Final Exam Study Guide

Question 1

What is the definition of a population?

Answer 1

A population is defined as a group of individuals of the same species living and interbreeding within a given area. Members of a Population often rely on the same resources, are subject to similar environmental constrains, and depend on the availability of other members to persist over time.

Question 2

How do births, deaths, emigration and immigration affect population growth through time? What controls the growth of a closed population?

Answer 2

Population changes is governed by the balance between birth rates and death rates. The death rate and brith rate must be the same to keep the population stable. If the death rate is higher than the brith rate the population will decrease, while the population will grow if the death rate is smaller than the birth rate.

Question 3

What is the equation for exponential population growth?

Answer 3

The equation for the exponential population growth is dN/dt = rN where r = (b-d)

Question 4

How does the rate of population growth (dN/dt) change with population size (N) in this equation?

Answer 4

The rate of population increase goes up with N.

Question 5

What does a negative intrinsic growth rate tell us about per capita birth and death rates?

Answer 5

A negative value means that the population is smaller at the end, so negative values describe declining populations and the tangent to the curve will have a negative slope.

Question 6

What does a positive intrinsic growth rate tell us bout per capita birth and death rates?

Answer 6

A positive value means that the population is larger at the end of the instant than at the beginning (no matter how tiny the difference is) and so the population is growing and the tangent line has a positive slope.

Question 7

What is the difference between density-dependent versus density-independent birth and death rates?

Answer 7

Density-dependent regulation can be affected by factors that affect birth and death rates such as competition and predation. Density-independent regulation can be affected by factors that affect birth and death rates such as abiotic factors and environmental factors, i.e. severe weather and conditions such as fire.

Question 8

What is the logistic growth equation for populations? (Be sure that you are able to understand its components and able to write it out from memory.)

Answer 8

The logistic growth equation is dN/dt = rN((K-N)/K) where k is the carrying capacity and N is the population size

Question 9

What is the role of carry capacity (K) in the logistic growth equation? What happens to population growth rate (dN/dt) when the population size (N) is greater than or less than the carrying capacity (K)?

Answer 9

When the population size is small, the population increases exponentially. However, as population size nears carrying capacity, the growth decreases and reaches zero at K

Question 10

What forms of competition does the Lotka-Voltera population growth model include?

Answer 10

The Lotka–Volterra model is frequently used to describe the dynamics of ecological systems in which two species interact, one a predator and one its prey.

Question 11

What is an ecological community?

Answer 11

A set of occurring species in a given time and place. A multi species population.

Question 12

What 3 broad processes / mechanisms control the
presence of absence of species at any given location relative to the ~2 million possible named species on Earth?

Answer 12

Historical Filter: Evolved in a different region, never dispersed to the site.
Physiological Filter: Can it grow and reproduce
Biotic Filter: Does it successfully compete or avoid competition, can it defend itself, is it resistant to
disease, etc

Question 13

What is a Central Aim of Community Ecology?

Answer 13

A Central Aim of Community Ecology is to quantify how communities are structured/ organized by indicating how species interact with one
another.

Question 14

What is the difference between species richness, evenness, and diversity?

Answer 14

Species Richness: The total number of species in a community
Species Evenness: The relative abundance of species in a community
Species Diversity: The total number of species and their relative abundance; combination of Richness and Evenness

Question 15

What is the ultimate source of energy used to sustain growth of an ecological community?

Answer 15

The vast majority of energy in food webs originates from the sun. Energy is not recycled in ecosystems and each ecosystem requires a continuous input of energy to sustain it. There is some energy transformed at each level of the food chain or food web in an ecosystem.

Question 16

What are trophic levels?

Answer 16

Trophic levels: The number of hierarchical levels in a community that share the same “function” within a food chain / web.

Question 17

Why is there more total biomass in lower trophic levels than higher trophic levels?

Answer 17

With less energy at higher trophic levels, there are usually fewer organisms a s well . Organisms tend to be larger in size at higher trophic levels, but their smaller numbers result in less biomass. Biomass is the total mass of organisms at a trophic level.

Question 18

What is the difference between bottom-up and top-down controls on community structure?

Answer 18

The bottom-up control is driven by the presence or absence of the producers in the ecosystem. Changes in their population will affect the population of all the species in the food web, and thus, the ecosystem.

Question 19

Can the behavior of predators influence the diversity of primary producers within a community? Is this a direct or indirect interaction?

Answer 19

An increase of top predators causes a decrease of intermediate consumers and benefits primary producers. The indirect positive effect on primary producers may also occur if the intermediate consumers reduce their foraging in the presence of top predators. In the top-down control, the populations of the organisms lower trophic levels (bottom of the pyramid) are controlled by the organisms at the top. This approach is also called the predator-controlled food web of an ecosystem

Question 20

What is meant by the phrase Trophic Cascade?

Answer 20

Trophic cascades are powerful indirect interactions that can control entire ecosystems. Trophic cascades occur when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level.

Question 21

What is a keystone species?

Answer 21

A keystone species is a species that has a disproportionately large effect on the community relative to its biomass.

Question 22

What is an Ecosystem?

Answer 22

An ecosystem is a system that environments and their organisms form through their interaction.

Question 23

What are some of the major materials (i.e. essential elements) of life?

Answer 23

Hydrogen, oxygen, carbon, nitrogen calcium, phosphorus, and sulphur.

Question 24

Which of the following major elements Ca, N, P, S are derived from weathered rock? Which comes from the atmosphere?

Answer 24

The major element derived from weathered rock is sulphur. The element nitrogen comes from the atmosphere.

Question 25

What are two major ways in which predators can influence Plant Community Composition and overall Ecosystem Function?

Answer 25

Predators mainly contribute to ecosystem functions by regulating prey populations and subsequent cascading effects on the lower trophic groups and associated process rates. In plant–herbivore–predator systems, predators can indirectly enhance plant production by reducing herbivore populations

Question 26

What were the major conclusions of the research by Oswald Schmitz entitled “Effects of Predator Hunting Mode on Grassland Ecosystem Function”?

Answer 26

Herbivore response to a predictable sit-and-wait hunting strategy led to lower rates of Carbon inputs into the ecosystem. Herbivore response to a predictable sit-and-wait hunting strategy led to lower rates of nutrient cycling between organic and inorganic forms.

Question 27

In general, what is the observed relationship between biodiversity and annual net primary productivity?

Answer 27

Biodiversity correlates directly to productivity of an ecosystem. The greater the biodiversity, the greater the productivity and stability of the ecosystem

Question 28

What is a species Niche? What does the phrase Niche complementarity mean?

Answer 28

The niche complementarity hypothesis states that niche differences among species, such as interspecific differences in resource use, should lead to more efficient acquisition of limiting resources and therefore higher productivity

Question 29

How does this relate to the observed positive relationship between biodiversity and net primary productivity (i.e. the rate of increase in plant biomass)?

Answer 29

The greater the number of species and number of interactions/complexity, the greater the biodiversity and ability of an ecosystem or habitat to survive and adapt to environmental pressures. Ecological productivity is a measure of the rate of generation of biomass or carbon per area of habitat or ecosystem.

Question 30

What is a monophyletic group?

Answer 30

A monophyletic group is a group of organisms that share a common ancestor.

Question 31

What is convergent evolution?

Answer 31

Convergent evolution occurs when organisms that aren’t closely related evolve similar features or behaviors, often as solutions to the same problems.

Question 32

What is homology?

Answer 32

Homology is the similarity of the structure, or development of different species of organisms based upon their descent from a common evolutionary ancestor.

Question 33

What is analogy?

Answer 33

Analogy is the similarity of function and superficial resemblance of structures that have different origins.

Question 34

What is the order of the classification of organisms?

Answer 34

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 35

What is the difference between speciation and natural selection?

Answer 35

Natural selection explains how genetic traits of a species may change over time. This may lead to speciation, the formation of a distinct new species.

Question 36

What are the four mechanisms of evolution?

Answer 36

The four mechanisms of evolution are natural selection, mutation, genetic drift, and gene flow

Question 37

What is the definition of evolution?

Answer 37

Evolution is the processes by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

Question 38

What is plasticity?

Answer 38

Plasticity is generally defined as the capacity of an individual organism to alter its behavior, gene expression, and or morphology in direct response to changing environmental conditions.

Question 39

What is the difference between allopatric speciation and sympatric speciation?

Answer 39

Allopatric speciation is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as a mountain, building, or social changes such as emigration. Sympatric speciation is speciation that occurs when biological populations of the same species become two different species while both continue to inhabit the same geographic region.

Question 40

What is the difference between post zygotic isolation pre zygotic isolation?

Answer 40

Prezygotic barriers act before fertilisation, ensuring preferential acceptance of conspecific pollen. Postzygotic barriers act after fertilisation, resulting in hybrid inviability and hybrid breakdown that reduces or prevents reproduction in the next generation.

Question 41

Describe directional selection.

Answer 41

Directional selection is defined as the change in a phenotype or genotype of a population in one direction away from the mean (average) in a particular environment over time.

Question 42

Describe stabilizing selection

Answer 42

Stabilizing selection is a form of natural selection wherein individuals with moderate or average phenotypes are more fit (more likely to survive and reproduce). This form of selection picks against phenotypic extremes (e.g. the largest and the smallest are less fit).

Question 43

Describe disruptive selection.

Answer 43

Disruptive selection occurs when both extreme traits are favored in an environment. Disruptive selection increases genetic and phenotypic diversity in a population, since more than one phenotype, or physical trait, is favored. As a result, disruptive selection is sometimes called diversifying selection.

Question 44

What makes Eukaryotes distinct from Archaea and Bacteria?

Answer 44

Archaea and bacterial cells lack organelles or other internal membrane-bound structures; unlike eukaryotes, archaea and bacteria do not have a nucleus separating their genetic material from the rest of the cell.

Question 45

What are the 5 characteristics that are shared by all land plants?

Answer 45

All land plants share the following characteristics: alternation of generations, with the haploid plant called a gametophyte, and the diploid plant called a sporophyte; protection of the embryo, formation of haploid spores in a sporangium, formation of gametes in a gametangium, and an apical meristem.

Question 46

What process produce haploid cells from diploid cells?

Answer 46

Sexual reproduction requires that diploid organisms produce haploid cells that can fuse during fertilization to form diploid offspring. The process that results in haploid cells is called meiosis.

Question 47

How does pollination differ from fertilization?

Answer 47

Pollination is a physical process in which movement of pollen grains are attained by certain physical factors. Fertilization is a biochemical process.

Question 48

What is the difference between an organic and inorganic compound?

Answer 48

Organic compounds are derived from or produced by living organisms and have carbon-hydrogen covalent bonds. Inorganic compounds are derived from nonliving components, and generally have ionic bonds, lack carbon-hydrogen bonds, and rarely, if ever, contain any carbon atoms.

Question 49

What are the two types of parasitic plants?

Answer 49

All parasitic plants have evolved from non-parasitic species. Some are only partially parasitic. These plants are known as hemiparasites and can photosynthesise but also drain water and nutrition from their hosts. Other parasitic plants, known as holoparasites, cannot photosynthesise and depend on their hosts for food.

Question 50

What are the three major groups of Bilaterian animals?

Answer 50

Deuterostomia, Ecdysozoa and Lophotrochozoa

Question 51

What are the five major groups or animals?

Answer 51

Porifera: The phylum Porifera comprises the sponges. Sponges are simple invertebrate animals that live in aquatic habitats. Although the majority of sponges are marine, some species live in freshwater lakes and streams
Placozoa: Placozoa is a phylum of marine and free-living animals. They are simple blob-like animals without any body part or organ, and are merely aggregates of cells.
Ctenophores: Ctenophora comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming, and they are the largest animals to swim with the help of cilia.
Cnidaria: Cnidaria is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in fresh water and marine environments, including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites
Bilateria: A major division of the animal kingdom comprising all forms with a bilaterally symmetrical body plan (that is, their left and right sides are mirror images, or nearly so) and organ systems that develop from three tissue layers

Question 52

In what order did the following traits evolve in the lineage leading to placental mammals? vertebral column, jaws/mineralized skeleton, lungs, lobed fins, legs, amniotic egg, milk, live birth.

Answer 52

Vertebral column , jaws, lungs, lobed fins, legs, amniotic egg, live birth, milk

Question 53

How do Monotremes and Marsupials differ from Eutherians?

Answer 53

Monotremes are organisms that lay eggs that hatch to give rise to young ones. Marsupials give birth to young ones who are very tiny and complete their development in the pouch of the mother. Eutherians are organisms that give rise to fully developed miniature young ones.