BIOL 1720 FINAL

What are the essential elements

light, water, and ~20 elements to support needs

What is macronutrients

Nutrients that plants require in large amounts

Micronutrients

trace elements that plants require in small amounts

Why is nitrogen a crucial nutrient for plants, and why can’t they use atmospheric nitrogen directly?

Vital component for chlorophyll/photosynthesis, amino acids, and DNA. The nitrogen from the atmosphere can not be broken down by plants and must be broken down into ammonia or a nitrate

Describe the role of nitrogen-fixing bacteria in the nitrogen cycle

rhizobacteria converts N to a usable form called nitrogen-fixation

How do legumes form mutualistic relationships with nitrogen-fixing bacteria?

The plant releases root exudates that attract bacteria and trigger chemical signaling

What are root nodules, and how are they formed?

Are specialized swelling on the roots of certain plants that house symbiotic nitrogen-fixing bacteria

What role do mycorrhizal fungi play in plant nutrition?

Act as an extension of plant roots to increase absorptive surface area

What are rhizobacteria, and how do they promote plant growth?

They convert N into sources plants can break down and in return promote plant growth

How have some plants adapted to nutrient-poor environments (e.g., carnivorous or parasitic plants)?

Epiphyte: Plants that grow on another plant

Parasite: Absorb water, sugars, & minerals from host plants

Carnivorous: Photosynthetic but supplement with insects

What are phytochromes, and how do they influence plant processes?

Red light that switches from being active(Pfr) or inactive(Pr) depending on the light absorbed

How does auxin promote growth?

It helps cell elongation when produced in the shoot tips and stimulates cell division

What major role does ethylene, gibberellins, and abscisic acid (ABA) play in plant growth

ehtylene: aids in fruit ripening

gibberellins: promotes cell elongation, cell division, and seed germination

abscisic acid(ABA): maintains seed dormancy, and promotes leaf abscission

What is photoperiodism, and how do plants respond?

The ability to use light to track time

How do plants detect and respond to gravity?

statoliths: sense changes in gravity

negative gravitropism: growth of the shoot apical tip upward

positive gravitropism: growth of the roots downward

How do plants communicate with herbivore-damaged neighbors?

They release chemicals that can attract predatory insects

Define ecology

The scientific study of the interaction between organisms and their environment

List the levels of ecological organization from smallest to largest and define each one

Organism: a single individual living thing

Population: A group of individuals of the same species living in the same geographic area

Community: All different populations and species that live and interact in a particular area

Ecosystem: A community of living things interacting with the non-living elements of their environment

Biome: A large geographic region defined by its distinct climate

Biosphere: The highest and most inclusive level encompassing all life on Earth and the environments

How do population density and dispersion differ?

Population density is the # of individuals per unit of area while dispersion is the pattern of spacing among individuals within boundaries of population

What are the three main types of dispersion patterns seen in populations?

Clumped(most common)

Uniformed

Random

What biological interactions can cause a uniform dispersion pattern?

Territoriality that claim and defend a physical space

What conditions typically lead to random dispersion?

due to absence of a strong attraction/repulsion

What does a survivorship curve show?

Plot of proportion/number of cohorts still alive at each age

Describe a Type I survivorship curve and give an example

High survivorship in earl & middle life, decline with old age (Bear)

What characterizes a Type II survivorship curve?

Survivorship declines linearly with a constant death rate through life (squirrel)

What defines a Type III survivorship curve and which organisms show it?

Low survivorship as juveniles, stabilizes for survivors(plants)

Compare and contrast the exponential and logistic models of population growth.

exponential is a model of population in which the population increases continuously at an exponential rate(J-shaped) while logistic describes the slowing growth of populations at high densities (S-shaped)

Give the base model (i.e. equations) for each and define the terms.

Exponential

dN/dt=rN

dN/dt: rate of population change over time

N: current population

r: rate of increases

Logistic

dN/dt=rN(1-K/N)

1-K/N: The unutilized resource space

r: maximum intrinsic rate of increase

K: carrying capacity

Identify levels of r where the population is stable, growing and declining

r>0 birth rates exceed death rates

r=0 births and deaths are perfectly balanced

r<0 death rates exceed birth rates

What are the assumptions of those models?

Exponential

unlimited resources

constant envirnment

no limitations

no migration

Logistic

constant carrying capacity

density-dependent

instantaneous response

What distinguishes semelparity and iteroparity in life histories? Give examples.

semelparity: reproduce once and die (salmon)

iteroparity: repeated reproduction, produce offspring repeatedly(polar bears)

Define biological community

A group of populations of various species living close enough for potential interaction

What is the competitive exclusion principle?

Two species competing for the same limiting resources cannot coexist in the same place

How does resource partitioning allows species coexistence?

By using differentiation of ecological niches, embalming similar spices to coexist in a community

What is the difference between a fundamental and a realized niche?

fundamental: is the niche potentially occupied by that species

realized: is the niche actually occupied by that species

Give an example of an animal defense adaptation against predators

hiding, fleeing, forming herds or schools, self-defense, and alarm calls

How is herbivory different from predation?

A positive-negative its the interaction in which an herbivore eats parts of a plant or alga

Describe parasitism,

A +/-, the parasite derives nourishment from another organism, its host

Describe mutualism (obligate and facultative) a

+/+ is a interspecific interaction that benefits both species

obligates: partners are strictly dependent on each other

facultative: where both species benefit but can survive independently

Describe commensalism

+/0 One species benefits and the other is neither harmed nor helped

What two components make up species diversity?

species richness and relative abundance

Why is high species diversity generally considered beneficial for ecosystems?

creates resilient, productive ecosystems

What is a keystone species?

exert strong control on a community by their ecological roles or niches

What is ecological succession? Contrast primary and secondary succession

It is the sequence of community changes after a disturbance

Primary: occurs where no soil exists when succession begins

Secondary: begins in an area where soil remains after a disturbance

What role do disturbances play in community structure?

low levels: allow dominant species to exclude less competitive species

high levels: exclude many slow-growing species

What distinguishes an ecosystem from a community?

Is a community of organisms & their interactions with abiotic envirnment

What is primary production?

The rate at which plants, algae, and certain bacteria convert inorganic carbon into organic matter

How does a food web differ from a food chain?

Web: A network of food chains that illustrate how organisms in a community feed on each other

Chain: path of energy & matter being transferred from one organism to another

What organisms are always at the base of a food chain?

primary producers

What happens to energy as it moves up trophic levels? Why is energy transfer between trophic levels inefficient?

It enters as sunlight and leaves as heat

How do decomposers contribute to nutrient cycling?

Act as nature’s recycling system by breaking down dead plants, animals, and waste

What are the three levels of biodiversity?

Genetic: genetic variation within/between populations

species: number of species in an ecosystem or across the biosphere

ecosystem: variety of ecosystems on Earth

Define an endangered species

In danger of becoming extinct throughout all/much of its range

What are the major threats to biodiversity?

Habitat loss

introduces species

overharvesting

global change

How do introduced species threaten native species?

Humans move species to new areas with now more competition

Soil Horizons

distinct, horizontal layers that make up soil profile, running parallel to the Earths surface

Humus

Remains of dead organisms & organic matter

Top Soild

inorganic, organic, and living components

phototropism

directional growths or bending of an organism in response to a light stimulus

Blue-light photoreceptors

phototropism and slow hypocotyl elongation

phytochromes

red light that can do seed germination, shade avoidance, and photoperiodism

biotic factors

all the living or once-living components of an ecosystem that shape their environment

abiotic factors

the non-living physical and chemical components of an ecosystem that shape its environment

immigration vs emigration

Emigration: leaving your home

immigration: entering/settling in a new home

per capita birth rate

Birth rate= total live birth/total population

per capita death rate

the average number of deaths per individual in a population over a specific time period

species richness

the total count of different species in a specific area, community, or ecosystem

Relative abundance

measures how common a specific item, species, or isotope is compared to other within a larger set

Tropic levels

describe an organisms specific position in a food chain or web determined by its feeding behavior and how it obtains energy

Primary, secondary, and tertiary consumers

primary: also known as herbivores

secondary: are carnivores or omnivores

tertiary: carnivores that eat other carnivores

eutrophication

the over-enrichment of water by nutrients primarily nitrogen and phosphorus

Energy pyramid

graphical model illustrating the flow of energy through an ecosystem's different feeding stages, called trophic levels

trophic efficiency

The percentage of energy transferred from one level of a food chain to the next

biogeochemical cycles

The continuous pathway by which essential elements and compounds (like carbon, nitrogen, and water) move through Earth's living (biotic) and nonliving (abiotic) components

Movement corridor

a continuous strip of natural habitat that connects separated wildlife populations