WEEK 2 - Q2 Earth and Life Science PDF

Week 2 2nd QUARTER Earth and Life Science At the end of the lesson the student must be able to: a. Discuss the historical development of the concept of life including theories, experiments and evidences; b. Describe the conditions on early Earth that made the origin of l...

Week 2 2nd QUARTER Earth and Life Science At the end of the lesson the student must be able to: a. Discuss the historical development of the concept of life including theories, experiments and evidences; b. Describe the conditions on early Earth that made the origin of life possible and the first life forms; and c. Discuss the unifying themes of life and how they are interconnected Many Scientists have dedicated themselves to finding out how life first appeared on Earth. All in the name of curiosity, science and discovery. Life is believed to have existed on earth for billions of years now. Scientists do not know exactly when did life begin on Earth. However, they are able to trace how life developed and evolved using some pieces of evidence. This is a difficult question to answer, largely because life itself is not a simple concept. If you try to write a definition of “life,” you will find that it is not an easy task, because of the loose manner in which the term is used. However, a phenomena called LIFE transcends a succinct one sentence/ phrase definition. It is because we recognized life by what living things do, apparently by the characteristics/ properties associated with life.  SENSITIVITY Living things are able to respond to the environment through a stimulus. Irritability is an example. Another example is a living thing‟s response to light by facing the sun and sweating as our body response to heat which is also connected to excretion.  REPRODUCTION Unicellular organisms reproduce by DNA replication and dividing equally as the new cell prepares to form two new cells while multicellular organisms often reproduce using its gametes in order to form new individuals. When there is reproduction, genes with DNA will passed from generation to generation to make sure that the offspring belong to the same species having similar characteristics.  GROWTH AND DEVELOPMENT Organisms grow and develop according to its genes that gives instruction that will direct the cellular growth and development ensure that the offspring will grow up and manifest many of the same characteristics from the parents. Mitosis and meiosis play an important role in this matter.  NUTRITION Living things take in minerals and food from the environment in order to survive and grow. It is the process of which organism obtain energy and raw materials from nutrients such as fats, carbohydrates and proteins.  RESPIRATION It is the process in which the energy from the food eaten is being released in all living cells. Organisms break down the food within their cells with a specific process to carry out the following processes.  MOVEMENT All living things move. Animals move from one place to another. Plants also move but not as usually observable than animals. Plants move in different ways in order to grow and their movement may be so slow that people cannot even recognize. A Makahiya leaf being touched is an example of movement through thigmotrophism.  EXCRETION All living things also excrete but in different ways. Excretion is the result of many chemical reactions happening in cells which they have to remove the waste products which might poison the cells. Excretion is the removal of toxic minerals in excess from the organism. There were many theories inferred by different scientists on the origin of the universe. Few of these are the Theory of Special Creation, Theory of Spontaneous Generation, Theory of Biogenesis, Theory of Biochemical Evolution, Theory of Panspermia, and Deep-sea hydrothermal vent theory. These theories may have or may have not scientific basis. Some believed that organisms were put to Earth by some divine forces (Canoy, 2016) while others say that life did not originate from Earth but from other celestial bodies. Among the scientists, the most accepted theory is that life came from lifeless matter. Alexander Ivanovich Oparin Russian March 2, 1894 – April 21, 1980 a Soviet biochemist notable for his theories about the origin of life, and for his book The Origin of Life. He also studied the biochemistry of material processing by plants and enzyme reactions in plant cells. John Scott Haldane Scottish May 2, 1860 –March 14/15 ,1936 a physiologist famous for intrepid self- experimentation which led to many important discoveries about the human body and the nature of gases. Oparin- Haldane Hypothesis This hypothesis suggested that if the primitive atmosphere was reducing (as opposed to oxygen-rich), and if there was an appropriate supply of energy, such as lightning or ultraviolet light, then a wide range of organic compounds might be synthesized. Primordial Soup Haldane coined the term 'prebiotic soup' or 'prebiotic atmosphere' that consisted of an abundance of methane, ammonia, and water. This term became a powerful symbol of the Oparin- Haldane view of the origin of life. Harold Clayton Urey American April 29, 1893 – January 5, 1981 a physical chemist played a significant role in the development of the atom bomb, but may be most prominent for his contribution to theories on the development of organic life from non-living matter. Stanley Lloyd Miller American March 7, 1930 – May 20, 2007 a chemist who made landmark experiments in the origin of life by demonstrating that a wide range of vital organic compounds can be synthesized by fairly simple chemical processes from inorganic substances. Stanley Miller and Harold Urey After a day, they observed a verified the primordial soup change of color in the solution. theory by simulating the After a week, the solution was formation of organic molecules tested, and they found out that on the early Earth. They several amino acids were confined methane, ammonia, produced. water, and hydrogen in a closed system and applied continuous electrical sparks to trigger the formation of the building blocks of life. All living things are made up of cells. Some are unicellular and some are multicellular. Unicellular organisms that are mostly known are paramecium, amoeba, bacteria, and yeast. The multicellular cells include animal cells, plant cells, and the human body and germ cells. Given what scientists know about relationships among modern species. Most assume that this common ancestor was prokaryotic, meaning it did not have a nucleus. There was a scarcity of oxygen during the early Earth‟s atmosphere so the ancestral cell must also have been anaerobic meaning capable of living without oxygen. What are the evidences to prove such statement? Cells are microscopic and cannot be seen through our naked eye and is difficult to fossilize. Furthermore, few ancient rocks that could hold early fossils still exist. Tectonic plate movements have destroyed nearly all rocks older than about 4 million years, most slightly younger rocks have been heated that destroy traces of biological material. What are the evidences to prove such statement? Structures formed by non-biological mechanisms sometimes resemble fossils. To avoid mistakes on accepting materials like genuine fossils, scientists repeatedly analyze purported (not definitely true or real) fossil finds and they often question one another‟s conclusion. What are the evidences to prove such statement? The Oldest Fossil Cells The divergence that separated the two prokaryotic domains, Bacteria and Archaea, occurred rarely in the history of life, and no fossils from before this divergence have been discovered. It has been studied that the first form of life is believed to have appeared 3.5 billion years ago. What are the evidences to prove such statement? The Oldest Fossil Cells Paleontologists are the scientists who study fossils found microscopic living cells known as microfossils in rocks that formed 3.5 billion years ago after Earth cooled and solidified using radioisotope dating (which uses radioactive materials such as the radioactive components of potassium-argon). What are the evidences to prove such statement? The Oldest Fossil Cells Paleontologists are the scientists who study fossils found microscopic living cells known as microfossils in rocks that formed 3.5 billion years ago after Earth cooled and solidified using radioisotope dating (which uses radioactive materials such as the radioactive components of potassium-argon). What are the evidences to prove such statement? The Oldest Fossil Cells The microfossils‟ filaments found in Western Australia resemble chains of modern photosynthetic bacteria and the rocks in which they occur are thought to be remains of ancient stromatolites which are mounded, layered structure that forms in shallow sunlit water when a mat of photosynthetic bacteria traps minerals and sediment. Example of microfossils of sulphur-metabolizing cells in 3.4-billion-year- old rocks of Western Australia Many types of bacteria carry out photosynthesis, but only one group, cyanobacteria, do so by an oxygen-producing pathway. The microfossils of cyanobacteria were among the easiest to recognize. The forms of these organisms were remained the same and left chemical fossils in the form of broken products from pigments. The first microfossil that showed remains of organisms with differences in structure and characteristics was seen 1.5 billion years ago on the rocks. They are bigger compared to bacteria and have internal membranes and thicker wall. These findings marked the beginning of eukaryotic organisms on Earth. The evolution of oxygen- producing photosynthesis in cyanobacteria had started on early life. About 2.5 billion years ago, oxygen released by these bacteria had begun to accumulate in Earth‟s air and creating a new, global selection pressure. Other species considered oxygen as toxic thus evolved gradually in its absence. How did multicellular organisms evolve? Multicellular organisms are believed to have evolved from unicellular eukaryotes and until now it is the concept that we believe. Single eukaryotic cells, just like unicellular algae, formed multicellular aggregates through association with another cell producing colonies. From colonial aggregates, the organisms evolved in order to form multicellular organisms through cell specialization. Organisms like protozoans, sponges, and fungi came to being. How did multicellular organisms evolve? The soft-bodied animals were the first fossilized animals which were discovered 580 million years. The continuous process of cell specialization brought the emergence of diverse plants and animals, including human beings and including the complex ones. Charles Darwin said that organisms change over time as a result of adaptation to their environment in order to survive. Rise of the Eukaryotes Nucleus is not often preserved during fossilization but other traits provide evidence that a fossilized cell was eukaryotic. These eukaryotic cells are generally larger than the prokaryotic cells. A cell wall with complex patterns, spines, or spikes probably belonged to a eukaryote. Researchers and scientists also look for biomarkers (substance that occurs only or predominantly in cells of a specific type) for each eukaryote just like the steroids found present only to eukaryotes.  Table 1. Difference between Prokaryotes and Eukaryotes Prokaryotic Cell Eukaryotic Cell „pro‟= pre, „karyon‟=nucleus „eu‟ = true , „karyon‟= nucleus Originated about 3.5 billion Originated about 1.2 billion years ago years ago Primitive forms Advanced Unicellular Multicellular Developing nucleus True nucleus present Small in size Larger in Size Non-bounded membrane Membrane-bounded  Table 2. Origin of Some Organelles Organelle Origin  Nucleus - The DNA (deoxyribonucleic acid) of the prokaryotes lies on unenclosed in the cell‟s cytoplasm while the DNA of the eukaryotes are enclosed with an endomembrane (group of members and organelles). The nucleus and endomembrane system evolve when plasma membrane of an ancestral prokaryote folded inward.  Mitochondria and - Mitochondria and chloroplasts resemble bacteria in their Chloroplast size and shape, and they replicate independently of the cell that holds them. Bacteria have their own DNA in the form of a singular chromosome and have at least two outer membranes and innermost membrane similar to bacterial plasma membrane. - Chloroplast is the site of photosynthesis.  Table 3: Functions of Other Cell Organelles Cell Function Organelles Ribosomes - Makes protein Golgi - Does the packaging and processing of Apparatus proteins Lysosomes - Contain enzymes to help break the food down Endoplasmic - Transports items around the cell Reticulum Vacuole - For water or food storage Chloroplasts - Present in plants only; uses sunlight to make food through photosynthesis Cell wall - Rigid; supports the cell One of the most important theories in biology is evolution. Ever since its formulation in the mid-1800s by two English naturalists, Charles Darwin and Alfred Russel Wallace, the theory of evolution has been supported by fossil finds, geological studies, radioactive dating of rocks, genetics, molecular biology, biochemistry, and breeding experiments. Evolution is the unifying theory that explains the origin of diverse forms of life as a result of changes in their genetic make-up. The theory of evolution states modern organisms descended, with modification, from pre- existing life-forms. In the word of biologist Theodosius Dobzhansky, “Nothing in biology makes sense, except in the light of evolution.” Why don‟t snakes have legs? Why are there dinosaur fossils but no living dinosaurs? Why are monkeys so like us, not only in appearance, but also in the structure of their genes and proteins? The answers to those questions, and thousands more, lie in the process of evolution. Evolution is so vital to our understanding and appreciations of biology that we must review its important principle before going further. https://bit.ly/MODULES_PA_MORE https://www.scribd.com/doc/317049780/Earth-and-Life-Science-Module