unit 4 exam

Question 1

What is a population?

Answer 1

group of individuals within the same species living in a particular space (have potential to interbreed)

Question 2

what is population ecology?

Answer 2

study of populations in relation to the environment and influences on population

Question 3

what are the 3 environmental influences population ecology can study

Answer 3

1. population size
2. age structure of individuals(different ages in environment)
3. density and distribution of individuals

Question 4

General Model of Populaion Growth

Answer 4

Nt+1 = Nt+ inflow - outflow

Question 5

what is the intrinsic rate of population growth?

Answer 5

Birth rate minus the death rate

Question 6

In a population of 1000 if there are 60 births what would be the birth rate?
A. 60
B. 0.06

Answer 6

0.06

Question 7

What is formula for exponential population growth?

Answer 7

dN/dt = r N

Question 8

what 4 factors contribute to density dependent birth and death rates?

Answer 8

-competition
-predation
-disease
-intrinsic social factors

Question 9

what is carrying capacity

Answer 9

maximum number of individuals that a specific area can support

Question 10

What is logistic population growth? what shape is the curve for logistic population growth?

Answer 10

occurs when a species is resource limited, as the population grows the birth rate slows. S shaped curve

Question 11

in the logistic population growth model the population declines as what is approached?

Answer 11

carrying capacity

Question 12

identify each of the following-
Bt
Nt
Et
It
Dt

Answer 12

-birth
-population
-emigration
-immigration
-death

Question 13

when thinking population growth when is population growth positive?

Answer 13

when the number of the population is lower than the carrying capacity

Question 14

what is an ecological community

Answer 14

a set of co-occurring species in a given time and place

Question 15

what are trophic levels?

Answer 15

The number of hiearchal levels in a community that share the same function within a food chain

Question 16

community interaction- predation (what is it?)

Answer 16

-asymmetrical interaction only the predator has direct benefit
-predators become more abundant as prey grows

Question 17

community interaction- competition (what is it?)

Answer 17

-resources become limited

Question 18

what is a keystone species?

Answer 18

species that has a disproportionately large effect on the community relative to biomass. They help maintain the ecosystem.

Question 19

organisms that only feed on photosynthetic forms of life are generally referred to as?

Answer 19

primary consumers

Question 20

what is a trophic cascade?

Answer 20

predators choices effect the prey population whether they are added or removed.

Question 21

what is primary productivity?

Answer 21

the rate of organic matter production

Question 22

what is an ecosystem?

Answer 22

organisms and biotic and abiotic factos interact to form a living environment

Question 23

what controls growth of a closed population

Answer 23

birth rate and death rate

Question 24

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

Answer 24

This means there are more deaths/emigrations and the population lowers. vice versa for positive

Question 25

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

Answer 25

Density-dependent birth and death rates are affected by environmental factors that change in relation to population size. independent are not

Question 26

What is the role of carry capacity (K) in the logistic growth equation

Answer 26

number of individuals a population can hold

Question 27

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

Answer 27

when greater than carrying the population decreases, when the number is less there is quicker growth

Question 28

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

Answer 28

intraspective- within the same species
interspective- different species competing for same resources

Question 29

What is a Central Aim of Community Ecology?

Answer 29

to understand how species diversity and the ecosystem changes over time.

Question 30

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

Answer 30

species richness is the amount of species in a community, species evenness is the spread of the species, and species diversity is the combination

Question 31

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

Answer 31

the sun

Question 32

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

Answer 32

different levels in the food chain, there is less energy and biomass towards the top

Question 33

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

Answer 33

bottom up limits resources and top down uses predation as a control

Question 34

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

Answer 34

they can do it directly by eating them or indirectly by suppressing primary consumers

Question 35

What is meant by the phrase Trophic Cascade?

Answer 35

trophic cascade is when a organism is removed or added and it affects the other organisms.

Question 36

What is a keystone species?

Answer 36

organism that maintains a ecosystems structure and balance

Question 37

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

Answer 37

Carbon,Calcium, Hydrogen,oxygen,sulfur,
Nitrogen, Phosphorus

Question 38

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

Answer 38

calcium, phosphorus come from weathered rock.

Nitrogen and sulfur come from atmosphere

Question 39

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

Answer 39

regulating prey population
dispersing nutrients and seeds

Question 40

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

Answer 40

predators using different hunting strategies, like stalking or ambushing, have distinct effects on herbivore populations and vegetation, ultimately shaping the health and stability of grassland ecosystems.

Question 41

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

Answer 41

when there are different plants and animals, plant growth rises due to competition lowering due to a resource not being crowded

Question 42

what are Quaternary consumers?

Answer 42

top of food chain usually carnivores

Question 43

what are tertiary consumers?

Answer 43

second level and eat secondary consumers

Question 44

What are secondary consumers?

Answer 44

eat primary consumers, 3rd level

Question 45

what are primary consumers?

Answer 45

on the second level and eat plants or algae to survive

Question 46

what are primary producers?

Answer 46

plants and algae on the first floor that are autotrophs an

Question 47

What 3 broad processes / mechanisms that influence the observed assemblage of species at any given location relative to the ~2 million possible named species on Earth?

Answer 47

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.