ECosystems

Question 1

Sustainablity

Answer 1

An ecosystem is described as being all
the interacting parts of a biological
community and its environment.
A sustainable ecosystem is one that is
capable of withstanding pressure and
giving support to a variety of organisms.

As noted by the Easter Island example on
page 7 of the text, humans have the
potential to inflict catastrophic changes on
an ecosystem. These changes can greatly
affect an ecosystem’s sustainability.

Question 2

Parts Of An Ecosystem

Answer 2

Every ecosystem has biotic and abiotic parts.
* Biotic refers to the living parts of an ecosystem (including
plants, animals, and micro-organisms).
* Abiotic refers to the non-living parts of an ecosystem
(including water, oxygen, light, nutrients, and soil).

Question 3

Cycling Of Matter And Earth’s Sphere

Answer 3

Ecological processes move matter from the biotic and abiotic parts of
an ecosystem and back again in continuous cycles.

*The lithosphere is the hard
part of Earth’s surface.
*The hydrosphere is all of the
water found on Earth (lakes,
oceans, and ground water).
*The atmosphere is the layers
of gas above Earth’s surface.
*The biosphere is the regions
of Earth where living
organisms exist.

Question 4

Nutrient Cycles:Water

Answer 4

Nutrients are chemicals that are needed by living things and
are continually cycled through ecosystems.
The water cycle moves water through the hydrosphere,
atmosphere, and lithosphere.
This occurs by way of:
 evaporation: the change of state from a liquid to a
gas.
 condensation: the change of state from a gas to a
liquid.
 precipitation: rain, snow, sleet, dew, formed by
condensation of water vapour in the atmosphere.

Question 5

The Water Cycle

Answer 5

The Earth’s water is stored in rivers, lakes and oceans
and as ground water under the surface of the land.
 The Sun’s light energy turns the water from the oceans
and other bodies of water into vapour through
evaporation and evapotranspiration.
 The vapour rises into the atmosphere and condenses
into water droplets to forming clouds.
 The clouds eventually drop the water in the form of
precipitation which could be rain, snow or ice pellets.
 The rain drains back into the rivers, lakes, oceans and
the ground water. Water from melting snow and ice
eventually joins the run-off.

Question 6

Carbon Cycle

Answer 6

The carbon cycle moves carbon through all of Earth’s
spheres.
 Carbon exists as a gas—carbon dioxide (CO2

)—in the
atmosphere. This gas is used by plants to make sugars.
 Sugars are broken down by organisms to release energy
and CO2
.

 Carbon is stored in fossil fuels buried within Earth and
in carbonate (CO3
2-
) rock found in the lithosphere.
 The largest carbon sink is in the oceans contained in
sedimentation and rock within these bodies of water.

(Page 15)

Question 7

The Nitrogen Cycle

Answer 7

• Nitrogen is used by life forms to carry
  out many of the functions of life.
  Nitrogen in its gaseous form is almost
  entirely unusable to life forms. It must
  first be converted or ‘fixed’ into a more
  usable form. The process of converting
  nitrogen is called fixation.
• There are specialized nitrogen fixing
  bacteria whose function it is to convert
  nitrogen so that it can be used by
  plants.
• Denitrifying bacteria do the reverse;
  they return nitrogen to its gaseous
  form.
• After nitrogen is fixed, it can be
  absorbed, and used by plants, and
  subsequently by animals.

Question 8

Nutirent Cycle: Nitrogen

Answer 8

The nitrogen cycle moves nitrogen through Earth’s spheres
(atmosphere, lithosphere, hydrosphere).
 nitrogen (N2

) is stored in the atmosphere - Earth’s atmosphere is

78% nitrogen.
 N2 must be converted to a form organisms can use.
 bacteria in the soil (terrestrial ecosystem) or cyanobacteria
(aquatic ecosystem) convert N2

into ammonium (NH4
+
).

 decomposers also breakdown dead organisms into ammonium.
 other bacteria convert ammonium to nitrate (NO3
-
).

 plants absorb both forms of nitrogen (ammonium and nitrate)
through roots nodules.
 organisms eat plants to use nitrogen.
 denitrifying bacteria convert nitrates to nitrogen gas (N2.)
 nitrogen can enter aquatic and terrestrial ecosystems when humans
fertilize soil.
 volcanic eruptions release nitrogen into the atmosphere.
 burning of fossil fuels releases nitrogen into the atmosphere.

Question 9

Nutrient Cycle:Phosphorus

Answer 9

The phosphorus cycle moves phosphorus from the
lithosphere to the hydrosphere:
 phosphorus is stored in the lithosphere (rocks, sediment on
ocean floor)
 weathering breaks down rocks releasing phosphate (PO4
3-
)

into the soil
 humans mine Earth for phosphate rock – used for
fertilizers and detergents
 plants absorb phosphate via roots
 animals eat plants
 decomposer bacteria break down dead organisms releasing
phosphate back into soil
 PO4

3- enters aquatic ecosystem via leaching and runoff

from land

Question 10

Human Activities And Nutrient Cycles

Answer 10

Aquatic ecosystems suffer when run-off contains high
amounts of agricultural fertilizers (which are high in nitrates
and phosphates).
Eutrophication is a process in
which nutrient levels in aquatic
ecosystems increase, leading to
an increase in the populations of
primary producers, such as
algae.

Eutrophication eventually
leads to a reduction in the
oxygen content of the water.

Question 11

Human Activities And Nutrient Cycles:2

Answer 11

Aquatic ecosystems suffer when run-off contains high
amounts of agricultural fertilizers (which are high in nitrates
and phosphates).

Question 12

All Activities Require A Source Of Energy

Answer 12

eg.
– campfire needs wood
– car needs gasoline
– hummingbird needs sugars

Question 13

All energy comes from the sun

Answer 13

• organisms in biosphere trap
  solar energy and use it to
  make food
• organisms use energy for life
  processes
  – locomotion, reproduction,
  respiration, circulation,
  ingestion, excretion, etc.

Question 14

Facts about Photosynthesis

Answer 14

• is a process that changes SOLAR ENERGY into
  CHEMICAL ENERGY (food – glucose/sugar)
• synthesis –
  Greek
  “putting
  together”
• photo –
  Greek
  “light”
• without light energy, photosynthesis can NOT
  occur
• sugars (glucose) are carbohydrates (carbon,
  hydrogen and oxygen)
  – plants get hydrogen from water, H2O via their roots
  – plants get carbon and oxygen from carbon dioxide gas,
  CO2
  from the atmosphere via tiny pores in their leaves
  called stomata

Question 15

Chlorophyll

Answer 15

• pigment that gives
  leaves their green
  colour
  – chloros – Greek
  “green”
  – phyllon – Greek
  “leaf”
• perform
  photosynthesis
• inside chloroplasts

Question 16

Benefits of Photosynthesis

Answer 16

1. animals eat plants
   and both use
   glucose for energy
   – to live
2. adds oxygen to the
   atmosphere which
   many organisms
   breathe
3. removes carbon
   dioxide from the
   atmosphere to
   maintain balance
   in carbon cycle

Question 17

Sense of scale

Answer 17

• Photosynthesis produces the equivalent of
  100 000 000 000 to 200 000 000 000 tones of
  sugar each year. This amounts of sugar is
  enough to make about 3.0 x 1017 or
  300 000 000 000 000 000 sugar cubes

Question 18

ENERGY – Cellular Respiration

Answer 18

• NOT all
  organisms
  undergo
  photosynthesis
• but ALL
  organisms get
  energy from
  glucose

Question 19

2 ways organisms break down glucose
to release its energy:

Answer 19

• Cellular Respiration
• Fermentation

Question 20

1.Cellular Respiration

Answer 20

• oxygen is present (aerobic conditions)
• humans, plants, animals, fungi
• most common and most efficient
• occurs in mitochondria in cells of organisms
• O2

comes from breathing it in from atmosphere

• glucose comes from eating plants
• oxygen and glucose react in cells
• producing H2O, CO2

and energy

Question 21

Cellular Respiration
VS. Photosynthesis

Answer 21

CELLULAR RESPIRATION
* consumes oxygen
* consumes glucose
* produces carbon dioxide,
water and energy
* in mitochondria

PHOTOSYNTHESIS
* produces oxygen
* produces glucose
* consumes carbon and water
dioxide, water and
energy
* in chloroplasts
-produces water

Question 22

2. Fermentation

Answer 22

• oxygen is absent
• also known as
  anaerobic respiration
• takes place in the
  cytoplasm
• bacteria
  (cyanobacteria), some
  fungi

Question 23

Plants and algae undergo BOTH

Answer 23

photosynthesis and cellular respiration

Question 24

ENERGY – Trophic Levels

Answer 24

• a category of organisms
  that is defined by how
  the organisms gain
  energy
• “feeder”
• matter moves though
  the biosphere by
  travelling from one
  trophic level to the next
  in a cycle
• e.g. producer, consumer

Question 25

Primary Producers / Autotrophs

Answer 25

* “self feeders” * can make their own food * 1 st trophic level * e.g. plants, algae

Question 26

Consumers / Heterotrophs

Answer 26

* can NOT make their own food * must eat other organisms to get the matter and energy they need to survive * e.g. animals, humans

Question 27

Primary consumers

Answer 27

* 2nd trophic level * feed on producers / autotrophs directly * herbivores * e.g. cow, deer, mice

Question 28

Secondary consumers

Answer 28

* 3rd trophic level * feed on consumers / autotrophs * omnivores, carnivores * primary carnivores

Question 29

Herbivores

Answer 29

These are animals that eat mainly plants this includes leaves, grass, flowers, seeds, roots, fruits, bark, pollen and much more. some herbivores are: deer ,horses, rabbits, cows, bees sheep, grasshoppers

Question 30

Carnivores

Answer 30

These are animals that eat mainly meat. This includes insects and all animals. some carnivores are: -felines(lions,tigers and all cats) -birds of prey(eagles, hawks, owls etc.) -sharks, frogs, spiders

Question 31

top carnivore

Answer 31

* not eaten by any other animal * top of the food chain/food web

Question 32

Omnivores

Answer 32

These are animals able to eat plants and animals. Some omnivores are: -humans -most bears -raccoons -most primates apes and monkeys) -seagulls and other birds

Question 33

Decomposers

Answer 33

They consume (eat) dead plants and animals and decomposes them-reduces them to simpler forms of matter primary decomposers fungi and bacteria

Question 34

Scavenger eats other animals that are already dead

Answer 34

striped hyena, crow, hag fish and vulture

Question 35

3 categories of consumers:

Answer 35

herbivores * eat only plants * e.g. cow carnivores * eat only animals * e.g. lion * top carnivore: not eaten by any other animal omnivores * eat both plants and animals * e.g. humans

Question 36

Food Chain

Answer 36

– a feeding sequence in which each kind of organism eats the one before it – one way flow for energy

Question 37

Food Web

Answer 37

– interaction of food chains * Note: direction of arrow indicates direction of energy flow; may read as “is eaten by”

Question 38

Arctic Food Wed

Answer 38

* lower biodiversity – fewer organisms, fewer types of organisms * number of producers is small – less sun → less photosynthesis * more direct relationships between organisms – loss of any one member can have a profound effect on all remaining organisms – each is more vulnerable

Question 39

Forest food Web

Answer 39

The forest food web consists of distinct components like producers, primary consumers, secondary consumers, scavengers, and decomposers. In the forest ecosystem, the producers are trees, which are of distinct kinds, the small plants and shrubs also produce their food. The primary consumers are deer, rhinoceros, etc.

Question 40

Energy in Ecosystems THERMODYNAMICS:

Answer 40

* the study of energy transformations * First Law of Thermodynamics: Energy cannot be created or destroyed, it can only be changed form one form to another. * Second Law of Thermodynamics: During any energy transformation, some of the energy is converted into an unusable form (e.g. heat = thermal energy) that cannot be passed on

Question 41

THEMODYNAMICS

Answer 41

* Every time energy is transferred within an ecosystem, some of it changes form – photosynthesis converts solar energy to chemical energy stored in glucose * Every time energy is transferred within an ecosystem, some of it is lost – plants and animals use chemical energy (food) to sustain life – once energy has been used, it is not available to be transferred – the further up a food chain you travel, the less energy is available – this limits the number of individuals that can be supported at the top of the food chain – because of the inefficiency of energy transfer among trophic levels, there are usually fewer carnivores than herbivores, and fewer herbivores than plants

Question 42

ENERGY PYRAMID:

Answer 42

* graph showing how energy flows from one trophic level to the next in a food chain

Question 43

TROPHIC EFFICIENCY

Answer 43

* measure of how much of the energy stored in organisms at one trophic level is transferred to the next higher trophic level * usually only 10% can be passed onto the next trophic level.

Question 44

Why is trophic efficiency less than 100%

Answer 44

1. herbivores may not eat all parts of a plant (e.g. eat top; leave the roots) 2. not everything eaten is digested (e.g. fur) 3. energy is lost as body heat 4. energy is used to carry out life functions (moving, breathing, reproducing, etc.) 5. waste is produced

Question 45

Other Pyramids:

Answer 45

* Pyramid of Numbers: shows the number of organism at each trophic level in an ecosystem * Pyramid of Biomass: shows the dry mass (after water has been removed) of the dry tissue in the organisms at each trophic level in an ecosystem

Question 46

BIOMASS

Answer 46

* total mass of living organisms (cells, tissues) in a defined group or area

Question 47

Pyramid of Numbers

Answer 47

* This type of pyramid does not always have the same shape as the other pyramids. * Depending on the ecosystem, it can have a variety of shapes.

Question 48

BIOACCUMULATION

Answer 48

* ingestion of toxins (e.g. PCBs, DDT, mercury, lead) at a faster rate than they are eliminated * greatest health problems show up at highest trophic levels

Question 49

BIOACCUMULATION

Answer 49

➢Bioaccumulation is defined as the increase in concentration of a substance(s) in an organism or a part of that organism. ➢Bioaccumulation takes place within an organism when the rate of intake of a substance is greater than the rate of elimination (excretion or metabolic transformation) of that substance. ➢Toxic substances are lipophilic or fat-loving; these substances are deposited and concentrated in the fat tissues of the organisms.

Question 50

BIOACCUMULATION 2

Answer 50

As the fish eats more of the smaller organisms, the amount of heavy metals increases. The heavy metals build-up in concentration in the larger living things (pelicans). The presence of mercury in tuna has lead to a great deal of concern about the safety of canned tuna.

Question 51

BIOMAGNIFCATION

Answer 51

➢Biomagnification is also called Bioamplification. ➢It is the increase in concentration of a substance in a food chain, not an organism. ➢Persistent organic pollutants (POPs) are chemical substances that stay in the environment. ➢These substances bioaccumulate through the food web and pose risk not only to humans but also other living organisms because of their adverse effects.

Question 52

GREENHOUSE GASES

Answer 52

* atmospheric gases that prevent heat from leaving the atmosphere, thus increasing the temperature of the atmosphere * e.g. water vapour, carbon dioxide (CO2 ), methane (CH4 ), ozone (O3 ), nitrous oxide (N2O), CFCs. GREENHOUSE GASES

Question 53

GREENHOUSE EFFECT

Answer 53

* the warming of the Earth as a result of greenhouse gases, which trap some of the energy that would otherwise leave Earth