Characteristics of Life Regents Biology Unit 1

“The Living Environment” The living environment is essentially a biology course Biology- the study of all living things – Biologists use the scientific method to study life and it’s processes What is Life?

To be alive… Nearly all living things share several characteristics Living things… – are made up of units called cells – reproduce – are based on a universal genetic code – grow and develop – obtain and use materials and energy – respond to their environment – maintain a stable internal environment – change over time

1) Made up of Cells Cells are the basic units of structure and function of all life Cells are the smallest unit of life, but are quite complex Organisms may exist as single cells (unicellular) or many cells (multicellular) – Examples: Unicellular= bacteria, protozoa (amoeba, paramecia), and algae Multicellular= complex plants, animals, and fungi

2) Reproduction All organisms produce new organisms (offspring) – Reproduction is necessary for the survival of a species, but is not necessary for the survival of an individual organism Species- a group of organisms that are genetically distinct from other groups – 2 types Asexual reproduction- one parent produce genetically identical offspring Sexual reproduction- two parents combine genetic information to produce genetically different offspring

Forms of repro

3) Based on a Universal Genetic Code All known organisms store all the information necessary for their life processes within a genetic code, written in a molecule of DNA – The DNA of all organisms is made of the same 4 bases- Adenine, Thymine, Cytosine, Guanine

4) Grow and Develop All organisms undergo some form of growth and development – Growth can be accomplished in 2 ways: Individual cells increase in size, like a balloon The number of cells in the organism increases – During Development, cells often change or differentiate into different structures

5) Obtain and use Materials and Energy All organisms must take in materials (nutrients) and energy to grow, develop, reproduce, and stay alive. – Nutrition- how an organism obtains food from the environment. – Metabolism- chemical reactions through which organisms make and use energy Synthesis- building molecules (storing energy) Respiration- breaking down molecules to make energy (ATP)

6) Respond to Their Environment Organisms detect and respond to stimuli from their environment. – Stimuli- signal to which an organism responds Ex. Light, water, temperature, seasons

Phototropism Behavioral reg.

7) Maintain a Stable Internal Environment Maintaining the conditions inside an organism in a stable manner is called homeostasis. – Balance of: Body temperature Sugar levels Hormone levels pH Ion concentrations or electrolytes Water Concentrations Homeostasis is constantly being threatened by changes in the environment

8) Change Over Time Taken as a whole (think species level) organisms change/evolve over time Changes are often not noticeable over individual lifetimes, but the small change become dramatic over many generations Organisms must change or adapt to survive in a variable world.

Fossil record

Essential Processes While all life is characterized by the characteristics we just talked about, there are also several very important processes that are essential to the survival of an organism or its species. Processes: 1.Obtaining nutrients from the environment and breaking them down for transport 2.Transporting materials through the organisms

Essential Processes 3.Respiration- Breaking down nutrients (sugar) into smaller units to release chemical energy (ATP) 4.Synthesis- combining simple substances into complex substances Ex. Glucose in plants, proteins in cells 5.Growth- increase in size or number of cells

Essential Processes 6.Excretion- the removal of any type of waste product from the organism 7.Reproduction- the creation of new organism from the parent 8.Regulation and Response- responding to various internal and external stimuli