Potassium argon dating advantages and disadvantages

Data are the results of an experiment, and are observable and objective rather than subjective. This article concentrates on the more specific definition. Maintaining organization and conducting life-sustaining processes require an outside source of energy, defined as the capacity to do "work." 2. Reproduction is the ability of every type of organism to give rise to another organism like itself. Bacteria, protozoans, and other unicellular organisms simply split in two (binary fission). Multicellular organisms often unite sperm and egg, each from a different individual, resulting in an immature individual which develops into the adult. The instructions for an organism's organization and development are encoded in genes. Genes are comprised of long molecules of DNA (deoxyribonucleic acid); DNA is the genetic code in all living things. Science as defined above is sometimes termed pure science to differentiate it from applied science, the application of research to human needs.1.1 How to Define Life A. Organization of living systems begins with atoms, which make up basic building blocks called elements. The cell is the basic structural and functional unit of all living things. Different cells combine to make up tissues (e.g., myocardial tissue). Tissues combine to make up an organ (e.g., the heart). Specific organs work together as a system (e.g., the heart, arteries, veins, etc.). Multicellular organisms (each an "individual" within a particular species) contain organ systems (e.g., cardiovascular, digestive, respiratory, etc.). A species in a particular area (e.g., gray squirrels in a forest) constitutes a population. Interacting populations in a particular area comprise a community. A community plus its physical environment is an ecosystem. The biosphere is comprised of regions of the Earth's crust, waters, and atmosphere inhabited by organisms. Each level of organization is more complex than the level preceding it. Each level of organization has emergent properties due to interactions between the parts making up the whole; all emergent properties follow the laws of physics and chemistry. The ultimate source of energy for nearly all life on earth is the sun; plants and certain other organisms convert solar energy into chemical energy by the process of photosynthesis. Food provides nutrient molecules used as building blocks for energy. Metabolism is all the chemical reactions that occur in a cell. All organisms must maintain a state of biological balance, or homeostasis. must be maintained within the tolerance range of the organism. Living things interact with the environment and with other living things. Response often results in movement of the organism (e.g., a plant bending toward the sun to capture solar energy, a turtle withdrawing into its shell for safety, etc.). Responses help ensure survival of the organism and allow the organism to carry out its biological activities. The collective responses of an organism constitute the behavior of the organism. Less formally, the word science often describes any systematic field of study or the knowledge gained from it. Evolution is defined as "descent with modification over time." a. The human population modifies existing ecosystems for its own purposes. Two biologically diverse ecosystems, rain forests and coral reefs, are severely threatened by the human population. Human beings depend on healthy working ecosystems for food, medicines, and raw materials. Taxonomy is the discipline of identifying and classifying organisms according to certain rules. Taxonomic classification changes as more is learned about living things, including the evolutionary relationships between species. Particular specialized studies that make use of empirical methods are often referred to as sciences as well. Adaptations are modifications that make organisms suited to their way of life. Natural selection is the process by which species become modified over time. The fact that all life forms are composed of cells, contain genes comprised of DNA, and conduct the same metabolic reactions suggests all living things have a common ancestor. One species can give rise to several species, each adapted to to a particular set of environmental conditions. Evolution is responsible for the great diversity of life on Earth.1.2 How the Biosphere is Organized A. The biosphere is the zone of air, land, and water where organisms exist. A population consists of all members of one species in a particular area. A community consists of all of the local interacting populations. An ecosystem includes all aspects of a living community and the physical environment (soil, atmosphere, etc.). Interactions between various food chains make up a food web. Ecosystems are characterized by chemical cycling and energy flow. Ecosystems stay in existence because of a constant input of solar energy and the ability of photosynthetic organisms to absorb it. Inductive reasoning allows a person to combine isolated facts into a cohesive whole. A scientist uses inductive reasoning to develop a possible explanation (a hypothesis) for a natural event; the scientist presents the hypothesis as an actual statement. Scientists only consider hypotheses that can be tested (i.e., moral and religious beliefs may not be testable by the scientific method). Testing a hypothesis involves either conducting an experiment or making further observations. Deductive reasoning involves "if, then" logic to make a prediction that the hypothesis can be supported by experimentation. An experimental design is proposed to test the hypothesis in a meaningful way. An experiment should include a control group which goes through all the steps of an experiment but lacks (or is not exposed to) the factor being tested. Scientists may use a model (a representation of an actual object) in their experiments. Results obtained from use of a model will remain a hypothesis in need of testing if it is impossible to test the actual phenomenon.

BIOLOGY NOTESFOR CIVIL SERVICER(PRELIM)-2008RAHUL DWIVEDI2084, ACES, TYPE IIIIT KANPURMOB-9452529255BIOLOGY NOTES(Rahul Dwivedi)Science (from Latin scientia - knowledge) refers to a system of acquiring knowledge – based on empiricism, experimentation, and methodological naturalism – aimed at finding out the truth.

The basic unit of knowledge is the theory, which is a hypothesis that is predictive. The domains Archaea and Bacteria are not yet categorized into kingdoms. Eukarya contains four kingdoms: Protista, Fungi, Plantae, and Animalia. Protists (kingdom Protista) range from unicellular forms to multicellular ones.

Organisms have intricate feedback and control mechanisms to maintain homeostatic balance.

Plants (kingdom Plantae) are multicellular photosynthetic organisms. Animals (kingdom Animalia) are multicellular organisms that ingest and process their food.


The term science also refers to the organized body of knowledge humans have gained by such research. Biochemical evidence suggests that there are three domains: Bacteria, Archaea, and Eukarya. The domains Bacteria and Archaea contain unicellular prokaryotes; organisms in the domain Eukarya have a membrane-bound nucleus. The prokaryotes are structurally simple but are metabolically complex. Archaea can live in water devoid of oxygen, and are able to survive harsh environmental conditions (temperatures, salinity, p H). Bacteria are variously adapted to living almost anywhere (water, soil, atmosphere, in/on the human body, etc.). Most scientists maintain that scientific investigation must adhere to the scientific method, a process for evaluating empirical knowledge under the working assumption of methodological materialism, which explains observable events in nature as a result of natural causes, rejecting supernatural notions. In natural selection, members of a species may inherit a genetic change that makes them better suited to a particular environment. These members would be more likely to produce higher numbers of surviving offspring.3. Biodiversity is the total number of species, their variable genes, and their ecosystems. Extinction is the death of a species or larger group; perhaps 400 species become extinct every day. The continued existence of the human species is dependant on the preservation of ecosystems and the biosphere.1.3 How Living Things Are Classified A. From smaller (least inclusive) categories to larger (more inclusive), the sequence of classification categories is: species, genus, family, order, class, phylum, kingdom, domain. The species within one genus share many specific characteristics and are the most closely related. Species in the same kingdom share only general characteristics with one another.



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