ECOL Midterm 1

Give two examples of prezygotic barriers.

1. Barriers in space or time: individuals never meet. 2. Behavioral isolation: females (or males) reject potential mates from other populations/species.

Give two examples of postzygotic barriers.

1. Hybrid inviability: hybrids do not develop or die before birth. 2. Hybrid sterility: hybrids survive but are sterile.

Which two elements make up water?

2 Hydrogen, 1 Oxygen

What is a detritivore?

Eats large amounts of detritus and excrete nutrients. They consume material to break it down

Define primary consumers

Eats plants (herbivores)

Define secondary consumers

Omnivores or carnivores that eat herbivores

What are the six main macronutrients? Why are they important?

Nitrogen, phosphorus, sulfur, potassium, calcium, magnesium. Required in larger quantities and dissolve in water.

Do prokaryotes have a nucleus?

No

Does rotating a branch on a phylogenetic tree change the evolutionary information?

No

Is all the water on earth drinkable?

No, most of it is saline (salt water)

What is allopatric speciation?

Occurs when a physical barrier arises, preventing interbreeding between populations. Separation in SPACE.

What is sympatric speciation?

Occurs when there is no physical barrier, but interbreeding between populations stops for another reason. Separation in TIME.

What is polarity?

Unequal sharing of electrons in water molecules

What are two problems with the biological species concept?

1. Appearance alone may not always indicate members of the same species. 2. It is difficult to determine which individuals actually interbreed.

How many years is earth's geologic timescale?

4.6 billion years

How much of the earth's surface is water?

71%

How much of the earth's water is saline versus freshwater?

97% saline, 3% freshwater

What is a monophyletic group?

A clade is the most recent common ancestor and ALL its descendants. Members are more closely related to each other than to any organisms outside the group

What is a genotype?

A description of the genetic basis of an individual, either entirely or for a specific trait.

What is a phylogenetic tree? What information does this tree convey?

A diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor(s)

What is a eukaryote?

A eukaryote is an organism consisting of cell(s) in which genetic information is contained within a distinct nucleus.

What is a paraphyletic group?

A grade shares the most recent common ancestor and SOME of its descendants. Some members are more closely related to organisms outside the group.

What is a species?

A group of individuals capable of interbreeding and reproductively isolated from other groups.

What is a trophic level?

A level in a food chain

What is a clade?

A monophyletic group that includes common ancestors and ALL descendants.

What is a grade on a phylogenetic tree?

A paraphyletic artificial grouping with a common ancestor but not all descendants.

What is a postzygotic barrier?

A postzygotic barrier is a barrier that occurs after zygote formation.

What is a prezygotic barrier?

A prezygotic barrier is a barrier that prevents the formation of a zygote.

How is a species different from a population?

A species is a group of individuals capable of interbreeding, while a population is a group of individuals of the same species in a given area.

What is the biomass pyramid?

A way to measure productivity, it measures the ecological efficiency and proportion to the next level.

What is a zygote?

A zygote is the first cell of a new organism, formed by the fusion of the egg and sperm nucleus.

How much energy is actually transferred from one trophic level to the next?

About 10% energy is transferred from one trophic level to the next.

How does an allele relate to a gene?

Alleles are different forms of genes.

What is a theory?

An explanation of a natural phenomenon supported by many observations in which the same results occur over and over

What is a heterotroph?

An organism that gets its energy by consuming other organisms

What is an autotroph?

An organism that produces its own food from inorganic molecules

Why is this first extinction considered 'unofficial' and not part of the 'Big 5'?

Anaerobic organisms did not go extinct, many just died

Define a plant

Autotrophic, eukaryotic, multicellular, generally adapted to a terrestrial existence, has a cell wall, and takes in carbon dioxide (CO2)

What is the current system used for naming organisms? Why is it preferred to the outdated system?

Binomial system creates a complete species name by using the Genus, specific epithet, and Author. The outdated version is way too long and complicated.

What is a decomposer?

Break down large organic molecules into smaller organic molecules that can be reabsorbed. They decompose nutrients on a molecular level

What type of energy do autotrophs use?

Capture sunlight energy and are self-nourishing or producers

What is evolution? Is it the same as natural selection?

Change in allele frequency over time; a mechanism of evolution.

Where does most photosynthesis occur?

Chloroplasts

Which soils have the highest nutrient availability? Why?

Clay and silt due to small particle size and less space between particles.

What does a node represent on a phylogenetic tree?

Common ancestor at the time of split where each node represents a speciation event

Define tertiary consumers

Consumer that usually eats other carnivores

What is photosynthesis? What is the equation for photosynthesis?

Conversion of CO2 into organic compounds using water and light energy. CO2 + H2O + light energy → glucose + oxygen.

What is ecological efficiency?

Describes the efficiency with which energy is transferred from one trophic level to the next.

What are two ecosystems that have very poor nutrient availability?

Desert and tropical rainforests.

What is variation? Is it always genetic?

Differences in traits; can be genetic or environmentally based.

What does it mean to be diploid versus haploid?

Diploid has two sets of chromosomes; haploid has one set of chromosomes.

What are the three parts of a complete species name?

Domain, Genus, Species

What is the first law of thermodynamics?

Energy cannot be created or destroyed, it can only change form

What is the Endosymbiotic Theory?

Eukaryotes evolved when different types of free-living prokaryotes were incorporated inside larger eukaryotic cells.

What is transpiration?

Evaporation of water through leaf pores.

What is transpiration and how does it use cohesion and adhesion?

Evaporation through leaves, water molecules pulled up due to cohesion and adhesion.

What did cells with mitochondria and chloroplasts evolve into?

Evolved into algae.

What did cells with mitochondria evolve into?

Evolved into animals, fungi, and protozoans.

What cause do all the 'Big 5' extinctions have in common?

Failure to adapt to environmental changes

What is the difference between a food chain and a food web?

Food chain links trophic levels, shows who consumes who, and describes the species occupying each trophic level in an ecosystem. Food web is more accurate than a chain.

What is an allele? What is allele frequency?

Form or variation of a gene; proportion of allele in a population.

What are stromatolites and when did they first form?

Fossils formed in Archean Eon by cyanobacteria

What evidence has been used to support the theory of continental drift?

Fossils of same species found on widely separated continents, rocks of the same type, structure, and age are found on opposite sides of the Atlantic Ocean, ancient glacier grooves and rock deposits are found on different continents close to the equator, ancient coral reefs are currently found in cold locations

What is Gross Primary Productivity?

GPP is the 1% that is absorbed by the producer. It is the overall rate of energy captured by the producer.

What is a population?

Group of potentially interbreeding individuals of the same species.

What is a polyphyletic group?

Groups that share NO common ancestor but may have similar characteristics.

Define an animal

Heterotrophic, eukaryotic, multicellular, takes in oxygen (O2) with few exceptions, specialized sensory organs

What does it mean if two groups are polyphyletic?

If two groups are polyphyletic they share NO common ancestor but may have similar characteristics

What happened during the Proterozoic Eon that led to the first mass extinction?

Increase in atmospheric oxygen (O2) toxic to anaerobic biosphere

What are the four important features necessary in a scenario of natural selection?

Individuals in a population vary in some trait, at least some variation is genetically-based (=heritable), the trait affects survival or reproduction, and differential survival or reproduction leads to changes in trait frequency in the population.

What are adaptations?

Inherited traits favored by natural selection.

Where do energy inputs come from? Where do energy outputs come from?

Inputs come from the sun, outputs radiate from the Earth

What are the three processes by which new species form?

Isolation/separation, genetic divergence, and reproductive isolation.

What role did heavy bombardment play in the origins of the planet and life?

Keeps crust molten, brings components for life

What is continental drift?

Land masses changing position over time

What is LUCA?

Last Universal Common Ancestor

What are Banded Iron Formations and how did they form?

Layers of deposits formed by dissolved iron reacting with O2

Approximately when did life on earth begin? Was it prokaryotic or eukaryotic?

Life on earth began approximately 3.5 billion years ago with prokaryotes.

What pieces of evidence are used in determining if fossils are eukaryotic?

Looks like modern algae/fungi, large size, defined cytoskeleton

What are three components that are essential to life that arose during the Hadean Eon?

Magnetic fields, moon, heavy bombardment

What are three ways animals have adapted to nutrient limitations?

Mechanistic, resource partitioning, metabolic.

What is Net Primary Productivity? What is its relationship to GPP?

NPP accounts for the energy used for metabolism and maintenance. NPP (net) is always lower than GPP (gross) because the energy used by the organism must be subtracted.

What is endosymbiosis?

The process by which early eukaryotes gain chloroplasts and mitochondria. It is a symbiotic relationship in which one organism lives inside another.

Approximately how much light energy is captured by plants?

Only about 1% makes it into the plant.

What is taxonomy?

Organizing organisms through a hierarchy of ranks

Where do people fit into trophic levels?

People can occupy multiple consumer trophic levels.

When did photosynthesis begin? In what kind of organism?

Photosynthesis began 2.8 billion years ago in early cyanobacterium, a later prokaryote.

Define producers

Photosynthetic organisms - autotrophs (gets energy from the sun and sequesters carbon)

What are epiphytes and how do they help plants retain moisture?

Plants growing on other plants, deriving moisture from air or debris.

How are plants able to absorb different types of light energy?

Plants have specialized molecules that are able to absorb some light wavelengths.

How does polarity work to dissolve substances in water?

Polar water molecules attract other polar molecules to dissolve them

When did prokaryotes arise? Eukaryotes? Mitochondria? True nuclei? Organelles?

Prokaryotes arose 3.5 billion years ago, eukaryotes arose 2.8 billion years ago, mitochondria, true nuclei, and organelles also arose 2.8 billion years ago.

What are the basic steps of the Scientific Method?

Question, background, hypothesis, test, analyze, report

What are four adaptations plants have come up with to deal with nutrient limitations?

Root allocation, succulent leaves and waxy cuticle, carnivory, spines and hairs.

What is the basic unit of the International Code of Nomenclature?

Species is the smallest unit of taxonomy

What is crypsis? What is an example of crypsis?

The ability of organisms to adapt their body color to match their backgrounds. An example of crypsis is a chameleon changing its skin color to blend with its surroundings.

What is the biological species concept?

The biological species concept defines a species based on the ability to interbreed.

How is the biomass pyramid different from the energy pyramid in aquatic ecosystems?

The biomass pyramid is upside down in aquatic ecosystems.

Where does the common ancestor go on a phylogenetic tree?

The common ancestor is at the root of each node

Why are plants green?

The green wavelengths are outside of the action spectrum, so nothing is really being absorbed. The green wavelengths are then reflected back.

How are traits represented on a phylogenetic tree?

The lineage continues to evolve independently as different traits (represented by red lines) arise (or some traits are lost)

What happens to the light energy that is NOT captured by plants?

The other 99% of light energy is absorbed by other animals, reflected, or passes through.

What is the basal part of a phylogenetic tree?

The root or earliest ancestor

What are the three domains of life?

The three domains of life are Domain Bacteria, Domain Eukarya, and Domain Archaea.

What is temporal isolation?

Type of reproductive isolation where populations are separated in time.

What is bedrock?

Underlying geology.

What is soil porosity and why does it vary?

Variation in soil's ability to hold nutrients due to particle size and room between particles.

What are the four mechanisms of evolution?

Variation, heritability, some genotypes produce more surviving offspring, selection.

What were the main causes of the 'Big 5' mass extinctions?

Volcanic eruptions, sea level falls, impact events, climate changes

What is cohesion?

Water molecules sticking to each other, creating surface tension

What is capillary action?

Water moving up the stem in xylem tissue system.

What is adhesion?

Water sticking to other things

What is an open energy system? Give an example.

When energy flows to AND from the Earth. Can be the flow of energy like boiling a pot of water.

What is ecosystem productivity?

When light energy comes from the sun and is absorbed by photosynthetic, primary producers. This is the rate at which energy is added to the bodies of a group of organisms as biomass.

What is a closed energy system? Give two examples.

When nutrients cycle WITHIN the earth. Nitrogen cycle and water cycle.

When is speciation considered complete?

When two populations or species can no longer interbreed when they encounter each other.