Ecology

Question 1

Species

Answer 1

A group of organisms that can interbreed and give fertile offspring.

Question 2

Population

Answer 2

A group of individuals of the same species living at the same
area at the same time.

Question 3

Gene Pool

Answer 3

All the possible genes and their alleles within a species.

Question 4

Evolution

Answer 4

Gradual change in the heritable characteristics of an
individual.

• Change can be caused by genetic mutations, either beneficial
  or detrimental.
• Result of environmental pressure that favours one characteristic within the species.

Question 5

Speciation

Answer 5

A process where a new species is formed from a pre-existing species.

Question 6

Habitat

Answer 6

Environment in which a species normally lives, or the location
of a living organism.

Question 7

Population

Answer 7

A group of organisms of the same species who live in the same
area at the same time.

Question 8

Community

Answer 8

A group of populations living and interacting with each other in
the same geographical area.

Question 9

Autotrophs

Answer 9

Synthesize their own organic compounds from simple
inorganic compounds found in the abiotic environment.

• By absorbing carbon dioxide, water, and other inorganic nutrients from the environment for synthesis (e.g., plants, algae, cyanobacteria (all of
  these are photosynthetic organisms).
• Aquatic ecosystems, carbon can be presented as hydrogen carbonate ions.
• Formed when water & carbon dioxide combine to form carbonic acid, dissociates to produce hydrogen carbonate ions
• Aquatic autotrophs absorb and use dissolved carbon dioxide and hydrogen carbonate ions in photo synthesis

Autotrophs are referred to as producers.

Question 10

Heterotrophs

Answer 10

Obtain organic compounds from other living organisms (e.g.,
humans, insects, fish, etc.).

Heterotrophs are referred to as
consumers.

Divided into three - Consumers, detritivores and saprotrophs

Question 11

Consumers

Answer 11

Organisms that obtain organic matter from other living or recently killed organisms

• Primary consumer: eats autotrophic organisms → herbivore
• Secondary consumer: eats herbivores → carnivore
• Tertiary consumer: eats secondary consumer → top carnivore

top carnivore can also be a quaternary consumer, depending on
the food chain

Question 12

Detritivores

Answer 12

Decomposers that internally digest dead organic matter like leaves and carcasses

• Earthworms and woodlice

Question 13

Saprotrophs

Answer 13

Decomposers that live in or on dead organic matter and externally digest
it, by secreting digestive enzymes and absorbing the products of digestion

• Fungus and bacteria

Question 14

Heterotrophic plants and Algae

Answer 14

Most plants & algae are autotrophs, but some species dont’ make their food using photosynthesis,

Instead use carbon compounds from other organisms, heterotrophs

• Some obtain carbon compuds from plants. Dodder( Cuscuta europaea). Feeds on stems
• Others from funfi living int tree roots, gosht orchid(Epipogium aphyllum)

So not all plant and alga are autotrophic

Question 15

Food Web

Answer 15

Complex network of feeding relationships in a community

Question 16

Abiotic Environment

Answer 16

Non-living surrounding of a community

Community interacting with abiotic environment make ecosystems

Question 17

Quadrant sampling in communities

Answer 17

Quadrat- Square sample used in ecological research

Question 18

Mesocosms

Answer 18

Small experimental area set up in an ecological research programme.

• Autotrophs- Produce carbon compounds & regenerate oxygen, used in cell respiration
• Saprotrophs- Decompose dead organic matter and recycle nutrients
• Consumers & detritivores- Ussually included.

Large animals are unethical as they cannot obtain enough food or oxygen

Question 19

Sunlight

Answer 19

• Main source of energy in ecosystems
• In a food chain, the most abundant level of organisms comprises autotrophs (plants and algae). producers.
• Since autotrophs are mainly
  photosynthetic organisms, sunlight is required as a main source of energy. To convert it into organic compounds and obtain the necessary nutrients for survival.
• Without sunlight, producers would not survive and primary
  consumers would not be able to feed, disrupting the food chain.

Question 20

Energy Source

Answer 20

Most organisms obatin their energy in one of the two ways

• Plant, algae & some bacteria absorb light energy & convert it by photosynthesis into chemical energy in carbon compounds. Known as producers
• Consumers, detritivores & saprotrophs obtain energy from their food. Energy in carbon compounds can pass from organisms in organisms on the food chain.

All food chains start with a producer that mad carbon compounds by photosynthesis.

Light is essential for the community

Question 21

Energy flow in ecosystems

Answer 21

• Food chain is a sequence showing the feeding relationships and energy flow between species sharing a habitat.
• The arrow shows the direction of the energy flow (energy is
  transported by ingestion to the next organism in the food chain).
• Organism’s position in a food chain or web is a tropic level

Question 22

Energy loss

Answer 22

Energy enters the ecosystem as sunlight, and is absorbed with about 20% efficacy by
autotrophic producers and transformed into chemical energy

Chemical energy is transferred from one trophic level to the next by means of feeding.

The chemical energy stored in bonds is released and made
available to an organism when carbohydrates, lipids, proteins and nucleic acids are digested

At each step, only about 10% of the energy is successfully
transferred to the feeding
organism. This is because energy is lost in several ways:

Question 23

How Energy is lost

Answer 23

• Not the entire organism is eaten. Bones, cartilage, hair and gall bladders are eaten
• Loss of carbon dioxide, water and other waste products throughout the organism’s life
• Some organisms die and decay before being eaten
• Warm-blooded and moving organisms lose more energy as heat
• Parts of organisms are indigestible, cellulose in food for humans. Undigested parts are egested in feces
• Energy losses restrict length of food chains and the biomass of the higher trophic levels

Question 24

Energy Pyramid

Answer 24

Diagram used to show the flow of energy through each topic level

• Producers- Primary consumers - secondary consumers - tertiary consumers
• Bar becomes 10 times smaller, as only 10 of energy is transferred
• Energy expressed in = kilojoules per square meter/pear year

Question 25

Nutrient Recycling

Answer 25

• Ecosystems have limited supplies of nutrients, nutrients don’t run out as they can be recycled
• Carbon, nitrogen, phosphorus and other essential elements are absorbed from the environment, used by living organisms and return to the environment

Question 26

How carbon enters ecosystems?

Answer 26

• Carbon enters an ecosystem in the form of carbon dioxide, is diffused into autotrophic producers.
• Autotrophs then convert carbon dioxide into complex carbohydrates
  (organic molecules) and other carbon-containing molecules ( proteins and lipids) through photosynthesis.
• Carbon dioxide is present in air; so terrestrial autotrophs can directly absorb it through specialized porous cuticles.
• In aquatic ecosystems, carbon can be dissolved into CO2 or in the form of (hydrogen carbonate ions), when resulting from the chemical reaction when water and carbon dioxide combine to form carbonic acid (H2
  CO3).
• Used molecules used in photosynthesis.
• These organic compounds are used in the process of cell respiration, leading to the regeneration of carbon dioxide
• Which is released into the water or the atmosphere as a by-product.

Question 27

Carbon cycle

Answer 27

Carbon dioxide enters ecosystems by diffusing into autotrophs,
transformed into organic compounds through photosynthesis.

Some carbon dioxide
returns to the atmosphere as a by-product of cell respiration that takes place in producers.

• Primary consumers feed on producers, taking up some carbon-containing compounds
• Secondary consumers feed on primary, etc.

Cell respiration leads to further generation of carbon dioxide released into the atmosphere.

• Consumers die, leftover carbon in their bodies taken by decomposers

Question 28

Methane in Carbon cycle

Answer 28

• Organic matter can get buried in areas with no/little oxygen.
• In that case, archaeans called methanogens to produce methane from the
  metabolic by-products of anaerobic respiration.
• Methane will either diffuse into the atmosphere or accumulate underground, forming natural gas deposits.
• Methane diffuses into the atmosphere and affects carbon dioxide concentrations as it then gets oxidized into water vapor and carbon dioxide.
• Methane persists for about 12 years in the atmosphere before being naturally oxidized.
• Rising number of cattle has increased the methane
  concentrations released into the atmosphere.

Question 29

Combustion

Answer 29

• Carbon dioxide is produced by the combustion of carbon compounds, a non-biological process that occurs naturally
• I.e Lighting setting fire to a forest or grassland, biomass then burns and releases CO2
• Combustion of fossil fuels in industrial factories produces CO2 that is released
  into the atmosphere in great quantities

Question 30

Atmospheric monitoring

Answer 30

• Air monitoring stations are worldwide, mesasuring concentrations of CO2, methane and other gases

Question 30

Atmospheric monitoring

Answer 30

• Air monitoring stations are worldwide, measuring concentrations of CO2, methane, and other gases
• Annual decrease in C02 concentration from May to October. Due to excess photosynthesis globally
• Increase in CO2 concentrations from decreased photosynthesis globally.

Question 31

Carbon fluxes

Answer 31

Photosynthesis = -120 gigatons year-1

Cell Respiration = +119.6 gigatons year-1

Ocean Uptake = -92.2 gigatons year-1

Ocean Loss = +90.6 gigatons year-1

Deforestation = +1.6 gigatons year-1

Combustion of Fossil Fuels = +6.4 gigatons year-1

Question 32

Limestone

Answer 32

Rock made of calcium carbonate

• Contains fossils mollusc shells & skeletal of hard rocks organisms intake calcium and carbonate ions and make calcium carbonate
• A lot of carbon is in limestones can be released is limestone reacts with acid

Question 33

Formation of peat and coal

Answer 33

In acidic and anaerobic conditions (swamps and bogs), saprotrophs cannot fully break down dead organic matter as they require oxygen.

Partially decomposed organic matter accumulates to form thick deposits called peat.

Peat deposits get compressed under sediments, and with heat underground, form highly concentrated material that undergoes chemical reactions and
becomes coal.

Question 34

Formation of oil and gas

Answer 34

Silt and the remains of dead organic organisms can sometimes accumulate in shallow seas.

Due to the anaerobic conditions, these organisms are only partially decomposed.

The slit accumulates and is buried under layers of sediment.

Through this compaction and heating, hydrocarbons are formed, which make oil and gas.

The process takes millions of years.

The oil and gas formed is forced out of the source and it accumulates in porous rocks.

Forced out of there when humans drill into such rocks

Question 35

The greenhouse effects

Answer 35

A naturally occurring phenomenon that has enabled life on Earth for millennia.

Sunlight enters the atmosphere in the form of waves.

Short-wavelength radiation is
partly absorbed by the ozone layer (mostly ultraviolet → about 25%).

75% of larger wavelengths radiation reach the Earth’s surface, where absorbed and produces heat.

The Earth’s surface re-emits radiation at much longer wavelengths
(infrared → heat).

A high percentage (75–80%) of this radiation is absorbed by greenhouse gases in the atmosphere.

These gases re-emit radiation, and some of it reaches the surface of the Earth again, causing warming

Question 36

Greenhouse Gases

Answer 36

Have the ability to absorb this long-wavelength radiation that is emitted from the Earth’s surface.

The main greenhouse gases are carbon dioxide and water vapor, with low concentrations in the atmosphere.

Oxides of nitrogen and methane are also greenhouse gases

Ozone is a greenhouse gas, ozone depletion does not increase the greenhouse effect.

Question 37

Enhanced Greenhouse Effect

Answer 37

• Increased levels of greenhouse gases in the atmosphere caused by
  industrialization cause heat in the atmosphere to increase.

The enhanced greenhouse effect- a phenomenon that has affected average global temperatures and climate patterns on Earth.

Human activity has cincreased the production of greenhouse gases
(carbon dioxide) in the last 200 years, starting after the onset of the
industrial revolution.

• Combustion of fossil fuels became a major source of fuels and energy

Some human activity ledding to increase in greenhouse gas:

• Burning of fossil fuels
• Use of ammonia-based fertilizers
• Industrial processes (e.g., production of nitric acid)
• Waste disposal in landfills
• Production and distribution of natural gas

Question 37

Global temperatures

Answer 37

These processes have led to an increase in carbon dioxide and methane in the atmosphere.

• Has caused a major increase in global temperatures in the last
  two centuries.
• Causing rises in sea level, destruction of Arctic habitats, coral reefs, and
  much more.

Question 38

Changes in atmospheric CO2 concentrations

Answer 38

Last 150 years, carbon dioxide emissions have increased mostly due to fossil fuel combustion in industry.

Clear correlation between an
increase in carbon dioxide emissions and an increase in global temperatures, other variable factors influence this process
(e.g the atmospheric concentration of other greenhouse gases)