Exam II

Question 1

Human Population Growth

Answer 1

Increasing exponentially. Problems that arise from having this many people: Number of available resources, the rate of resource consumption, rates are regionally and economically based, the change in resources

Question 2

When/why did humans migrate out of Africa?

Answer 2

100,000 years ago, because of their hunter-gatherer lifestyle

Question 3

Pre-agricultural period

Answer 3

100,000 years ago. It took tens of thousands of years for human population to double. At the end of this period, there are 5-10 million people. Marked by a hunter-gatherer culture

Question 4

Agricultural period (Neolithic Revolution)

Answer 4

10,000 years ago. Plants and animals are domesticated
Doubling time is shortened to 1,000 years. There are 500 million people at the end of this period. Population density increases. Specialization of professions begins. High birth rates

Question 5

Industrial period

Answer 5

~1800. Huge technological advances are made. Fossil fuels begin to be used at huge rates. Advances in sanitation and medicine are achieved. Death rates decline. High birth rates maintained for some time

Question 6

Demographic transition model

Answer 6

Pretransition: a pre-economy lifestyle. Birth dates and death rates are high. Mortality transition: economic development occurs. Birth rates are high and death rates are low. Fertility transition: low birth and death rates. The US is at this stage. Stability transition: birth rates and death rates are approximately equal

Question 7

Age structure

Answer 7

Determined by survivorship and age-specific birth rate

Question 8

Point of crisis

Answer 8

Developed by Thomas Malthus. When the available resources can no longer carry any more of a population

Question 9

Effects of age structure

Answer 9

Too young puts pressure on resources; too old puts pressure on the workforce/economy

Question 10

Resource competition

Answer 10

Interspecific competition: competition between two or more species. Intraspecific competition: competition between multiple members of the same species

Question 11

Niche

Answer 11

Ecological niche: the role an organism fills within its habitat. Fundamental niche: the complete range of areas in which an organism could exist. Realized niche: the range in which an organism actually exists due to competition. Niche differentiation: potential competitors will coexist, division of resources will occur

Question 12

Competition mechanisms

Answer 12

Exploitation (quick consumption) and interference (denial)

Question 13

Trophic levels

Answer 13

First trophic level: primary producers (autotrophs)
Second level: primary consumers (herbivores)
Third level: secondary consumers (carnivores)
Fourth level: tertiary consumers (top carnivores)

Question 14

How much energy is available to the next trophic level?

Answer 14

Only ~10%

Question 15

Keystone species

Answer 15

A species that is highly important to a food web

Question 16

Trophic cascade

Answer 16

When a change in one trophic level has effects in other trophic levels

Question 17

Pools

Answer 17

Where matter resides in an ecosystem

Question 18

Flux

Answer 18

The rate at which matter moves

Question 19

Mass-balancing accounting

Answer 19

The process that accounts for the abundance for an element in an ecosystem

Question 20

Capital

Answer 20

The total mass of an element in the pool

Question 21

Equilibrium

Answer 21

When capital in a pool remains constant

Question 22

Residence time

Answer 22

Average time an element stays in a pool

Question 23

Cycling time

Answer 23

Average time it takes an element to move through the cycle

Question 24

Hydrological cycle

Answer 24

Energy of solar radiation and gravity drive the cycle. Evaporation, transpiration, and precipitation all involved. After precipitation, water can return to the atmosphere via evaporation or transpiration, percolate through soil/rock to become groundwater (aquifer), or join other bodies of water

Question 25

Where is most carbon found?

Answer 25

Most carbon is found in sedimentary rocks,

Question 26

Nitrogen cycle

Answer 26

Nitrogen is the most abundant element in the atmosphere. It enters the biosphere through nitrogen fixation (bacteria convert N2 to NO3-). Soil bacteria carry out nitrification (NO3- to NO2-). Ammonification occurs (NO2- to NH3)

Question 27

Long-term climate patterns

Answer 27

In the past 10,000 years, Earth has gone through periods of ups and downs. In the past 1,000 years, Earth has warmed, cooled, and warmed again

Question 28

Pleistocene

Answer 28

Occurred two million years ago. The cycles of this period lasted ~100,000 years each. 800,000 years ago, a cold period brought severe glaciers, these glaciers covered most of North America.The most recent cool period took place from 110,000 to 12,000 years ago

Question 29

Holocene

Answer 29

Started 10,000 years ago. The Earth is in a warm interglacial period

Question 30

The Little Ice Age

Answer 30

Took place from 1000-1300 CE

Question 31

Neanderthals

Answer 31

Neanderthals lived in Europe during the Ice Age. They lived 130,000 years ago. They had short, squatty bodies and large sinuses

Question 32

Forecasting global warming

Answer 32

Global circulation models (GCMs) forecast climate change and are checked by the process of backcasting. Three baselines: today’s world (0° change), business as usual (4°C increase by 2100), sustainable world (1.8° increase by 2100)

Question 33

Committed warming

Answer 33

0.1°C per decade