Characteristics of Life

Objectives

Characteristics of Life There is no one definition of life that is accepted by scientists. However, life is defined by the properties and functions characteristic of living things Life Functions {Properties of Life} are the various activities carried on by living things.

Properties of Life Order Reproduction Growth and Development Nutrition Energy Utilization Respiration Response to Stimuli

Order All other characteristics of life emerge from an organism’s complex organization Made up of cells A single cell can be an organism Bacteria Unicellular Most organisms are multicellular

Energy Utilization Energy is used to grow, develop and reproduce Anabolism Process in a living thing that involves putting things together, or synthesizing complex substances from simpler substances Photosynthesis Photo = Light Synthesis = put together

Energy Utilization #2 Catabolism Metabolism Changing complex substances into simpler ones Results in a release of energy Can animals perform photosynthesis? Metabolism The total sum of all chemical reactions in the body The balance of anabolism and catabolism

Growth and Development Growth involves the increase in cell number and cell size What growth spurt are you going through right now? When does an organism stop growing/developing? What tells our body that it is time for a cell to die? How often do humans replace every cell in their body? Growth-->Aging-->Death How can you tell when a tree has died?`

Reproduction New cells arising from preexisting cells Organisms can reproduce their own kind Produce organisms of the same “type” Species Sexual Reproduction Asexual Reproduction 2 Cells combining to produce the first cell of a new organism Single organism that can reproduce without the aid of another

Plants Dicots Plants contain both sperm and eggs Fertilization Located in the flower of the plant Fertilization Self Pollination The sperm fertilizes the egg of the same plant Cross Pollination The sperm of Plant A fertilizes the sperm of Plant B

Response to Stimuli/Environment Involves behaviors, metabolism and growth What are some environmental pressures that you, as a human, respond to? Light, temperature, odor, sound, gravity, heat, water and pressure

Response to Stimuli/Environment II Is it always hot in Florida? What does your body do to cool off? Sweat--Brain perceives that you are losing water--Become thirsty

Response to Stimuli/Environment III Homeostasis Process by which organisms respond to stimuli in ways that keep their body suitable for life Refers to an organism’s ability to maintain a constant or stable condition Regulation mechanism to maintain an organisms internal environment Provides capacity to evolve--”micro-evolution” What household appliance provides a great example of homeostasis?