Ecology Exam 1

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1. Explain the differences between the levels of ecology and provide one example of each type: individual, population, interactions, community, ecosystem, and biosphere.

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An individual is a specific organism.

A population is a group of individuals of the same species that live within the same area.

Interactions are the communications or actions that occur between two organisms or objects.

A community consists of a group of many different organisms living and interacting with one another in a particular environment.

An ecosystem is when organisms interact with the environment in the context of the ecosystem. It has two types of aspects; they are the living (organisms) which are considered biotic and the nonliving (the physical and chemical parts within the environment).

The biosphere is the thin layer of the Earth that supports life. It includes all the ecosystems on land and in water.

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2. What are the levels of ecology? Give an example of when the “flow” of these levels does not apply.

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The simplest level starts off with the individual organism that is living with other individuals in a population of individuals who are of the same species. The interactions between a number of populations and the environment together make up an ecosystem. All the ecosystems on Earth combined make up the biosphere.
The flow of these levels does not always apply because the order varies from case to case.

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3. What are the main elements of climate? How does climate and geography interact to produce abundance and distribution patterns of organisms in the Biosphere?

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The main elements of climate are temperature, water, humidity, precipitation, wind, cloudiness, and other atmospheric conditions.

Climate and geography interact to produce abundance and distribution patterns of organisms in the biosphere by solar radiation, air masses, pressure systems, ocean currents and differences in the Earth’s surface.

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4. Why are mountains so diverse? Why is there a west-east gradient in climate, and therefore biomes?

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Mountains are created by different characteristics. Different features like precipitation levels, and how much moisture there is.

The rain shadow effect is one example. Since the windward of the mountain range receives all the moisture from the precipitation, its ability to support organisms’ lives is different from the leeward side which creates another habitat for organisms. The wind tunnel is also an example that shows how different scenarios emerge from mountains’ diversity.

There is a west-east gradient in climate because of factors like precipitation.

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5. How is the intertidal ecosystem similar to deserts? In what ways do they differ? Be sure to discuss both the physical conditions and adaptations organisms possess to live in each ecosystem?

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The intertidal ecosystem is similar to deserts because both lack fresh water, and are harsh environments.

In an intertidal ecosystem organisms must put up with high waves(having to stick to a substrate to be kept from getting washed away) and changing of the tides, while in the desert organisms must have some way of retaining water(kangaroo rats), dealing with drought(plants have to use methods to fight against water loss) and handling hits from high winds.

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6. How are kelp forests similar to tropical rainforests? In what ways do they differ? Be sure to discuss both the physical conditions and adaptations organisms possess to live in each ecosystem.

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Kelp forests are similar to tropical rainforests because they are affected by light levels, are located around the same latitude degrees and are structured with different canopy levels.

Kelp forests are in an aquatic setting, and are affected by tide levels and being washed in and out by high waves. Organisms that live in the levels which are highly affected by tide changes have to make sure to hang onto a substrate to avoid getting washed away.

Rainforests are in a terrestrial setting and get heavy rainfall and usually go through warm humid weather. In rainforests, floor leveled plants have to adapt to having bigger darker leaves which can then absorb enough light for energy production. These same plants have to worry about being washed out with the rainfall and flooding too.

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7. Describe the water cycle, including definitions of the terms precipitation, evapotranspiration, evaporation, sublimation, infiltration, interception.

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Precipitation is occurs when water vapor in the atmosphere eventually falls down as rain.

Evapotranspiration is the total amount of evaporated water, coming from the ground and vegetation.

Evaporation occurs when liquid water vaporizes and is returned to the atmostsphere.

Sublimation occurs when snow directly changes into water vapor in the air without melting first.

Infiltration is precipitation that has reached the ground and has soaked into the ground.

Interception occurs when some of the precipitation lands on vegetation, dead organic matter, or on the ground.

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8. Explain how the various properties of water are important to life (beyond the fact that water is the major component of our cells).

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A. Cohesion, hydrogen bonds holding water molecules together, and adhesion, the clinging of one substance to another, help plants to receive water from their roots.
Water is also a good solvent and a vital part of many metabolic processes within the body. In addition, the ability of water to dissolve oxygen is absolutely vital for all aquatic animals.
It also affects climates and helps creating many different biomes.
Water is also important in the process of neutralizing acids and bases as well as in photosynthesis and respiration of plants.

B. High heat capacity these properties allow water to moderate Earth's climate by buffering large fluctuations in temperature.
Forms hydrogen bonds – relates to heat capacity
Adhesive cohesive – makes water stick together and also polar
Ice liquid gas – if ice sinks life would die but since ice floats due to density it allows life to live under water in cold places by forming a protective layer. Liquid form is use to maintain life (go into detail). Gas form moves

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9. Explain how columns of water move up through the roots, xylem and leaves. What effect does changing the thickness of the leaf boundary layer have on water loss? What adaptation can influence the boundary layer to benefit the plant? What type of root structure might be found in plants growing in low nutrient soils that rely primarily on precipitation for water?

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Evaporation from leaves pulls water upward from the roots thru water-conducting cells. Cohesion and adhesion properties of water contribute to this transportation by helping countering the downward pull of gravity.

The boundary layer once increases in thickness; it will reduce the transfer of water between the leaves and the atmosphere.
Plants growing in low nutrient soils would increase root production in order to maximize the nutrient uptake from the soil.

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10. Why are most plants on Earth C3 plants? Explain the difference between a C3 and CAM plant in terms of the photosynthetic process. If a plant is a facultative CAM plant, in what conditions would it undergo C3 photosynthesis rather than CAM?

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C3 plants make the most energy but they also use the most water. Since water is fairly abundant on earth plants want to get the most energy for their water intake.

Both C3 photosynthesis and CAM photosynthesis take place in the same part of the leaf.

The difference is that CAM plants only open their stomata at night to take up CO2 and stores it for the day to make sugar out of it but, C3 plants leave their stomata open during photosynthesis and everything takes place at the same time.

CAM plants can save water this way, but it costs more energy.

If the plant is a facultative CAM plant, meaning it can be either CAM or C3 plant, then it would much rather use C3 photosynthesis because more energy is made but it will only be able to when there is water around.

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11. Why does light saturation occur in plants? Explain why shade adapted plants have a higher Specific Leaf Area than shade intolerant plants. Plant A is a shade intolerant species and Plant B is a shade tolerant species. On the graph, label the light compensation point and light saturation point for each species. Explain why the light compensation point is lower for plant B than plant A.

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Because plants have a limit on how much photosynthesis they can perform. Shade plants have higher SLA because it maximizes the light use for photosynthesis. Shade intolerant has lower SLA because they are in direct sunlight therefore were adapted to not needing bigger leaves, or more chlorophyll cells.

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12. Compare an ectothermic animal to an endothermic animal in terms of thermoregulation. What limitations does each type have and what benefits does each type have?

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Ectotherms are organisms that allow their body temperature to practically match the environmental temperature. Ectotherms do not create enough heat to affect body temperature, therefore they have low metabolic rates (which leads to low heat production). Ectotherms adjust their body temperature according to behavior (using the environmental temperature to their advantage or disadvantage).

Endotherms use negative feedback control to control their temperature. The components of a negative feedback system are the sensor (cells in the brain, skin and body core) which measures the temperature, the comparator (controller/hypothalamus) which compares the actual value compared to the desired setpoint, and an effector (producting heat or cooling mechanisms like shivering or sweating) responds to signals from the controller and changes the intensity of the parameter.

Ectoderms need less food overall, but do not have the endurance that endotherms have.

Ectoderms may not have the ability to regulate their body temper

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13. Explain the differences in gas exchange in birds compared to mammals. Which one is more efficient in gas exchange and why must this be so?

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Both birds and mammals have lungs.
In addition, birds have accessory air sacs to keep air flowing thru the lungs as they inhale of exhale. Air flows one way only, forming a continuous circuit thru the interconnected system regardless of whether the bird is inhaling or exhaling.
Birds’ gas exchange method is more efficient since they always have air flows anytime. This is crucial for them since flying needs more oxygen.

Birds have two chambers to get the most oxygen. The first breath goes into one chamber. On the second breath the remaining air goes into another chamber where the rest of O2 is absorbed. Only then is the breath released. Birds need to be able to get a lot of oxygen because it flies in altitudes with low oxygen. Mammals just have one chamber to breath the air is only used once before its released.

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14. Explain the difference in gas exchange in fish compared to mammals. Why is there a difference?

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Fishes do gas exchange in water using their gills. Mammals do gas exchange in the atmosphere to obtain oxygen using their lungs. Fish gills are a countercurrent exchange system. The water flow goes in one direction and blood goes in the opposite direction. This maximizes the amount of oxygen the fishes gain from the water.

There is a difference because the oxygen levels in water are lower than in the air and water is a liquid and air is gas. Therefore, fishes need a different method of getting oxygen than mammals.

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15. Provide an example of an organism in a natural population showing an adaptation for a particular environment, and discuss how that adaptation may shower higher or lower fitness in a new environment. Why is it that only populations, and not individuals, evolve?

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Cactus adapt to the desert by having smaller leaves, grow compactly and close to the ground, and a non-porous covering on their leaves such as wax. Hair on the leaves on the plant helps to reduce the evaporation of moisture from the surface of leaves by reflecting sunlight and inhibiting air movement. If a cactus is moved to a wet environment it would have lower fitness because it would probability die or not grow well because it’s not adapted for wet environments.

Individual organisms don't evolve. Populations evolve. Because individuals in a population vary, some in the population are better able to survive and reproduce given a particular set of environmental conditions. These individuals generally survive and produce more offspring, thus passing their advantageous traits on to the next generation. So over time, the population changes.

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16. What are the 5 main assumptions of the Hardy-Weinberg Equilibrium? Be able to use the equation to determine if evolution has occurred for a trait (BRING A CALCULATOR).

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The main five assumptions of the Hardy Weinberg Equilibrium equation are that there are no mutations within the population, there is random mating(equal chances of mating), there is a large population (in which there is no genetic drift), there must be consist conditions in the environment (with no migrations), and lastly there is no natural selection occurring.

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17. Explain the differences and similarities between allopatric speciation and sympatric speciation.

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Allopatric speciation occurs when there is a geographic barrier that separates a population. The divided population turns into two different populations and evovle differently to become reproductively isolated.

Sympatric speciation occers when there is a change within a subgroup of the population. It is reproductively isolated because individuals with specific preferences only wish to mate with other individuals with the same interests.

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18. If you discover a new species, what information would you need to know to determine how that species diverged from another species?

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Species that diverged from each other long ago have more differences in their DNA than species that diverged recently. Scientists use this degree of difference as a molecular clock to help them predict how long ago species split apart from one another. In general the longer ago two species split, the more distantly related they are. Because the DNA sequence determines a protein's amino acid sequence, a gene shared by two closely related organisms should have similar, or even identical, amino acid sequences. That's because closely related species most likely diverged from one another fairly recently in the evolutionary span. Thus, they haven't had as much time to accumulate random mutations in their genetic codes.

B.The information that would be looked at would be phylogeny differences/similarities, etc.

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19. What factors can influence the reproductive success of an organism? When would it be beneficial to allocate more resources to growth rather than reproduction?

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The ability of one the male to capture the interest of the female and maybe provide a safe and suitable place to raise their young-lings.

Factors that affect reproductive success of an organism – environment, survival, resources, genes, and adaptation.

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20. For a given allocation to reproduction, there is a trade-off between the number and the size of offspring produced. What types of environment would favor plant species with a strategy of producing many small seeds rather than few large ones?

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A.Plants in competitive environment would produce many small seeds because it would increase the chances that there would be offspring that survive. Producing large seeds would decrease the chance of having an offspring survive in because there might be too much competition for resources for the large seed to develop and grow.

B.The larger the offspring produced the more energy and resources went into making the offspring and the single offspring has a higher chance of survival and less competition. Having many offspring means that your genes aren’t supported by only one child. Some offspring will and can die but your genetic coding will continue on. Environments rich in nutrients warm temperature and fresh water would favor large clutches.

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21. Discuss the difference between a R selected species and a K selected species. Give an example of an organism in each group.

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R-strategists are short lived, have high reproductive rates, rapid development, small in size, large number of offspring, and minimal parental care. Some r-strategists have wide dispersal, are good colonizers, and respond rapidly to disturbance.

K-strategists are competitive species with stable populations of long lived individuals. They have slower growth rate at low populations, but they maintain growth rate at high densities.

K-strategists can cope with physical and biotic pressures. They have late reproduction and have large body size and slow development. They also have few offspring and usually care for the offspring. They are efficient users of a particular environment, but their populations are at near carrying capacity and resources are limited. They lack the means for wide dispersal making them poor colonizers.

An example of a K-selected specie is whales. Whales are long lived and have small populations. Whales have very few offspring and take care of their offspring. They grow and mature over

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22. When does McArthur and Wilson’s and K selected species model not apply? What does Grime’s plant life history model and Winemiller’s models include that is not covered by McArthur and Wilson’s model)

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McArthur and Wilson's r and K selected species only are classified as K and r if they follow certain aspects including amount of offspring, reproduction, body size, time of reproduction, amount taken for maturity, competitive ability, and intrinsic rate
Grime plant life history model compares Intensity of competition,Intesity of stress, and Intensity of disturbance. Winemillers model has Juvenille survivalship, age of reproductive maturity and fecundity (ability to reproduce.)

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23. What are the characteristics of a population? What factors limit the distribution of a population?

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The characteristics of a population are the number of births, the number of deaths, the number of reproductively mature individuals, the survival rate, and the immigration/ emigration.

Limiting factors are food, water, space, precipitation, temperature, diseases, sex ratio, quality of habitat, oxygen, natural disasters, competition (interspecific and intraspecific).

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24. When would a population have a clumped distribution and when would a population have a uniform distribution (what are the advantages and disadvantages to each distribution type)?

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A. Clump distribution is when individuals occur in groups. For example, suitable habitat or other resources may be distributed as patches resulting in clump distributions. Uniform distribution is when individuals are spread apart equally. For example, when competition for resources is intense it tends to be uniform distribution.
Advantages of clump distribution are – protection from predator, raising offspring, and increasing chance of catching prey. Disadvantages are – resources are limited, competition among each other
Advantages of uniform – more resources for the individual Disadvantages -

B.A population has a clumped population when there are social interactions between the individuals. Another reason would be there are small colonies. Also when there is no distribution of seeds, like when the annual seeds just drop.
A population has a uniform population when resources are scarce and the other individuals will press the other individual out.