CP BiologyUnit 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 cellsa. cell – basic unit of lifeb. unicellular organisms

– bacteria, amoeba, etc.c. multicellular organisms – cells specialize

2. Have DNAa. Instructions for all life functionsb. Cells copy DNA and pass it to offspringc. “Universal” code – same for all organisms

3. Obtain and use energya. Food – for energy and raw materialsb. 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 CYCLEEnvironment producers consumers decomposers back to environment

Sun producers other organisms. Energy is used to sustain life, some lost as heat.

Energy does NOT cycle

4. Grow and Develop

a. Grow – increase in size (add more cells)b. Develop – change while maturing

a. Multicelled begin as a single cellb. Cells copy and specialize (differentiate)c. Form many different kinds of cellsd. Organisms change as they

grow older

Stem Cells

a. Can become different kinds of cellsb. Depends on chemical signals from

their environment

Cells – different parts do specific functions

5. Are organized

Multicelled - Levels of Organizationa. Cells differentiate specialized cellsc. Different kinds of cells form tissuesd. Different kinds of tissues form organse. Organs work together to form organ

systemsf. Body systems work together to keep an

organism alive.

Cells tissues organs organ systems organism

6. Reproduce

a. New cells by cell divisionb. Form a new organismc. Asexual – one parent - identical offspringc. 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 reactionb. Response - reaction to a stimulusc. Internal or external stimulid. Must keep homeostasis (constant internal conditions)

8. Evolvea. Species can slowly change over time to

better fit an environmentb. Individual organisms DO NOT evolvec. Earliest life 3.5 billion years ago

Unity and DiversityLife is unified – by evolution - all living things do same life functions - same chemical make-up and processes shared ancestorLiving things are diverse – by evolution - special features for different environments

Structure and Functiona. “Form follows function”b. Features evolve to perform a

function betterc. Different environments need

different kinds of adaptations

Other life traits1. Contain many complex chemicals 2. Have recognizable shape and size3. Have limited life span

Life ProcessesHow 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. Make their own food b. Photosynthesis c. Base for all food chains d. 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 vesselsPlants 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 bloodLiver – detoxify wastesLungs – exhale Skin - sweat

5. SynthesisMake any needed substance• Use molecules from food• Use energy from cellular respiration • Example: make muscle tissue from protein

6. ReproductionMake new cells or organism• New cells – for growth, repair• New organism – continues the species

7. Grow and DevelopIncrease 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 ScienceEvidence: can be observed or measured1. Discovery science - tries to describe nature2. Experimental science - tries to explain nature - hypothesis – possible answer/ solution - can be testedQuestion 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”