Biogenesis is a principle which states that all living things come from living things. However, in the 1700’s, people believed in spontaneous generation. They used this to explain maggots in meat and fish in ponds that had been dry. A few scientist help change these thoughts.
Figure 1
Fransisco Redi (Figure 1)
He took jars, and place meat inside them. In half, he left them open (control group). In the other half, he covered with a net to prevent flies from landing on the meat. After a few days, maggots were on the meat in the open container but not in the netted.
Figure 2
Lazzaro Spallanzani (Figure 2)
Around the same time, scientists began using the microscope. They discovered all sorts of tiny organisms that they concluded spontaneously generated from vital force. Spallanzani took two flasks of broth made of boiled meat. The control groups tops were left open. The experimental group was sealed with glass. After a period of time, the sealed flasks stayed clear and the open flask turned brown. However, critics of Spallanzani and believers in spontaneous generation were quick to deny this by saying that he sealed out the vital force.
Figure 3
Loius Pasteur (figure 3)
Loius Pasteur, in the mid 1800s, won an award for his proof that spontaneous generation isn't real. He made a curve neck flask that allowed air inside the flask to mix with the air outside. He made broth the same way as Spallanzani. After 1 year, the S-curve broth flask remained clear. The microbes got stuck in the S-curve and did not contaminate the flask. Pasteur then broke off the curve. After 1 day, the broth became cloudy and contaminated.
14.2 Earth's History
Around 5 billion years ago, the solar system was swirling gas. Over time, the material was pulled together to create the Sun and the planets. The Earth is estimate to be about 4 billion years old. Radiometric dating helps find out how old something is by using isotopes, versions of elements with varying numbers of neutrons. The mass number of an isotope is the total number of protons and neutrons in the nucleus. When describing an isotope, you write the name of the element and then the mass number, for example, carbon-14. If an isotopes nuclei is unstable, it will go through radioactive decay, giving off energy until it becomes stable. The length of time it takes for one-half of any size sample of an isotope to decay to a table form is called the half-life. Organic material can be dated by comparing the amount of carbon-14, an unstable isotope, with the amount of carbon-12, a stable isotope.
Figure 4
The early atmosphere was thought to contain Ammonia, Hydrogen gas, water vapor, and compounds made of hydrogen and carbon, like methane.Alexander Oparin and Jon Haldane thought that at high temperatures, these gasses might have formed simple organic molecules. In 1953, Stanley L. Miller, and his professer, Harold Urey, set up an experiment to test this. The experiment created many organic compounds, like amino acids. (figure 4)
Another hypothesis is that organic material arrived to Earth on space debris. In 1970, a large variety of organic material was found in a newly fallen meteorite.
Sydney Fox and others studied the first types of life. He found that cell like structures, microspheres, can form randomly from organic chemicles. These are sphericle in shape and made of protein molecules arranged like a membrane. Coacervates are another type of early organism, collections of droplets that are composed of molecules of different types, including lipids, amino acids, and sugars. However, these do not have hereditary material, and cannot undergo natural selection.
14.3 The First Life-Forms
DNA serves as the tempelate for RNA, which in turn serves as the template for proteins. RNA molecules are much more versatile than DNA. Thomas Cech found that a type of RNA is able to act as a chemical catalyst. A ribozyme is an RNA molecule that can act as a catalyst and promote a specific chemical reaction. Self-replicating molecules of RNA have been creating in laboratories, and indicate that life could have started with self-replicating RNA. These may have actually competed with each other. Another theory is that they lived inside microsphers or coacervates. Archaea are a related group of unicellular organisms, many of which thrive under extremely harsh environments. They perform chemosynthesis to get their energy from sources other than light. Some forms of life became photosynthetic by 3 billion years ago. Most of the oldest fossils are similar to modern cyanobacteria, unicellular, photosynthetic prokaryotes. Oxygen, a byproduct of photosynthesis, was orginall harmful to most early organisms. It could destroy coenzymes vital to functioning. Within some organisms, oxygen bonded to parts, and did not harm them. This was the first step to aerobic respiration. Oxygen gas (O2), reaches the upper parts of the atmosphere. The suns rays split the oxygen gas into single atoms of oxygen. These react with present oxygen gas to form ozone (O3). Ozone is poisonous to plants and animals, but in the upper atmosphere, it absorbes ultraviolet light.
A large amount of evidence shows that 2 to 1.5 billion years ago, a small aerobic prokaryote was engulfed by and and began to live and reproduce inside a larger aerobic prokaryote. This theory is called endosymbiosis. (figure 5) Scientists believe that endosymbiotic aerobic prokaryotes evolved into modern mitochondria, which perform aerobic respiration. Scientists believe that chloroplasts and mitochondria evolved in this manner as the reproduce sperately and have their own DNA.
Figure 5
Chapter 15: Theory of Evolution
15.1 History of Evolutionary Thought
Charles Darwin visited the Galapagos Islands and noticed that groups of animals varied slightly from island to island. He became convince that, over time, organisms had changed. He called this change over time evolution. His theories have become a basis for modern thought. In the 18th century, the earth was thought to be a few thousand years old. Scientists began studying strata, layers of rock. Georges Cuvier spent years creating fossils from bone fragments. Cuvier suggested catastrophism, the idea that sudden changes led to the extinction of species. Charles Lyell shared some of Cuvier’s ideas, but thought that the same geological processes of the past are ever-working. His writings supported Darwin’s. Jean Baptiste Lamarck also believed that populations of organisms change over time. He believe that traits acquired during a lifetime could be passed on. Darwin called evolution descent with modification. He saw many different species of finches in the Galapagos islands, but he believed that they all came from the same ancestor.
Natural Selection
Darwin proposed the idea of natural selection.
1.) Overproduction More offspring are produced than need to survive to maturity. The environment places limitations that are responsible for the deaths of many of the excess organisms.
2.) Genetic Variation Within a population, individuals have genetic differences. These genetic variations generally affect a small group of organisms within a populations.
3.) Struggle to Survive Individuals must compete with each other. The environment also affects the death rate. A trait that makes an individual successful in its environment is called an adaptation.
4.) Differential Reproduction Darwin concluded that organisms with the best adaptations are most likely to survive and reproduce. These adaptations will then become more prevalent in the population.
Fitness is a measure of an individual’s hereditary contribution to the next generation. Adaptation is change over long periods of time, while Acclimatization is a short-term process in which physiological changes take place in a single being in its lifetime.
15.2 History of Evolutionary Thought
A fossil is the remains or traces of an organism that died long ago. Nicolaus Steno proposed the principle of superposition. The principle states that if the rock at a location has not been disturbed, the lowerstratum was formed before the one above it. Geologists can often tell a fossils relative age, its age in comparison with other fossils. For some rocks, scientists can calculate the absolute age of the rock. From fossils, we can infer that different organisms lived at different times. Furthermore, we can tell that organisms that lived in similar time periods were more similar than those living in far apart times. A transitionalspecies is one that contains characteristics of a hypothesized ancestor and a modern descendent. Biogeography is the study of the locations of organisms around the world. For example, many of the animals in Australia are marsupials, suggesting that they evolved from a common ancestor in isolation. Embryology is the study of how organisms develop. Homologous structures are anatomical structures that have a similar structure that arrive from a common ancestor. The key thing here is the structure. Analogous structures have closely related functions [example, bird, bat, and moth wings] The key thing here is the function. Vestigial structures are structures that seem to serve no function but resemble structures with functional roles in related organisms. An example is the tailbone, coccyx, in human beings.
Organisms that share more traits should have more recent common ancestor than organisms than those that share fewer traits. Scientists can study DNA and RNA to learn more about evolutionary relationships. In a process called modern synthesis, scientists are seeking to blend the theory of natural selection with new understanding of genetics. Scientists try to model phylogeny, the relationships by ancestry among groups of organisms. Each branch on the tree is thought to take place at a later time than the ones before it.
Figure 6
15.3 Biogenesis
Evolution is apparent in many island situations. In the Caribbean islands, anole lizards come in many types. Tree-dwelling anoles have stocky bodies and long legs. Grass-dwelling anoles are more slender. Biologists did tests and found an example of convergent evolution, when different species, without a recent ancestor, develop similar traits. Divergent evolution occurs when descendants of a single ancestor differentiate into more than one species that have different niches. Sometimes a new population in a new environment will undergo divergent evolution until the organism fills many parts of the environment. This pattern of divergence is called adaptive radiation. Artificial selection is when a human breeder chooses individuals that will parent the next generation. This is popular in dog breeding and horse breeding. When two or more species evolved adaptations to each other’s influence, it is called coevolution. This can be in beneficial symbiosis, or when prey tries to evolve methods to escape predator, but predator keeps evolving new ways to catch the pray.
17: Classification of Organisms
17.1 Biodiversity
Biodiversity is the variety of organisms considered at all levels from populations to ecosystems. The science of describing, naming and classifying organisms is called taxonomy. Any group within a taxonomic system is a taxon. The ancient greek philosopher Aristotle classified things as either plants or animals. Obviously Common names, like jellyfish, are misleading, so therefore we use the system devised by Carolus Linneaus. From largest to smallest, the groupings are:
Domain Kingdom Phylum Class Order Family Genus Species
Linnaeus gave an organism name with two parts, called binomial nomenclature: first the genus name, then the species identifier. The genus name is usually capitalized, and both are in italics.[Homo Sapiens]
Variations of species that live close to each other have a subspecies that is said after the species identifier [Homo Sapiens
17.2 Systematics
Phylogenetics is the analysis of the evolutionary relationships between taxa (groups).A phylogenetic tree is a diagram that shows evolutionary relationships through branching lines. Fossils are important when studying evolutionary relationships, but they lack evidence about small soft organisms such as worms, fungi, and bacteria. Systematists compare homologous features (common ancestry and similar structure, not to be confused with analogous, which is just having the same function).
Willi Hennig developed cladistics, a system of analysis that uses shared and derived characters as the only criteria from grouping taxa. A shared derived character is a feature that all members of a group have in common [like hair in mammals, or feathers in birds] *The book does not do a good job of explaining this, so I looked this up online*
A clade is a group of organisms that includes an ancestor plus all of its descendants. A cladogram uses strict criteria of cladistics, which are sometimes slightly different than those used by other scientists.[For example, most scientists put crocodiles with snakes, but a clade may show it with birds]
When making a clade, you must make an out-group, a group that is only distantly related to the others. Then, you pick a characteristic that the outgroup does not have, but all the others do. (See Below) In a molecular cladogram branch lengths are proportional to the number of amino acid changes. The changes in DNA and RNA can be used as a molecular clock, telling the sequence of past evolutionary events. It is also possible to compare karyotypes. If two species have the same banding pattern in regions of similar chromosomes, the regions are likely to have been inherited from a single ancestor.
*The book keeps using pangolians as an example. Pangolians are scaled animals that look like armadillos, but are more related to dogs.*
Cladogram
17.1 Modern Classification
There are two fundamental types of cells, eukaryotes, which have a membrane bound nucleus and organelles, and prokaryotes, which lack a nucleus and membrane-enclosed organelles. Because eukaryotes and prokaryotes are so different, scientists use DNA and RNA to compare the two. Domain Bacteria
This domain is made of small, single-celled prokaryotic organisms that usually have cell wall and reproduce by cellular fission. Most are quite small. Domain Archaea
Archaea are also prokaryotes, but have distinctive cell membranes and other unique biochemical properties. Some are autotrophic and use chemosynthesis. Some create flammable gasses, like methane, as a waste product. Many live in harsh conditions like deep sea vents, salty lakes, wastewater from mining, and animal intestines. Scientists believe these to be Domain Eukarya
The most familiar group, these all have a true nucleus and organelles.
There are 6 kingdoms. Kingdoms Kingdom Eubacteria
“True bacteria.” This kingdom is mainly to distinguish between archaea and other prokaryotes. Kingdom Archaebacteria
“Ancient bacteria.” Archaea are actually quite different than bacteria, so scientists prefer to write archaea. Kingdom Protists
Protists are eukaryotes that are not plants, animals, or fungi. This was a bad decision on scientists’ part, because they are defined by what they are not, rather than what they are. Many have less in common than plants and animals. Kingdom Fungi
The kingdom Fungi consists of eukaryotic, heterotrophic organisms that are unicellular or multicellular and that gain nutrients through absorption. Kingdom Plantae
Most plants are autotrophic, use photosynthesis as a cource of energy and develop from embryos. Kingdom Animalia
Animals are eukaryotic, multicellular, and heterotrophyic organisms that develop from embryos. Most have symmetrical body organization.
Since the time of Linnaeus, many biologists have proposed alternative to this 6 kingdom system. Some say that more kingdoms need to be created to replace protists. Some say subkingdoms are the way to go.
*Make sure to study the Clade and the Tree and the Clade* Drije told 3rd period that those would be the majority of the diagrams for this section!
14.1 Biogenesis
Biogenesis is a principle which states that all living things come from living things. However, in the 1700’s, people believed in spontaneous generation. They used this to explain maggots in meat and fish in ponds that had been dry. A few scientist help change these thoughts.
Fransisco Redi (Figure 1)
He took jars, and place meat inside them. In half, he left them open (control group). In the other half, he covered with a net to prevent flies from landing on the meat. After a few days, maggots were on the meat in the open container but not in the netted.
Lazzaro Spallanzani (Figure 2)
Around the same time, scientists began using the microscope. They discovered all sorts of tiny organisms that they concluded spontaneously generated from vital force. Spallanzani took two flasks of broth made of boiled meat. The control groups tops were left open. The experimental group was sealed with glass. After a period of time, the sealed flasks stayed clear and the open flask turned brown. However, critics of Spallanzani and believers in spontaneous generation were quick to deny this by saying that he sealed out the vital force.
Loius Pasteur (figure 3)
Loius Pasteur, in the mid 1800s, won an award for his proof that spontaneous generation isn't real. He made a curve neck flask that allowed air inside the flask to mix with the air outside. He made broth the same way as Spallanzani. After 1 year, the S-curve broth flask remained clear. The microbes got stuck in the S-curve and did not contaminate the flask. Pasteur then broke off the curve. After 1 day, the broth became cloudy and contaminated.
14.2 Earth's History
Around 5 billion years ago, the solar system was swirling gas. Over time, the material was pulled together to create the Sun and the planets. The Earth is estimate to be about 4 billion years old. Radiometric dating helps find out how old something is by using isotopes, versions of elements with varying numbers of neutrons. The mass number of an isotope is the total number of protons and neutrons in the nucleus. When describing an isotope, you write the name of the element and then the mass number, for example, carbon-14. If an isotopes nuclei is unstable, it will go through radioactive decay, giving off energy until it becomes stable. The length of time it takes for one-half of any size sample of an isotope to decay to a table form is called the half-life. Organic material can be dated by comparing the amount of carbon-14, an unstable isotope, with the amount of carbon-12, a stable isotope.
Another hypothesis is that organic material arrived to Earth on space debris. In 1970, a large variety of organic material was found in a newly fallen meteorite.
Sydney Fox and others studied the first types of life. He found that cell like structures, microspheres, can form randomly from organic chemicles. These are sphericle in shape and made of protein molecules arranged like a membrane. Coacervates are another type of early organism, collections of droplets that are composed of molecules of different types, including lipids, amino acids, and sugars. However, these do not have hereditary material, and cannot undergo natural selection.
14.3 The First Life-Forms
DNA serves as the tempelate for RNA, which in turn serves as the template for proteins. RNA molecules are much more versatile than DNA. Thomas Cech found that a type of RNA is able to act as a chemical catalyst. A ribozyme is an RNA molecule that can act as a catalyst and promote a specific chemical reaction. Self-replicating molecules of RNA have been creating in laboratories, and indicate that life could have started with self-replicating RNA. These may have actually competed with each other. Another theory is that they lived inside microsphers or coacervates. Archaea are a related group of unicellular organisms, many of which thrive under extremely harsh environments. They perform chemosynthesis to get their energy from sources other than light. Some forms of life became photosynthetic by 3 billion years ago. Most of the oldest fossils are similar to modern cyanobacteria, unicellular, photosynthetic prokaryotes. Oxygen, a byproduct of photosynthesis, was orginall harmful to most early organisms. It could destroy coenzymes vital to functioning. Within some organisms, oxygen bonded to parts, and did not harm them. This was the first step to aerobic respiration. Oxygen gas (O2), reaches the upper parts of the atmosphere. The suns rays split the oxygen gas into single atoms of oxygen. These react with present oxygen gas to form ozone (O3). Ozone is poisonous to plants and animals, but in the upper atmosphere, it absorbes ultraviolet light.
A large amount of evidence shows that 2 to 1.5 billion years ago, a small aerobic prokaryote was engulfed by and and began to live and reproduce inside a larger aerobic prokaryote. This theory is called endosymbiosis. (figure 5) Scientists believe that endosymbiotic aerobic prokaryotes evolved into modern mitochondria, which perform aerobic respiration. Scientists believe that chloroplasts and mitochondria evolved in this manner as the reproduce sperately and have their own DNA.
Chapter 15: Theory of Evolution
15.1 History of Evolutionary Thought
Charles Darwin visited the Galapagos Islands and noticed that groups of animals varied slightly from island to island. He became convince that, over time, organisms had changed. He called this change over time evolution. His theories have become a basis for modern thought. In the 18th century, the earth was thought to be a few thousand years old. Scientists began studying strata, layers of rock. Georges Cuvier spent years creating fossils from bone fragments. Cuvier suggested catastrophism, the idea that sudden changes led to the extinction of species. Charles Lyell shared some of Cuvier’s ideas, but thought that the same geological processes of the past are ever-working. His writings supported Darwin’s. Jean Baptiste Lamarck also believed that populations of organisms change over time. He believe that traits acquired during a lifetime could be passed on. Darwin called evolution descent with modification. He saw many different species of finches in the Galapagos islands, but he believed that they all came from the same ancestor.
Natural Selection
Darwin proposed the idea of natural selection.
1.) Overproduction More offspring are produced than need to survive to maturity. The environment places limitations that are responsible for the deaths of many of the excess organisms.
2.) Genetic Variation Within a population, individuals have genetic differences. These genetic variations generally affect a small group of organisms within a populations.
3.) Struggle to Survive Individuals must compete with each other. The environment also affects the death rate. A trait that makes an individual successful in its environment is called an adaptation.
4.) Differential Reproduction Darwin concluded that organisms with the best adaptations are most likely to survive and reproduce. These adaptations will then become more prevalent in the population.
Fitness is a measure of an individual’s hereditary contribution to the next generation. Adaptation is change over long periods of time, while Acclimatization is a short-term process in which physiological changes take place in a single being in its lifetime.
15.2 History of Evolutionary Thought
A fossil is the remains or traces of an organism that died long ago. Nicolaus Steno proposed the principle of superposition. The principle states that if the rock at a location has not been disturbed, the lowerstratum was formed before the one above it. Geologists can often tell a fossils relative age, its age in comparison with other fossils. For some rocks, scientists can calculate the absolute age of the rock. From fossils, we can infer that different organisms lived at different times. Furthermore, we can tell that organisms that lived in similar time periods were more similar than those living in far apart times. A transitional species is one that contains characteristics of a hypothesized ancestor and a modern descendent. Biogeography is the study of the locations of organisms around the world. For example, many of the animals in Australia are marsupials, suggesting that they evolved from a common ancestor in isolation. Embryology is the study of how organisms develop. Homologous structures are anatomical structures that have a similar structure that arrive from a common ancestor. The key thing here is the structure. Analogous structures have closely related functions [example, bird, bat, and moth wings] The key thing here is the function. Vestigial structures are structures that seem to serve no function but resemble structures with functional roles in related organisms. An example is the tailbone, coccyx, in human beings.
Organisms that share more traits should have more recent common ancestor than organisms than those that share fewer traits. Scientists can study DNA and RNA to learn more about evolutionary relationships. In a process called modern synthesis, scientists are seeking to blend the theory of natural selection with new understanding of genetics. Scientists try to model phylogeny, the relationships by ancestry among groups of organisms. Each branch on the tree is thought to take place at a later time than the ones before it.
15.3 Biogenesis
Evolution is apparent in many island situations. In the Caribbean islands, anole lizards come in many types. Tree-dwelling anoles have stocky bodies and long legs. Grass-dwelling anoles are more slender. Biologists did tests and found an example of convergent evolution, when different species, without a recent ancestor, develop similar traits. Divergent evolution occurs when descendants of a single ancestor differentiate into more than one species that have different niches. Sometimes a new population in a new environment will undergo divergent evolution until the organism fills many parts of the environment. This pattern of divergence is called adaptive radiation. Artificial selection is when a human breeder chooses individuals that will parent the next generation. This is popular in dog breeding and horse breeding. When two or more species evolved adaptations to each other’s influence, it is called coevolution. This can be in beneficial symbiosis, or when prey tries to evolve methods to escape predator, but predator keeps evolving new ways to catch the pray.
17: Classification of Organisms
17.1 Biodiversity
Biodiversity is the variety of organisms considered at all levels from populations to ecosystems. The science of describing, naming and classifying organisms is called taxonomy. Any group within a taxonomic system is a taxon. The ancient greek philosopher Aristotle classified things as either plants or animals. Obviously Common names, like jellyfish, are misleading, so therefore we use the system devised by Carolus Linneaus. From largest to smallest, the groupings are:Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Linnaeus gave an organism name with two parts, called binomial nomenclature: first the genus name, then the species identifier. The genus name is usually capitalized, and both are in italics.[Homo Sapiens]
Variations of species that live close to each other have a subspecies that is said after the species identifier [Homo Sapiens
17.2 Systematics
Phylogenetics is the analysis of the evolutionary relationships between taxa (groups).A phylogenetic tree is a diagram that shows evolutionary relationships through branching lines. Fossils are important when studying evolutionary relationships, but they lack evidence about small soft organisms such as worms, fungi, and bacteria. Systematists compare homologous features (common ancestry and similar structure, not to be confused with analogous, which is just having the same function).Willi Hennig developed cladistics, a system of analysis that uses shared and derived characters as the only criteria from grouping taxa. A shared derived character is a feature that all members of a group have in common [like hair in mammals, or feathers in birds] *The book does not do a good job of explaining this, so I looked this up online*
A clade is a group of organisms that includes an ancestor plus all of its descendants. A cladogram uses strict criteria of cladistics, which are sometimes slightly different than those used by other scientists.[For example, most scientists put crocodiles with snakes, but a clade may show it with birds]
When making a clade, you must make an out-group, a group that is only distantly related to the others. Then, you pick a characteristic that the outgroup does not have, but all the others do. (See Below) In a molecular cladogram branch lengths are proportional to the number of amino acid changes. The changes in DNA and RNA can be used as a molecular clock, telling the sequence of past evolutionary events. It is also possible to compare karyotypes. If two species have the same banding pattern in regions of similar chromosomes, the regions are likely to have been inherited from a single ancestor.
*The book keeps using pangolians as an example. Pangolians are scaled animals that look like armadillos, but are more related to dogs.*
17.1 Modern Classification
There are two fundamental types of cells, eukaryotes, which have a membrane bound nucleus and organelles, and prokaryotes, which lack a nucleus and membrane-enclosed organelles. Because eukaryotes and prokaryotes are so different, scientists use DNA and RNA to compare the two.Domain Bacteria
This domain is made of small, single-celled prokaryotic organisms that usually have cell wall and reproduce by cellular fission. Most are quite small.
Domain Archaea
Archaea are also prokaryotes, but have distinctive cell membranes and other unique biochemical properties. Some are autotrophic and use chemosynthesis. Some create flammable gasses, like methane, as a waste product. Many live in harsh conditions like deep sea vents, salty lakes, wastewater from mining, and animal intestines. Scientists believe these to be
Domain Eukarya
The most familiar group, these all have a true nucleus and organelles.
There are 6 kingdoms.
Kingdoms
Kingdom Eubacteria
“True bacteria.” This kingdom is mainly to distinguish between archaea and other prokaryotes.
Kingdom Archaebacteria
“Ancient bacteria.” Archaea are actually quite different than bacteria, so scientists prefer to write archaea.
Kingdom Protists
Protists are eukaryotes that are not plants, animals, or fungi. This was a bad decision on scientists’ part, because they are defined by what they are not, rather than what they are. Many have less in common than plants and animals.
Kingdom Fungi
The kingdom Fungi consists of eukaryotic, heterotrophic organisms that are unicellular or multicellular and that gain nutrients through absorption.
Kingdom Plantae
Most plants are autotrophic, use photosynthesis as a cource of energy and develop from embryos.
Kingdom Animalia
Animals are eukaryotic, multicellular, and heterotrophyic organisms that develop from embryos. Most have symmetrical body organization.
Since the time of Linnaeus, many biologists have proposed alternative to this 6 kingdom system. Some say that more kingdoms need to be created to replace protists. Some say subkingdoms are the way to go.
*Make sure to study the Clade and the Tree and the Clade* Drije told 3rd period that those would be the majority of the diagrams for this section!