Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Academic Decathlon 2024-2025 > Science Section 3 - Part 1 > Flashcards

Science Section 3 - Part 1 Flashcards

1
Q

What is

Growth Rate

A

Percentage change of a population; depending on births, death, immigration, and emigration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is

crude birth/death rate

A

The number of births/deaths per 1000 people

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are

higher-income countries

A

Europe, North America, etc.—comprising 1.3 billion people.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are

lower-income countries

AKA less-developed

A

Haven’t or still are industralizing—comprises 6.7 billion people

Includes China and India

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How has the population difference between more- and less-developed countries changed?

A

Populations in less-developed countries have continued to grow rapidly (~1.5%), while richer countries’ have almost leveled off (~0.2%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is

environmental degradation

A

Pollution and other disturbances to the environment, human & natural

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What contributes to environmental degradation?

A

The extraction, processing, use, and disposal of human-used resources

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is

environmental impact

A

The population ✕ Resource use per person ✕ The impact of the resource

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How has energy use changed over time?

A

Energy use has increased at a greater rate than population growth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What was the population and fossil fuel consumption in 1960?

A
  • 3 billion people
  • 3,000 million tons of oil equivalent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What was the population and fossil fuel consumption in 1999?

A
  • 6 billion people
  • 7,900 million tons of oil equivalent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What was the population and fossil fuel consumption in 2022?

A
  • 8 billion people
  • 11,500 million tons of oil equivalent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How has energy use changed over time?

A

Energy use has increased at a greater rate than population growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is

fertility rate

A

The average number of children born to each woman through her child-bearing years, in a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is

replacement fertility rate

A

The average number of children per woman required to replace a population (maintain population levels); around 2.1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is

life expectancy

A

Years expected to live of an infant born in a given year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does life expectancy differ between men and women?

A

Women generally live longer than men, due to lifestyle choices and dangerous workplaces; gap is decreasing as women enter the workforce.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is

infant mortality

A

The number of deaths of infants (age<1) per 1000 births

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Does the USA 🇺🇸 have the lowest infant mortality?

A

Canada 🇨🇦, Finland 🇫🇮, Iceland 🇮🇸, Ireland 🇮🇪, Japan 🇯🇵, Sweden 🇸🇪, and France 🇫🇷 have rates 1–2 deaths per thousand lower than the US, which spends more per capital on healthcare.

FALSE. FALSE. FALSE. FALSE. FALSE. FALSE. FALSE. FALSE. FALSE.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How can you measure the level of healthcare of a country?

A

Life expectancy and infant mortality; NOT crude death rate, because that is a reflection of age (e.g. mexico (5) vs USA (9))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why does US 🇺🇸 infant mortality differ from comparable countries?

A
  • No Universal Healthcare
  • Less generous time off
  • Disparity in healthcare for minorities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the

%<15/%>65 figure

A

Percent of the population younger than 15
vs.
Percent of the population older than 65

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is an

age structure diagram

A

A chart showing a population divided by age groups and gender, representing age distribution.

Brainscapes charges to add images. Google it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a

population pyramid

A

A pattern appearing in lesser-developed countries, where fertilty rate is high; there are lots of young people, so the age-structure diagram looks like a pyramid.

Older countries get an inverse pyramid. Stable populations are columns.

Google it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the layers of the Earth?

A
  • The dense core
  • The mantle (80% of volume)
  • The crust on top
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the distribution of iron in the Earth?

A

The whole Earth is 35% iron, while only 6% of the lithosphere is iron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the

lithosphere

A

The first 100km of rock, where the rock cycle occurs and soil gets elements from; includes the crust and outer mantle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the elements of the atmosphere?

A
  1. Nitrogen (78%)
  2. Oxygen (21%)
  3. Argon (0.9%)
  4. CO₂ (0.036%, trace gas)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the

building blocks of life

A
  • Carbon
  • Hydrogen
  • Oxygen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the

macronutrients

A

>0.1% of dry weight:
* Nitrogen
* Phosphorus
* Potassium
* Calcium
* Sulfur
* Magnesium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the

micronutrients

A

<0.1% of dry weight:
* Manganese
* Iron
* Copper
* Zinc
* Molybdenum
* Chloride
* Boron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the

aqueous phase

A

A chemical form of an element that can dissolve in water (necessary for plants)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is

soil water

A

The water in pore spaces between soil particles that faciliate element exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What does weathering do?

A

Physical/chemical breakdown that releases elements from mineral rock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What does erosion do?

A

Moves elements around via wind/water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How is weathering accomplished?

A
  • Water
  • Wind
  • Acid Rain
  • Other chemicals
  • Roots of growing plants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Where are calcium, magnesium and potassium derived from?

A

Primarily rocks and decomposed vegetation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What rock types do calcium and magnesium occur in high concentrations?

A

Limestone, dolomitic limestone, and marble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What ecosystems are calcium and magnesium found in?

A

Those overlying limestone and some other rock type

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What elements did the dust storms of the ’20s and ’30s carry?

A

Calcium and magnesium, carried westerly into the central and eastern states

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What caused the dust bowls of the ’20s–’30s?

A

The topsoil was destroyed by:
* Heat
* Drought
* Wind
* Poor agricultural practices
* Other human land use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the gaseous component of sulfur?

A

Sulfur dioxide, SO₂

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What form of sulfur do plants take up?

A

The sulfate anion, SO²⁻₄; also comprises acid rain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is a natural atmospheric source of sulfur?

A

Volcanoes, which release the natural pool of sulfur in rocks and mineral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

TRUE OR FALSE

Sulfur deposition is higher than that of nitrogen

A

TRUE! Although air regulations have decreased it since 1995 in the US 🇺🇸

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

TRUE OR FALSE

Sulfate does not leach easily from soils and ecosystems

A

FALSE!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What are the benefits of soil?

A
  • Plants grow in it
  • Filters water
  • Bacteria, fungi, disgusting insects, other animals live in it; some very important decomposers
  • Filter some air/sewage pollution
  • Bonus: Food. Be grateful.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are

soil horizons

A

Layers of soil distinguished by physical/chemical/biological factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the

O horizon

A

Specifically the top layer in forests, consists of needles, leaves, woody material, animal bodies, animal droppings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is the

A horizon

A

Usually the top layer, consists of humus (organic material) and mineral soil that has been mixed together, by animals/plants/humans.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What is the

E horizon

A

Only exists in more acidic soils; chemicals have leached out, and is left light in color. Below the O or A horizon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is the

B horizon

A

Where chemicals accumulate from the O, E, and A horizons, along with elements that weathered in place. Always exists.

53
Q

What is the

C horizon

A

Least weathered, always occurs below B horizon. Similiar to the parent material (original soil material). Contains roots/microbes in humid regions; otherwise they extend only into the B horizon.

54
Q

What is

humus

A

Organic material in the soil from plant and animal matter

55
Q

What are

state variables (soil)

A

The factors that cause soil to progress and determine its nature:
* Parent material
* Climate
* Topography
* Organisms
* Time

56
Q

What is

bedrock

A

The solid rock underlying the soil. Usually synonymous with parent material; not when e.g. glaciers have spread a layer of sediment on top of the bedrock, separating the parent material.

57
Q

What is

parent material

A

The original rocky material from which the soil is derived; a state variable that determines the nature of the soil.

58
Q

How does climate affect soil formation?

A

A state variable; the sum of weather-related variables over time:
* Temperature increases weathering and soil formation
* Freeze-thaw cycle increases surface area for weathering
* Precipitation (also causes weathering) and temperature increases leaching
* Also influences the type of vegetation, and the rate of decomposition

59
Q

How does topography affect soil formation?

A

The surface configuration of a landscape; a state variable:
* Soils on steep slopes face erosion and landslides
* Landslides are hazardous to soil, ecosystems, and people
* Horizontal soils & those at the bottom of mountains tend to accumulate material
* Windward sides of mountains have more precipitation than the leeward sides

“Despite these well-known dangers, people continue
to build on such soils—often quite expensive structures—and seem surprised when they are destroyed.”

60
Q

What are

detrivores

A

Organisms that consume dead plant and animal matter

61
Q

What organisms account for 80–90% of biological activity in soils?

A

These eat plants (dead&alive), + animal waste (detritus); majority are detrivores. Bacteria liberate nitrogen & sulfur from the soil for plants to use.
* Fungi
* Bacteria/Archaea
* Protozoa (single-celled organisms, e.g. algae)

(detrivores: consume dead plants and animals)

62
Q

How many more detrivores than herbivores are there in the first 15cm of soil?

A

There are 10 times as many detrivores than herbivores.

(detrivores: consume dead plants and animals)

63
Q

In the temperate zone, what is the most important macrofauna?

(Macrofauna: Large (relatively speaking) animals)

A

Earthworms!
They can ingest 2–30 times their weight in soil every day! Also they:
* Extrete nutrient-rich organic matter, which improves soil quality
* Aerate the soil
* Improve water drainage
* Mix upper and lower layers of soil
* Are sensitive to acidic soil; do best in neutral pH

64
Q

How does soil change over time?

A

Time spent unfrozen influences soil development:
* New soil has very little separation into different horizons
* Soils develop horizons and characteristics over time
* Grassland soils in e.g. the Great Plains have very thick and nutritious and delicious A and B horizons that developed over hundreds of thousands of years

65
Q

What is

soil degradation

A

The loss of some or all of a soil’s ability to support plants

66
Q

What is

topsoil

A

Soil of the A or O horizons; can take centuries to replenish

67
Q

What are the causes of soil degradation

A
  • Erosion which carries away disturbed (by e.g. plowing) topsoil by water or wind
  • Compaction from machines
  • Nutrient depletion from intensive use
  • Irrigation
  • Chemical damage from e.g. pesticides
68
Q

How has soil degradation affected the world today?

A

Worldwide, there has been a 17% reduction in food production, most prevalent in Africa and Europe

69
Q

How is climate change affecting soil degradation?

A
  • Slightly warmer temperatures may increase decomposition
  • But dryer soils may slow decomposition
70
Q

TRUE OR FALSE

Soil in areas of extreme temperature/precipitation recover from soil degradation slowly.

A

TRUE!

71
Q

How much water is fresh water?

A

3%, most of which is in ice—only 1% of all water is potentially usable by humans and terrestrial organisms

72
Q

How much of Earth’s water is in lakes, rivers, reservoirs, the atmosphere, and within organisms?

A
  • only 0.009% in lakes, rivers, and reservoirs
  • perhaps 0.001% in the atmosphere
  • less than 0.0001% within organisms
73
Q

What is an

aquifer

A

Permeable layers of rock and sediment that hold water

74
Q

What is an

unconfined aquifer

A

An aquifer of porous rock (such as sandstone or other consolidated sediments) covered simply by soil.

75
Q

What is the

water table

A

The top of the area within an aquifer saturated with water

76
Q

What is an

aquiclude

A

An impermeable layer of clay that stops groundwater flowing from an aquifer; confines the aquifer

77
Q

What is a

confined aquifer

A

An aquifer confined from above and below by an aquiclude

78
Q

What is an

artesian well

A

A well drilled into a confined aquifer, which can have water flow without needing a pump

79
Q

What is one type of surface water that is fed by groundwater?

A

A spring; a small stream that “springs” out of an aquifer during wet seasons.

80
Q

What are the problems introduced by constructing an aqueduct in a desert/grassland?

A
  • Vegetation is disrupted
  • Soils are disturbed
  • Animal habitats are altered or destroyed
81
Q

How much water is lost due to leakage from old or damaged pipes in Jordan and the Occupied Territories of Israel?

A

As much as 55%

82
Q

Countries from the Middle East and North Africa are responsible for how much of the world’s fresh water produced through desalination?

A

More than 50%

83
Q

How is water desalinated through distillation, and what is its downside?

A

Water is evaporated, leaving behind salts; the steam is then condensed, producing pure water. This is, however, a highly energy intensive process.

84
Q

How is water desalinated through reverse osmosis, and what are it’s benefit and downside?

A

Water is forced through a membrane; the water passing through is very pure, and that left behind is highly salty brine. This is cheaper and more efficient than distillation, but brine released into the ocean can impact local ecosystems.

85
Q

In 2023, how much water was used in the US 🇺🇸?

A

408 billion gallons per day, or 1,300 gallons per person per day

Lower water use in most other countries

This includes domestic use, commercial and municipal use, irrigation for agriculture, and cooling for electrical power plants.

86
Q

How much of worldwide food production benefits from irrigation?=-

A

40%

87
Q

How much water does it take to produce one ton of grain?

A

1,000 tons

(250,000 gallons)

88
Q

What is

conventional irrigation

A

Water runs through a ditch alongside crops; 60% efficient

89
Q

What is

drip irrigation

A

A tube buried in the ground releases water slowly; 95% efficient, but more expensive.

90
Q

What is the effect of prolonged droughts on soil?

A

Can dessicate the soil to such an extent that the topsoil blows away; Land can’t be farmed for decades; Subject to erosion from flooding, as it can no longer absorb much water

des·ic·cate
/ˈdesəˌkāt/
verb
remove the moisture from (something); cause to become completely dry.

91
Q

What happens to an aquifer during a drought?

A

During droughts, aquifers usually contain some water. If an aquifer is overpumped though, it can be depleted, which may result in wells going dry.

92
Q

What happens when a well next to a coastline is overpumped?

A

Nearby saltwater will be drawn into the aquifer, saltifying the water in a process known as saltwater intrusion

93
Q

What are two recent major floodings?

A
  • West Bengal, India (2000) — destroyed >800k homes, killed hundreds of people
  • Worldwide flooding in 2023, driven by increasingly intense storms
94
Q

What are the environmental benefits of floods, hurricanes, and torrential rains?

A

When water overflows a river’s banks, nutrient-rich sediment improves the soil quality

95
Q

How many people do not have access to safe drinking water?

A

1–2 billion people, most in the developing world

96
Q

What are

point sources

A

A distinct, confined source of pollution

(such as a sewage pipe, or factory)

97
Q

What are

non-point sources

A

A diffuse (spread out) area from which pollution originates

(such as a parking lot, or farm)

98
Q

How can pathogens contaminate water?

A
  • Malfunctioning sewage treatment/septic systems (point)
  • Wildlife (non-point)
99
Q

What pathogens are common in the US 🇺🇸?

A
  • Hepatitis A, originating in unclean restaurants
  • The bacterium Cryptosporidium, which has caused outbreaks of gastrointestinal illness
  • The parasite Giardia, which has been transmitted into mountain waters by hikers
100
Q

What is

oxygen-demanding waste

A

Organic material in water (like leaves and twigs) that attract decomposing bacteria which deplete the oyxgen levels of the body of water

101
Q

What is

biochemical oxygen demand (BOD)

A

A measure of oxygen-demanding waste—the amount of oyxgen used over (usually) 5 days at (usually) 20℃ in a certain amount of water. Lower numbers mean more pristine water.

Sewage may have 200 mg of BOD per liter of water; natural water may have 5–20.

102
Q

How do different amounts of dissolved oxygen (in ppm, parts per million) affect ecosystems?

A

When dissolved oyxgen is high, BOD is low—and vice versa.

8–9ppm is high quality and ideal for aquatic ecosystems. ~4ppm is polluted, where fish have trouble functioning.

103
Q

What is

eutrophication

A

The excessive growth of algae due to an oversupply of nutrients; when the algae dies, BOD increases sharply and the fish population suffocates.

104
Q

How does nitrogen and phosphorus enter bodies of water?

A

Nitrogen: farm runoff, sewage treatment, acid precipation

Phosphorus: naturally occuring rocks and minerals, fertilizer, and in the past, detergents.

105
Q

What metals are among the most toxic water pollutants?

A
  • lead
  • copper
  • arsenic
  • mercury
106
Q

What is the US 🇺🇸’s largest source of mercury emissions?

A

Coal- and oil-fired power plants that deposit it on land and in waterways

107
Q

How does inorganic mercury (Hg) become methylmercury?

A

In wet, anaerobic environments such as wetlands, aquatic sediment, and temporarily saturated soils, bacteria convert mercury to methylmercury.

an·aer·o·bic
/ˌanəˈrōbik/
adjective

relating to, involving, or requiring an absence of free oxygen.
“anaerobic bacteria”

108
Q

How is methylmercury toxic to humans?

A

Damages the central nervous system, including coordination and the senses of touch, taste and sight, especially in embryos and small children

109
Q

What are

persistent organic pollutants (POP)

A

Toxic, industrial chemicals that persist for decades or longer, accumulating in organisms throughout food webs.

110
Q

What are

PCBs (polychlorinated biphenyls)

A

Highly toxic and carcinogenic, they were used in plastics and insulation until 1979; they are still present today.

111
Q

What was the cause of PCB pollution into the Hudson River?

A

A General Electric plant.

112
Q

What was done to clean up the Hudson River of PCBs?

A

The EPA ruled in 2002 that General Electric must pay for the dredging and removal of PCB-contaminated sediment from the river bed. Under a 2006 agreement, dredging began in 2009 and finished in 2015; it is still monitors for developments.

113
Q

What are sources of sediment that pollute water?

A
  • Housing & shopping development
  • Agriculture
  • Dam construction (sediment accumulates in unmoving water; runs downstream when mobile again)
114
Q

How does sediment water pollution affect ecosystems?

A

Sediment can clog fish gills and otherwise impede oxygen intake, particularly in bottom feeders (oysters, clams). Also stops sunlight, decreasing primary productivity.

115
Q

What causes thermal pollution in water?

A
  • When water moves slower
  • When water receives more sunlight
  • When water enters a shallower waterway
  • When used for cooling in industrial areas and power plants

(all humans causes)

116
Q

How does thermal pollution in water affect ecosystems?

A
  • reduces the possible amount of dissolved oxygen
  • Increases the respiration of organisms, further reducing dissolved oxygen
  • Stresses organisms, making them more susceptible to disease
  • May also affect reproduction
117
Q

What is the most notorious recent oil spill?

A

The Deepwater Horizon spill of 2010 in the Gulf of Mexico, which had 210 million gallons of oil cover ocean and coastlines, deeply impacting local ecosystems; cleanup continues to this day

118
Q

What are the cleanup methods of the Deepwater Horizon oil spill?

A
  • Floating booms to prevent oil from spreading
  • Skimming oil off the water’s surface
  • Chemical dispersants that break down oil until it’s small enough to be destroyed by sunlight and bacteria
119
Q

What are the sizes of microplastics and nanoplastics?

A

Smaller than 5mm and 0.0001mm respectively

120
Q

What is

gray water

A

Wastewater that is not from toilets, like from sinks or showers; can be used without treatment for e.g. watering lawns

121
Q

Properties of sewage?

A
  • High BOD
  • Pathogens
  • High levels of nitrates and phosphates
122
Q

How is sewage decomposed?

A
  1. Bacteria break down organic matter into CO₂ and inorganic compounds like nitrates and phosphates
  2. Dissolved oxygen levels are reduced in the water
  3. Eventually, BOD goes down, and oxygen levels recover

Sewage treatment plants replicate this process (usually quicker)

123
Q

What is

primary treatment

A

Removal of 40–50% of solid waste material from sewage; becomes sludge

124
Q

What is

sludge

A

Solid material from primary treatment that has settled and dried

125
Q

What is

secondary treatment

A

Acceleration of the natural breakdown of organic matter in sewage; by the end, roughly 85–90% of original pollutants have been removed. After disinfection, the water can be released into a body of water to join the water cycle.

126
Q

What is the history of water quality in the US?

🇺🇸?

A
  • 40–50 years ago, harbors and waterways were badly polluted
  • the Clean Water Act (passed 1972 and amended since then)
  • the Safe Drinking Water Act of 1986
  • the Water Resources Development Acts (1986–92)
127
Q

What did the Clean Water Act (1972) accomplish?

A
  • establishment of Water Quality Standards that limit the concentration of specific pollutants in major bodies of water
  • to achieve these Standards, established a Total Maximum Daily Loads for each pollutant—the maximum amount of each that can be discharged from any point or non-point source
128
Q

What did the Safe Water Drinking Act (1986) establish?

A

Established maximum containment levels (MCL) for 77 different elements or substances that is the enforceable amount that must not be exceeded.

enforceable, not harmful. reflects the feasibility and cost of reaching ‘good’ levels

Academic Decathlon 2024-2025 (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions