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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

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2
Q

What is

crude birth/death rate

A

The number of births/deaths per 1000 people

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3
Q

What are

higher-income countries

A

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

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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

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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%)

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6
Q

What is

environmental degradation

A

Pollution and other disturbances to the environment, human & natural

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7
Q

What contributes to environmental degradation?

A

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

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8
Q

What is

environmental impact

A

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

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9
Q

How has energy use changed over time?

A

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

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10
Q

What was the population and fossil fuel consumption in 1960?

A
  • 3 billion people
  • 3,000 million tons of oil equivalent
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11
Q

What was the population and fossil fuel consumption in 1999?

A
  • 6 billion people
  • 7,900 million tons of oil equivalent
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12
Q

What was the population and fossil fuel consumption in 2022?

A
  • 8 billion people
  • 11,500 million tons of oil equivalent
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13
Q

How has energy use changed over time?

A

Energy use has increased at a greater rate than population growth

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14
Q

What is

fertility rate

A

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

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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

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16
Q

What is

life expectancy

A

The average time that an infant born in a year is expected to live

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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.

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18
Q

What is

infant mortality

A

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

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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.

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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))

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21
Q

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

A
  • No Universal Healthcare
  • Less generous time off
  • Disparity in healthcare for minorities
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22
Q

What is the

%<15/%>65 figure

A

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

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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.

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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.

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25
Q

What are the layers of the Earth?

A
  • The dense core
  • The mantle (80% of volume)
  • The crust on top
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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.

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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

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28
Q

What are the elements of the atmosphere?

A
  1. Nitrogen (78%)
  2. Oxygen (81%)
  3. Argon (0.9%)
  4. CO₂ (0.036%, trace gas)
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29
Q

What are the

building blocks of life

A
  • Carbon
  • Hydrogen
  • Oxygen
30
Q

What are the

macronutrients

A

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

31
Q

What are the

micronutrients

A

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

32
Q

What is the

aqueous phase

A

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

33
Q

What is

soil water

A

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

34
Q

What does weathering do?

A

Physical/chemical breakdown that releases elements from mineral rock

35
Q

What does erosion do?

A

Moves elements around via wind/water

36
Q

How is weathering accomplished?

A
  • Water
  • Wind
  • Acid Rain
  • Other chemicals
  • Roots of growing plants
37
Q

Where are calcium, magnesium and potassium derived from?

A

Primarily rocks and decomposed vegetation

38
Q

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

A

Limestone, dolomitic limestone, and marble

39
Q

What ecosystems are calcium and magnesium found in?

A

Those overlying limestone and some other rock type

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

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

42
Q

What is the gaseous component of sulfur?

A

Sulfur dioxide, SO₂

43
Q

What form of sulfur do plants take up?

A

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

44
Q

What is a natural atmospheric source of sulfur?

A

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

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 🇺🇸

46
Q

TRUE OR FALSE

Sulfate does not leach easily from soils and ecosystems

A

FALSE!

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.
48
Q

What are

soil horizons

A

Layers of soil distinguished by physical/chemical/biological factors

49
Q

What is the

O horizon

A

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

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.

51
Q

What is the

E horizon

A

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

52
Q

What is the

B horizon

A

Where chemicals from the O, E, and A horizons have leached into; accumulate with elements that weathered there. 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

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

A

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

61
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.

62
Q

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

Megafauna: 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

63
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

64
Q

What is

soil degradation

A

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

65
Q

What is

topsoil

A

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

66
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
67
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

68
Q

How is climate change affecting soil degradation?

A
  • Slightly warmer temperatures may increase decomposition
  • But dryer soils may slow decomposition
69
Q

TRUE OR FALSE

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

A

TRUE!

70
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

71
Q

How much of Earth’s water is in lakes, river, and reservoirs (which supply half of the drinking water in the US 🇺🇸), 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
72
Q
A

Academic Decathlon 2024-2025 (22 decks)

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