EVS 207 Midterm Study Guide

·      Photosynthesis is the process by plants converting light energy usually from the sun into chemical energy stored in glucose

o   Produces glucose, serving as an energy source for plants and produces oxygen as a byproduct that is released into the atmosphere

o   Typically happens during the day where there is sunlight

·      Respiration is the process by which cells break down glucose and other organic molecules to release energy that is used for various cellular activities

o   Produces energy in the form of adenosine triphosphate

o   Ongoing process that happens all the time as cells need constant energy

o   Vital for energy production in all living organisms and happens continually

·      Tertiary consumer (4^th trophic level): fox

·      Secondary consumer (3^rd tropic level): owl, spider

·      Primary consumer (2^nd trophic level): bug, mouse

·      Primary producer (1^st trophic level): plants

K-strategists: organisms that demonstrate a logistic population growth curve and usually reproduce conservatively (birds, predatory fish, larger mammals): stable

·      Niche specialists, predators

·      Long life, slower growth, late maturity

·      High parental care or protection

·      High trophic level, few, large offspring

r-strategists: organisms that grow at their maximum rate of biotic potential and demonstrate exponential growth curves to secure a place in the environment (bacteria, insects, weeds): unstable

Characteristics of r-strategists:

·  Niche generalists, pioneers, prey

·      Short life, rapid growth, early maturity

·      Little parental care or protection

·      Low trophic level, many, small offspring

·      Exponential growth curve: the growth rate of the population accelerates (J curve) – r- strategists

·      Logistic growth curve: the rate accelerates, point of maximum growth, the rate slows down (S curve) – K-strategists

·      Humans are K-strategists;  

·      duckweeds are r-strategists

four demographic factors in human population growth:

·      birth rates

·      death rates

·      immigration

·      emigration

What is the Rule of 70?: doubling time (dt) for a country indicates the predicted year that the current population will double

·      r-growth rate (as a %)

·      dt=70/r

Describe the demographic stages (1-5

·      stage 1: low growth rate due to high birth and death rates

·      stage 2: high growth rate due to high birth rates and lower death rates

·      stage 3: low growth rate due to decreasing birth and low death rates

·      stage 4: low to zero growth rate due to stable/low birth and death rates

·      stage 5: low to declining growth rate due to low birth rates and death rates…but immigration

·      habitat: place where an organism lives (environment); supports many kids of organisms that must share common resources

o   soil type and moisture

o   slope

o   sunlight availability

o   degree of human disturbance

o   precipitation

o   temperature

·      niche: role an organism plays in its ecosystem; everything that affects the organism and all of the impacts of the organism has on its surroundings

o   role

o   feeding habits

o   breeding habits

o   migration habits

o   competition with other species

o   services for other species

·      niche generalists: a species with a broad niche that is easily adaptable to many environmental conditions; more likely to survive by more easily relocating, changing food sources, and adapting in other ways

·      niche specialists: a species with incredibly specific needs in order to survive; require a detailed and consistent climate, diet, and regimen to keep them alive

·      community: different species of organisms that interact with each other (to include competition)

o   competitive exclusion principle: no two organisms can occupy the same niche at the same time; will result in harmful competition

o   niche differentiation: separation of organisms into distinct niches to resolve competition

§  growing taller, spreading out, eating different of a plant, nesting in a different part of a tree

·      principle of competitive exclusion: no two species can occupy the same ecological niche for long

o   the more efficient species will eventually exclude the other

·      resources partitioning/niche differentiation: process by which species evolve to use resources differently

o   allows several species to use different parts of the same resource and coexist within one habitat

·      Lethal Dose (LD₅₀): dose at which 50% of the test population is sensitive (killed)

Toxicity testing levels – how do we distinguish between them?:

·      Moderate toxin takes about 1g/kg of body weight to produce a lethal dose

·      Very toxic materials require about 10% of that amount (100 mg/kg)

·      Extremely toxic materials require 1% of that amount (10 mg/kg)

·      Supertoxic chemicals can be lethal in a dose of a few micrograms

·      Toxins are poisons produced naturally by an organism (plant, animal, insect)

·      Toxicants are type of poison that are made by humans or introduced to environment by human activity

Different soil particle sizes?:

·      Gravel: largest soil particles (greater than 2mm)

·      Sand: larger soil particles (0.05-2 mm)

·      Silt: medium-sized particles

·      Clay: small particles

·      Water-holding capacity: the difference between the field capacity and the wilting point

o   Largely determined by soil textire but organic matter is also important

·      Porosity: measure of how much water a soil can hold (open space between particles)

·      Permeability: measure of how easily a fluid (water) moves through soil

·      O horizon: uppermost level; organic material

·      A horizon: dark-colored, rich in organic matter and high in biological activity; organic matter mixed w/ mineral matter

·      E horizon: zone of leaching; fine-grained components removed by percolating water

·      B horizon: zone of accumulation; clays and iron oxides leached down from above; formation of hardpan in wet climates  

·      C horizon: partially weathered bedrock