UNIT 11-how did life begin

The solar system formed by a condensing...

• nebula

• star

• explosion

• comet

Answer explanation

clouds of gas an dust in space

earth is

• 4.5 billion years old

• 6 billion years old

• 5.5 billion years old

• 4 billion years old

Life first evolved in the...

• sky

• ocean

• molten rock

• clouds

Answer explanation

evolved in the oceans.. when the Earth was cool enough

how did they measure earth's age?

• carbon dating

• radiometric dating

• astronomical observations

Answer explanation

-measure the content of radioactive isotopes

- break down and give off energy(radiation)

The time it takes for 1/2 of a radioisotope to decay

Primordial Soup Model:

early oceans contained many___ molecules

Answer explanation

these molecules formed spontaneously with energy from the sun.

Primordial Soup Model:

No ___ in the atmosphere

Miller-Urey Model:

1. put gas into a flask

2. used electrical sparks to mimic lightning

3. formed...

• chemicals

• prokaryotes

• amino acids

• cells

Answer explanation

this model proved to be false because there wasn't an ozone layer for protection.

Bubble Model:

proposes that the process that sparked life started with gases released by volcanoes and hydrothermal vents

carried by the wind, molecules are exposed to____

• lightning

• air

• rain

• heat

Answer explanation

they then fell into the ocean as rain

Where cells first come from.

Microspheres- chains of ___ ___ gathered into droplets