Download EVSC 3200 Exam 1 Fundamentals Of Ecology 2025-2026 Questions With Correct Answers 100% A+ and more Exams Ecology and Environment in PDF only on Docsity!
EVSC 3200 Exam 1 Fundamentals Of
Ecology 2025-2026 Questions With
Correct Answers 100% A+
Ecology
study of structure and function of nature, distribution and abundance of organisms, and interactions among them and their environments
Ecological Hierarchy
Individual-->Population-->Community--> Ecosystem-->Landscape-->Biome--> Biosphere
Scientific Method
1.) Observations:of a natural phenomenon
2.) Question:observations give rise to a question that seek to explain the observed natural phenomenon
3.) Hypothesis: a proposed answer to the question
4.) Predictions: testable items that follow the hypothesis
5.) Hypothesis Testing:results interpreted to see if hypothesis was correct or not
Homeostasis
Maintenance of nearly constant internal environment in the midst of a varying external environment; more generally, the tendency of a biological system to maintain itself in a state of stable equilibrium.
All about negative feedbacks (e.g. physiological or behavioral regulations)
Environmental Variation faced by Organisms
Temporal Variations: cyclical changes (days, seasons, climate cycles); directional (global warming, geological changes, volcanic activity); erratic (disturbances, natural disasters)
Spatial Variation: availability of resources needed for life of an organism (light availability, water availability, space competition)
Environmental Tolerances
limits to survival, growth, and/or reproduction
it is a step-ladder: in order for an organism to grow it must be able to survive, and in order for an organism to reproduce it must first must satisfy the conditions for growth
predict short term metabolic function, lifetime survival, growth, and reproduction, and long-term distribution and abundance
Niche
Grinnell: a habitat, subdivision of the environment, and the ultimate distributional unit within which a species is held by its structural and functional limitations
Elton: role of the species and its relationship to food and enemies
Hutchinson: hyper-volume; the physical and environmental variables that limit the persistence or distribution of an organism each of which can be considered a point in multi-dimensional space
Fundamental Niche vs. Realized Niche
Fundamental: a set of condition under which there is the possibility for a species to exist
Hardy-Weinberg Principle
under conditions of random mating, and in absence of natural selection, mutation, genetic drift, and migration, the frequency of alleles and genotypes in a population remains constant from generation to generation
Natural Selection
differential success of individuals that results in elimination of maladaptive traits from a population
variation in heritable traits causes individuals to leave different numbers of descendants of varying "fitness"
Evolution
change in gene frequency through time resulting from natural selection and producing cumulative changes in characteristics of a population
Constraints and Tradeoffs
no species can do everything well
causes decisions
Photosynthesis
6CO(2)+12H(2)O-->C(6)H(12)O(6) + 6O(2)+6H(2)O
Light Reactions
occurs in the light
high-energy ATP and strong reductant, NADHP, produced during light reaction are essential for dark reactions
Dark Reactions
occurs all the time, do not require presence of sunlight, but are dependant upon the products of light reactions and therefore on sunlight
CO(2) is biochemically incorporated into simple sugars
Chlorophyll
the substance in plant cells that allows the plant to absorb energy from light
Stomata
pores in the leaf or stem of a plant that allow gaseous exchange between the internal tissues and the atmosphere
Rubisco
(ribulose biphosphate carboxylase-oxygen-ase) enzyme in photosynthesis that catalyzes the initial transformation of CO(2) into sugar
Photorespiration
the process of plants taking up oxygen in the light and giving out carbon dioxide
bundle sheath cells
mid to high temps, high photosynthetic rate, less energy efficiency, moderate water efficiency
CAM (crassulacean acid metabolism)
adaptation to water stress
also uses PEP carboxylase
high internal CO2, so less photorespiration
slow and inefficient
desert shrubs and succulents
mid temps, low photosynthetic rate, less energy efficient that C3 but high water efficiency
PEP Carboxylase
The enzyme that catalyzes the fixation of CO2 into four carbon acids, malate, and asparate.
Bundle Sheath Cells
cells surrounding small vascular bundles in the leaves of vascular plants
Aquatic Photosynthesis
no stomata, CO2 diffuses into leaf
many plants also use HCO3-
carbonic anhydrase (CA) converts HCO3- to CO
active transport of HCO3- into leaf or CA released to water outside
Dark Respiration
distinct from photorespiration
in mitochondria
generation of energy from oxidizing carbohydrates to form ATP
occurs in all cells dark or light
Two Components of Respiration
Rg (growth and synthesis, rate of photosynthesis) and Rm (maintenance: plant size, temperature)
Net Carbon Gain
=sum A - sum (RsubL+RsubS+RsubR)
Carbon Allocation
allocates carbon to different parts of the plant depending on resource availability (need more water=carbon goes to growing root systems)
Relationship between temperature and gross photosynthesis, respiration, and photosynthesis
net photosynthesis: average of two curves, peaked at about 25 degrees
gross photosynthesis: slower in cold temps but also goes down in temps over 40.
Respiration does most in warm weather, tail to the left
temp of leaf not air controls rate of photosynthesis
LAI=Total leaf area/ projected ground area
typically greater than one in forests but less in grasslands
Beer's Law: ALi=e^(-LAIi *k)--light extinction equation (where LAIi is leaf area index above height and k is the light extinction coefficient)
Light Attenuation
degree to which leaves absorb and reflect light
exponential decline from top of canopy, lake, etc. to the bottom/ground
plants affect their own light environment through LAI
Root:Shoot Ratio
will adapt to needs and resource availability
more shoot means there is a steady rate of precipitation; more roots means tends to happen in the off season where water availability is less predictable; episodic is when roots spread out to try to gather as much nutrients as possible
Transpiration
relationship between transpiration stomatal conductance and photosynthesis
Water Potential
atm<leaf<root<soil
water moves along a pressure gradient from areas of high pressure to low pressure
Matric Potential
pressure related to water adherence to surfaces (e.g. soil particles)
matric potential decreases (becomes more negative i.e. greater tension) with decreasing particle size (greater surface area) e.g. water moves through sand faster than clay...it has greater matric potential (easier to get water from)
clear up confusion: clay has a more negative water potential because it has more pull and tension to hold water (think of it like a vacuum)
Responses to Moisture Stress
Physiological: alternate photosynthetic pathways, wilting (decreased transpiration, lowered ability to dissapate heat) curling is an attempt to reduce leaf area and thus reduce water loss and hear gain)
morphological: change in root architecture(see root shoot), leaf size, leaf hairs, leaf cuticles
prolonged water stress leads to inhibited chlorophyll production and premature yellowing/fall coloration
Relationships between plant properties/leaf attributes and water availability
more water=larger, flatter leaves
because they can catch more water
Properties of water-adapted vs dry-adapted plants
wet environment: large flat leaves that catch as much water as possible. more leaves per plant, higher growth rates, thin leaves, less roots
dry environment: smaller thicker leaves, less per plant, lower growth rater, more roots; these traits minimize transpiration loss and maximize water pick up through roots
Properties of plants adapted to low- and high-nutrient environments
low-adapted: will respond less to higher levels of fertilization; lower leaf nutrient concentrations, lower max photosynthetic rates, lower max growth rate, larger allocation of carbon to root tissue, increase leaf longevity
more nutrients usually equals less roots
Nitrogen retranslocation
nutrient resporption: can recycle nutrients...will take back unused nutrients and store them in leaves over winter
N2 fixation
bacteria takes N2 from atmosphere and makes ammonium (energy rich compound) requres a lot of energy and is not common...bacteria has a symbiotic relationship with plants
Mycorrhizal Associations
another symbiotic relationship (fungus)
helps plants to take up ammonium and phosphates and in return gets carbohydrates
relationships more likely in nutrient poor environments because help is needed
Autotrophs vs Heterotrophs
Autotrophs: energy- PAR, reduced inorganic compunds, organic carbon. Carbon (CO2, HCO3-). Nutrients: mineral (atmospheric water, soil substrate C:N=40:1) Water- roots(in) stomata(out) Evolution but no co- evolution with resources
Heterotrophs: energy and carbon-organic carbon; nutrients: organic compunds, C:N=15:1, herbivores rely on other decomposers; water: food/drink (in) breathe, excrete (out) Evolution and co-evolution with food sources; morphology and behavior
Homeotherms vs Poikliotherms
Homeotherms (constant temp/warm-blooded), endothermy; maintain a relatively stable body temperatures through metabolizing carbohydrates constantly to do this, biggest problem is dealing with cold
Poikliotherms: (ectothermy/cold blooded) external sources of heat, have a lot more flexibility in terms of body temp, less metabolic cost but rely on sun to heat them up
Relationships between ambient temperatures, body temperatures, and metabolic rates
homeotherms: despite ambient temps, homeotherms tend to maintain a relatively constant internal body temp but the more the body has to compensate with the ambient temp to maintain homeostasis the more metabolic cost
poikliotherms: body temp is greatly influenced by ambient temp as they rely on external source to warm them, this means they have a lower metabolic rate as they do not have to produce their own heat
Relationship between body mass and mass-specific metabolic rate
M=Ko (Tb-Te)
heat flux= thermal conductance of animal (body core temp-environment temp)
high Ko equals a large heat loss or gain
Problems associate with defining the boundaries and number of individuals present in a population
migration can lead to extensive home ranges
hard to capture who is and isn't interacting (interaction is a key part of being in a population)
topography ex. groups on different sides of a mountain (same pop. or different?)
plants make it hard to identify individual because of clonal properties/asexual reproduction
Genet vs Ramet
genet-produced sexually
ramet-produced asexually (clone can be a group of ramets)
Metapopulation
separated populations of a species interconnected by dispersal of individuals among habitat patches in heterogeneous landscapes
movement of individuals between subpopulations leads to a better chance for survival as well as genetic variation
if there is no inflow of new individuals to a subpopulation it can go extinct
Attributes of populations
size distribution
age distribution: stable:birth and death rates do not change can be growing or declining, constant age structure (unchanging age ration) vs stationary (special case of stable) in which growth and decay are non existent (births=deaths) both uncommon naturally
density
sex ratio
birth and death rates
Dispersion vs Dispersal
dispersion: the spatial patterning of individuals
dispersal: the act of moving from an area
Types of Dispersion
uniform: competitive interactions occurs in managed systems (agricultural) where nutrients/resources are evenly distributed
random: independent occurs uniform environment
clumped: water availability, heterogeneity of resources; optimal habitats/habitat preferences; reproduction habits; facilitation (makes a habitat more suitable for an individual ex. an acacia tree provides shade for shade tolerant plants in a savanna)
Plant vs animal dispersal
for animals dispersal is typically active (moving on own accord) distance traveled depends on density of populations...the denser a population the fewer resources per individual which may lead to dispersal to another area
plants tend to survive where resources are better and require other means whether animal, wind, or water to move them
Emigration, Immigration, Migration
emigration: one way movement out of a habitat
