What is life?Prentice Hall: Life Science (2005), pp. 34-41

Objective(s): I canList the characteristics all

living things share.Explain where living things

come from.Identify what all living

things need to survive.

Key termsOrganismCellUnicellularMulticellularStimulusResponse

DevelopmentSpontaneous

generationAutotrophHeterotrophHomeostasis

Key ConceptsWhat characteristics do

all living things share?What do living things

come from?What do living things

need to survive?

IntroductionOrganisms are living things.Organisms include: plants,

dogs, sharks, sting rays, moss, bacteria, humans, worms, spiders, etc.

Living things in an environment are also referred to as biotic factors.

The Characteristics of Living ThingsLiving things share important

characteristics.Characteristic- a feature or

quality that makes somebody or something recognizable

All living things have a cellular organization, contain similar chemicals, use energy, respond to their surroundings, grow and develop, and reproduce.

Cellular Organization

All organisms are made of small building blocks called cells.

Cells are the basic units of structure and function in all living things.

Unicellular = one celled organismMulticellular = hundreds to trillions of

cells working together

Cells are the building blocks of life.

The Chemicals of Life

Organism

CarbohydratesC, H, O

Provide energy

Proteins Chemical Reactions

Build & repair cells

Nucleic AcidsTransfer genes

Produce proteins

LipidsMostly C, HFats & Oils

Store energy

WaterH, OMost

abundant

Energy is the ability to do work and cause change

• Walking

•Talking

•Thinking

•Breathing

•Playing

•Studying

All require

energy!

Where do living organisms get their energy?

Living things obtain and use energy

Response to environment

Organisms respond to the environment around them. What are some common responses to your environment?

Stimulus: A change in the environment that occurs and causes a reaction.

Response: The way an organism reacts to the stimulus

Growth and Development

Growth is the process of becoming larger.

Development is the process of change that occurs during an organism’s life to produce a more complex organism.

Living things all grow and change. Whether talking about a person or a tree changes will take place as long as the organism is alive.

ReproduceAsexual Reproduction: single

organism reproduces without the aid of another

Sexual Reproduction: two cells from different individuals unite to produce the first cell of the new individual

All organisms must reproduce-offspring are

the result of reproduction.

Eliminate WasteAn organism may not

use all the nutrients from their energy sources.

The excess materials are eliminated/removed from the organism.

Life comes from Life Living things arise from living things

through reproduction.

At one time people believed that life could appear from nonliving material.

This mistaken idea that living things can arise from nonliving sources is called spontaneous generation.

It took hundreds of years to convince people that spontaneous generation does not occur.http://www.dreamstime.com/stock-photo-large-fly-on-a-wall-

image10562960

Redi’s Experiment•An Italian doctor

•Helped disprove spontaneous generation during 1600s

•Designed a controlled experiment to show flies don’t arise from decaying meat

Pasteur’s Experiment

• A French Chemist

• Designed controlled experiments that finally rejected spontaneous generation in the mide-1800s

The Needs of Living Things

Though surprising, flies, bacteria, and all other living things have the same basic needs as you.

All living things must satisfy their basic needs for water, food, living space, substances found in air, and stable internal conditions.

WaterAll living things need water to

survive.Most organisms can live for

only a few days without water.Organisms need water to obtain

chemicals from their surroundings, break down food, grow, move substances within their bodies, and reproduce.

http://www.hickerphoto.com/waterfall-pictures-4109-pictures.htm

FoodOrganisms need a source of energy

to live.Food is used as the energy source.Some organisms, such as plants,

capture the sun’s energy and use it to make food.

Organisms that make their own food are called autotrophs. Auto- means “self” and –troph means “feeder.”

FoodOrganisms that cannot make their own

food are called heterotrophs. Hetero- means “other.”

Heterotrophs obtain their energy by feeding on others.

Some heterotrophs eat autotrophs and use the energy I the autotroph’s stored food.

Other heterotrophs consume heterotrophs that eat autotrophs.

Therefore, heterotroph’s energy source is also the sun- but in an indirect way.

Living SpaceAll organisms need a living space- a

place to get food and water and find shelter.

Whether an organism lives in the freezing Antarctic or the scorching desert, its surrounding must provide what it needs to survive.

Because there is a limited amount of space on Earth, some organisms must compete for space.

Stable Internal ConditionsOrganisms must be able to keep the

conditions inside their bodies stable, even when conditions in their surroundings change significantly.

The maintenance of stable internal conditions is called homeostasis.

Homeostasis keeps internal conditions just right for cells to function.

Stable Internal ConditionsThink about your need for water

after a hard workout.When water levels in your body

decrease, chemicals in your body send signals to your brain, causing you to feel thirsty.

Other organisms have different mechanisms for maintaining homeostasis.

Homeostasis

SummaryAll living things share common

characteristics.All living things have basic

needs in order to survive.Redi and Pasteur designed

experiments to disprove spontaneous generation.

Life comes from life.