BIOLOGYBIOLOGY WORKSHEET WORKSHEET CHAPTER 17 HISTORY OF CHAPTER 17 HISTORY OF LIFE ON EARTH - NOVAKLIFE ON EARTH - NOVAK

• Ws Ch17HistoryOfLife K1-12.docWs Ch17HistoryOfLife K1-12.doc

Chapter 12 Section 1Chapter 12 Section 1

• How Did Life BeginHow Did Life Begin

How long ago did the Earth How long ago did the Earth form? ___form? ___

• FOUR POINT FIVE BILLIONFOUR POINT FIVE BILLION

What did the water vapor What did the water vapor condense into? ___condense into? ___

• OCEANSOCEANS

Scientist think life has Scientist think life has evolved over hundreds of evolved over hundreds of ___ of years?___ of years?

• MILLIONSMILLIONS

Evidence of Evidence of the age of the the age of the Earth can be Earth can be found by found by measuring the measuring the age of ___.age of ___.

• ROCKSROCKS

___ ___ is the estimation of ___ ___ is the estimation of the age of an object by the age of an object by measuring its content of measuring its content of certain radioactive isotopes.certain radioactive isotopes.

• RADIOMETRIC DATINGRADIOMETRIC DATING

___ are unstable isotopes ___ are unstable isotopes that break down and give off that break down and give off energy in the form of energy in the form of charged particles called ___. charged particles called ___.

• RADIOISOTOPES AND RADIATIONRADIOISOTOPES AND RADIATION

What is this breakdown What is this breakdown called? ___called? ___

• RADIOACTIVE DECAYRADIOACTIVE DECAY

___ ___ is the time it takes for ___ ___ is the time it takes for one half of a given amount of one half of a given amount of a radioisotope to decay. a radioisotope to decay.

• HALF LIFEHALF LIFE

• Half life from radioactive decayHalf life from radioactive decay

By measuring By measuring the proportions the proportions of certain of certain radioisotopes radioisotopes and their and their products of products of ___, scientists ___, scientists can compute can compute how many half how many half lives have lives have passed since a passed since a rock was rock was formed.formed. • DECAYDECAY

The half life of uranium is The half life of uranium is 760 million years. 760 million years.

If the age of the earth is 4.2 If the age of the earth is 4.2 billion years, then 4.2/.76 = billion years, then 4.2/.76 = about 6 doublings or about 64 about 6 doublings or about 64 times as much uranium times as much uranium existed on earth at creation as existed on earth at creation as exists now.exists now.

• Half life from radioactive decayHalf life from radioactive decay

These chemical reactions These chemical reactions produced many different produced many different simple ___ molecules.simple ___ molecules.

• ORGANICORGANIC

Energized by the ___ Energized by the ___ and ___ heat, these and ___ heat, these simple molecules simple molecules formed more formed more complex molecules complex molecules that eventually that eventually became the building became the building blocks of the first blocks of the first cells.cells.

• SUN & SUN & VOLCANICVOLCANIC

The hypothesis that many of The hypothesis that many of the organic molecules the organic molecules necessary for life can be necessary for life can be made from molecules of ___ made from molecules of ___ matter has been tested and matter has been tested and supported by results of lab supported by results of lab experiments.experiments.

• NONLIVINGNONLIVING

In the 1920s A. I. Oparin and In the 1920s A. I. Oparin and J.B.S. Haldane suggest that J.B.S. Haldane suggest that the early ___ contained large the early ___ contained large amounts of organic amounts of organic molecules.molecules.

• OCEANSOCEANS

What did this hypothesis What did this hypothesis become known as? ___become known as? ___

• PRIMORDIAL SOUP MODELPRIMORDIAL SOUP MODEL

They also hypothesized the They also hypothesized the molecules formed molecules formed spontaneously in chemical spontaneously in chemical reactions activated by ___ reactions activated by ___ radiation, ___ eruptions, and radiation, ___ eruptions, and ___.___.

• SOLAR AND VOLCANIC AND SOLAR AND VOLCANIC AND LIGHTNINGLIGHTNING

The early Earth’s The early Earth’s atmosphere lacked ___ atmosphere lacked ___ making formation of organic making formation of organic molecules possible.molecules possible.

• OXYGENOXYGEN

Name four common Name four common compounds in Earth’s early compounds in Earth’s early atmosphere NOT including atmosphere NOT including water. ___ ___ ___ ___ ___water. ___ ___ ___ ___ ___

• NITROGEN GAS AND HYDROGEN NITROGEN GAS AND HYDROGEN GAS AND AMMONIA AND METHANE GAS AND AMMONIA AND METHANE

In 1953, who tested the In 1953, who tested the primordial soup model? ___primordial soup model? ___• STANLEY MILLER AND HAROLD STANLEY MILLER AND HAROLD

UREYUREY

According According to Figure 2, to Figure 2, Miller-Urey Miller-Urey heated ___ heated ___ in a flask.in a flask.

• WATERWATER

29. According 29. According to Figure 2, to Figure 2, Miller-Urey Miller-Urey they then they then added water added water vapor and vapor and what other what other gases to the gases to the tubes? ___ tubes? ___ ___ ___ ___ ___ ___ ___ ______

• NITROGEN GAS AND HYDROGEN GAS AND NITROGEN GAS AND HYDROGEN GAS AND AMMONIA AND METHANEAMMONIA AND METHANE

According to According to Figure 2, Miller-Figure 2, Miller-Urey, after the Urey, after the spark and the spark and the vapors had been vapors had been condensed, what condensed, what did they find in the did they find in the beaker below?beaker below?

• ORGANIC COMPOUNDSORGANIC COMPOUNDS

These results support the These results support the hypothesis that some basic hypothesis that some basic chemicals of ___ could have chemicals of ___ could have formed ___ under conditions formed ___ under conditions like those in the experiment.like those in the experiment.

• LIFE AND SPONTANEOUSLYLIFE AND SPONTANEOUSLY

Recent discoveries have Recent discoveries have caused scientists to ___ the caused scientists to ___ the Miller-Urey experiment.Miller-Urey experiment.

• REEVALUATEREEVALUATE

Four billion years ago, Earth Four billion years ago, Earth did not have a protective did not have a protective layer of ___ gas.layer of ___ gas.

• OZONEOZONE

Without ozone, ___ radiation Without ozone, ___ radiation would have destroyed any would have destroyed any ammonia or methane in the ammonia or methane in the early atmosphere.early atmosphere.

• ULTRAVIOLETULTRAVIOLET

36. If these 36. If these gases are gases are absent from absent from the Miller-the Miller-Urey Urey experiment, experiment, ___ ___ biological biological molecules molecules are NOT are NOT made.made.

• KEYKEY

If the chemicals If the chemicals needed to form needed to form life were not in life were not in the atmosphere the atmosphere some scientists some scientists argue that the argue that the chemicals ere chemicals ere produced within produced within ocean ___ or ocean ___ or ocean ___.ocean ___.

• BUBBLES AND VENTSBUBBLES AND VENTS

In 1986, geophysicist Louis In 1986, geophysicist Louis Lerman hypothesized the ___ Lerman hypothesized the ___ model of chemical origins.model of chemical origins.

• BUBBLEBUBBLE

The bubbles The bubbles protected the protected the methane and methane and ammonia ammonia needed to make needed to make amino acids amino acids from ___ ___.from ___ ___.

• ULTRAVIOLET RADIATIONULTRAVIOLET RADIATION

Next, the bubbles rose to the Next, the bubbles rose to the surface and burst, releasing surface and burst, releasing simple ___ molecules into simple ___ molecules into the air.the air.

• ORGANICORGANIC

Once in the wind, these Once in the wind, these simple organic molecules simple organic molecules were exposed to ultraviolet were exposed to ultraviolet radiation which provided ___ radiation which provided ___ for further reactionsfor further reactions

• ENERGYENERGY

Scientists ___ about the Scientists ___ about the details of the process that details of the process that lead to the origin of life.lead to the origin of life.

• DISAGREEDISAGREE

However, short However, short chains of ___ chains of ___ have been have been made to form made to form on their own in on their own in water.water.

• RNARNA

RNA is the RNA is the nucleic nucleic acid that acid that does what? does what? __________________

• HELPS CARRY OUT DNA’S HELPS CARRY OUT DNA’S INSTRUCTIONSINSTRUCTIONS

In The 1980s, In The 1980s, Thomas Cech Thomas Cech hypothesized hypothesized that ___ was the that ___ was the first self-first self-replicating replicating information-information-storage storage molecule.molecule.

• RNARNA

Certain lipids, when Certain lipids, when combined with other combined with other molecules, can form a tiny molecules, can form a tiny droplet whose surface droplet whose surface resembles a ___ ___.resembles a ___ ___.

• CELL CELL MEMBRANEMEMBRANE

Short chains of amino acids Short chains of amino acids can gather into tiny droplets can gather into tiny droplets called ___.called ___.

• MICROSPHERESMICROSPHERES

Another type of Another type of droplet, called a droplet, called a ___ is composed ___ is composed of molecules of of molecules of different types, different types, including linked including linked amino acids and amino acids and sugars.sugars.

• COACERVATESCOACERVATES

Why do scientists think Why do scientists think microspheres are important? microspheres are important? __________________

• THEY MIGHT HAVE BEEN THE FIRST STEP THEY MIGHT HAVE BEEN THE FIRST STEP TOWARD CELLULAR ORGANIZATIONTOWARD CELLULAR ORGANIZATION

Scientists disagree about Scientists disagree about the origin of ___.the origin of ___.

• HEREDITYHEREDITY

Many Many scientists scientists agree that agree that double-double-stranded stranded DNA evolved DNA evolved after ___.after ___.

• RNARNA

RNA “___” RNA “___” catalyzed catalyzed the the assembly assembly of the of the earliest earliest ___.___. • ENZYMES AND ENZYMES AND

PROTEINSPROTEINS

But But researchers researchers do not yet do not yet understand understand how DNA, how DNA, RNA and RNA and hereditary hereditary mechanisms mechanisms first ___.first ___.

• DEVELOPEDDEVELOPED

END of Chapter 12 Section 1END of Chapter 12 Section 1