Chapter 1

 What does it mean to be alive? On a sheet of paper, write a definition for life or living. Do this independently. Try not to consult your group members!

UNICELLULARMULTICELLULAR  single-celled organisms  free-living and contain structures, called organelles, that allow them to be self- sufficient.  Example: bacteria  Many celled organisms  More complex  Humans: cells are organized into tissues.tissues  Have a common function like a muscle  Tissues are organized into organs like the heart. organs  Organs are organized into organ systems, like the cardiovascular system. organ systems  Organ systems functioning together make up a living organism. organism

 Most of us call this EATING!  Science calls it “ingestion” – the taking in of food  We have to be able to convert our food, a form of energy, to chemicals our cells can use through metabolism. AutotrophsBacteriaHeterotrophs Make their own food (mostly through photosynthesis) Plants, algae, microorganisms Chemosynthesis – production of chemicals (nutrients) as part of their metabolism Capture their own food Animals & fungi

 Energy (usually sugars) obtained from the environment  Anabolism - a process (such as tissue growth) that involves synthesizing, or putting together, complex substances from simpler substances (sugars) (REQUIRES ENERGY)  Catabolism- final breakdown (digestion) of complex substances into simpler ones, ( RELEASES ENERGY )  Metabolism- total sum of all chemical reactions in the body, or the balance between anabolism and catabolism

 Living things will make changes in response to a stimulus in their environment.  anything that causes an organism to react  A behavior is a complex set of responses.  This often results in movement of the individual toward safety.  As young children we learned to avoid hot stoves and busy streets.  Plants:  They grow up toward the sun, and some have leaves able to turn to follow the sun, allowing them to photosynthesize better. Their roots grow down to search for water and minerals. If a plant doesn't get enough sunlight, water or minerals it will die.

 In order to survive, organisms must be able to achieve homeostasis.homeostasis  an organism’s ability to maintain the constant or stable conditions necessary for life.  Each type of organism has a specialized way to stay in balance with its outside and inside environments.  A paramecium has a contractile vacuole that pumps excess water out of its cell in order to survive in a fresh water environment.  We have an internal "thermostat" that helps us maintain a body temperature of about 98.6 degrees Fahrenheit.

 All living things reproduce in one of the following ways:  Asexual reproduction - Producing offspring without the use of gametes.  Produces genetically identical offspring “clones”  Example: many invertebrates such as - sea anemones, sea stars; bacteria split; budding plants  Sexual reproduction - Producing offspring by the joining of sex cells.  Union of a sperm cell from male united with egg cell from female.  Offspring is different from either parent, although it contains characteristics from both “unique”  In living things, we call this genetic biodiversity.biodiversity

 Cell division - the orderly formation of new cells.  Cell enlargement - the increase in size of a cell. Cells grow to a certain size and then divide.  An organism gets larger as the number of its cells increases.

 Life does not necessarily mean continuous growth  During growth organisms undergo a cycle of changes called development.  Bodily maintenance occurs throughout life (requires energy). Aging occurs when an organism loses its ability to maintain itself.

Fetal Growth & Development: 1)Zygote: formed at fertilization; has all of the genetic information necessary to become a child 2)Embryo: a multicellular organism; earliest stage of growth and development 3)Fetus: a developing mammal from nine weeks to birth

 Adaptation: an inherited structure, behavior or internal process that enables an organism to respond to environmental factors and live to produce offspring  Inherited from previous generations  As the environment changes  some adaptations are more suited to the new conditions than others  Individuals with more suited adaptations survive and reproduce  The gradual change in a species through adaptations over time is evolution

 How does the dolphin demonstrate life?  IF an organism is missing a limb, does it still meet all criteria to be considered living?