IB 150 Content 1.1-1.8 (Unit 1 study guide)

Gibbs free energy

measures whether a chemical or physical process is thermodynamically nonspontaneous (endergonic) or spontaneous (exergonic)

Delta G: change in gibbs free energy

G>0 (positive G) external energy is required for reaction to occur (exergonic)

G<0 (negative G) no external energy is required for reaction to occur

Endergonic

Nonspontaneous: no external energy input is required

Exergonic

Spontaneous: an input of external energy is required (input of free energy)

Delta H

Represents change in enthalpy of a system/ change in total energy within a system

Enthalpy

total energy within a system

Exothermic

Delta H<0 (delta H is negative) system releases heat to it’s surroundings

Endothermic

Delta H>0 system absorbs heat from its surroundings when delta H is positive

T (of Gibb’s free energy equation)

represents temperature in kelvin

Delta S (of gibb’s free energy equation)

measures change in entropy of a system. measures change of disorder within a system Delta S is positive more disorder Delta S is negative means less disorder

H as a variable (related to delta H)

H measures positional energy related to charges (measures potential energy) ask yourself how strong are the bonds

How can you determine potential energy by looking at molecular compounds

How strong are the bonds of the molecules (what bonds will release the most energy)

Energy

The capacity to induce change

1st law of thermodynamics

Energy cannot be created nor destroyed only transferred

Second law of thermodynamics

total entropy/disorder of an isolated system will always increase over time due to spontaneous processes (remember there is only endergonic and exergonic and endergonic will not change entropy)

Entropy

Measures degree of disorder

What processes are more energetically favorable and why?

Exergonic processes because they require an input of external energy which helps the universe move towards greater disorder which is why they are favorable (because they are spontaneous)

Exergonic (spontaneous) graph

releases free energy and delta G is negative when exergonuc

Endergonic reaction graph

Energy is absorbed and delta G is positve

Exponential growth population model

delta N(1-0)/delta t= r(N0) Calculates rate of change over time

Exponential equation variables: Delta N(1-0)/Delta t

calculates the rate of population change over time

Exponential equation variables: r

r: growth rate per capita/individual growth rate

Exponential equation variables: N0

N0: initial population

what does r represent in the exponential growth model

r=b-d (rate of population change= births-deaths)

how is r calculated

r= delta N(1-0)/N0 (change in population/initial population)

what occurs when the r variable is constant

exponential growth will continue to occur over time

logistic growth population model

delta N(1-0)/delta t= N0(r-max)((K-N)/K)

How does the logistic growth model differ from the exponential growth model?

The portion of (K-N)/(K) accounts for carrying capacity limitations on the rate of growth

r-max

the maximum growth rate when carrying capacity is accounted for

K

carrying capacity

N

Population

K-N/K

when the graph begins to decrease and have a horizontal asymptote it is reaching its limit by the carrying capacity

carrying capacity

maximum amount of individuals that can be supported by limited resources

ecology

the study of living organisms and their interactions with their abiotic environment

how does energy flow in the ecosystem

sun, plants, herbivores, carnivores (loss of energy should be accounted for) also detritivores exist in this system

size of different energy pools

1) plants 2)herbivores 3) carnivores (energy pools become increasingly smaller because of energy loss

10% rule

from one trophic level to the next only 10% of energy is withheld and the other 90% is lost which is why the energy pools shrink

10% rule applied to energy pools

sun 100% plants 10% herbivores 1% carnivores 0.1%

thermoregulation strategies

how do animals maintain a certain body temperature required for survival

homeotherms: maintain a constant body temperature'

poikilotherms: have varied body heat

endotherms

produce their own body heat through chemical reactions (endotherms have a faster metabollism because they need to generate their own body heat.

ectotherms

rely on heat in their surroundings to maintain their body temperatures

• receive heat from radiation and conduction

how do energy expenditure of ectotherms and endotherms vary?

endotherms:

1) majority of energy is used for cellular respiration to maintain body heat (~75%)

2) ~8% of energy is used biomass egestion and excretion

ectotherms

1) only around ~50% of energy is utilized for cellular respiration

2) the other 50% is used for biomass excretion and egestion

biomass

renewable energy that comes from plants and animals

excretion

the ways in which organisms eliminate metabollic waste (getting rid of the byproducts of chemical reaction)

egestion

elimination of indegistable compounds

exothermic trophic levels

exothermic trophic levels have less energy loss because they do not perform as much cellular respiration (exotherms have a higher ecological efficiency) therefore there is more energy available at each of the trophic levels

r- strategists

maximize amounts of birth by using energy expenditures

K- strategists

lower birth rate lower death rate they use energy to provide stability to reduce death rate

r-strategists vs K-strategist

r-strategist graph

higher tendency to overshoot K (carrying capacity)

K strategist graph

less likely to overshoot carrying capacity because of lower birth rate

why are all species not K-strategists

when predation is a contributing factor higher reproduction rate of r-strategists allow the species to exist in a larger population

when can K-strategists overshoot their carrying capacity

environmental degradation that limits resources

when does the overshooting of the carrying capacity occur

carrying capacity decreases

very high r-max due to high birth rates

exploitative competition

when resources are limited and species are in indirect competition by utilizing resources through consumption

interference competitition

active mechanisms to acquire and defend resources

ecological niche

the role a species inhabits in the environment and what it can and cannot tolerate (food size, environment temp)

niche graphs

shows optimum range of tolerance of environmental variables expressed as what K (carrying capacity can be achieved at different values of an environmental variable

niche graphs with the same optimum but one has a lower K

graph with higher K will always outcompete the species that has a lower K because they are more energetically efficient within their ecological niche

how do competing species coexist

1) their niches do not completely overlap

2) the environment they exist within is variable enough to the point where they can outcompete eachother of certain ranges

fundamental niche

the actual range of tolerance of a species not taking into account how competition alters this

realized niche

the contraction of a niche based on competition and where they actually exist

niche differentiation

reduction of overlap between competition due to intense competion for resources

predation and competitive exclusion

predation decreases competition between herbivorous species by putting them below their carrying capacity making resources more available to the species that are surviving within the population

pronounced predator prey cycles (rare)

as prey decreases predators increase and vice-versa

predator prey cycles

predators remain stable while prey populations fluctuate but multiple prey are taken into account

Predators…

• do not get as much prey when the prey are hiding

• population growth is diminished due to predation cycles

• predation can prevent competitive exclusion

top down trophic cycle

predators influence the amount of energy available at different levels due to consumption

bottom up trophic levels

energy levels based on loss and energy available determines the amount of energy at different levels

how does predation support biodiversity

predation supports biodiversity by decreasing competition allowing more populations to live below their carrying capacity in their environment

commensalism (+/0)

one species benefits from this type of interaction and the other species is not impacted in any way

competition (-/-)

both species do not benefit from this interaction and population decreases because of this

consumption (+/-)

one species eats another

mutualism (+/+)

when both species interact in a way that they are both benefitted

what is the difference between non-living and living matter

living matter requires and input of energy

7 properties all living organisms have

• cells

• grow and reproduce

• genetic information processing'

• energy

• evolution

• maintaining homeostasis

• adapting to their environment

what is the purpose of energy

to supply reactions with fuel to maintain homeostasis

density dependent

factors occurring within a population that impact the growth/ population size

• examples: disease, predation, competition, buildup of waste in crowded communities

density independent factors

factors that limit the population regardless of how crowded or sparse the population is

• example: natural disasters / environmental change (typically abiotic)

how does diffusion relate to the second law of thermodynamics

the particles move from higher order to more disorder and total enthalpy of system delta h is equal to zero

what happens when molecules within a system are distributed evenly

equillibrium is reached and molecules will continue to diffuse at equal rates and net flow=0

ranked medium categories

• gas

• liquid

• living cells

• dead cells