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 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 cell b.Cells copy and specialize (differentiate) c.Form many different kinds of cells d.Organisms change as they grow older

Stem Cells a.Can become different kinds of cells b.Depends on chemical signals from their environment

Cells – different parts do specific functions 5. Are organized

Multicelled - Levels of Organization a. Cells differentiate  specialized cells c. Different kinds of cells form tissues d.Different kinds of tissues form organs e.Organs work together to form organ systems f.Body systems work together to keep an organism alive.

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. 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 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”