EALS Reviewer T - Biology Past Paper PDF

EALS REVIEWER T\_\_T **The Historical Development on the Concept of Life** Amino Acids -- Building blocks of protein Prokaryotes -- Organisms that do not have a nucleus Cyanobacteria -- The first photosynthetic organism to form Multicellular -- Formed from single eukaryotic cells, like unicellu...

EALS REVIEWER T\_\_T **The Historical Development on the Concept of Life** Amino Acids -- Building blocks of protein Prokaryotes -- Organisms that do not have a nucleus Cyanobacteria -- The first photosynthetic organism to form Multicellular -- Formed from single eukaryotic cells, like unicellular algae. Primordial Soup -- Theory stating that life started in a soup of organic molecules. **What is life?** A property of all living things Characteristics: - Movement - Reproduction - Response to Stimuli - Growth and Development - Metabolism - Regulation of Body Energy **Theories** Creationism / Divine creation Theory Primordial Soup Theory (Alexander Oparin and John Haldane) - Heterogeneous mixture of organic and inorganic compounds in the primitive ocean - Caused spontaneous synthesis of biomolecules in extreme conditions - Where life is believed to have originated - Life began in a pond or ocean as a result of the combination of chemicals from the atmosphere and some form of energy to make amino acids, which would then evolve into all species Volcanic Eruptions and Lightning - Release of water and gases like methane, ammonia, and hydrogen into the atmosphere - Formed electric sparks resulting to lightning - Generated the building blocks of proteins called amino acids Extraterrestrial origin - This hypothesis explains that life originated on another planted outside the solar system Panspermia (Svante Arrhenius 1908) - This theory presumes that the seed of life exists all over the universe and can be propagated through space, and that life on earth originated from those seeds - Life came from other planets - Evidenced by Deinococcus radiodurans: - Highly resistant to radiation - Can prote4ct itself while entering Earth's atmosphere Origin from nonliving matter - Scientists believe that life arose on Earth from inanimate matter from Earth had cooled. - Random events probably produced stable molecules that could self replicated - Natural selection favored changes in the rate of reproduction, which eventually led to the first cell. **Experiments that modeled conditions which may have enabled the first life forms to evolve** Electrical Discharge Experiment (Stanley Miller and Harold Urey) - simulated the formation or organic molecules on the early earth. They confined methane, ammonia, water, and hydrogen in a closed system and applied continuous electrical sparks to trigger the formation of the building blocks of life. - Observed a change of color in the solution, after a day. In a week, the solution was tested and they found several amino acids were produced Thermal Synthesis (Sidney Fox) - Demonstrated in his experiment the origin of life using specific mixture of pure, dry, amino acids. In his experiment after heating themixture, an aqueous solution was formed and cooled into microscopic globules called protenoid microspheres. - Globules looked like coccoid bacteria and seemed to be budding, which is a form of reproduction in some microorganisms. - He claimed that the protenoid microspheres constituted protocells -- almost true cells, and multiplied through division like true cells. He believed that these cells were the link between the primordial environment and the true living cells. Protocell Experiment (Jack 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 **Early Forms of Life** Prokaryotes - are known to be the earliest forms of life. They have survived the extreme conditions of the early environment. They started to make their own food by utilizing the energy from the sun and carbon dioxide in the atmosphere. Cyanobacteria - are the first photosynthetic organisms to form. Their microfossils are among the easiest to recognize. Their morphology remained the same and they left chemical fossils The first microfossil that showed remains of organisms with differences in structure from the simple form of life was seen in rocks about 1.4 billion years old. They are larger than bacteria and have internal membranes and thicker wall. These findings marked the beginning of the eukaryotic organism on Earth Multicellular organisms - are believed to have evolved from unicellular eukaryotes. Some single eukaryotic cells, like unicellular algae formed multicellular aggregates through association with another cell producing colonies. - From colonial aggregates, the organisms evolved to form multicellular organisms through cell specialization. Protozoans, sponges and fungi came to being Dickinsonia - The first fossilized animals which were discovered 580 million years ago were soft-bodied. The continuous process of cell specialization brought the emergence of complex and diverse plants and animals including human beings Evidence from fossil layers proved that different forms of life were present and has evolved through time. According to Charles Darwin, organisms change over time as a result of adaptation to their environment in order to survive. **Unifying Themes of Life** Biology -- The scientific study of all forms of life DNA (deoxyribonucleic acid) -- carries the instruction for growth and development Evolution -- The change of living things over time Ecosystem -- A physical environment with different species that interact with one another and with nonliving things Adaptation -- An inherited trait that gives an advantage to individual organisms and is passed on to future generations System -- An organized group of related parts that interact to form a whole Cell -- the basic unit of life Organism -- any individual living thing Metabolism -- All the chemical processes that build up or break down materials Biodiversity -- The variety of life What are the characteristics that living organisms share? - Biological Organization Levels of Biological Organization Cellular basis of life - All organisms are made of cells. - Cells are an organism's basic units of structure and function Form and Function - The relationship between structure and function is apparent in the entire organism and the physiological systems that serve them - The structure determines function, function reflects structure - How something works is related to its structure Thumb -- opposable digit  Reproduction and Inheritance - the biological process by which new individual organisms (offspring) are produced from their "parents" - can be sexual or asexual - Organisms reproduce their own kind - Each cell contains copy of ALL DNA in your genome - Inherited info in the form of DNA enables organisms to reproduce their own kind Interaction with the Environment Each organism interacts continuously with its environment - Transfer of chemicals between organisms and the environments - React to environmental stimuli - There is a constant sensing and responding to changes in the environment Energy and Life - Moving, growing, reproducing and other activities of life require energy 28 - Energy is obtained from chemical reactions -- Sugars, fats and other "fuellike" molecules in the food produce energy - Energy enters the ecosystem as sunlight. - Plants are producers that convert light energy to chemical energy stored in food. - Animals and other consumers obtain their energy in chemical form by eating - Energy exist in the ecosystem as heat, which all organisms generate as they perform work - Energy is needed in chemical form ▫ Carbohydrates, lipids, etc. Regulation/Homeostasis - ability of the body or a cell to seek and maintain a condition of equilibrium or stability within its internal environment when dealing with external changes - Homeostasis= regulation of internal conditions - A state of balance among all the body systems needed for the body to survive and function correctly. Adaptation - An adaptation is an inherited trait that helps the organism\'s ability to survive and reproduce in its particular environment. Adaptation = an inherited trait that helps an organism's ability to survive and reproduce Population = localized group of organisms of the same species Evolution Natural selection = individuals with beneficial variations may live longer and produce more offspring than those that don't Evolution = generation-to-generation change in the proportion of different inherited genes in a population - Explains changes in organisms over long periods of time - Adaptation allows life forms to acquire new characteristics in response to their environment through the process of natural selection For example, in the beetle example, genes for dark color are becoming more common and genes for light color are becoming less common over the generations of beetles. The beetle population is said to be undergoing evolution, or evolving. Biology and Society - More than ever before, modern biology is changing humans\' everyday lives. - New findings about DNA affect such fields as medicine and agriculture. Research on the nervous system is improving the treatment of certain mental illnesses. The study of evolution is helping health professionals understand how disease-causing bacteria become resistant to antibiotic drugs. Environmental issues such as water and air pollution are changing how people think about their relationship to the biosphere What is the highest level of the biological system? Biosphere Form fits function, true or false? True What is the basic unit of life? Cell The normal human body temperature? 37°C What unifying theme states that a system consist of related parts that interact with each other to form a whole? Biological Organization/System What type of adaptation is being shown by the chameleon? Camouflage Change of living things over time? Evolution Environment with the interaction of living things and on living things? Ecosystem