Checkpoint Questions Ecology Exam 1 PDF
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This document contains checkpoint questions on ecology. It explores various key concepts, including the study of organisms in relation to their environment and abiotic factors, and how ecologists consider individuals and ecosystems as ecological systems.
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Chapter 1 .1 1 What is ecology? - Ecology is the study of organisms concerning their environment and abiotic factors - Ecology is the scientific study of how living organisms interact with each other and their physical environm...
Chapter 1 .1 1 What is ecology? - Ecology is the study of organisms concerning their environment and abiotic factors - Ecology is the scientific study of how living organisms interact with each other and their physical environment, examining the relationships between individuals, populations, communities, and ecosystems within a given habitat Why do ecologists consider both individuals and ecosystems to be ecological systems? - Individuals have processes and functions that are in response to their environment, yet in a way that functions separately much like an environment would - Ecologists consider both individuals and ecosystems as ecological systems because they are interconnected, with individual organisms influencing their environment and the broader ecosystem impacting individual behaviors What are the unique processes that are examined when taking the individual, population, community, and ecosystem approaches to studying ecology? - The unique processes examined depend on the level of ecological complexity. An individual, for instance, would examine bodily processes such as respiration, while an ecosystem would examine broader, expansive processes such as nutrient cycling. - Individual level: - Focuses on physiological adaptations, behavior, and how individual organisms acquire resources within their environment, including factors like feeding strategies, mating patterns, and responses to environmental stimuli. - Population-level: - Analyzes the dynamics of a group of individuals of the same species within a given area, looking at factors like population growth rates, distribution patterns, competition, and the impact of environmental changes on population size. - Community level: - Examines interactions between different species within a particular habitat, including competition, predation, mutualism, and how species composition changes over time due to these interactions. - Ecosystem level: - Studies the flow of energy and nutrients through an entire ecological system, including both living organisms and non-living components (abiotic factors like water, soil, climate), considering how energy is transferred between trophic levels and the cycling of essential elements. 1.2 escribe how ecological systems are governed by physical and biological D principles. - Physical principles, such as the law of energy conservation that limits energy to transformation, and biological processes, such as natural selection, govern and limit ecological systems to unique responses and occurrences that create specificity. - Ecological systems are governed by both physical principles like climate, soil composition, and water availability, and biological principles like species interactions, population dynamics, and energy flow through food webs What does it mean when we say that ecological systems are in a dynamic steady state - It means that these systems are in constant gain and loss, in a way that creates balance in an ecological system. - "Dynamic steady state" means that while an ecosystem may appear stable overall, its components are constantly changing and fluctuating around a balanced average, with births, deaths, and movements of organisms occurring continuously, maintaining a relatively consistent system structure despite these fluctuations What are the three conditions required for evolution by natural selection to occur? - Variation: Individuals within a population must exhibitnatural variations in traits. - Heritability: These variations must be passed on fromparents to offspring through genetic inheritance. - Differential reproduction: Individuals with advantageoustraits are more likely to survive and reproduce, leading to a change in the population over time 1.3 How do the sources of energy acquired by plants, animals, and fungi differ? - Plants obtain their energy via photosynthesis and are mostly autotrophs save for some carnivorous plants that are consumers. Animals are exclusively consumers, either via herbivory (plant/producer consuming), carnivory (consumption of other consumers), or omnivores (both). Fungi are also consumers via the decomposition of decaying organic matter. Animals and fungi can be parasitic - Plants primarily acquire energy through photosynthesis, using sunlight to convert carbon dioxide and water into sugar, while animals and fungi are heterotrophs, meaning they obtain energy by consuming other organisms or organic matter; plants are the primary producers in an ecosystem, while animals and fungi are consumers, with fungi specializing in breaking down dead organic matter through external digestion What are the major types of species interactions? - The major types of species interaction are mutualistic (both benefit), commensalism (one benefits, the other is unaffected), competitive (fighting over shared resources), predator/parasitic (one hunts another), and herbivory (consumption of producers). Compare and contrast an organism’s habitat and an organism’s niche - A n organism’s habitat is the specific geographical place and environmental conditions it resides in (ie: the Sahara Desert) while its niche consists of the role, resources, and conditions it requires to live in this habitat (ie: only consuming one kind of plant). 1.4 What is the problem with assuming that two correlated variables represent causation? - Correlation does not equal causation: while the trends of two processes/occurrences may align, it does not signify a connection. Attributing correlation to causation may incorrectly explain processes and inaccurately describe interpretations of data What is the difference between a manipulation treatment and a control treatment? - A manipulation treatment involves the manipulation of a condition/resource or aspect of the experiment a group is involved in (ie: changing sunlight) while a control treatment serves as a basis for comparison to the manipulated treatment, with no manipulation of change to experimental conditions. In what ways do manipulative experiments differ from natural experiments? - Manipulative experiments are in a closed setting under specific manipulations of experimental conditions (ie: changing oxygen levels), while natural experiments observe how a system naturally changes without any manipulation (ie tree populations over time). - Control over variables: In a manipulative experiment,the researcher actively controls the independent variable, assigning different levels of the treatment to different groups. In a natural experiment, the researcher observes naturally occurring variations in the independent variable, with less control over other potential confounding factors. - Causality: Manipulative experiments can more confidentlyestablish causal relationships because of the controlled manipulation of the independent variable. Natural experiments can only identify correlations, as the researcher cannot fully control all aspects of the situation 1.5 Had the sea otter gone extinct, how might the marine environment along the California coast be different today? - As a keystone species, if sea otters faced extinction, the California coastal ecosystem would have little instances of kelp forests due to uncontrolled grazing by sea urchins. Why was it important to researchers to better understand the niche of the sea otter? - Understanding the niche of the sea otter defines how changes to their population might affect their surrounding ecosystem, and also how to address threats to their population. Chapter 2 .1 2 What are the steps involved in the greenhouse effect? 1. Solar radiation reaches Earth: Sunlight enters the Earth's atmosphere, with some being absorbed by the surface and the rest reflected into space. 2. Greenhouse gases absorb radiation: Greenhouse gases like carbon dioxide, methane, and water vapor absorb some of the infrared radiation emitted by the Earth's surface as it tries to radiate heat back into space. 3. Heat trapped in the atmosphere: These greenhouse gases then re-radiate the absorbed heat energy in all directions, including back towards the Earth's surface, trapping more heat within the atmosphere How does the human production of greenhouse gases lead to global warming? - Increased greenhouse gas emissions: Human activities,primarily burning fossil fuels for energy production, transportation, and industrial processes, release large amounts of carbon dioxide and other greenhouse gases into the atmosphere. - Enhanced warming: As the concentration of greenhousegases increases, more infrared radiation is trapped, causing the Earth's average temperature to rise, leading to global warming. If 99 percent of all gases in the atmosphere (excluding water vapor) are nitrogen and oxygen, why aren’t climate researchers focused on changes in the concentrations of these gases? - While nitrogen and oxygen are the most abundant gases in the atmosphere (around 99% combined), they are not considered primary greenhouse gases because they don't significantly absorb infrared radiation like carbon dioxide, methane, and nitrous oxide. Changes in the concentration of nitrogen and oxygen primarily affect atmospheric pressure, not temperature, which is the key concern in climate change studies. Therefore, climate research focuses on the changes in concentrations of greenhouse gases that directly trap heat and contribute to global warming 2.2 Why is solar energy per unit area more intense near the equator than near the poles? - Due to the Earth's spherical shape, the sun's rays hit the equator directly, concentrating more solar energy per unit area compared to higher latitudes where the rays strike at an oblique angle, resulting in less energy distributed over a larger surface area. What is the albedo effect? - The albedo effect refers to the reflectivity of a surface, meaning how much sunlight is reflected back into space rather than absorbed. Different surfaces ave different albedo values, with snow and ice having a high albedo (reflecting h most sunlight) and dark surfaces like asphalt having a low albedo. What is the solar equator, and what does its changing position suggest about the location of the intertropical convergence zone (ITCZ)? - The solar equator is the imaginary line on Earth where the sun is directly overhead at noon. Since the Earth's axis is tilted, the solar equator shifts throughout the year, moving between the Tropic of Cancer and the Tropic of Capricorn. The location of the ITCZ, a band of rising air and heavy precipitation, closely follows the position of the solar equator, as the intense sunlight at the equator drives convection currents that lead to cloud formation and rainfall in that region. What processes drive atmospheric currents? - Atmospheric currents are primarily driven by the uneven heating of the Earth's surface due to the sun's radiation. This creates temperature differences between the equator and the poles, leading to pressure gradients that cause air to move from high to low-pressure areas. Other factors influencing atmospheric currents include the Earth's rotation (Coriolis effect) and the specific heat capacity of different surfaces like land and water. 2.3 What processes cause the formation of gyres? - Gyres are formed primarily by the interaction of prevailing winds blowing across the ocean surface, the Earth's rotation (Coriolis effect), and the presence of landmasses, which together create large, circular ocean current Why are areas of ocean upwelling important to commercial fishing? - Areas of ocean upwelling are vital to commercial fishing because they bring nutrient-rich deep water to the surface, supporting a high abundance of marine life For El Niño–Southern Oscillation events, what causes the oscillation? - El Niño-Southern Oscillation (ENSO) events are caused by fluctuations in the trade winds across the tropical Pacific Ocean, leading to changes in sea surface temperatures and atmospheric pressure patterns, creating an oscillation between warm (El Niño) and cool (La Niña) phases 2.4 What is the impact of continental land masses on the amount of precipitation falling in the Northern versus the Southern Hemisphere? - Continental land masses significantly influence precipitation patterns by creating more pronounced differences in rainfall between the Northern and Southern Hemispheres, primarily due to the interaction of ocean currents, wind patterns, and land properties Why do coastal continental temperatures typically fluctuate less than inland temperatures? - Coastal continental areas experience less temperature fluctuation compared to inland areas because of the moderating effect of water's high heat capacity. How do rain shadows cause desert formation? - R ain shadows occur when mountains block moisture-laden clouds, resulting in arid conditions on the leeward side of the mountain range. 2.5 Why do unrelated plants often assume the same growth form in different parts of the world? - Unrelated plants often assume the same growth form in different parts of the world due to a phenomenon called "convergent evolution," where different species evolve similar adaptations to similar environmental conditions, essentially leading to similar forms even if they are not closely related; this happens because the best way to survive in a particular environment often leads to similar traits regardless of ancestry How do we break down terrestrial biomes into three broad temperature categories? Low-latitude, tropical biomes: - Characterized by consistently high temperatures throughout the year, typically found near the equator. (ie: tropical rainforests) Mid-latitude, temperate biomes: - Experience distinct seasons with moderate temperatures, including warm summers and cool winters. (ie: temperate rainforests) High-latitude, polar biomes: - Dominated by very cold temperatures with long, cold winters and short, cool summer (ie: tundras) What information about a biome can you obtain from a climate diagram? Average temperature and precipitation patterns: - A climate diagram visually displays the average temperature and precipitation levels throughout the year, revealing the climate conditions that define a specific biome. Growing season: - By analyzing the temperature trends, one can determine the length of the growing season where plants can actively grow. Seasonal variations: - The fluctuations in temperature and precipitation throughout the year indicate the seasonal changes a biome experiences. Potential vegetation types: - Based on the climate data, one can infer which types of plants are likely to thrive in that biome 2.6 Why is the boreal forest biome found on several different continents, including North America, Europe, and Asia? - The boreal forest biome is found on several different continents, including North America, Europe, and Asia, because it requires a specific climate with cold winters and short summers, which is prevalent in these high-latitude regions across the Northern Hemisphere; this climate is suitable for the cold-tolerant coniferous trees that dominate the biome hat types of terrestrial plants are found in each of the four biomes situated W at temperate latitudes? Temperate deciduous forest: - Dominated by broadleaf deciduous trees like oak, maple, and hickory, which shed their leaves in the fall. These forests experience moderate temperatures and distinct seasons. Temperate coniferous forest: - Primarily composed of evergreen coniferous trees like spruce, fir, and pine, with cooler temperatures and higher precipitation than temperate deciduous forests. Mediterranean [scrub] forest: - Characterized by hot, dry summers and mild, wet winters. Vegetation includes drought-resistant shrubs, sclerophyllous trees (with thick, leathery leaves), and herbaceous plants. Grassland: - Dominated by grasses and herbaceous plants due to low precipitation and/or extreme temperature fluctuations. Trees are sparse or absent. Why do tropical rainforests experience two peaks of rainfall? - Tropical rainforests experience two peaks of rainfall because of the movement of the Intertropical Convergence Zone (ITCZ), a band of low pressure where warm, moist air rises and condenses, causing heavy precipitation. As the Earth's axis tilts and the sun's apparent position shifts over the year, the ITCZ migrates north and south, bringing periods of intense rainfall to different regions twice annually. This results in two distinct rainy seasons and dry seasons. 2.7 How do headwater streams and larger rivers differ in their major source of organic material? - Headwater streams primarily derive their organic material from fallen leaves and other terrestrial debris washed into the stream from the surrounding land, while larger rivers rely more on in-stream primary production from algae and aquatic plants due to their slower currents and greater light penetration Why does productivity in the ocean differ between the photic and aphotic zones? - The productivity in the ocean differs between the photic and aphotic zones because only the photic zone receives enough sunlight to support photosynthesis, leading to significantly higher primary production in that region What are the five types of saltwater biomes? - The five types of saltwater biomes are typically categorized as: neritic zone, oceanic zone, coral reefs, estuaries, and deep sea vents. Chapter 3 .1 3 What is unique about water with regard to how temperature affects its density? - W ater is unique because, unlike most substances, it becomes less dense as it cools down below 3.98°C (39.16°F), meaning that solid ice is less dense than liquid water, allowing it to float on the surface. This unusual behavior is crucial for life on Earth as it prevents bodies of water from freezing solid from the bottom up, allowing aquatic organisms to survive during cold winters. Describe two strategies aquatic animals use to adapt to the high viscosity of water Streamlined body shape: - Many aquatic animals, like fish and dolphins, have streamlined bodies to minimize drag and efficiently move through the viscous water. Fins and appendages: - Fins and appendages, such as fins in fish or tentacles in squid, act as paddles or rudders, helping with steering and maneuverability in the viscous environment Describe the changes in the mineral content of water as it moves from rainwater to lake water and, eventually, to ocean water. Rainwater: - Rainwater is initially pure, with minimal dissolved minerals. Lake water: - As rainwater collects in lakes, it picks up dissolved minerals from the surrounding rocks and soil, increasing its mineral content and salinity. These minerals can include calcium, magnesium, sodium, and potassium. Ocean water: - Ocean water has the highest mineral content due to centuries of accumulation from rivers and weathering of landmasses. Saltwater is primarily composed of sodium chloride, but also contains other dissolved minerals. This high salinity makes ocean water denser than freshwater, which is why saltwater organisms have adaptations to cope with the higher salt concentration. 3.2 What is the difference between passive and active transport of solutes? - Passive transport refers to the movement of solutes across a cell membrane without requiring energy, meaning substances move from an area of high concentration to an area of low concentration, like diffusion or facilitated diffusion through channels in the membrane. - Active transport, on the other hand, requires energy (ATP) to move solutes against their concentration gradient, allowing cells to move substances from a low concentration area to a high concentration are Compare and contrast the terms hyperosmotic and hyposmotic. - Hyperosmotic refers to a solution with a higher solute concentration than another solution, meaning it will draw water towards it due to osmosis. - Hyposmotic refers to a solution with a lower solute concentration than another solution, meaning it will lose water to the more concentrated solution Describe one adaptation for osmoregulation in freshwater animals, saltwater animals, and saltwater plants. Freshwater animals: - K idneys: Excrete dilute urine to conserve water and maintain proper solute concentration. - Highly permeable skin: Allows for easy uptake of water through osmosis. Saltwater animals: - Salt glands: Excrete excess salt to maintain proper water balance. - Specialized kidneys: Adapt to excrete concentrated urine to conserve water. Saltwater plants: - Thick, waxy cuticle: Reduces water loss through transpiration. - Specialized root systems: Absorb water efficiently from the salty environment. 3.3 Why does the boundary layer surrounding a photosynthetic organism make it more difficult to exchange CO2 and O2? - A boundary layer surrounding a photosynthetic organism makes it difficult to exchange CO2 and O2 because the thin layer of fluid around the organism creates a barrier, slowing down the diffusion of these gases to and from the cell, primarily due to low viscosity and heat generated during photosynthesis. What is the equilibrium reaction that illustrates the conversion of co2 to bicarbonate? - CO2 (g) + H2O (l) H2CO3 (aq) HCO3- (aq) + H+ (aq) Why are deep ocean waters typically low in oxygen? Oxygen consumption by decomposing organic matter: - As organic material sinks to the depths, it decomposes, consuming oxygen. Limited diffusion from the surface: - Oxygen dissolves more readily in cold water, but the deep ocean is colder than the surface, meaning less oxygen can be held in solution. Oxygen usage by deep-sea organisms: - The few organisms that live in the deep ocean use the available oxygen for respiration. 3.4 Explain the adaptation that allows thermophiles to survive in very high temperatures. - Thermophiles can survive in very high temperatures due to specialized enzymes called "thermozymes" that maintain their structure and function at extreme heat, achieved through modifications like increased disulfide bonds and hydrophobic residues within their protein chains; t - Their DNA and cell membranes are also adapted to withstand high temperatures with unique molecular structures that prevent damage. Describe the adaptations that enable fish to survive in very cold seawater. - Fish living in very cold seawater often have "antifreeze proteins" in their blood which inhibit ice crystal formation, preventing them from freezing in subzero temperatures - Some species also have increased glycerol content in their bodies to further lower their freezing points. Why should we be concerned about thermal pollution? - T hermal pollution is concerning because it can drastically alter the natural temperature of aquatic ecosystems, impacting the survival of many species that are adapted to specific temperature ranges. - This can lead to disruptions in food chains, mass fish kills, and altered reproductive cycles, ultimately impacting the entire ecosystem's health Chapter 4 .1 4 Explain the relationship between soil particle size and the field capacity of soil. - Soil particle size has a direct relationship to field capacity, meaning that smaller particles (silt and clay) have a higher capacity to hold water due to their larger surface area, allowing for more water to be available to plants. Why is the availability of plant water highest in soils with a mixture of particle sizes? - Soils with a mixture of particle sizes offer the optimal balance, providing both good drainage from larger particles and water retention from smaller particles, making it accessible to plant Why does the process of soil salinization pose a major challenge for plants that are not adapted to salty environments? - Soil salinization significantly reduces plant water availability because the dissolved salts attract water more strongly than plant roots, making it difficult for them to extract the necessary water from the soil, leading to stress and stunted growth in non-adapted plants. 4.2 Explain how light serves as the ultimate source of energy for a meat-eating animal. - Light serves as the ultimate source of energy for a meat-eating animal because the energy in the meat ultimately comes from plants, which use sunlight through photosynthesis to create their own food - The energy is then passed up the food chain when the meat-eating animal consumes the herbivore that ate the plant Why is c3 photosynthesis inefficient when the concentration of CO2 in a leaf is low? - C3 plants use an enzyme called Rubisco to fix carbon dioxide during photosynthesis. However, Rubisco can also bind to oxygen, which leads to a process called photorespiration, which is inefficient and wastes energy. When carbon dioxide concentrations are low, the chance of Rubisco binding to oxygen increases, making C3 photosynthesis less efficient under these conditions. Explain how plants use structural adaptations to reduce water loss. Thick cuticle: - A waxy layer on the leaf surface that minimizes water loss through transpiration Stomata on the underside of leaves: - This placement minimizes exposure of stomata (pores for gas exchange) to direct sunlight, reducing water loss Sunken stomata: - S tomata that are recessed into pits on the leaf surface, creating a microenvironment with higher humidity and reducing water loss Narrow leaves: - Reduces the surface area exposed to air, minimizing water loss Leaf hairs: - Tiny hairs on the leaf surface that trap air and moisture, further reducing water loss 4.3 Why does homeostasis require negative feedback? - Homeostasis requires negative feedback loops because they actively counteract changes to maintain a stable internal environment within an organism, essentially bringing conditions back to a set point when they deviate from the ideal. - Negative feedback loops work by sensing a change, triggering a response that opposes the initial change, thus restoring equilibrium Describe the costs and benefits associated with the different nitrogenous waste products excreted by fish, mammals, and birds. Fish primarily excrete ammonia as waste - Highly toxic - Requires minimal energy to produce and can be readily diffused into the surrounding water Mammals excrete urea - A less toxic option - Requires more energy to produce - Allows for efficient water conservation Birds excrete uric acid - A non-toxic paste - Requires the most energy to produce - Enables maximum water conservation, making it ideal for animals with limited access to water Why is there a relationship between the amount of precipitation in the environment and relative kidney size? - There is a direct relationship between the amount of precipitation in an environment and the relative kidney size of an organism. In environments with high precipitation, where water is readily available, organisms can afford to have smaller kidneys because they need to excrete less concentrated waste. - Conversely, in environments with low precipitation, organisms need larger kidneys to process and concentrate urine, thus conserving water. This adaptation ensures that organisms can maintain proper osmoregulation regardless of the water availability in their environment. 4.4 If a snake is lying on a rock in the desert sun, how is the snake’s body temperature affected by radiation, conduction, convection, and evaporation? Radiation: - T he primary way a snake gains heat is through radiation from the sun. Sunlight radiates heat onto the snake's body, directly warming it up. Conduction: - When the snake is in contact with the rock, it gains heat through conduction. Heat transfer occurs through direct contact between the snake's body and the rock surface. Convection: - Convection is the transfer of hea through the movement of air. As air around the snake warms up, it transfers heat to the snake's body. Evaporation: - While snakes can lose some heat through evaporation, it's generally a less significant factor compared to the other heat transfer mechanisms, especially in arid desert environments where humidity is low As an animal increases in size, why does its surface area increase more slowly than its volume? - As an animal increases in size, its surface area increases more slowly than its volume because when you scale up an object, the volume increases proportionally to the cube of its dimensions, while the surface area only increases proportionally to the square of its dimensions - This means that as an object gets larger, its volume grows much faster than its surface area relative to its size. Under what conditions could an ectotherm be homeothermic? - An ectotherm can be homeothermic (having a relatively constant body temperature) under certain conditions. This typically requires access to a stable and warm environment, such as a consistently sunny rock or a microenvironment. Chapter 5 .1 5 How do phenotypic trade-offs favor the evolution of phenotypic plasticity? - Phenotypic trade-offs favor the evolution of phenotypic plasticity because they allow organisms to adapt to changing environmental conditions without needing to evolve entirely new genetic adaptations for each specific scenario, essentially giving them the flexibility to adjust their phenotype based on the environmental cues they encounter. Why do phenotypically plastic responses depend on reliable environmental cues? Predicting Environmental Changes: - For phenotypic plasticity to be effective, the environmental cue triggering the phenotypic change needs to be reliable. If the cue is unreliable, the organism might produce a maladaptive phenotype, which could decrease its fitness. For example, an insect that changes its coloration to mimic a toxic butterfly species would only benefit from this if the cue signaling the presence of the toxic butterfly is accurate. Evolutionary Advantage: - W hen an organism can reliably predict environmental changes based on a cue, it can adjust its phenotype accordingly, optimizing its chances of survival and reproduction in the changing environment. This allows for better adaptation to diverse conditions without the need for complete genetic evolution. How do different types of traits differ in how quickly they respond and how easily they can be reversed? - Different types of traits vary in how quickly they respond to environmental cues and how easily they can be reversed. Some traits, like skin color change in response to sunlight exposure, can be reversed quickly. Others, such as the size and shape of an organism's body, may take longer to change and be less reversible. - Factors influencing this include the underlying physiological mechanisms involved, the developmental stage at which the change occurs, and the genetic basis of the trait's plasticity. 5.2 How might predators and prey both evolve phenotypically plastic strategies to improve their fitness? - Predators and prey can evolve phenotypic plasticity to improve their fitness by adapting their traits based on environmental cues, allowing them to optimize their survival and reproductive success in different situations. - For example, a predator might develop longer claws or sharper teeth when encountering prey with tougher exoskeletons, while prey might change their coloration or behavior patterns to avoid detection How is the phenotypic plasticity of intestines an adaptation to variable food availability? The phenotypic plasticity of intestines allows organisms to adjust their digestive systems based on the availability of different food sources, enabling efficient digestion and nutrient absorption regardless of the food types. - Enzyme production: Different food sources requiredifferent digestive enzymes. An organism's intestines can adapt by adjusting the production of specific enzymes to break down the components of the food they are consuming. - Gut length and size: The length and size of the intestinescan also change depending on the diet. A diet rich in easily digestible food may require a shorter intestine, while a diet rich in hard-to-digest food may require a longer intestine to allow for more time for digestion If self-fertilization causes lower fitness than cross-fertilization, under what environmental conditions would self-fertilization be the superior strategy? - Self-fertilization can be advantageous in situations where finding a mate is difficult, but it generally leads to lower fitness due to reduced genetic diversity. This makes self-fertilization a superior strategy in environments with limited population size or dispersal, or when encountering harsh conditions that restrict movement and mating opportunities. .3 5 How does the function of isozymes represent an example of phenotypic plasticity? - Isozymes represent phenotypic plasticity because they allow an organism to express different forms of the same enzyme depending on environmental conditions, essentially producing different phenotypes from the same genotype - Isozymes are multiple forms of an enzyme that catalyze the same reaction but have slightly different properties, allowing an organism to fine-tune its metabolism based on environmental cues Why do plants alter their root-to-shoot ratios? Plants adjust their root-to-shoot ratios to maximize nutrient uptake depending on the nutrient availability in the soil. - When nutrients are scarce, a plant will allocate more resources to root growth to better access nutrients, resulting in a higher root-to-shoot ratio. - Conversely, when nutrients are abundant, the plant can invest more in shoot growth, leading to a lower root-to-shoot ratio. What are three adaptations humans undergo in response to decreased oxygen at high elevations? Increased Red Blood Cell Production: - When exposed to low oxygen levels at high altitudes, the body increases the production of red blood cells, which carry oxygen throughout the body, to compensate for the thinner air. Increased Breathing Rate: - Humans at high altitudes tend to breathe more rapidly to intake more oxygen. Mitochondrial Changes: - Mitochondrial function can adapt to high altitudes by becoming more efficient at utilizing oxygen, allowing for better energy production in low oxygen conditions. 5.4 Explain how migration and dormancy are both examples of phenotypic plasticity. Migration: - When animals move to different geographical locations in response to seasonal changes, like birds migrating south for winter or insects migrating to new food sources, they are exhibiting phenotypic plasticity. This change in behavior is triggered by environmental cues and allows them to survive in unfavorable conditions. Dormancy: - This is a period of inactivity or reduced metabolic rate in response to adverse conditions, such as hibernation in mammals during winter or estivation in some insects during summer. By entering a dormant state, organisms can conserve energy and survive until conditions improve. Why would it be adaptive for subtropical trees to shed their leaves during seasonal periods of drought? - S ubtropical trees shed their leaves during periods of drought as a mechanism to conserve water. When water is scarce, dropping leaves minimizes water loss through transpiration, the process of water evaporation from leaves. This adaptation allows the tree to survive until the rainy season returns. Explain the differences between the four types of dormancy in animals. Diapause: - This is a period of arrested development in insects, often triggered by environmental cues like changes in temperature or day length. It allows the insect to wait for favorable conditions before continuing its life cycle. Aestivation: - This is a state of dormancy during hot and dry periods, often seen in reptiles and amphibians. It allows them to avoid extreme temperatures and conserve energy until conditions moderate. Topor - Torpor is a state of decreased physiological activity in animals, characterized by a reduction in body temperature, heart rate, and metabolic rate. It's a way for animals to conserve energy and survive when food is scarce. Hibernation: - Similar to brumation, hibernation is a period of sleep-like dormancy during cold winters, characterized by reduced metabolic rate and body temperature. 5.5 Why is optimal foraging an example of phenotypic plasticity? - Optimal foraging is considered an example of phenotypic plasticity because an animal's foraging behavior can adapt and change depending on the environmental conditions it encounters, allowing it to adjust its strategy to maximize energy gain or minimize costs, just like how a plant can change its leaf shape in response to different light condition Why does central place foraging cause animals that travel farther to bring back larger amounts of food? Central place foraging: - This is a foraging strategy where an animal returns to a fixed central location (like a nest or burrow) to store food. This means they need to consider the distance to the food source, the time and energy required to acquire it, and the travel time back to the central location. Traveling farther for larger amounts: - If an animal encounters a patch of high-value food items that are further away, it may be beneficial to travel the distance to acquire a larger quantity, even if it takes longer, as the overall energy gain per unit time is maximized. What are the costs and benefits that animals must consider during risk-sensitive foraging? Costs: - Increased exposure to predators: Spending more time in exposed areas while foraging increases the risk of being caught by a predator. - E nergy expenditure: Traveling longer distances or handling larger prey items requires more energy, which can leave the animal vulnerable. - Time cost: Time spent foraging can decrease the time available for other activities like mating or resting. Benefits: - Higher energy intake: Acquiring more nutritious or plentiful food sources can provide a significant energy boost. - Reduced competition: By accessing harder-to-reach food sources, an animal may avoid competition with other individuals.
