM BIOSPHERE
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