1. Theory of Evolution
Day 1

2. Origins of Life

3. Benchmarks
SC.912.L Describe the scientific explanations of the origin of life on Earth. AA
SC.912.N Recognize that the strength or usefulness of a scientific claim is evaluated through scientific argumentation, which depends on critical and logical thinking, and the active consideration of alternative scientific explanations to explain the data presented.
SC.912.N Identify sources of information and assess their reliability according to the strict standards of scientific investigation.
SC.912.N Identify what is science, what clearly is not science, and what superficially resembles science (but fails to meet the criteria for science).

4. Prior Knowledge Discussion
Describe and investigate the process of photosynthesis, such as the roles of light, carbon dioxide, water and chlorophyll; production of food; release of oxygen.
Identify current methods for measuring the age of Earth and its parts, including the law of superposition and radioactive dating.
Explain and give examples of how physical evidence supports scientific theories that Earth has evolved over geologic time due to natural processes.
Describe how the composition and structure of the atmosphere protects life and insulates the planet.
These are the middle school benchmarks that are considered “fair game” for the assessment of today’s Biology benchmark SC.912.L.15.8.

5. Prior Knowledge Discussion
Distinguish science from other activities involving thought.
Explain that scientific knowledge is durable because it is open to change as new evidence or interpretations are encountered.
Explain that scientific knowledge is the result of a great deal of debate and confirmation within the science community.
Identify an instance from the history of science in which scientific knowledge has changed when new evidence or new interpretations are encountered.
Distinguish between scientific and pseudoscientific ideas.
Discuss what characterizes science and its methods.
These are the middle school benchmarks that are considered “fair game” for the assessment of today’s Biology benchmark SC.912.L.15.8.

6. Objectives
SWBAT...
Explain several scientific explanations for the origin of life.
Explain how the scientific claims are strengthened through scientific argumentation.
Identify a theorist’s sources of information and assess their reliability according to the strict standards of scientific investigation.
Explain why theories on the origins of life are considered “science” and contrast them with explanations that are not considered science and with what superficially resembles science (but fails to meet the criteria for science).

7. Essential Questions
If the work of many scientists has shown that spontaneous generation does not occur, and the idea of biogenesis is true, how do we explain the origin or the first living things?
What properties do coacervates share with cells? How are they different than cells?

8. How did life begin on Earth?
According to the cell theory:
All living things are made up of cells
Cells are basic unit in living things
New cells are produced from existing cells
This is called biogenesis
Quickly refresh students’ memories on the cell theory.

9. How did life begin on Earth?
There have been a few hypotheses for how life first appeared on early Earth.
However, even today’s strongest hypotheses are based on a relatively small amount of evidence.
Therefore, the gaps and uncertainties make it likely that scientific ideas about the origins of life will continue to change over time.
SC.912.N Identify what is science, what clearly is not science, and what superficially resembles science (but fails to meet the criteria for science)…..Remind students that one of the defining features of science its that scientific knowledge is based on evidence! Also note that test items assessing a scientific claim are limited to the scientific explanations of the origins of life on Earth.

10. HOW did life Begin? Hydrothermal Vents Electric Spark
These vents release important hydrogen-rich molecules
Mineral catalysts could have made critical reactions occurs faster
Can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen
Demonstrated in the famous Miller-Urey experiment reported in 1953
New evidence suggest that it may have occurred in volcanic clouds

11. HOW did life Begin? Panspermia Community Clay Ice Earth
Life could have come from outer space in a comet or meteorite.
Clay may have provided the foundation for first organic compounds.
Mineral crystals in clay could have arranged organic compounds into organized patterns.
Ice Earth
3 billion years ago ice might have covered the oceans.
Protected from UV light, organic compounds may have formed and reacted with one another.

12. Early Earth The Earth was formed about 4.5 billion years ago.
The oldest fossils of microorganisms are about 3.5 billion years old.
But where did they come from???
Refer to this ”clock” analogy when explaining the timescale we are discussing. The entire clock represents 5 billion years. Be sure to point out the tiny sliver that represents the existence of the human species so that students can gain a sense of the amount of time we are dealing with. However, you should know that test items will not require specific knowledge of the age of Earth or its eras, periods or epochs.

13. Theories - Spontaneous Generation
Until the early 19th century, people generally believed in the “Spontaneous Generation” of life from non-living matter.
Francisco Redi (1668) – Rotten Meat Experiment
Louis Pasteur (1864) – Curved Flask Experiment
Use the figures to describe these two important experiments and how they disproved the idea of spontaneous generation. Test items may assess how contributions of scientists such as Pasteur, Oparin, Miller and Urey, Margulis, or Fox aided in the development of scientific explanation of the origin of life but WILL NOT assess what each scientist contributed.

14. Theories - Chemical Evolution
Conditions on the early Earth were very different from the Earth we know today.
The early atmosphere contained no free oxygen and probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide and water.
Energy for chemical reactions between these gases could come from electric discharge in storms or solar energy (no ozone layer).
Could organic molecules have evolved under these conditions?
This theory is also known as the “Primordial Soup Theory”. Test items may assess the conditions required for the origin of life.

15. Theories - Chemical Evolution
Mixture of gases simulating atmosphere of early Earth
Alexander Oparin (1920’s), hypothesized that they could.
In the 1950‘s Harold Urey and Stanley Miller tried to answer that question by simulating the conditions on the early Earth in a laboratory setting.
Spark simulating
lightning storms
Cold water cools chamber, causing droplets to form.
Use the figure to explain chemical evolution and Urey and Miller’s experiment. They wanted to know if it would have been possible for organic molecules to evolve under “early earth” conditions.
Water
vapor
Liquid containing amino acids (15) and other organic
compounds

16. Theories - Chemical Evolution
Miller and Urey's experiments suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds present on a primitive Earth.
This formation of organic molecules (such as amino acids, sugars, fatty acids, and nucleotide bases ) from inorganic molecules is also known as abiogenesis.
Be sure to ask students what the difference between spontaneous generation and abiogenesis is! Many students confuse them. They should understand that Miller and Urey did not create life from non-life (like the idea of maggots coming from meat). They simply created the ingredients for life (organic molecules), from inorganic molecules. Scientists believe that we do not see this process occur in nature today because present day conditions on Earth are so different from the conditions present on early Earth.

17. The First Cells
Geological evidence suggests that cells similar to modern bacteria were common 3.8 billion years ago.
However the stew of organic molecules suggested by Miller and Urey is a long way from a living cell.
Ask students what the defining characteristics of a cell are. Be sure to stress that in order to have a cell, you must have a membrane.
Cells must have a membrane and genetic material.

18. The First Cells
Organic molecules have a tendency to aggregate (combine).
Phospholipids form lipid bilayers when they are surrounded by water.
As a result, membrane-like vesicles called coacervates, form easily under certain conditions.
Quickly refresh students’ memories on the structure and function of the phospholipid bilayer that cell membranes are made of.
Click on the picture to play a short video clip of “proto-cell” formation. If the embedded video does not play, you can find it in the Topic 15 folder.
Video Clip

19. Coacervates Coacervates are made mostly of aggregated lipids.
They grow by adding new polymers.
They form a semi-permeable membrane.
When they get too big they divide.
Hypotheses suggest that structures similar to microspheres might have acquired more characteristics of living cells.
Compare these characteristics of coacervates to the characteristics of cells. How are they similar? How are they different?

20. The Origin of Heredity Remember…
One of the characteristics of life, is that all living things contain hereditary information (DNA) which is passed from cell to cell during cell division.
Scientists speculate that RNA may actually have been the first hereditary molecule.
There are several hypotheses for how RNA could have evolved into modern cellular life.

21. The First Eukaryotic Cells
The Endosymbiotic Theory, proposed by Lynn Margulis in 1967, proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms. According to the theory, eukaryotic cells formed from a symbiosis among several different prokaryotes.
Plants and plantlike protists
Aerobic
bacteria
Photosynthetic bacteria
Nuclear envelope
evolving
Test items may refer to the endosymbiotic theory but may not assess the term in isolation.
Mitochondrion
Primitive Photosynthetic
Eukaryote
Animals, fungi, and
non-plantlike protists
Ancient Anaerobic
Prokaryote
Primitive Aerobic
Eukaryote 21

22. Theory of Evolution
Day 2

23. Darwin’s Theory of Evolution by Natural Selection
***Warning – DON’T KISS LIONS!!!

24. Benchmarks
SC.912.L Describe the conditions required for natural selection, including: overproduction of offspring, inherited variation, and the struggle to survive, which result in differential reproductive success. AA
SC.912.N.1.3 Recognize that the strength or usefulness of a scientific claim is evaluated through scientific argumentation, which depends on critical and logical thinking, and the active consideration of alternative scientific explanations to explain the data presented.
SC.912.L Describe how mutation and genetic recombination increase genetic variation.

25. Prior Knowledge Discussion
Explore the scientific theory of evolution by recognizing and explaining ways in which genetic variation and environmental factors contribute to evolution by natural selection and diversity of organisms.
Explore the scientific theory of evolution by relating how the inability of a species to adapt within a changing environment may contribute to the extinction of that species.
Understand and explain that every organism requires a set of instructions that specifies its traits, that this hereditary information (DNA) contains genes located in the chromosomes of each cell, and that heredity is the passage of these instructions from one generation to another.
Compare and contrast the general processes of sexual reproduction requiring meiosis and asexual reproduction requiring mitosis.
These are the middle school benchmarks that are considered “fair game” for the assessment of today’s Biology benchmark SC.912.L

26. Prior Knowledge Discussion
Describe and investigate various limiting factors in the local ecosystem and their impact on native populations, including food, water, shelter, space, disease, parasitism, predation, and nesting sites.
Explain that scientific knowledge is the result of a great deal of debate and confirmation within the science community.
Explain that scientific knowledge is durable because it is open to change as new evidence is encountered.
Identify an instance from the history of science in which scientific knowledge has changed when new evidence or new interpretations are encountered.
These are the middle school benchmarks that are considered “fair game” for the assessment of today’s Biology benchmark SC.912.L

27. Objectives
SWBAT...
Describe the processes of adaptation and evolution using the 4 tenets of Darwin’s theory.
Describe how mutation and genetic recombination increases inherited genetic variation of offspring (and relate this to Darwin’s 2nd principle).
Explain how the scientific claims made by Darwin were strengthened through scientific argumentation, which depends on critical and logical thinking, and the active consideration of alternative scientific explanations to explain the data presented.

28. Essential Questions
Some biologists say that fitness is measured in grandchildren. What do they mean?
What are the conditions that are necessary for natural selection to occur and why is each one so important?

29. Charles Darwin’s Theory
From 1831 to 1836, Darwin made a voyage around the word in which he collected and studied thousands of plant and animal specimens.
During his travels, Darwin made numerous observations and collected evidence that led him to propose a hypothesis about the way life changes over time.
That hypothesis has become the Theory of Evolution.

30. Charles Darwin’s Theory
In the development of his theory, Darwin did not just take his own observations and ideas into account. In fact, it took him years to put together data from many sources and to account for the ideas of several other scientists of his time.
Georges Cuvier – gave convincing evidence that organisms from the past differed greatly from living species, based on his observation of fossils from different rock layers.
Charles Lyell - shared Cuvier’s ideas but also believed that geologic process that shaped the Earth in the past still continue today.
Thomas Malthus – suggested that if the human population continued to grow unchecked, sooner or later there would be insufficient food and living space for everyone.
SC.912.N.1.3 Recognize that the strength or usefulness of a scientific claim is evaluated through scientific argumentation, which depends on critical and logical thinking, and the active consideration of alternative scientific explanations to explain the data presented…..Stress to the students that Darwin was influenced by many many other scientists of his time. These 3 scientists are just a sampling.

31. Charles Darwin’s Theory
In 1859, Darwin published a book titled, On the Origin of Species.
In this book he presented all the evidence he had gathered over the past several years supporting his theory that evolution has been taking place for millions of years—and continues in all living things.
“In this book he presented all the evidence he had gathered over the past several years…” Both from his own observations and from the influential work of others.
In his book he also proposed a mechanism for evolution called Natural Selection.

32. Natural Selection
The ability of an organism to survive and reproduce in its specific environment is called fitness.
Individuals with characteristics that are not well suited to their environment either die or leave few offspring, while individuals that are better suited to their environment survive and reproduce most successfully.
Darwin called this process Survival of the Fittest, or Natural Selection.
Use the silly duck example to emphasize the idea of fitness as having advantageous characteristics. Ask the students to identify the duckling which is most fit for its environment (in the context of the picture).

33. Tenets of Darwin’s Theory
Darwin’s theory can be summarized by describing the 4 basic conditions required for natural selection to occur:
THIS IS THE MAIN IDEA OF TODAY”S LESSON!

34. Tenets of Darwin’s Theory
1. Overproduction of Offspring
Organisms produce more offspring than can survive. Many of the offspring do not survive to reproductive age.

35. Tenets of Darwin’s Theory
2. Inherited/Genetic Variation
Individual organisms within the population differ. Most of this variation is determined by genetic inheritance (recombination), but sometimes it is the result of genetic mutations.
SC.912.L Describe how mutation and genetic recombination increase genetic variation.

36. Tenets of Darwin’s Theory
3. Struggle for Existence
Because so many offspring are produced, many will die due to a lack of resources, predation, disease, or other unfavorable conditions.
Have students analyze the pictures. Ask them to explain the struggle for existence that is evident in each.
1) The slowest or weakest wildebeests will succumb to predation before fast or strong ones.
2) Competition for limited (food) resources leaves some members of the group, probably the smallest or least agile, hungry.

37. Tenets of Darwin’s Theory
4. Differential Reproduction
Individuals suited to environment survive and reproduce. Their advantageous traits are passed to their offspring while disadvantageous traits die out or produce fewer offspring.

38. Descent with Modification
This process of natural selection causes species to change over time. Species alive today descended with modification from ancestral species.