CP Biology
Unit 1: The Nature of Life
Chapter 1:
Characteristics of Life
All living things share the same
traits of life
1. Made
of one or more cells
a. cell – basic unit of life
b. unicellular organisms
– bacteria, amoeba, etc.
c. multicellular organisms – cells specialize
2. Have DNA
a. Instructions for all life functions
b. Cells copy DNA and pass it to offspring
c. “Universal” code – same for all organisms
3. Obtain and use energy
a. Food – for energy and raw materials
b. Producers – use sunlight to make food
c. Consumers – find food in environment
Cycling of Materials
a. All forms of life depend on each other and
on physical environment
a. Biotic and abiotic
b. Take in light, food, water, air
- For energy, material for growth and repair
c. Remove wastes, die, decompose
Chemicals CYCLE
Environment
 producers
 consumers
 decomposers
 back to environment
Energy does NOT cycle
Sun  producers  other organisms. Energy
is used to sustain life, some lost as heat.
4. Grow and Develop
a. Grow – increase in size (add more cells)
b. Develop – change while maturing
a.
b.
c.
d.
Multicelled begin as a single cell
Cells copy and specialize (differentiate)
Form many different kinds of cells
Organisms change as they
grow older
Stem Cells
a. Can become different kinds of cells
b. Depends on chemical signals from
their environment
5. Are organized
Cells – different parts do specific
functions
Multicelled - Levels of Organization
Cells differentiate  specialized cells
Different kinds of cells form tissues
Different kinds of tissues form organs
Organs work together to form organ
systems
f. Body systems work together to keep an
organism alive.
a.
c.
d.
e.
Cells  tissues  organs
 organ systems  organism
6. Reproduce
a. New cells by cell division
b. Form a new organism
c. Asexual – one parent
- identical offspring
c. Sexual – two parents
- offspring gets genes
from both parents
- must be same species
Is mule a species?
Parents – horse and donkey
Hybrid - offspring from two
closely-related species
- cannot reproduce
 NOT a species
7. Respond to environment
a. Stimulus - causes a reaction
b. Response - reaction to a stimulus
c. Internal or external stimuli
d. Must keep homeostasis (constant
internal conditions)
8. Evolve
a. Species can slowly change over time to
better fit an environment
b. Individual organisms DO NOT evolve
c. Earliest life 3.5 billion years ago
Unity and Diversity
Life is unified – by evolution
- all living things do same life functions
- same chemical make-up and processes
 shared ancestor
Living things are diverse – by evolution
- special features for different environments
Structure and Function
a. “Form follows function”
b. Features evolve to perform a
function better
c. Different environments need
different kinds of adaptations
Other life traits
1. Contain many complex chemicals
2. Have recognizable shape and size
3. Have limited life span
Life Processes
How do living things stay alive?
All life processes work to
maintain homeostasis
Metabolism – all the chemical processes
an organism performs
1. Cellular Respiration
• Break down food molecules for
energy
• NOT digestion, NOT “breathing”
• Aerobic or anaerobic
2. Nutrition
• Get or make food; process it for cells to use
• Nutrients – for energy, raw materials
1. Autotrophs (producers)
a.
b.
c.
d.
Make their own food
Photosynthesis
Base for all food chains
Plants, algae, some bacteria
• Plants make food from small
compounds in the environment.
• Use sunlight energy
Autotrophs make food
for other organisms
2. Heterotrophs (consumers)
a. Take in food from environment
b. Digest – break large molecules down
3. Decomposers
a. break down wastes, dead organisms
b. recycle nutrient molecules
Digestive System
• Breaks down food
into molecules small
enough to enter cells
• Nutrients and water
absorbed by cells
• Liver, pancreas,
others make enzymes
3. Transport
Move materials in a cell or organism
• Cross cell membranes
• Spread throughout cell
• Deliver needed materials, remove
wastes
• Multicellular – need way to transport
throughout organism
Animals have a
circulatory system
- heart, blood vessels
Plants have transport
tissue (veins)
4. Excretion
Remove chemical wastes
• Out of cell or organism  environment
• Wastes are toxic
• Animals have excretory system
• Kidneys, skin, lungs
• Plants have pores in leaves
Excretory System in Humans
Kidneys – filter blood
Liver – detoxify wastes
Lungs – exhale
Skin - sweat
5. Synthesis
Make any needed substance
• Use molecules from food
• Use energy from cellular respiration
• Example: make muscle tissue from protein
6. Reproduction
Make new cells or organism
• New cells – for growth, repair
• New organism – continues the species
7. Grow and Develop
Increase in size and mature
•
•
•
•
Cells reach max size, then divide
Grow bigger – make more cells
Develop: cells differentiate
Egg  embryo  young  adult
8. Regulation
Control rate and kinds of
chemical reactions
•
•
•
•
Respond to stimuli
Keep homeostasis
Unicells, Plants – chemical messages
Animals – nerves and chemicals
Nervous system
• Electric signals along nerves
• Fast but short-live
Endocrine system
•
•
•
•
Hormones sent into blood stream
Cause response only in specific tissue
Slower, but last longer
Example: adrenaline, growth hormone
The Process of Science
Evidence: can be observed or
measured
1. Discovery science
- tries to describe nature
2. Experimental science
- tries to explain nature
- hypothesis – possible answer/ solution
- can be tested
Question  hypothesis  data  confirmation
Independent or Dependent?
• Variables – affect outcome
• Controlled Experiment – change ONE variable
• Independent variable – the one you change
“Manipulated”
• Dependent variable – depends on the
independent variable
“Responding”