Download Ch. 12 SG Questions w/ answers

Chapter 12 Study Guide Questions
Name ____________________
Study your Reading guide and Timeline
Use the questions below to help you focus on the main points.
1.
Draw a flow chart showing how the Earth’s early atmosphere changed over time until the first cell.
Fiery molten rock gases cooled water condensed oceans formed
2.
Where did life first begin on Earth? In the oceans
3.
What gas was missing (that we need now) in the early atmosphere of Earth? Oxygen
4.
What were the first types of cells? Heterotrophic prokaryotes autotrophic prokaryotes
5.
What are the two groups of Prokaryotes? Archaebacteria and Eubacteria
a.
6.
What are the four groups of Eukaryotes? Protists, Fungi, Plants, Animals
a.
7.
Which group came first? Archaebacteria
Which group is considered the ancestors to the other three groups? Protists
Name 3 differences between Prokaryotes and Eukaryotes.
Prokaryotes are smaller
Prokaryotes do not have a true nucleus
Prokaryotes do not have membrane bound organelles
Eukaryotes are larger
Eukaryotes have a nucleus
Eukaryotes have organelles
8.
How did the ozone layer affect how life evolved on Earth?
It provided a barrier that kept oxygen in so the organisms could use it for respiration and it blocked out
harmful UV rays.
9.
What organelles does the endosymbiosis theory explain?
How the chloroplast and mitochondrion became part of the eukaryotic cell.
a.
How did these organelles become part of eukaryotic cells?
Small prokaryotes (bacteria) entered the larger prokaryote as parasites or prey and then the
became part of the host cell
10.
Describe organisms that are unicellular and multi-cellular.
Unicellular means one cell and these organisms have to do all of the functions by themselves; multicellular means more than one cell and these organisms can have cells do specific tasks  cell
specialization
11.
What happened before organisms could come in land? The ozone layer had to form
12.
What were the first organisms to come on land? Fungi living with plants and algae
a.
How did these organisms help each other survive?
Plants provided the food and fungi provided the minerals
13.
Dinosaurs are considered ancestors to what major group of organisms? Birds
14.
Therapsids are considered ancestors to what major group of organisms? mammals
How is this significant to the history of the evolution of life?

Oxygen- was not present in earth’s early atmosphere

Endosymbiosis- theory that states that mitochondria and chloroplasts were prokaryotic cells that invaded a host
cell, then became part of it

Ozone- layer formed after buildup of oxygen; protected land organisms from harmful UV light and held in oxygen
gas for breathing

Primordial soup- model that said that organic molecules spontaneously formed from chemical reactions in the
oceans, energy was from the sun, volcanoes, and lightning

Bubble model- bubbles from the ocean released chemicals

Trilobites- marine arthropod that became extinct 250 mya

Arthropods- first animals to successfully invade the land

Unicellular- one-celled; this one cell must perform all cell tasks

Multicellular-more than one cell; cells that specialize in certain tasks

Extinction-the death of all members of species

Mass Extinction- many different species that die at the same time

Mycorrhizae- partnership formed by plant and fungi; allowed these two types of organisms to survive on land
early on

Therapsids- ancestors to mammals

Dinosaurs-ancestors to birds

Homo sapiens- first humans 0.5 mya

Prokaryotes- no nucleus, single-celled organism

Eukaryotes- cells that have a nucleus and organelles

Archaebacteria- prokaryotes, first cells, live in extreme environments

Eubacteria- prokaryotes, disease causing and bacteria of decay

Protists- first eukaryotes, ancestors to fungi, plant, and animal kingdom

Oceans- formed as the Earth cooled; where life is thought to have begun

Insects- the most plentiful and diverse group of animals in Earth’s history; first organisms to have wings (success
linked to their ability to fly)