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

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What is life?

Prentice Hall: Life Science (2005), pp. 34-41

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Objective(s): I can

List the characteristics all living things share.

Explain where living things come from.

Identify what all living things need to survive.

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Key terms

Organism

Cell

Unicellular

Multicellular

StimulusResponse

Development

Spontaneous generation

Autotroph

Heterotroph

Homeostasis

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Key Concepts

What characteristics do all living things share?

What do living things come from?

What do living things need to survive?

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Introduction

Organisms 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.

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The Characteristics of Living Things

Living 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.

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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 organism

Multicellular

= hundreds to trillions of cells working together

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Made of cells

Cells are the

building blocks of

life.

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The Chemicals of Life

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Use Energy

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

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Response to environment

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

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Responding to the Environment

Stimulus

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

Response

: The way an organism reacts to the stimulus

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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.

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Growth and Development

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.

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Reproduce

Asexual 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

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Reproduction

All organisms must reproduce-offspring are the result of reproduction.

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Eliminate Waste

An organism may not use all the nutrients from their energy sources.

The

excess materials

are

eliminated/removed

from the organism.

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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

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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

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Pasteur’s Experiment

A French Chemist

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

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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.

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Water

All 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.

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

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Food

Organisms 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.”

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Food

Organisms 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.

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Living Space

All 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.

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Stable Internal Conditions

Organisms 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.

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Stable Internal Conditions

Think 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.

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Homeostasis

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Summary

All 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.