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2013 AP Biology EK Project
Transcript of 2013 AP Biology EK Project
Populations and Growth
Abiotic vs Biotic Factors
Abiotic factors vary in the environment and determining the types and numbers of organisms that exist in that environment.
Biotic factors are all the living things or their materials that directly or indirectly affect an organism in its environment.
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another.
Negative feedback is the diminution or counteraction of an effect by its own influence on the process giving rise to it, as when a high level of a particular hormone in the blood may inhibit further secretion of that hormone, or where the result of a certain action may inhibit further performance of that action.
Negative Feedback Mechanisms
Temperature regulation- Countercurrent heat is a method of regulating heat loss to the environment by returning heat to the core.
Insulin and Glucagon- When your body senses low blood sugar, glucagon is secreted to stimulate glycogen degradation. This will result in glycogen being broken down back into glucose and transferred back to the blood.
Dehydration and Antidiuretic Hormone-The hypothalamus sends a message to the pituitary gland which releases ADH. This travels in the blood to your kidneys so more water is reabsorbed into your blood. As a result you make a smaller volume of more concentrated urine. The level of water in your blood increases until it is back to normal.
Calcitonin and Parathyroid Hormone- When blood calcium levels rise, calcitonin is released by the thyroid gland. Calcitonin stimulates calcium deposits in bone and inhibits osteoclasts from breaking down bone. Osteoblasts are stimulated to make more bone tissue.
Global warming and Increased Cloud Cover- Low level clouds are known to have a net cooling effect — so if rising temperatures lead to more low-level clouds, this negative feedback mechanism could mitigate global warming.
A feedback in which the system responds to the perturbation in the same direction as the perturbation.
Positive Feedback Mechanisms
Lactation in mammals- The action of the baby suckling stimulates the hypothalamus, which produces oxytocin and sends it through the posterior pituitary gland, stimulating milk letdown.
Onset of labor- During childbirth, the pressure of the baby's head causes stretching of the uterus which stimulates uterine contractions, which causes further stretching, heightening the contractions and so the cycle continues until the foetus is expelled from the uterus
Ripening of fruit- When a fruit ripens, it release ethylene which is taken up by surrounding fruit. This causes the fruits to produce more ethylene, amplifying the process.
Phototropism is the growth of organisms in response to light. Most plant shoots exhibit positive phototropism, and rearrange their chloroplasts in the leaves to maximize photosynthetic energy and promote growth.
The response of an organism to changes in its photoperiod, especially as indicated by vital processes. Plants need to be able to detect the difference between one season and another in order to flower at the correct time of year.
Hibernation, Estivation, and Migration
Hibernation- A state of inactivity and metabolic depression in endotherms. The function of hibernation is to conserve energy during a period when sufficient food is unavailable.
Estivation- Prolonged torpor or dormancy of an animal during a hot or dry period. Animals are known to enter this state to avoid damage from high temperatures and the risk of desiccation.
Migration- A seasonal movement of animals from one region to another. This is often an effort to find food, a more hospitable climate or places to breed.
Factors which determine the types and numbers of organisms of a species in an ecosystem are called limiting factors.
A kind of population growth in which the growth rate is constantly decreasing with the increased number of individuals. When the population reaches its maximum, the growth rate becomes zero.
A growth in which the rate is proportional to the increasing number or size in an exponential or logarithmic progression.
Food Web vs. Food Chain
Density Dependent Factors
Human Population Growth Impact on Niches of Other Organisms
Age Distribution Graphs
A food web is many food chains linked together to show a more accurate model of the possible feeding relationships in an ecosystem.
A food chain is a hierarchy in which organisms in an ecosystem are grouped into nutritional levels are shown in a succession to represent the flow of food energy and feeding relationships between them.
A factor whose effect on the size or growth of population vary with the population density.
Food and water are examples of density dependent factors.
Humans are constantly taking over more and more land which will have a negative impact on other organisms. There is competition for limited resources that occur, and with advanced technology, usually humans will win.
The statistical data relating to the population and particular groups within it.
The quality or power of reproducing abundantly.
Also called a population pyramid, these graphs show the distribution of various age groups in a population.
Loss of Keystone Species
A keystone species can be the central supporting element that allows the ecosystem to function as we know it. The loss of them can lead to a trophic level collapse.
Tiger sharks are a great example of a keystone species. They will eat practically anything. This controls the population of sea turtles and other species who may cause overgrazing of sea grass in Western Australia. Since that grass is where many fish lay their eggs, overgrazing would lead to fewer fish.
By Katie Frock
Energy in an Ecosystem
Loss of Biodiversity
Environmental Effects on Gene Expression and Development
Shivering and Sweating
A motion or orientation of a cell, organism, or part in response to an external stimulus.
A daily cycle of biological activity based on a 24-hour period and influenced by regular variations in the environment, such as the alternation of night and day.
Shivering is a bodily function in response to early hypothermia or just feeling cold. When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis. Muscle groups around the vital organs begin to shake in small movements, creating warmth by expending energy. Shivering can also be a response to a fever, as a person may feel cold.
Sweating is an essential and natural biological process that starts soon after we are born. Sweating, or perspiring, is the body’s mechanism of keeping us cool and preventing us from overheating in a warm environment or during exercise or exertion. Our body also produces sweat when we experience strong emotions or stressful situations, during hormonal changes and it helps to play a role in fighting infections.
Populations, Communities, and Ecosystems
Quorum Sensing in Bacteria
Populations- A group of organisms of one species that interbreed and live in the same place at the same time
Communities- A group of interdependent organisms living and interacting with each other in the same habitat.
Ecosystems- A system that includes all living organisms (biotic factors) in an area as well as its physical environment (abiotic factors) functioning together as a unit.
The close association between two or more organisms of different species, often but not necessarily benefiting each member.
A symbiotic relationship between individuals in different species in which both individuals benefit from the association. Through this relationship both species enhance their survival, growth or fitness.
A form of symbiosis in which one organism (called a parasite) benefits at the expense of another organism usually of different species (called the host).
A form of symbiotic relationship between two organisms of unlike species in which one acts as predator that captures and feeds on the other organism which serves as prey.
A form of symbiosis between two organisms of different species in which one of them benefits and the other is largely unaffected.
Quorum sensing is a system of stimulus and response correlated to population density. Many bacteria use it to coordinate gene expression according to the density of their local population.
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both can be a factor.
An organism that is not native and has negative effects on our economy, our environment, or our health. Not all introduced species are invasive.
Three ways they get introduced into different ecosystems:
Natural range extentions
Exotic pet trade escape
Ships and wood products can have fish and insects
The study of the distribution of different species of organisms around the planet and the factors that influenced that distribution.
Change in Free Energy Impact on Ecosystem
Energy and Matter
Climate Change and Primary Productivity
Atmospheric Composition and Primary Productivity
Other Trophic Levels Relationship with Primary Productivity
Human Activities Impact on Ecosystems
Changes in free energy availability can result in changes in population size.
Change in the producer level can affect the number and size of other trophic levels.
Change in energy resources levels such as sunlight can affect the number and size of the trophic levels.
Matter is made up of molecules that exist in both living and nonliving objects. As these objects age or die, the molecules are broken down and will often find their way back into the Earth in the form of soil. Energy, on the other hand, originates from the sun and is transferred mostly as heat. Once this transfer occurs the energy is lost and is never capable of recycling itself.
A measure of the rate at which new organic matter is developed through photosynthesis and chemosynthesis in producer organisms based on the oxygen released and carbon taken in.
Global climate change is influenced by many factors. One of which is the primary productivity of earths ecosystems. Photosynthesis and transpiration influence the balance of Carbon and Oxygen within the atmosphere, thus regulating solar radiation reaching earth’s surface. If primary production increases, then the excess of Carbon can be stored within the plants as biomass, and release more oxygen to balance out the atmospheres primary elemental equilibrium.
The plant requires sunlight, carbon dioxide, water, and nutrients, and through photosynthesis the plant produces reduced carbon compounds and oxygen. The carbon dioxide and nutrients can come from the atmosphere.
Without autotrophs, there would be no energy available to all other organisms that lack the capability of fixing light energy. However, the continual loss of energy due to metabolic activity puts limits on how much energy is available to higher trophic levels
As energy passes from trophic level to trophic level, the following rules apply:
Only a fraction of the energy available at one trophic level is transferred to the next trophic level. The rule of thumb is 10%, but this is very approximate.
Typically the numbers and biomass of organisms decrease as one ascends the food chain.
Human activity has modified the carbon cycle by changing its component's functions and directly adding carbon to the atmosphere.The largest and most direct human influence on the carbon cycle is through direct emissions from burning fossil fuels.
Over the past several centuries, human-caused land use has led to the loss of biodiversity, which lowers ecosystems' resilience to environmental stresses and decreases their ability to remove carbon from the atmosphere. Deforestation for agricultural purposes removes forests, which hold large amounts of carbon, and replaces them, generally with agricultural or urban areas.
Genetic Diversity's Affect on a Species' Survival
Generalist and Specialist
Generalist and Specialist Response to Economic Change
Genetic diversity refers to both the vast numbers of different species as well as the diversity within a species. The greater the genetic diversity within a species, the greater that species' chances of long-term survival. This is because negative traits (such as inherited diseases) become widespread within a population when that population is left to reproduce only with its own members.
Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of the success of these individuals
A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different
resources. Example: Omnivores are usually generalists. (Raccoon)
A specialist species can only thrive in a narrow range of environmental conditions or has a limited diet. Example: A herbivore is usually a specialist. (Koala)
When environmental conditions change, generalists are able to adapt, while specialists tend to fall victim to extinction much more easily.
Mechanisms for Obtaining Nutrients and Eliminating Wastes
Homeostatic Control Systems
Failure of Homeostatic Control Systems
Cell Differentiation During Development
Transcription Factors' Aid in Gene Expression
The Effect of Abiotic Factors on Seed Germination
Effect of Genetic Mutations on Development
Organisms have various mechanisms for obtaining nutrients and eliminating wastes.
• Gas exchange in aquatic and terrestrial plants
• Digestive mechanisms in animals such as food vacuoles, gastrovascular cavities, one-way digestive systems
• Respiratory systems of aquatic and terrestrial animals
• Nitrogenous waste production and elimination in aquatic and terrestrial animals
All living organisms depend on maintaining a complex set of interacting metabolic chemical reactions. From the simplest unicellular organisms to the most complex plants and animals, internal processes operate to keep the conditions within tight limits to allow these reactions to proceed. Homeostatic processes act at the level of the cell, the tissue, and the organ, as well as for the organism as a whole.
Many diseases involve a disturbance of homeostasis.
As the organism ages, the efficiency in its control systems becomes reduced. The inefficiencies gradually result in an unstable internal environment that increases the risk of illness, and leads to the physical changes associated with aging.
The study of the processes by which an organism develops from a zygote to its full structure. This field includes the study of cellular differentiation as well as body structure development.
Cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of tissues and cell types. These changes are largely due to highly controlled modifications in gene expression.
Transcription factors are essential for the regulation of gene expression and are, as a consequence, found in all living organisms. The number of transcription factors found within an organism increases with genome size, and larger genomes tend to have more transcription factors per gene.
A developmental gene that specifies the anterior-posterior axis, as well as segment identity during the early embryonic development of certain organisms.
The influence of one cell group (inducer) over a neighboring cell group (induced) during embryogenesis.
Inside seeds, the germ layer holds dormant plant embryos. When conditions are favorable, the embryo breaks through the germ layer and sprouts, or germinates. Excessive or insufficient light, water, temperature and wind can hinder seed growth or cause seed mortality.
By changing a gene’s instructions for making a protein, a mutation can cause the protein to malfunction or to be missing entirely. When a mutation alters a protein that plays a critical role in the body, it can disrupt normal development or cause a medical condition.In s ome cases, genetic mutations are so severe that they prevent an embryo from surviving until birth. These changes occur in genes that are essential for development, and often disrupt the development of an embryo in its earliest stages. Because these mutations have very serious effects, they are incompatible with life.
MicroRNA is a cellular RNA fragment that prevents the production of a particular protein by binding to and destroying the messenger RNA that would have produced the protein.
Aptosis is the process of programmed cell death (PCD) that may occur in multicellular organisms.
In the womb, our fingers and toes are connected to one another by a sort of webbing. Apoptosis is what causes that webbing to disappear, leaving us with 10 separate digits.