chpt 12: the history of life

Chpt 12: The History of Life

Warm-Up

• Which of these structures are the best evidence of an evolutionary relationship?

A. bat wing and bee wingB. bat lower jaw and whale lower jawC. whale flipper and bee wingD. bat wing and whale flipper

Objectives 1. Students will be able to describe the ways that fossils can form. 2. Students will be able to recognize the role of index fossils in

determining the ages of rocks.3. Students will be able to recognize the role microbes played in

the shaping of life on Earth. 4. Students will be able to summarize the theory of Endosymbiosis. 5. Students will be able to relate increased biodiversity to sexual

reproduction. 6. Students will be able to examine the evolutionary relationships

between humans and other primates.7. Students will be able to recognize the names and relative ages of

extinct hominids. 8. Students will be able to summarize the events and forces that

shaped human evolution.

Chpt 12 Sec 12.1: The Fossil Record

• Key Concept • Fossils are a record of life that existed in the

past.


• Fossils can form in several ways 1. Permineralization: • Occurs when minerals are carried by water

and deposited around a hard structure 2. Natural Casts:• Form when flowing water removes all of

the original bone or tissue, leaving just an impression in sediment


• Fossils can form in several ways 3. Trace fossils: • Record the activity of an organism

4. Amber-preserved fossils: • Organisms that become trapped in tree resin that

hardens into amber after the tree gets buried underground

5. Preserved remains: • Entire organisms become encased in material such

as ice or volcanic ash or immersed in bogs


• Fossils can form in several ways 1. Explain why some organisms are not

fossilized

2. Propose a reason for why so few complete fossils are discovered.


• Fossils can form in several ways 1. Explain why some organisms are not fossilized• Some organisms cannot withstand the extreme

pressures of the rock.• Some organisms do not have the appropriate

structural integrity2. Propose a reason for why so few complete fossils

are discovered.• Natural disasters • Decomposition occurs

Chpt12 Sec 12.2: The Geologic Time Scale

• Key Concept • The geologic time scale divides Earth’s history

based on major past events

Chpt 12 Sec 12.2: The Geologic Time Scale

• Index fossils are another tool to determine the age of rock layers.1. Identify one way that scientist can determine

how old rocks are.


• Index fossils are another tool to determine the age of rock layers.1. Identify one way that scientist can determine

how old rocks are. • They can look at the composition of

minerals present in the rock material• They can look at the strata where the rock

is located


• Index fossils are another tool to determine the age of rock layers.• Index fossils are fossils of organisms that

existed only during specific spans of time over large geographic areas. • The shorter the life span of a species, the more

precisely the different strata can be correlated• An example of a index fossil is a Fusulinid ---------------------------


• The geologic time scale organizes the Earth’s history • Geologic time scale: a representation of the

history of the Earth. It organizes Earth’s history by major changes or events that have occurred, using evidence from the fossil and geologic records.

60 Seconds

http://www.youtube.com/watch?v=YXSEyttblMI&feature=bf_prev&list=PLD59FA88BE081CE07&lf=results_main

Chpt 12 Sec 12.3: The Origin of life

• Key Concept • The origin of life on Earth remains a puzzle


• Think back…. Recall what a hypothesis is…


• A hypothesis is a proposed explanation or answer to a scientific question. It is stated as an if then statement.

Chpt12 Sec 12.3: The Origin of life

• Several sets of hypotheses propose how life began on Earth 1. Organic molecule hypothesis • Miller-Urey experiment • 1953 Stanley Miller and Harold Urey designed

an experiment to test a 1920s hypothesis • Scientists had proposed that an input of energy

from lightening led to the formation of organic molecules from inorganic molecules present in the atmosphere of early Earth

• The four gases thought to be present in the atmosphere were methane, ammonia, hydrogen, and water vapor


• Several sets of hypotheses propose how life began on Earth 1. Organic Molecule Hypotheses • Meteorite hypothesis • A meteorite fell near Murchison Australia in

1969 showing…• Organic molecules can be found in space • From this meteorite more than 90 amino acids

have been found • How many of the numerous amino acids

identified from the meteorite can be found on Earth?


• Several sets of hypotheses propose how life began on Earth 2. Early cell structure hypothesis • Iron-sulfide bubble hypothesis • Iron-sulfide rising from the ocean floor

combined with cooler waters of the ocean tend to form chimney structures

• Biological molecules combined with the compartments of these “chimneys” 4 billion years ago

• The walls of these structures acted as the first cell membranes


• Several sets of hypotheses propose how life began on Earth 2. Early cell structure hypothesis • Lipid membrane hypothesis • Lipid molecules spontaneously for

membrane enclosed spheres called liposomes

• Liposomes could form around organic molecules

• Give rise to the first true cells


• Several sets of hypotheses propose how life began on Earth 3. RNA as early genetic material • RNA, rather than DNA, was the genetic material that

stored information in living things on early Earth• Ribozymes are RNA molecules that can catalyze

specific chemical reactions • Where can ribosomes be found within the cell? • Unlike DNA, RNA can replicate itself without enzymes • Short chains of RNA will form inorganic materials in a

test tube• What process could be responsible for the shift from

RNA to DNA

Chpt 12 Sec 12.4: Early Single-Celled Organisms

• Key Concept • Single-celled organisms existed 3.8 billion years

ago


• Microbes have changed the physical and chemical composition of Earth • Single-celled organisms changed the Earth’s

surface by depositing minerals • Name some minerals you have previously

learned about • Single-celled organisms changed the

atmosphere by giving off oxygen as a byproduct of photosynthesis • Before photosynthesis evolved bacteria

would have to be anaerobic


• Microbes have changed the physical and chemical composition of Earth • The earliest prokaryotic single-celled organism

is called the cyanobacteria • Bacteria that can carry out photosynthesis • Single-celled prokaryotic organism with no

membrane bound organelles • Stromatolites are domed, rocky structures

made of cyanobacteria and sediment


• Eukaryotic cells may have evolved through endosymbiosis • Eukaryotic organisms evolved by 1.5 billion

years ago• Identify what a eukaryotic cell has that a

prokaryotic cell does not. • Endosymbiosis: a relationship in which one

organism lives inside the body of another. Bothe will benefit from this relationship. • Name the two organelles that are said to be

examples of endosymbiosis.


• The evolution of sexual reproduction led to increased diversity• Recall what a-sexual reproduction is.

• Define sexual reproduction.


• The evolution of sexual reproduction led to increased diversity• Recall what a-sexual reproduction is.• A single parent produces offspring that are

genetically similar to itself • Can produce many offspring quickly.

• Define sexual reproduction. • Needs two parents • Both parents give genes to their offspring • Sexual reproduction allows new combinations of

genes to come together • Sexual reproduction creates more genetic variation

Chpt 12 Sec 12.6: Primate Evolution

• Key Concept • Humans appeared late in Earth’s history


• Humans share a common ancestor with other primates • The qualities that make an organism a primate

are 1. Flexible hands and feet 2. Forward looking eyes 3. Enlarged brains 4. Arms that can rotate in a circle 5. Have thumbs


• Humans share a common ancestor with other primates • Prosimians: oldest living primate group • Nocturnal animals

• Anthropoids: humanlike primates • Old World Monkeys • New World Monkeys

• Hominoids • Lesser apes • Greater apes • AND…

Chpt 12 Sec12.6: Primate Evolution

• Humans share a common ancestor with other primates • Hominoids:• Hominids

1. Walk upright 2. Have long lower limbs 3. Thumbs that oppose 4. Large brains • Includes all of the species in the human

lineage


• Humans share a common ancestor with other primates • Animals that can walk upright are called

bipedal


• There are many fossils of extinct hominids

Australopithecusafarensis

Homo habilis Homo neanderthalensis

Homo sapiens

•Lived in Africa •Brain the size of a modern chimpanzee •Humanlike limbs

•“Handy Man” because of the tools associated with the skeleton •Lived in Kenya and Tanzania •Brain resembles the current human brain

•Commonly called Neanderthals•Found in the Near Valley in Germany

•Modern humans •Lived in Ethiopia


• Modern Humans arose about 100,000 years ago • The first appearance of Homo sapiens, dates to

roughly 100,000 years ago in what is now Ethiopia. • Tools are a marker of human evolution. • Genes controlling the size and complexity of

the human brain evolved faster than analogous genes in nonhuman primates.

Reflection

1. Describe the ways that fossils can form. 2. Recognize the role of index fossils in

determining the age of rocks 3. Summarize the theory of endosymbiosis4. Recognize the names of extinct

hominids.

chpt 12: the history of life

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