unit 15 introduction to life science

Unit 15

Introduction to Life Science Table of Contents

Table of Contents 1

Introduction 3

Essential Questions 4

Review 4

Lesson 15.1: The Evolving Concept of Life 5 Objectives 5 Warm-Up 5 Learn about It 6 Key Points 14 Web Links 14 Check Your Understanding 15 Challenge Yourself 16

Lesson 15.2: Classical Experiments That Led to the Discovery of First Life 17 Objectives 17 Warm-Up 17 Learn about It 18 Key Points 22 Web Links 23 Check Your Understanding 23 Challenge Yourself 25

Lesson 4.3: Early Forms of Life 26 Objectives 26 Warm-Up 26 Learn about It 28 Key Points 36

Web Links 36 Check Your Understanding 37 Challenge Yourself 38

Lesson 15.4: Connections and Interactions Among Living Things 39 Objectives 39 Warm-Up 39 Learn about It 41 Key Points 47 Web Links 47 Check Your Understanding 48 Challenge Yourself 49

Laboratory Activity 50

Performance Task 53

Self Check 54

Key Words 55

Wrap Up 57

Photo Credits 57

References 58

Copyright © 2018 Quipper Limited 2

GRADE 11/12 | EARTH AND LIFE SCIENCE

Unit 15 Introduction to Life Science

In the 21st century, humans become more interested in understanding the origin and the concept of life. “What is life?” is a common question that human race keep on asking since the dawn of mankind. During the Greek era, Aristotle, a great naturalist, enumerated several concrete ideas on the definition of “life” that has been passed from one generation to another. However, through the advent of Science and the emergence of curious minds, these ideas were invalidated and the deductive understanding of life has been beset with difficulties. With several discoveries that allow human to understand the complexity of life like the “double helix structure” of the DNA illustrated by Watson and Crick in 1953, several doors were opened to direct the path for the emergence of modern life science. With life science, it became possible for humans to understand life with the use of concepts and principles from other Sciences like physics, chemistry, and mathematics that are continuously being refined over time. Life science as a body of knowledge has rapidly developed and provided humans with the knowledge on different organisms with regards to its origin, structures, and other complexities.


This unit covers the basic definition of life science and tackles the different prevailing theories concerning the origin of life and the evolution of the first living organism that appeared on Earth. How is it possible that all organisms emerge from a single-celled life form that existed during the primitive Earth?

Essential Questions

At the end of this unit, you should be able to answer the following questions.

● How do primitive organisms emerged on Earth? ● What are classic experiments that model conditions which may have enabled

first forms of organisms to evolve? ● How unifying themes in the study of life show the connections and

interactions among living things and their environment?

Review

● Biology is the study of life. Recall that “bio” refers to life and “logos” means study; making biology as the study of life. Some branches of biology include microbiology, zoology, botany, ecology, and genetics.

○ Microbiology is the study of minute microscopic organisms dealing with their interactions with one another and other living organisms.

○ Zoology is the study of animals with regards to their physiology, classification, growth and development, and behavior.

○ Botany is the study of plants. Traditionally, botany has also included the study of fungi and algae.

○ Ecology is the study of the interactions of living organisms with each other and with the nonliving things in their environment.

○ Genetics is the study of heredity and genetic materials like genes and genetic variation in living organisms.

● Scientists have calculated that the Earth is 4.54 billion years old. ● The earliest life forms emerged on Earth 3.77 billion years ago or possibly

as early as 4.28 billion years ago after the oceans were formed.


Lesson 15.1: The Evolving Concept of Life

Objectives In this lesson, you should be able to:

● enumerate theories that explain how life emerge on Earth; and ● explain how life was formed and evolved.

Life is believed to have existed on Earth for billions of years now. Scientists do not know exactly when life began on Earth, however, they have proposed several theories on how life developed and evolved based on pieces of evidence. What are the theories that tried to explain the origin of life? Which of these are still valid and recognized by Science?

Warm-Up

What is Life? This activity aims to introduce life by determining the characteristics that make it different from nonliving things. Through observation of ecosystem, several distinct characteristics can be noted from the living organisms. Materials:

● pencil ● paper ● illustration of an ecosystem

● What is Life Activity Quipper. 2018. ‘What is Life Activity.’ https://drive.google.com/drive/folders/1f-P_UILzF9c_eU9qVts_O35EskiPqVDG?usp=sharing


http://leiwenwu.tripod.com/primordials.htm

https://drive.google.com/drive/folders/1f-P_UILzF9c_eU9qVts_O35EskiPqVDG?usp=sharing

https://drive.google.com/drive/folders/1f-P_UILzF9c_eU9qVts_O35EskiPqVDG?usp=sharing

Procedure: 1. Find a partner and form a pair. 2. Using the provided link, download the image to be evaluated. 3. Using the figure, enumerate the different organisms present. 4. After enumerating the organisms, identify the characteristics they exhibit in

the photo that proves they are alive. 5. Summarize your answer using the table below. 6. Present your answer in the class and see if you got everything correctly.

Organisms Exhibited Characteristic of Life

Guide Questions:

1. How many organisms were you able to identify? 2. What is the most common characteristic shown in the figure that proves

existence of life? 3. How do you think each organism in the figure interact with one another? 4. Sharing similar characteristics of life, do you think these organisms came

from similar ancestors? Why?


Learn about It

Life Science as a Science Life science is a collection of disciplines that is made up of theories and principles that tackles the structure and function of living things starting from the molecular level up to entire ecosystems. This field advances our knowledge about the anatomy, cell biology, ecology, genetics, molecular biology, and physiology of all living things on Earth. Life science is a vital field for understanding issues about the web of life on Earth. It is an interdisciplinary field that involves concept of Biology, Biochemistry, Chemistry, and Physics. Characteristics of Life Not all people of Science agree on a single concept regarding life. But several characteristics describe most living things and these distinguishing features separate a living from a nonliving thing. These allow us to have a unifying understanding of the concept of life and classify an individual living creature as an organism. Organisms belonging to different kinds share the following characteristics that allow us to identify that they are living:

1. They respond to their environment. 2. They grow and develop. 3. They are capable of reproduction. 4. They exhibit metabolism. 5. They maintain homeostasis. 6. They are made up of cells.

The succeeding discussions focus on each of these characteristics. Response to Their Environment All living organisms respond to its environment. In order to survive, a living thing must know what is going on around them, and be capable of responding to the changes on its environment. Adaptation is the process of adjusting to the changes in the environment. This includes structural, physiological, or even behavioral changes that increase the likelihood of survival. For example, humans tend to perspire whenever exposed to hot environment. This is one method to regulate temperature inside their bodies.


Growth and Development All living things have the ability to grow and change, like seeds grow into whole new plants while animals develop to reach full adulthood and be sexually mature for reproduction. Growth refers to the ability of organisms to increase in size, weight, and height, while development refers to the differentiation of cells to form highly specialized structures in your body. Organisms grow by increasing their size, height, or weight. On the other hand, development is evident in the formation of organs like the development of the mammary gland during puberty in humans.

Fig. 1. Development of a human embryo as seen

in an ultrasound imaging machine. Reproduce and Have Offsprings All living organisms is capable to reproduce. Living things create new offsprings to have a population of new generation which will sustain the species’ continuity of existence. Most animals produce its offspring through birth or external fertilization. As for plants, reproduction often happen by the formation of seeds enclosed in fruits that develop into new individuals. Exhibit Metabolism All living things have several metabolic processes happening in their body. Metabolism refers to the total chemical reactions in an organism that allow it to function properly. Simple example of metabolism in animals are breathing, excretion, and perspiration. These are chemical processes that happen in order to maintain balance in the body.


Maintain Homeostasis Homeostasis refers to the equilibrium state in an organism’s body. A human body has a temperature of 37 degrees Celsius and this must be maintained to allow several processes to occur efficiently. Living things keep a stable internal environment within a certain range despite the several changes in their external environment. There are several ways in which organisms maintain homeostasis. One common example is thermoregulation in animals and water conservation in plants. These are all dependent on the changes in the environment. Made up of Cells All living things are highly organized up to the microscopic level, starting from atoms up to the entire living organism. The cell is the fundamental structural and functional unit of all living organisms. Cells with similar function work together and form tissues, then, tissues form the organs. Organs are connected with one another and form organ systems, which can work together to form the entire organism. Trying to observe an animal or plant tissue under the microscope will let you notice several building blocks in the form of cells. These serve as the basic structural and functional unit in all organisms. Theories on the Origin of Life Theories that describe how life on earth first existed include the spontaneous generation theory, primordial soup theory and theory of panspermia. Theory of Spontaneous Generation The theory of spontaneous generation described that life comes from lifeless or nonliving material through a mysterious process. The idea of abiogenesis or the formation of life from nonliving materials, had popularized this theory. Abiogenesis is the process by which life emerges naturally from inanimate or nonliving materials.


This theory was assumed to have originated from Anaximander, a Greek philosopher in the 6th century BCE. Other philosophers including Aristotle adapted and expanded Anaximander’s idea. Moreover, Aristotle explained in his writing, The History of Animals written in 350 BCE, that some organisms appeared from inanimate objects spontaneously. For instance, when hay was piled, mice appeared. When garbage was left for some time, maggots appeared. From these coincidences, he assumed that clutter gave rise to vermin through spontaneous generation, a process that transmuted lifeless objects to living organisms by supernatural means. In order to disprove the abiogenesis concept of the spontaneous generation theory, Francesco Redi challenged the idea using the concept that maggots came from rotting meat. In his experiment, a rotting meat was placed in a variety of open container with cloth cover to allow entry of air (uppermost left); sealed container (uppermost right), open container without the cloth cover (lowermost left), and partially covered jars (lowermost right). He insisted that maggots will not be formed (or appear) in totally and partially sealed containers. However, results of this experiment did not convince the scientific community during that time.

Fig. 3. Experiment of Francesco Redi in 1668 on abiogenesis.


In contrary, John Needham (1745) conducted an experiment on boiled broths to support spontaneous generation theory. He believes that boiling kills microorganisms in the broth. He actually conducted an experiment with boiled broth and sealed it afterwards. He hypothesized that the broth would become cloudy and still form microorganisms, thus supporting the belief in spontaneous generation. This experiment was criticized by a lot of people including Lazzaro Spallanzani. In 1768, Lazzaro Spallanzani made some modifications on Needham’s experiment by excluding the possibility of contamination factor prior sealing the bottle after boiling. He boiled the broth in a partially sealed jar with the air partially evacuated to avoid explosions while boiling. He did not observed any growth, although the issue of the role of air remains in question to disprove spontaneous generation theory.

Francesco Redi Lazzaro Spallanzani (1626 - 1697) (1729 - 1799)


Lastly, in 1859, a french scientist, Louis Pasteur made an experiment to totally disprove the spontaneous generation theory. In his experiment, Pasteur boiled a meat broth in a goose-like flask having a long curved neck. He explained that the bend in the neck prevent particles from reaching the meat broth and still allow free air to flow. On his observation, the flask remained clear and there was no cloud formation observed for an extended period. This experiment of Pasteur convinced a lot of scientist during his time and led to the exclusion of spontaneous generation theory as a valid idea to explain the origin of life. Theory of Panspermia The theory was proposed by the astronomer Fred Hoyle in the 19th century. It states that life on Earth was seeded from a celestial source. The theory of panspermia is also called exogenesis, as some of its hypotheses suggest that building blocks of life came from another planet. These include comets colliding to Earth and depositing living cells or the precursors of life, and aliens making life-essential materials in a laboratory. Most scientists who believe in panspermia stick to the origin of life from comets. This particular theory does not focus on the origin of life itself but on the possible transmission of life that allowed it to be distributed to different parts of the planet. Organisms like bacteria and other microorganisms might have travelled in dormant stages within comets and asteroid that heat the Earth. These dormant organisms became activated and started colonizing the Earth which serve as their new environment. Until now, the integrity of the theory remained in question as there are no evidence supporting its hypothesis.


Primordial Soup Theory Primordial soup theory is the most predominant theory about the origin of life. According to the primordial soup theory proposed by Alexander Oparin and John Haldane, life started in a primordial soup of organic molecules. This theory explains how catalysts for nonliving things became living cells from chemical compounds abundant on early Earth. It begins with the assumption that life first formed

from primitive seas when simple molecules of the early atmosphere reacted to produce complex molecules. At this time, Oparin and Haldane failed to conduct an actual experiment to prove their theory. However, the principles of the theory remained strong and logical that considered the theory valid until now. Formation of life based on primordial soup theory has been theorized based on the following series of events:

1. The surface of the early Earth was very hot. There were a lot of volcanoes that erupted frequently and spewed gases such as methane, ammonia, sulfur, hydrogen, water vapor, carbon dioxide, and inert nitrogen. These gases were the major components of the primitive atmosphere.

2. The gases on the early atmosphere were constantly exposed to high voltages coming from the lightning, high energy particles from immense radioactivity, and high ultraviolet radiation from the sun due to lack of ozone layer.

3. As the gases were exposed to high energy particles, their molecules reacted, and the reactions formed larger, more complex molecules.

4. As the temperature cooled at night, the water vapor condensed, forming fogs or clouds. The condensed water droplets formed new molecules.

5. Droplets fell to the earth and gradually formed more highly concentrated molecular pools in ponds or cracks in the surface of Earth. The primordial soup of organic molecules was formed.


6. From the primitive sea or primordial soup bowls, all building blocks of life like amino acids, fatty acids, nucleobases, and sugars were assumed to have condensed to form life on earth.

Below is a schematic representation of the early Earth and how biological molecules were synthesized from gases and minerals.

Fig. 5. Schematic diagram of the processes that happened during the primitive

Earth according to the primordial soup theory.

At present, the most valid theory about the origin of life is presented by the primordial soup theory that was validated experiments of Miller and Urey. Several scientists validated their experiments and obtained the same outcome. Several


modified experiments are still being conducted to determine the dynamics of organic materials in the primordial soup present during the primitive Earth.

Key Points

● Life science is a collection of disciplines that is made up of theories and

principles that tackles the structure and function of living things starting from the molecular level up to entire ecosystems.

● An individual living creature is termed as an organism. ● All living organisms are capable of reproduction, growth and

development, adaptation, movement, exhibiting metabolism, and maintaining homeostasis.

● The spontaneous generation theory and the panspermia are two of the classical theories regarding the origin of life.

● The primordial soup theory is one of the most valid theory trying to explain the origin of life on Earth.

Web Links

To learn more about the evolving concept of life, you can check the following web links:

● Read more about the primordial soup theory. Leuwenwu. 2015. The Primordial Soup Theory.’ http://leiwenwu.tripod.com/primordials.htm

● Spontaneous generation theory in a wrap! Visit this website to learn more Brian Cardella. 2015. ‘Spontaneous Generation Theory.’ Video. https://youtu.be/7rOr-mEycwA

● Watch this short magnificent clip on the origin of life supporting the claims of the theory of panspermia. Labidiomas. 2017. Órigin of Life: Panspermia.’ Video. https://youtu.be/51V363V1bkI




https://youtu.be/2bX99Es3UNY

https://youtu.be/7rOr-mEycwA

https://youtu.be/51V363V1bkI

https://youtu.be/51V363V1bkI

Check Your Understanding

A. Using the Venn diagram below, compare the three prevailing theories on the

origin of life.

B. Write the word true if the given statement is correct and false if otherwise.

1. Abiogenesis states that living organisms originated from preexisting living organisms.

2. The spontaneous generation theory is still considered as a valid theory up to date.

3. All living organisms are made up of cells. 4. Maintaining a stable internal condition is not important to living things. 5. Microorganisms that cause clouding in the experiment of John Needham

came from the boiled broth.


Challenge Yourself

Briefly answer the following questions.

1. What do you think is the problem with John Needham’s experiment? 2. If you are given the chance to modify John Needham’s experiment, what part

will you improve? Rationalize your choice. 3. Do you agree with Louis Pasteur’s experiment in disproving spontaneous

generation theory? Why? 4. Do you believe in abiogenesis theory on the origin of life? Why? 5. What do you think is the most useful characteristic of life that advanced the

existence of living organisms on Earth?


Lesson 15.2: Classical Experiments That Led to the Discovery of First Life


● enumerate classical experiments that explain early life formation on Earth; and

● describe how these classical experiments proved the formation of early life forms.

About 4.6 billion years ago, Earth began to exist. The existence of life, as believed by many scientists, started from the moment Earth’s environment became stable to support life. When was the first time that a life-form emerge on Earth? What are the experiments conducted to explain how the first life-form on Earth emerged?

Warm-Up Writing Earth’s History Scientists estimated that the Earth was formed 4.6 billion years ago. The Earth started as a lifeless planet that is filled with hydrogen and methane but is devoid of water. It is way different from the the planet you call your home today. In this activity, you are about to write milestones in Earth’s history. Materials:

● 46 sheets of paper ● a laptop ● a working internet connection ● reference books ● marker


Procedure: 1. The 46 sheets of paper represent 100 million years in the lifespan of the

Earth history. 2. Using the marker, label each sheet as follows: 4.6 billion years ago; 4.5 billion

years ago; 4.4 billion years ago; 4.3 billion years ago; and so on. 3. After labelling, look for important geologic events that happened within the

given time frame represented by each sheet of paper. You can use reference books and the given links below for this purpose.

● The geologic time scale. International Commission on Stratigraphy. 2015. ‘Geologic Time Scale.’ https://web.archive.org/web/20140530005940/http://www.stratigraphy.org

● GSA geologic time scale. Geological Society of America. 2013. ‘GSA Geologic Time Scale.’ Video. https://youtu.be/7rOr-mEycwA

4. Present your Earth’s geologic timescale in front of the class and point out

important milestones in Earth’s life history. Guide Questions:

1. Which time period exhibited the most number of developments on Earth? 2. At which period the first life-form emerged? What do you think is the

condition of the Earth’s environment during that time? 3. How long have the animals existed? What about human beings? 4. How much time would the average human existence cover on the scale you

have constructed?


https://web.archive.org/web/20140530005940/http://www.stratigraphy.org/index.php/ics-chart-timescale



https://youtu.be/2bX99Es3UNY

https://youtu.be/7rOr-mEycwA

Learn about It

Several scientists conducted different experiments that modeled conditions which may have enabled the first life forms to evolve. Among these experiments are the electrical discharge, thermal synthesis, and the protocell experiments. Electrical Discharge Experiment The electrical discharge experiment was conducted by Stanley Miller and Harold Urey in 1953. Miller and Urey recreated the primitive earth as described in Oparin-Haldane theory by simulating the formation of organic molecules in early Earth. They confined methane, ammonia, water, and hydrogen in a closed boiler representing the ocean and applied continuous electrical sparks with the use of electrodes (lightning in the atmosphere) to trigger the formation of the building blocks of life. The boiler was also exposed to heat using the burner for the simulation of the heat that goes to the ocean from the sun.

Stanley Miller Harold Urey (1930 - 2007) (1893 - 1981)

After a day, they observed a change in color of the solution. The continuous electrical sparks in the experiment may be compared to lightning which could have a similar effect on the gases in the primitive atmosphere. After a week, the solution


was tested, and they found out that several amino acids such as glycine, alanine, and aspartic acid were produced. In this experiment, Miller and Urey were able to prove the formation of amino acids and carbohydrates from the mixture of organic substances. The purpose of this experiment was not to try and produce amino acids; rather, its purpose was to explore the conditions of the early Earth and what naturally occurring results would be. In 2007, scientists tried to reexamine the experiment of Urey and Miller. They were able to detect different amino acids from sealed vials preserved from the original experiment. More recent evidences point out that the Earth's original atmosphere could be different from the gas composition used in the experiment of Urey and Miller.

Fig. 6. The electrical discharge experiment of Stanley Miller and Harold Urey.

The Thermal Synthesis Experiment The thermal synthesis experiment was conducted by Sidney Walter Fox in 1958. Fox demonstrated the origin of life in his experiment using a specific mixture of pure, dry amino acids. After heating the mixture, he observed that an aqueous solution was formed and cooled into microscopic globules called protenoid microspheres.


The globules looked like coccoid bacteria and seemed to be budding. Budding is a form of reproduction in some microorganisms. Fox claimed that the protenoid microspheres constituted protocells — spherical materials that looked like cells, and even multiplied through division like true cells. He believed that these cells were the link between the primordial environment and the true living cells.

Fig. 7. Protenoid microspheres under a microscope.

Recent reviews about the thermal synthesis of amino acids from interstellar components similar to ammonia and formaldehyde is considered in the context of the origin of life. The self organization of thermal proteins to cells is instantaneous. This process includes the extrusion of hot and dry amino acids and its conversion into peptides present in aqueous environment that occurs as the second step of self organization in living organisms. The Protocell Experiment The protocell experiment was conducted by Jack Szostak. Szostak thought that the simplest possible living cells or protocells just required two components to be formed: a nucleic acid genome to transmit the genetic information and a lipid sac which encapsulated the genome and let itself grow and divide. The formation of compartmentalizations within cells is important in explaining the emergence of life. The membranes form enclosed compartments that separate internal areas from the external environment of the cell. These allow cells to have specialized functional aqueous spaces. Because of the semipermeability of the lipid bilayer of cell membranes, cells have membrane transport systems that import important molecules and export wastes. Construction of the protocells can be very


challenging from molecular assemblies. The protocell must have vesicles which are important to cellular functions, such as membrane transport and cell division with the use of fat-loving molecules. During the primitive Earth, chemical reactions of organic and inorganic compounds produced the building block molecules of life. During this phase, the production of vesicle molecules played an important role in the evolution from molecular assembly to cellular life. Szostak built lipid sacs made in fatty acids and a replicase — an RNA molecule that catalyzes its own replication in a test tube. He found out that lipid sacs with more RNA grew faster. He suggested that such test tube evolution was possible. The results suggested that the early forms of life with just a single gene, an RNA gene, could have undergone a Darwinian evolution.

Fig. 8. A model showing replication and growth of a protocell.

Key Points

● The electrical discharge experiment was conducted by Stanley Miller and Harold Urey in 1953.

● Miller and Urey recreated the primitive earth as described in Oparin-Haldane theory by simulating the formation of organic molecules in early Earth.


● The thermal synthesis experiment was conducted by Sidney Walter Fox in 1958. Fox demonstrated in his experiment the origin of life using a specific mixture of pure, dry amino acids.

● The protocell experiment was conducted by Jack Szostak. Szostak thought that the simplest possible living cells or protocells just required two components to be formed: a nucleic acid genome that can transmit genetic information and a lipid sac which can encapsulate the genome and let itself grow and divide.

Web Links

To learn more about the classical experiments that lead to the discovery of first life, you can check the following web links:

● Want to look at an accurate visual illustration of the Urey-Miller experiment? Visit this site: Stated Clearly. 2015. ‘What was the Urey-Miller Experiment?.’ Video. https://youtu.be/NNijmxsKGbc

● Can’t get enough of the protocell experiment? Learn more by visiting this site: Exploring Origins. 2012. ‘Exploring Life’s Origin.’ http://exploringorigins.org/protocells.html

● What do you think is the earliest life form on Earth? And where do you think we can find them? Pappas, Stephanie. 2017. ‘What Was the First Life on Earth?.’ https://www.livescience.com/57942-what-was-first-life-on-earth.html


A. Using the Urey-MIller experiment, explain the importance of each component of their experiment in the simulation of the early condition of the Earth and the formation of essential molecules for the creation of life.

1. boiler flask with water


https://youtu.be/NNijmxsKGbc

https://youtu.be/NNijmxsKGbc

http://exploringorigins.org/protocells.html

http://exploringorigins.org/protocells.html

https://www.livescience.com/57942-what-was-first-life-on-earth.html

https://www.livescience.com/57942-what-was-first-life-on-earth.html

2. electrodes 3. condenser 4. methane, hydrogen gas, water, and ammonia 5. heating burner

B. Match the given words in set A to the items listed in set B.

Set A Set B

1. Stanley Miller a. The scientist who proposed the electric discharge experiment.

2. Jack Szostak b. It is a method of reproduction where cells split into two equal parts.

3. protocells c. He is the proponent of the protocell experiment.

4. budding d. It is the material used in the electric discharge experiment which represented the presence of thunder


during the primitive Earth.

5. Sidney Walter Fox e. It is the material used in the electric discharge experiment which represented the heat coming from the sun during the primitive Earth .

6. protenoid microspheres f. It is the material used in the electric discharge experiment which represented ocean water during the primitive Earth.

7. electrode g. It is the material used in the electric discharge experiment which represented the cooling of the atmosphere at night during the primitive Earth.

8. heating burner h. It is a structure that is highly similar to a true cell due to the presence of membrane divisions.

9. boiler i. These are microscopic globules formed during cooling of the primitive Earth.

10. condenser j. He is the proponent of the thermal synthesis experiment.

Challenge Yourself

Briefly answer the following questions. 1. How do you think the primary components of the Earth’s atmosphere affect

the formation of the early life forms on Earth? 2. If given the chance to modify the Urey-Miller experiment, what modifications

will you do? 3. What is the implication of the thermal synthesis experiment in the formation

of the first living cell on Earth?


4. What is the implication of the protocell experiment in the formation of the first cell on Earth?

5. How do you think the first living cell survived the harsh environmental condition during the primitive Earth?


Lesson 4.3: Early Forms of Life


● identify early life forms on Earth; and ● describe course of evolution for these organisms.

The first form of life is believed to have appeared some 3.5 billion years ago. From this point, the diversity in form and structure of living organisms became more complicated to adapt in extreme, unpredictable changes in the evolving environmental conditions on Earth. How do the first living forms on Earth look like? Are they similar to humans?

Warm-Up Who is our Oldest Ancestor? Knowing our common ancestor is an interesting part of Science. In this activity, the common ancestor of organisms can be determined with the use of shared and unique characteristics present in specific organisms. Materials:

● pen ● paper ● figures of nails and nuts

● Hardware Organism Key NOVA Online. 2012. ‘The Missing Link.’ https://www-tc.pbs.org/wgbh/nova/education/activities/pdf/2905_link_02.pdf


https://www-tc.pbs.org/wgbh/nova/education/activities/pdf/2905_link_02.pdf

https://www-tc.pbs.org/wgbh/nova/education/activities/pdf/2905_link_02.pdf

Procedure: 1. Click the given link to access the images of nails and nuts that will represent

different “hardware organisms”. 2. Observe the physical appearance of the following and focus on the following

traits: a. a cylindrical object with head b. presence of a partly threaded shaft c. presence of a completely threaded shaft d. presence of a flat bottom e. presence of a nut f. presence of a nut fixed to thread

3. Complete the table below by determining whether the given characteristic is present or absent in each hardware organism. Put ‘1’ if present and ‘0’ if absent.

Trait A Trait B Trait C Trait D Trait E Trait F

common nail

flat head wood screw

flat head sheet metal screw

flat head stove bolt

flat head machine screw with nut

round head


wood screw

round head sheet metal screw

round head machine screw with nut

carriage bolt with nut

4. Analyze the table. The presence of several characteristics in one hardware

organism makes it well adapted to its environment by exhibiting new additional trait that allows it to work on certain conditions in its environment.

5. On the other hand, organism with the least acquired characteristic makes it the oldest form and the ancestor of the rest of hardware organisms.

Guide Questions:

1. Based on your table, which do you think is the earliest hardware organism that existed?

2. Based on your table, which hardware organism is the youngest and has the most well adapted traits? based on the table?

3. How does these hardware organisms adapt to its environment and develop new and advanced ‘species’?

4. If these are real organisms, what do you think are the common environmental factors that drive their evolution?


Learn about It

Early Evidence of Life on Earth The Earth was formed for about 4.5 billion years ago while the first life form emerged 3.7 billion years ago. All present-day organisms are known to have a shared common ancestor that evolved through time. The earliest known evidence of life on Earth includes the stromatolite fossils collected from various samples of metasedimentary rocks in western Greenland and were aged 3.7 billion years old. Stromatolites are layered columns of sedimentary rocks formed through the growth of cyanobacteria, a single-celled photosynthesizing microbe. This fossils provide records of ancient life on Earth.

Series of new fossils were found by several scientists. In 2015, fossils of potential biotic life dated 4.1 billion-year-old were collected in Western Australia. In 2017, researchers have reported evidence of the oldest life on Earth in the form of fossilized microorganisms collected from hydrothermal vent precipitates in Quebec, Canada. This was dated to be 4.280 billion years ago, which is occured 200


million years after the first ocean was formed.

The evolution of photosynthetic organisms was dated at around 3.5 billion years ago and led to the buildup of its by-product, oxygen gas, in the Earth’s atmosphere. The increase in the concentration of oxygen in the atmosphere of the Earth at around 2.4 billion years ago is responsible for providing optimum living conditions to organisms. One of the organisms that emerged are the multicellular eukaryotes that dated 1.85 billion years ago. The emergence of multicellular organisms with highly differentiated cells performing specialised functions was observed to be around 1.7 billion years ago. Animals with proportional body symmetry appeared by 555 million years ago while the earliest complex land plants dated back to around 850 million years ago. The most advanced form of animals such as the vertebrates or animals with backbones first appeared at 525 million years ago during the Cambrian explosion. It is an event that happened 541 million years ago in the Cambrian period and was responsible for the emergence of most major animal phyla. This event resulted in the divergence of most modern animal and plant organisms. Prior to this event, most living things are simple and only consist of individual cell that clump together and form colonies. For over 70 to 80 million years after the cambrian explosion, the rate of diversification of organisms accelerated that formed a variety of life forms that is present today.


Early Life on Earth Cyanobacteria and Blue Green Algae Cyanobacteria or the blue green algae are form of organisms that obtain their energy from sunlight through photosynthesis. Cyanobacteria are prokaryotic organisms that lack nuclei in their cells. As a consequence, most prokaryotes are unicellular in nature. Cyanobacteria lack a true nucleus in their cells and are unicellar but often form colonies. Their colonies may be in the form of filaments, sheets, balls, or thick-walled microstructures. Cyanobacteria is a diverse group of microorganisms. They are present in different habitats from the equator to the poles. They thrive in freshwater lakes, oceans, and even in damp soils. These organisms are highly visible when they bloom or overgrow due to the presence of high nutrients in both freshwater and saltwater ecosystems. Lastly, they are capable of converting atmospheric nitrogen into nitrate or ammonia which are essential components of the nitrogen cycle.

Fig. 12. Algal bloom of cyanobacteria that covers the water in the pond.


Red Algae

The first multicellular organisms are thought to be red algae that appeared 1.2 billion years ago. The earliest microfossils of red algae were collected in northern arctic Canada and was dated 1.2 billion years ago. The red algae are unique as it started sexual reproduction in organisms.

The use of sexual reproduction through egg and sperm cells is a characteristic of most multicellular organisms. This allowed the emergence of more complex life forms like humans to eventually evolve and adapt to the changes in Earth’s condition.

Trilobites Trilobites were the dominant species during Cambrian period. This organisms are extinct forms of arthropods, animals having hard shells and jointed legs. Trilobites were relatives of modern lobsters and horseshoe crabs. This first animal on Earth had three segmented top-plated bodies. They curl up likes balls to protect themselves in seas with predators. Trilobites have several varieties. It usually range from an inch to more than 2 feet in length. These organisms have been the most successful prehistoric animals. More than 17,000 species are known to have existed that survived for 300 million years.


Anomalocaris One of the most dominant animals of the Cambrian Period is the giant Anomalocaris. They trap preys using their two claws lined with hooks located in front of their mouths and eyes. These are gigantic creatures that reach up to six feet in length. Anomalocaris is a free-swimming animal that moves like a dolphin. They feed on trilobites and other arthropods and worms. Anomalocaris is considered as the largest and most fearsome predator of the Cambrian Period.

Land Plants About 450 million years ago, plants began to thrive on land. The first plants penetrated marshland where they could easily obtain water from the damp soil that is needed for photosynthesis. Earliest plants do not have vascular tissue that transport water very well so these species were forced to stay close to water sources. Another leap on the evolution of land plants is the widespread evolution of spores which is also present in today’s fern species. Spores are unicellular structures that are mobile and are capable of reproducing new plant individuals. The spores eventually evolved into seeds, which contain multicellular structures needed for the reproduction of higher plant species. For approximately 430 million years ago, the first appearance of vascular plants started. These are the common plants that you usually see in the environment. These plants contain veins that allowed the transport of water and nutrients to different parts of their body. As a consequence, plants of this era grew larger and function internally like plants of today.


Fig. 16. Fern with spores that is use for reproduction of plants.

Lastly, at around 300 million years ago, conifers appeared and thrived the terrestrial ecosystem. These are cone bearing plants that include pine trees, cycads, and ginkgos.

Fig. 17. Ginkgo biloba, the living fossil.


Land Animals

The transition from living in water to land was a major step that requires a lot of time. Primitive Earth did not have an ozone layer that protects the organisms against the effects of UV radiation from sunlight. With the oxygen rich atmosphere, an ozone layer was formed that made land a safer ecosystem to tread. The first large animals to walk the Earth is probably in the form of a walking fish which still lived in water.

Eventually, the primitive animals that have four limbs and spinal column like vertebrates called tetrapods walked on land 400 years ago based on the oldest known fossil evidence. Tetrapods were aquatic creatures that lived in swamps and ventured to land occasionally. The tetrapods migrated to land and survived on small insects and plants from the green algae family. The development of the vertebrate structure led to more advanced animals like humans.

One of the earliest known tetrapod is the Acanthostega. It is an extinct group of tetrapod which is considered as one of the oldest organisms with distinct recognizable limbs. This emerged during the late Devonian period which is 365 million years ago. Scientists are telling that the Acanthostega is the missing link between the lobe-finned fishes and tetrapods.

Fig. 18. Acanthostega, one of the early tetrapods on Earth.


Key Points

● The Earth was formed for about 4.5 billion years ago while the first life form

emerged 3.7 billion years ago. ● The Cambrian explosion is an event that happened at around 541 million

years ago in the Cambrian period and was responsible for the emergence of most major animal phyla. This event resulted in the divergence of most modern animal and plant organisms.

● Cyanobacteria or blue green algae are form of microorganisms that obtain their energy from sunlight through photosynthesis. Cyanobacteria are prokaryotic organisms that lack nuclei in their cells and are mostly unicellular in nature.

● The first multicellular organisms are thought to be red algae that appeared between 1.4 and 1.2 billion years ago.

● Trilobites were the dominant species during cambrian period. Trilobites are extinct form of arthropods, animals having hard shells and jointed legs.

● The most dominant animal of the Cambrian Period is the giant Anomalocaris, that traps prey with two claw-tipped appendages lined with hooks in front of its mouth and eyes.

● About 450 million years ago, plants began to transition to land. ● The tetrapods have four limbs and spinal column like vertebrates. They

walked on land about 400 years ago.

Web Links

To learn more about the early forms of life, you can check the following web links:

● Where can we find the oldest evidence of life form on Earth? Gohse, Thia. 2017. ‘Oldest Evidence of Life on Earth Possibly Found in Australian Rocks.’ https://www.livescience.com/59025-oldest-evidence-for-life-found-in-australia.html


https://www.livescience.com/59025-oldest-evidence-for-life-found-in-australia.html

https://www.livescience.com/59025-oldest-evidence-for-life-found-in-australia.html

● Here is a website that illustrated earliest life-forms on Earth! Visit this website: News, Science, tech, and Health. 2017. ‘What was the first life form on Earth?’ Video. https://youtu.be/81chq_0QvK8

● Know more about the first tetrapod which walked the Earth! This website features Acanthostega, the first primordial animal: Devonian Times. 2016. ‘Acanthostega gunneri.’ http://www.devoniantimes.org/Order/re-acanthostega.html


A. Complete the table by identifying the most unique characteristic of each

given primitive organism.

Organism Characteristic

cyanobacteria

red algae

trilobites

Anomalocaris

fern

gymnosperms

Acanthostega

B. Write the word true if the given statement is correct and false if otherwise.

1. Red algae is the multicellular living organisms on Earth. 2. Cyanobacteria are photosynthetic organisms. 3. Trilobites are primitive arthropods. 4. Tetrapods are similar to most reptiles that we have in the current time. 5. Cyanobacteria has the tendency to overgrow and create algal blooms.


https://youtu.be/81chq_0QvK8

https://youtu.be/81chq_0QvK8

http://www.devoniantimes.org/Order/re-acanthostega.html

http://www.devoniantimes.org/Order/re-acanthostega.html

Challenge Yourself

Briefly answer the following questions. 1. How did aquatic organisms transition to the land ecosystem? 2. How do you think the oxygen-rich atmosphere contributed to the increase in

forms of living organisms on Earth? 3. What do you think happened during the Cambrian explosion that led to the

increase in species of organisms on Earth? 4. What are the distinct characteristics of tetrapods that made it survive on

Earth for a long time? 5. If given the chance to live during the primitive form of the Earth, what do you

think are the characteristics that you should have to survive?


Lesson 15.4: Connections and Interactions Among Living Things


● describe how living organisms are connected in an ecosystem; and

● enumerate different kinds of interaction between these organisms.

An ecosystem is a community that is consist of living organisms and nonliving components. This also includes interactions among organisms, and between organisms and their environment. How are organisms connected in an ecosystem? What kind of interactions do they exhibit to survive?

Warm-Up

Ecological Interactions Organisms in the ecosystem are well connected to one another. These interactions are necessary to control population and maintain balance in the ecosystem. This activity provide simulation of the selected interactions happening in the ecosystem. Materials:

● a bowl of coated chocolates ● three note cards ● three plastic spoons ● three empty cups

Procedure:

1. Group yourself into three. Each student is assigned to a different species, labelled species A, B and C.

2. Secure a bowl of coated chocolates for your group.


3. Each student gets a spoon, a cup, and a set of note cards. Each note card contains instruction indicated in the table below.

4. Put the bowl of coated chocolates in the center of the group. 5. Each member must use the spoon to collect coated chocolates one at a time

and transfer to its own cup left on the table and not on hand. 6. For each round that takes a minute, each member should follow their given

instruction provided below on how they can survive during winter.

Note card instructions for each species

Species A Species B Species C

Round 1 Gets green coated chocolates only

Gets green coated chocolates only

Gets yellow coated chocolates only

Round 2 Gets green coated chocolates only

Gets yellow coated chocolates only

Gets green coated chocolates from Species A without harming it

Round 3 Gets green and yellow coated chocolates and share it with species B

Gets green and yellow coated chocolates and share it with species A

Gets blue coated chocolates only

7. At the end of each round, count the coated chocolatess collected and

complete the table below.

Round

Number of coated chocolates

Species A Species B Species C

Round 1

Round 2

Round 3


Guide Questions: 1. In round one, species A and B competes in getting green coated chocolates.

What do you think is the disadvantage of this interaction? 2. In reference to question 1, do you think species A and B can live in one place

together for a long period of time? If no, what could happen to the other species?

3. In round two, species C is highly dependent on the coated chocolates that species A gather. What do you think will happen to species A?

4. In round three, species A and B shares common cup for collected coated chocolates. Could they harm each other? What’s their effect on species C?

Learn about It

Ecosystem An ecosystem is consist of biotic or living components and abiotic or nonliving components. Biotic components are made up of species that live in the same habitat, while abiotic components include environmental materials and conditions. Ecosystems can be dissected into two parts: one, it has interdependent collections of living organisms structured as communities governed by general rules and two, it requires cycling of energy and matter. The abiotic components include climatic conditions that refer to atmospheric conditions persistent over a long period of time and edaphic factors that describe terrestrial and aquatic conditions in the environment. Biotic factors include the producers, consumers and decomposers that represents all form of living organisms on Earth. The ecosystems include the different interactions that happen among organisms and the interaction between these two components. Moreover, an ecosystem requires cycling of energy and matter. The energy from the sun, water, and soil minerals are important abiotic components that must be properly regulated to sustain life forms. Ecosystems are highly dynamic, where it is often subjected to periodic changes due to disturbances but must maintain equilibrium to sustain the needs of all of its components.


Fig. 19. Structure of an ecosystem.

Connections Between Living Things in an Ecosystem Living organisms in an ecosystem are connected through the food chain. It is the feeding relationship between organisms in an ecosystem. A food chain represents how energy is being transferred across a series of organisms in the form of food. Basically, higher forms of organism eat lower forms of organism until they reach the level of plants that have the capability of producing their own food.

Fig. 20. An example of a food chain.

In the food chain, producers or autotrophs that are mostly represented by plants can produce their own food through the process of photosynthesis. Organisms that are on trophic levels higher than producers called consumers (or heterotrophs) depend directly or indirectly on producers as their source of energy.


Heterotrophs are classified as primary, secondary, and tertiary consumers. This classification refers to the level of hierarchy in terms of their position in the food chain. Primary consumers directly feed on producers and include herbivores (e.g. caterpillar, cow, goat) or omnivores (e.g. humans). Secondary consumers feed on the primary consumers and includes both carnivores (e.g. snake, lion, shark) and omnivores. Even secondary consumers can be eaten, and these organisms are classified as tertiary consumers.

Fig. 21. Each stage of a food chain corresponds to a trophic level.

In an ecosystem, a simple and linear form of food chain rarely exists. A food web is an interlinked multiple food chains that happens in different types of ecosystems. Through a food web, food chains happening in terrestrial ecosystems can be connected to processes of energy transfer in marine ecosystems. Food webs exist because most consumers feed on different types of organisms which may belong to different trophic levels. It basically represents feeding relationships in the whole community, and just like the food chain, it shows the movement of food energy from the source to the next consumer. Food webs are consist of a number of food chains interconnected to one another. Involved food chains include a series of arrows that point from one species to another, representing the movement of food energy from one feeding group to another.


Fig. 22. An example of a food web in terrestrial habitat.

Interactions Between Living Organisms Each organisms interact with one another to survive in an ecosystem. This kind of interaction is called symbiosis. There are different types of symbiotic relationships. A symbiotic relationship usually involves organisms from two or more different species. Commensalism is a form of symbiotic relationship wherein an organism of a species benefits without affecting the other organism of a different species. A good example of a commensal relationship is an orchid attached to a tree trunk. The bark of the tree serves as the source of nutrient for the orchids and it does not compete for the nutrients that is supposed to be for the tree.

Fig. 23. Aerial wild orchids that attach to tree barks.


Mutualism is a symbiosis where two organisms from different species benefit from each other. It is characterized as a positive form of symbiosis. Both organisms in this relationship help each other to grow and survive in their environment. This symbiotic relationship is exhibited by the relationship between the flower and bees that pollinate it. As bees feed on flowers by gathering nectar and making food out of it, some pollen gets attached to their bodies that help flowers pollinate and reproduce.

Fig. 24. A bee collecting nectar from the flower.

Competition is an important interaction which is commonly observed in an ecosystem. Some organisms emerge on top of the competition while those who lose are left to die. Interspecific competition happens among organisms of different species while intraspecific competition happens within same species. In a forest, plants compete for sunlight and water, in order to survive. Some plants tend to be shorter compared to others that limit their competency to gather sunlight.

Fig. 25. Limited penetration of sunlight in forest floor due to tree canopies.


Predation exhibits an eat-and-be-eaten relationship. The animals which eat or hunt for another animal is called the predator. The animal which is eaten is called the prey. Animals can both be a prey and a predator depending on the situation. As the snake eats a rat, it is a predator. But as the snake is eaten by an eagle or a hawk, it is considered a prey.

Fig. 26. A flying eagle trying to look for prey.

Parasitism is an interaction where one organism of a certain species harms an organism of another species to benefit from the relationship. The organism that harms and benefits from parasitism is called a parasite. On the other hand, host is the term used to describe the organism which is harmed. This kind of interaction is often observed in the parasitic worms inside the digestive tract of mammals. The parasite compete with the nutrient from the food of the host and even create complications. Parasitism is different from predation as it is an interaction that slowly harm the host and do not immediate require killing.

Fig. 27. A liver fluke which is a common parasitic worm in mammals.


Key Points

● An ecosystem can be defined as a system that is consist of biotic or living

components and abiotic or nonliving components. ● Living organisms in an ecosystem is connected through the food chain. It is a

series of feeding relationships between organisms in an ecosystem. ● A food web is an interlinkage of multiple food chains that happens in

different types of ecosystems. ● Each organism requires interaction with one another to survive in an

ecosystem. This kind of interaction is a relationship called symbiosis. ● There are different types of symbiotic relationships. A symbiotic relationship

usually involves organisms from two or more different species. Common examples are:

○ commensalism, when one species benefits while the other species is unaffected;

○ parasitism, when one species benefits while the other species is harmed;

○ mutualism, when both species benefit; ○ predation, when one species eat the other species; and ○ competition, when two species compete for the same resources.

Web Links

To learn more about connections and interactions among living things, you can check the following web links:


● Want to know more about the organisms that live inside you? Know more about parasitism in humans by checking this link: ParasitesinHumans. 2016. ‘Parasites in Humans.’ http://www.parasitesinhumans.org/

● Is it always good being at the top of the food chain? Read this website and know that some harmful chemicals may accumulate when you are at the top:. Flanders. 2001. ‘Accumulation of chemicals in the food chain bioaccumulation and biomagnification.’ http://www.flandershealth.us/toxic-effects

● Watch some amzing ecological interactions in the planet by visiting this site: Chris Pautler. 2012. ‘Ecological Interactions.’’ Video. https://youtu.be/chHj2OhUa6A


A. Using the given figure, draw an arrow to arrange each organism on its proper place in the food chain.

B. Complete the sentence by providing the missing terms.

An (1) _______________ can be defined as a system that is consist of (2) _______________ or living components and (3) _______________ or nonliving components that includes environmental conditions that govern the existence of organisms. Living organisms in an ecosystem are connected through (4) _______________. It is the feeding relationships between organisms


http://www.parasitesinhumans.org/

http://www.parasitesinhumans.org/

http://www.flandershealth.us/toxic-effects/accumulation-of-chemicals-in-the-food-chain-bioaccumulation-and-biomagnification.html

http://www.flandershealth.us/toxic-effects/accumulation-of-chemicals-in-the-food-chain-bioaccumulation-and-biomagnification.html

https://youtu.be/chHj2OhUa6A

https://youtu.be/chHj2OhUa6A

in an ecosystem. A (5) _______________ is an interlinkage of multiple (6) _______________ that happens in different types of ecosystems. Each organisms require to interact with one another to survive in an ecosystem. This kind of interaction is a relationship called (7) _______________. There are different types of symbiotic relationships. A symbiotic relationship usually involves organisms from two or more different species.

Challenge Yourself

Briefly answer the following questions.

1. What will happen to organisms if they fail to interact with one another? 2. How do you think the process of coevolution is related to symbiosis? 3. Why is it important for organisms to compete for resources in an ecosystem? 4. In predation, what will happen to the predator if the supply of the prey

becomes depleted? 5. What is the importance of abiotic factors in an ecosystem?


Laboratory Activity

Activity 15.1 Predator - Prey Simulation

Objectives At the end of this laboratory activity, the students should be able to:

● understand how predation works in an ecosystem; ● determine the importance of both predator and prey in ecosystem; and ● identify complications of predation in population of organisms in the

community. Materials and Equipment

● masking tape ● ruler ● rabbit squares ● lynx square

The hare and the lynx icon.

Procedure

1. Plot a 12 inch x 12 inch square with the use of masking tape.


2. Begin the simulation with 3 hare icons spread out within the square plot. 3. Toss one lynx icon into the square habitat to capture the hare (i.e. land on

any portion of the hare icon) as many hares as possible. 4. The following are the rules of this activity.Rule:

○ For the lynx to survive and reproduce, it should be able to capture at least 3 hares.

○ If successful, the lynx survives and produces offspring. One offspring is produce for every 3 hares captured. Some examples are shown below.

■ If 1 lynx catches 0-2 hares, then it produces no offspring. ■ If 1 lynx catches 3-5 hares, then it produces 1 offspring. ■ If 1 lynx catches 6-8 hares, then it produces 2 offsprings.

○ For every toss of the lynx, captured hares must be removed before tossing the next lynx icon.

○ The remaining hare can reproduce one offspring every one round of tossing. The offspring hares must be placed in the habitat square with the parent before the next toss.

5. Record the number of lynx and hare for every toss generation. 6. Repeat steps 2-4 for 20 generations. 7. Complete the table below and graph the population of starting number of

lynx and hare for each generation. Data and Results Table 1. Summary of lynx and hare population in the predation simulation.

Generation Starting no. of hares

No. of hares eaten

No. of hares

survived

No. of hare

offsprings

Starting no. of lynx

no. of lynx died

No. of lynx

survived

No. of lynx offsprings

1 3 1

2

3

4

5

6

7


8

9

10

11

12

13

14

15

16

17

18

19

20

Graph of the population dynamics of the lynx and hare.


Guide Questions 1. What type of interaction does the lynx and the hare exhibit? 2. What characteristics were exhibited in this kind of relationship in the

ecosystem? 3. Describe your graph. What patterns did you notice? 4. How does the size of the hare population affect the lynx population? 5. How does the size of the lynx population affect the hare population?

Performance Task

Interactions in my Community Goal

● Your goal is too create an illustration diagram connecting the early theories on the emergence of first living cell, namely: electrical discharge, thermal synthesis, and protocell experiment.

Role

● You are a student taking Earth and Life Sciences and you are responsible for creating an illustration diagram to connect the ideas of the three experiments on the emergence of the first living cell on Earth.

Audience

● The output will be presented to the entire class and will be evaluated by your teacher.

Situation

● The video clip will be presented in class and shall be graded by the teacher. Product, Performance, and Purpose

● You are expected to provide an illustration diagram showcasing the three experiments on the emergence of first living cell on Earth.

Standards and Criteria Your performance will be graded by the following rubric.


Criteria Below Expectations, 0% to 49%

Needs Improvement

50% to 74%

Successful Performance 75% to 99%

Exemplary Performance

100%

Content. Detailed facts are presented well. Content related to the task.

Details not presented. Content is not related to the task.

Details are presented but not organized. There are some content that are not related to task.

Details are presented in an organized manner.Content are related to the task.

Details are presented in an organized matter that can be easily understood. Content are related to the task. Additional supporting details are presented.

Communication Skills. Presentation was done in a clear and logical manner.

Presentation was not done.

Presentation was done but in a disorganized and illogical manner.

Presentation was done smoothly but the concepts are presented in such a way that should be rearranged for better understanding.

Presentation was done clearly. Concepts were presented in a logical manner and easily understandable by the audience.

Self Check

This unit aims to discuss different theories regarding the origin of life on Earth. You are expected to have better understanding on the process of evolution from single cell living organisms to a more complex ones. Put a check on the space provided below if you agree on the given statements.

Check I can…

explain how does the primitive organisms emerged on Earth.

enumerate the classic experiments that model conditions which may have enabled the first forms of organisms to evolve.

discuss the unifying themes in the study of life show the connections and interactions among living things and their environment.


Key Words

Abiogenesis The process by which life emerges naturally from

inanimate or nonliving materials.

Cambrian explosion It is an event that happened at around 541 million years ago in the Cambrian period and was responsible for the emergence of most major animal phyla. This event resulted in the divergence of most modern animal and plant organisms.

Cyanobacteria It is a form of organism that obtain their energy from sunlight through photosynthesis. Cyanobacteria are prokaryotic organisms or those organisms that lack the presence of nucleus in their cells and mostly unicellular in nature.

Development This is the process of differentiation of cells to form highly specialized structures in your body.

Electrical discharge experiment

It is an experiment that recreated the primitive earth as described in Oparin-Haldane theory by simulating the formation of organic molecules in early Earth.

Ecosystem It is defined as a system that is consist of biotic or the living components and the abiotic or the nonliving components that includes environmental conditions that govern the existence of organisms.

Food chain These are feeding relationships between organisms in an ecosystem.

Food web These are interlinked multiple food chains that happen in different types of ecosystems on Earth.

Homeostasis This refers to the equilibrium state in an organism’s body.

Growth This refers to the ability of organisms to increase in size, weight, and height.


Life science This is a collection of disciplines that is made up of theories and principles that tackles the structure and function of living things starting from the molecular level up to entire ecosystems.

Metabolism This refers to the total chemical reactions in an organism that allow it to function properly.

Primordial soup theory

It is the most predominant theory about the origin of life.

Protocell experiment

It is an experiment that explains that the simplest possible living cells or protocells just required two components to be formed: a nucleic acid genome to transmit the genetic information and a lipid sac which encapsulated the genome and let itself grow and divide.

Theory of spontaneous generation

It is a theory explaining that life comes from lifeless or nonliving material through a mysterious process.

Theory of panspermia It is a theory suggesting that the building blocks of life came from another planet.

Thermal synthesis experiment

It is an experiment that demonstrated the origin of life using a specific mixture of pure, dry amino acids. After heating the mixture, his observed that an aqueous solution was formed and cooled into microscopic globules called protenoid microspheres.

Trilobites It is the dominant species during cambrian period. Trilobites are extinct form of arthropods, an animals having a hard skin shell and jointed legs.


Wrap Up

Introduction to Life Sciences

Photo Credits

Fig 3. Esperimento abiogenesiby Aushulz is licensed under CC BY-SA 3.0 via

Wikimedia Commons. Jack Szostak. Nobel Laureate Jack W. Szostak (Medicine) by US Embassy Sweden is

licensed under CC BY 2.0 via Wikimedia Commons. Fig. 17. Ginkgo biloba MN 2007 by SEWilco is licensed under CC BY-SA 3.0 via

Wikimedia Commons. Fig. 18. Acanthostega model by Dr. Günter Bechly is licensed under CC BY-SA 3.0

via Wikimedia Commons.


https://commons.wikimedia.org/wiki/File:Esperimento_abiogenesi.jpg

https://commons.wikimedia.org/wiki/User:Aushulz

https://creativecommons.org/licenses/by-sa/3.0/legalcode

http://commons.wikimedia.org/

https://commons.wikimedia.org/wiki/File:Nobel_Laureate_Jack_W._Szostak_(Medicine).jpg

https://www.flickr.com/people/45235740@N06

https://creativecommons.org/licenses/by/2.0/legalcode


https://commons.wikimedia.org/wiki/File:Ginkgo_biloba_MN_2007.JPG

https://commons.wikimedia.org/wiki/User:SEWilco



https://commons.wikimedia.org/wiki/File:Acanthostega_model.jpg

https://commons.wikimedia.org/wiki/User:Dr._G%C3%BCnter_Bechly



Fig 27. Clonorchis sinensis 2 by Banchob Sripa, Sasithorn Kaewkes, Paiboon

Sithithaworn, Eimorn Mairiang, Thewarach Laha, Michael Smout, Chawalit Pairojkul, Vajaraphongsa Bhudhisawasdi, Smarn Tesana, Bandit Thinkamrop, Jeffrey M. Bethony, Alex Loukas & Paul J. Brindley is licensed under CC BY 2.5 via Wikimedia Commons.

References

Aleksandr Ivanovich Oparin. 2003.The Origin of Life. Massachusetts: Courier Corporation.

Matthew S. Dodd, Dominic Papineau, Tor Grenne, John F. Slack, Martin Rittner,

Franco Pirajno, Jonathan O’Neil & Crispin T. S. Little. 2017. Evidence for early life in Earth’s oldest hydrothermal vent precipitates. Nature: 543, pages 60–64.

Larry L. Hench. 2001. Science, Faith, and Ethics.Singapore: World Scientific. Lisa A. Shiel. 2009. The Evolution Conspiracy, Vol 1: Exposing Life’s Inexplicable

Origins and the Cult of Darwin.Texas: Jacobsville Books. Sandra Alters. 2000.Biology: Understanding Life. Massachusetts: Jones & Bartlett

Learning. Shri Hemant Roy. 2005.Comprehensive MCQs in Biology.New Delhi: Golden Bells. Rakesh Kumar Rastogi. 2007. Concepts of Biology XII. New Delhi: Rastogi

Publications. Peter J. Russell, Paul E Hertz, and Beverly McMillan. 2016. Biology: The Dynamic

Science, Boston: Cengage Learning. Jason P. Schrum, Ting F. Zhu, and Jack W. Szostak. 2010. The Origins of Cellular Life.

Cold Spring Harbor Perspectives Biology.


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unit 15 introduction to life science

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