Especialidades JA/Ecología - Avanzado/Respuestas

Ecología - Avanzado
Asociación General Estudio de la naturaleza	Destreza: 3 Año de introducción: 1972

Requisitos

1. Tener la especialidad de Ecología.

Para consejos e instrucciones, véase Ecología.

1

Tener la especialidad de Ecología.

Para consejos e instrucciones, véase Ecología.

2

Decir la primera y segunda ley de la termodinámica y explicar la forma en que son importantes para la ecología.

Primera ley

«En cualquier proceso, la energía total del universo permanece constante.»

Más sencillamente, la Primera Ley establece que la energía no puede ser creada o destruida; más bien, la cantidad de energía perdida en un proceso de estado estacionario no puede ser mayor que la cantidad de energía ganada.

Esta es la declaración de conservación de energía para un sistema termodinámico. Se refiere a las dos formas en que un sistema cerrado transfiere energía hacia y desde su entorno - por el proceso de calentamiento (o enfriamiento) y el proceso de trabajo mecánico. La tasa de ganancia o pérdida en la energía almacenada de un sistema está determinada por las tasas de estos dos procesos. En los sistemas abiertos, el flujo de la materia es otro mecanismo de transferencia de energía y los términos adicionales deben ser incluidos en la expresión de la primera ley.

En un sentido ecológico, la primera ley muestra que la energía de una criatura debe venir de «alguna parte» y debe «irse» a otra parte también. Los productores primarios transfieren la energía del sol a los consumidores primarios y a los consumidores secundarios en la parte superior de la cadena alimentaria. A lo largo del camino, parte de la energía se disipa en forma de calor.

Segunda ley

«La entropía de un sistema aislado que no esté en equilibrio tenderá a aumentar con el tiempo, acercándose a un valor máximo en equilibrio.»

Se puede considerar la entropía como una medida del caos o del desorden. Un alto nivel de entropía significa un alto nivel de desorden. Un bajo nivel de entropía significa un alto nivel de orden. Así, por ejemplo, un vaso roto tiene menos orden y más caos que uno intacto. Del mismo modo, los cristales sólidos, la forma más organizada de la materia, tienen valores de entropía muy bajos; y los gases, que están altamente desorganizados, tienen altos valores de entropía. Más al punto, un árbol es una unidad biológica altamente organizada, pero cuando se quema, la mayor parte de su energía se transforma en calor, que es altamente desorganizado.

La segunda ley establece que el desorden de un sistema aislado aumenta o que el orden en ese sistema disminuye. Se vuelve más caótico con el tiempo. La ciencia de la termodinámica se ocupa de la transferencia de energía. La segunda ley dicta que cuando la energía se transfiere de un estado a otro, la entropía del universo debe aumentar. Un buen ejemplo sería cuando un animal de sangre caliente emite calor. La energía comienza en una forma altamente organizada dentro del animal. A medida que el animal metaboliza su energía alimentaria y forma calor, el calor irradia desde el animal en una forma altamente desorganizada.

Cada vez que la energía se transfiere de un organismo a otro, parte de esa energía se pierde, sobre todo en forma de calor. De hecho, sólo un 10% de la energía de un organismo a un nivel trófico bajo puede transferirse a un organismo al siguiente nivel trófico. Debido a esta ineficiencia, los niveles tróficos «siempre» aparecen como pirámides, con los productores primarios formando la base, y los consumidores secundarios y terciarios formando el ápice.

3

Explicar los tres niveles tróficos básicos (de alimentación) y dar un buen ejemplo de una planta o un animal para cada una de ellos.

Los tres niveles tróficos básicos son «productores primarios», «consumidores» y «descomponedores».

En los ecosistemas terrestres, las plantas, como la hierba, son los productores primarios y forman el primer nivel trófico (productores primarios). A continuación están los herbívoros (consumidores) que comen la hierba, como conejos. A continuación están los carnívoros (consumidores secundarios) que comen los conejos, como los linces. Los descomponedores son aquellos seres vivos que obtienen la materia y la energía de los restos de otros seres vivos, como los hongos.

Keep in mind that trophic relationships are rarely this simple. Very often they are more of a "web" than a "chain." For example, mountain lions may eat both rabbits and bobcats. The trophic categorization of the mountain lion exists on two levels, possibly more.

4

Explicar o diagramar las tres tipos de pirámides ecológicas en la cadena alimenticia. Dar un ejemplo de cada una de los niveles de la pirámide.

For more information see http://www.botany.uwc.ac.za/sci_ed/grade10/ecology/trophics/troph.htm

Number Pyramid

A number pyramid attempts to illustrate trophic relationships by showing the number of organisms at each trophic level. The number of grass plants will always be higher than the number of zebras, which will be higher than the number of lions. Number pyramids tend to overemphasize the importance of the lower levels because it does not take into account the size of the organisms, only the count.

Number pyramids quantify each level using organisms per square meter.

Biomass Pyramid

A biomass pyramid illustrates trophic relationships by showing the amount of biological mass (excluding water) at each tropic level. This is an improvement over the number pyramid, but it still tends to overemphasize the importance of the lower levels because it does not account for the productivity of each level. In the ocean, algae forms the base of the food pyramid. And though algae is short lived, it reproduces very quickly. This causes it to have a biomass that is actually less than the biomass of the zooplankton, the next higher trophic level. Zooplankton lives much longer than algae, and it has a slower rate of reproduction.

Biomass pyramids often quantify each level using grams per square meter.

Energy Pyramid

An energy pyramid illustrates trophic relationships by showing the amount of energy available at each trophic level. Because not all energy is transferred up the pyramid, it also shows the efficiency of each level.

Energy pyramids often quantify each level using calories per square meter.

5

Definir el ciclo bio-geoquímico y explicar o diagramar todos lo componentes básicos por los cuales pasa el ciclo.

In ecology and Earth science, a biogeochemical cycle is a circuit or pathway by which a chemical element or molecule moves through both biotic ("bio-") and abiotic ("geo-") compartments of an ecosystem. In effect, the element is recycled, although in some such cycles there may be places (called "sinks") where the element is accumulated or held for a long period of time.

All chemical elements occurring in organisms are part of biogeochemical cycles. In addition to being a part of living organisms, these chemical elements also cycle through abiotic factors of ecosystems such as water (hydrosphere), land (lithosphere), and the air (atmosphere); the living factors of the planet can be referred to collectively as the biosphere. All the chemicals, nutrients, or elements — such as carbon, nitrogen, oxygen, phosphorus — used in ecosystems by living organisms operate on a closed system, which refers to the fact that these chemicals are recycled instead of being lost and replenished constantly such as in an open system. The energy of an ecosystem occurs on an open system; the sun constantly gives the planet energy in the form of light while it is eventually used and lost in the form of heat throughout the trophic levels of a food web.

The Earth does not constantly receive more chemicals as it receives light; it has only those from which it formed, and the only way to obtain more chemicals or nutrients is from occasional meteorites from outer space. Because chemicals operate on a closed system and cannot be lost and replenished like energy can, these chemicals must be recycled throughout all of Earth’s processes that use those chemicals or elements. These cycles include both the living biosphere, and the nonliving lithosphere, atmosphere, and hydrosphere. The term "biogeochemical" takes its prefixes from these cycles: Bio refers to the biosphere. Geo refers collectively to the lithosphere, atmosphere, and hydrosphere. Chemical, of course, refers to the chemicals that go through the cycle.

The chemicals are sometimes held for long periods of time in one place. This place is called a reservoir, which, for example, includes such things as coal deposits that are storing carbon for a long period of time. When chemicals are held for only short periods of time, they are being held in exchange pools. Generally, reservoirs are abiotic factors while exchange pools are biotic factors. Examples of exchange pools include plants and animals, which temporarily use carbon in their systems and release it back into the air or surrounding medium. Carbon is held for a relatively short time in plants and animals when compared to coal deposits. The amount of time that a chemical is held in one place is called its residence.

The most well-known and important biogeochemical cycles, for example, include the carbon cycle, the nitrogen cycle, the oxygen cycle, the phosphorus cycle, and the water cycle.

Biogeochemical cycles always involve equilibrium states: a balance in the cycling of the element between compartments. However, overall balance may involve compartments distributed on a global scale.

Biogeochemical cycles of particular interest in ecology are:

• nitrogen cycle
• oxygen cycle
• carbon cycle
• phosphorus cycle
• sulfur cycle
• water cycle
• hydrogen cycle
• nutrient cycle

Nitrogen cycle

Schematic representation of the flow of nitrogen through the environment.

The nitrogen cycle is a much more complicated biogeochemical cycle but also cycles through living parts and nonliving parts including the water, land, and air. Nitrogen is a very important element in that it is part of both proteins, present in the composition of the amino acids that make up proteins, as well as nucleic acids such as DNA and RNA, present in nitrogenous bases. The largest reservoir of nitrogen is the atmosphere, in which about 78% of nitrogen is contained as nitrogen gas (N₂). Nitrogen gas is “fixed,” in a process called nitrogen fixation. Nitrogen fixation combines nitrogen with oxygen to create nitrates (NO₃).

Nitrates can then be used by plants or animals (which eat plants or eat animals that have eaten plants). Nitrogen can be fixed either by lightning, industrial methods (such as for fertilizer), in free nitrogen-fixing bacteria in the soil, as well as in nitrogen-fixing bacteria present in roots of legumes (such as rhizobium). Nitrogen-fixing bacteria use certain enzymes that are capable of fixing nitrogen gas into nitrates and include free bacteria in soil, symbiotic bacteria in legumes, and also cyanobacteria, or blue-green algae, in water.

After being used by plants and animals, nitrogen is then disposed of in decay and wastes. Detritivores and decomposers decompose the detritus from plants and animals, nitrogen is changed into ammonia, or nitrogen with 3 hydrogen atoms (NH₃). Ammonia is toxic and cannot be used by plants or animals, but nitrite bacteria present in the soil can take ammonia and turn it into nitrite, nitrogen with two oxygen atoms (NO₂). Although nitrite is also unusable by most plants and animals, nitrate bacteria changes nitrites back into nitrates, usable by plants and animals. Some nitrates are also converted back into nitrogen gas through the process of denitrification, which is the opposite of nitrogen-fixing, also called nitrification. Certain denitrifying bacteria are NOT responsible for this.

6

Diagramar o explicar los pasos básicos en el flujo de energía a través del entorno biótico (elemento) de un ecosistema. Comenar con el sol.

Energy and matter flows through an ecosystem (adapted from the Silver Springs model; Odum 1971). H are herbivores, C are carnivores, TC are top carnivores, and D are decomposers. Squares represent biotic pools and ovals are fluxes or energy or nutrients from the system.

7

Explicar la Ley de Liebig de la capacidad mínima y la Ley de la tolerancia de Shelford, e indicar cómo estas leyes nos dicen cómo y por qué ciertas plantas y animales están en peligro de extinción o son eliminados cuando su hábitat o comunidad son interrumpidos o quedan fuera de su balance.

Liebig's Law of The Minimum

Liebig's Law of the Minimum, often simply called Liebig's Law or the Law of the Minimum, is a principle developed in agricultural science by Carl Sprengel (1828) and later popularized by Justus von Liebig. It states that growth is controlled not by the total of resources available, but by the scarcest resource. This concept was originally applied to plant or crop growth, where it was found that increasing the amount of plentiful nutrients did not increase plant growth. Only by increasing the amount of the limiting nutrient (the one most scarce in relation to "need") was the growth of a plant or crop improved.

Liebig used the image of a barrel—now called Liebig's barrel—to explain his law. Just as the capacity of a barrel with staves of unequal length is limited by the shortest stave, so a plant's growth is limited by the nutrient in shortest supply.

Liebig's Law has been extended to biological populations (and is commonly used in ecosystem models). For example, the growth of an organism such as a plant may be dependent on a number of different factors, such as sunlight or mineral nutrients (e.g. nitrate or phosphate). The availability of these may vary, such that at any given time one is more limiting than the others. Liebig's Law states that growth only occurs at the rate permitted by the most limiting.

Shelford's Law of Tolerance

Shelford's Law of Tolerance states that a species' distribution is controlled by the environmental factors for which it has the narrowest tolerance. This law explains why a species is present in some areas, but absent in others. Remember that tolerance has both a lower limit and an upper limit - not enough or too much of a resource will limit a species' ability to survive. When any one of these factors exceeds the tolerance, the species will die out. Small - and even major - alterations to a creatures environment may or may not cause it to die. Survival depends on that creature's tolerance to the altered factor.

8

Escoger una comunidad biológica en su área, como un bosque o selva; un pantano, lago o estanque; pastos o praderas de pastizales; un cañón o un bosque maderero, etc., que está perturbado o ecológicamente fuera de equilibrio de alguna manera. Hacer una descripción del mismo, incluyendo cómo y en qué medida es perturbado. A continuación, hacer recomendaciones en cuanto a la forma en que la comunidad puede mejorar y cuando sea posible, dar seguimiento y contribuir a mejorar a la comunidadbiológica de alguna forma.

This requirement and requirement 5 of the Environmental Conservation honor can both be met with the same activity. Any Pathfinder interested in Ecology should also find an interest in Environmental Conservation, so it would be advantageous to work on both the honors at the same time. Also, both these honors (and Ecology, which is a prerequisite to this honor) count towards the Conservation Master Award, so there is added impetus to earn all three.

9

Dedicar un mínimo de 20 horas haciendo trabajo activo y productivo en un proyecto de ecología en su área. Esto puede hacerse individualmente o como grupo. Describir el proyecto en general, pero informar específicamente su parte en él.

This project could be the one identified in the previous requirement, or it could be a different project all together. The report may be written or oral, or it may be a presentation made to a group of Pathfinders during a campout, a Sabbath School class, or even to the church body on Sabbath morning.

10

Definir los siguientes términos:

10a

Comunidad

In ecology, a community is an assemblage of populations of different species, interacting with one another.

10b

Las materias primas

Raw materials are the materials an organism needs but cannot manufacture on its own. They must found in the organism's environment.

10c

La fotosíntesis

Photosynthesis is the conversion of light energy into chemical energy by living organisms. The raw materials are carbon dioxide and water, the energy source is sunlight, and the end-products include glucose and oxygen. It is arguably the most important biochemical pathway, since nearly all life depends on it.

10d

Quimio-síntesis

Chemosynthesis is the biological conversion of one or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e.g. hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight, as in photosynthesis. Large populations of animals can be supported by chemosynthetic primary production at hydrothermal vents, methane clathrates, cold seeps, and whale falls.

10e

Autótrofos

Autotrophy (from the Greek autos = self and trophe = nutrition) is the production of complex organic compounds from simple inorganic molecules and an external source of energy, such as light or chemical reactions of inorganic compounds. Autotrophs are considered producers in a food chain. Plants and other organisms that carry out photosynthesis are phototrophs (or photoautotrophs). Bacteria that utilize the oxidation of inorganic compounds such as hydrogen sulfide, ammonium or ferrous iron as an energy source are chemoautotrophs (some are known as lithotrophs).

10f

Heterótrofos

Heterotrophy (Greek heterone = (an)other and trophe = nutrition) is the use by an organism of organic substrates to get its carbon for growth and development. A heterotroph is known as a consumer in the food chain. Contrast with autotrophs which use inorganic carbon dioxide or bicarbonate as sole carbon source. All animals are heterotrophic, as are fungi and many bacteria.

10g

Equilibrio ecológico

An ecosystem is in ecological balance if all its biogeochemical cycles are able to complete their circuits.

10h

Saprofito

A saprobe (or saprotroph) is an organism that obtains its nutrients from non-living organic matter, usually dead and decaying plant or animal matter, by absorbing soluble organic compounds. Since saprotrophs cannot make food for themselves, they are considered a type of heterotroph. They include many fungi (the rest being parasitic, commensal or mutualistic symbionts), bacteria, and protozoa. Animal scavengers, such as dung beetles, vultures, and a few unusual non-photosynthetic plants are also sometimes referred to as saprotrophs, but are more commonly called saprophages.

10i

Descompositor

Decomposers and detritivores utilize energy from wastes or dead organisms, and so complete the cycle by returning nutrients to the soil or water, and carbon dioxide to the air and water.

10j

Productor

Producers (autotrophs) utilize energy from the sun and nutrients from the abiotic environment (carbon dioxide from the air or water, other nutrients from the soil or water) to perform photosynthesis and grow. Producers are generally green plants (those with chlorophyll).

10k

Consumidor

Consumers (heterotrophs) are organisms that feed on other organisms.

10l

Factor limitante

In biology, agricultural science, physiology, and ecology, a limiting factor is one that controls a process, such as organism growth or species population size or distribution. The availability of food, predation pressure, or availability of shelter are examples of factors that could be limiting for a species population in a specific area.

11

Encontrar una cita del Espíritu de Profecía y un texto bíblico referente a la ecología y esplicar su relevancia y aplicación en nuestros días.

This requirement repeats Requirement 9 of the Ecology Honor. The following is the example provided in the Ecology Honor. We suggest looking for additional quotes yourself. Adventist Youth Honors Answer Book/Ecology quotations