C4.2

Question 1

Food Webs

What is an Ecosystem?

Answer 1

• Refers to both biotic communities and the abiotic factors in an area.

How does energy move throughout an ecosystem?
- sunlight,
- heat
- gasses like CO2, heat and compounds like glucose and ATP.

Question 2

Food Webs

What does the First Law of Thermodynamics say?

Answer 2

(Law of Conservation)
“Energy can be neither created nor destroyed”
- It can change forms but the amount remains constant.
- Energy consumed originated as solar energy absorbed by plants. It further changes from chemical energy to crating ATP and kinetic energy (for movement) and some is converted to heat and released.

Question 3

Food Webs

What does the Second Law of Thermodynamics say?

Answer 3

“When energy transfers forms it often is transofrmed into a less usuable form”.
(entropy or disorganisation of a system increases when energy is transformed –> meaning that –> less usable heat energy is generated when energy changes forms)

Question 4

Food Webs

What is the role of a PRODUCER in an ecosystem?

Answer 4

All energy needed for the maintaining of life can be traced back to the input of sun into an ecosystem.
- Every cell needs ATP to function –> ATP is produced by converting organic carbon compounds (carbohydrates, fats, and proteins).
- The carbon compounds all come from carbs made from plants, algae and some bacteria in the process of photosynthesis. –> they are able to use solar energy to break the bonds in H2O and CO2 and convert them into sugars. —> sugars are turned into ATP in their own cells and are eaten by consumers who are then eaten by more consumers.
- Producers create the carbohydrates that fuel the entire ecosystems, and thus are photosynthetic (or sometimes chemosynthetic) organisms.

Question 5

Food Webs

What is the role of a CONSUMER in an ecosystem?

Answer 5

• They obtain energy from the carbon compounds on which they feed.
• they are a subset of heterotrophs, and they specifically notable in discussing ebergy interactions since they directly transfer energy in ecosystems. –> as they kill and ingest living organisms.

Question 6

Food Webs

What is the role of DECOMPOSERS

Answer 6

• Decomposers help to remove the exoskeletons/ bones and plant matter that is left behind in the environment, alongside feces from animals.
• They release enzymes and can break down and use those unconsumed parts –> providing energy for them also retunring compounts, RECYLING NUTRIENTS, to the soil to help future plants grow.
• They prevent the build up of unused matter which would waste habitat space.

Question 7

Food Webs

What do we mean by a Trophic Level?

Answer 7

• Trophic level –> as a feeding role in the ecosystem.
• The official definition –> indicates how many organisms in an ecosytem energy has flower through.
• Plants are the first trophic level as they represent the first transfer of solar energy into chemical energy.
• A consumer who then eats the plants –> second trophic level –> as it is the second energy transfer.

Question 8

Food Webs

What is Assimilation?

Answer 8

• We do not only require glucose, we also need other molecules to build proteins for msucle and tissues and create fat for our cell membrances.
• The process of digesting food contiaining carbon based compounds and then using the component s of it to build new things for the body –> ASSIMILATION.
  (post-digestion use of the nutrients)

Question 9

Food Webs

Different between an open and closed ecosystem.

Answer 9

In both —> energy has the potential to enter (as solar energy) and leave (as heat into the atmosphere)

OPEN: new matter can enter and leave, like water entering and leaving, and species migrating. Ecosystems are typically open.

CLOSED: matter can not enter or leave, only be recyled. EG: a terrarium.

Question 10

Food Webs

Difference between primary, secondary and tertiary consumer.

Answer 10

PRIMARY: eats a producer
SECONDARY: eats a pimary consumer
TERTIARY: eats a secondary consumer.

• However, many animals have more than one food source, thus can be different types of consumer at differernt types. (track the origin of all its food on a food web.)

Question 11

Food Webs

Difference between a food chain and a food web.

Answer 11

NOTE: Arrows represent the direction of flow of energy.

FOOD CHAIN: Following a producer through a linear set of consumers.

FOOD WEB: Interlinking food chains, more accurate, shows how most organisms have more than one predator and more than one avilable prey.

Question 12

Food Webs

Difference between photoautotrophs and chemoautotrophs.

Answer 12

Autortrophs synthesize their organic molecules from inorganic substances.

PHOTOAUTOTROPHS: take light energy from the sun and combine it with substances (H20 AND CO2) to make glucose through photosynthesis.

CHEMOAUTOTROPHS: also take CO2 but instead of sunlight –> they use other inorganic compounds such as iron or sulphur as the energy source to fix carbon dioxide into glucose. –> can also oxidize chemicals and use the energy from those (exothermic) reactions to synthesise glucose. (EG: bacteria and archae)

Question 13

Food Webs

Primary Prodction.

Answer 13

“The accumultation of carbon compounds in biomass by autrotrophs.” –> essentioally measures how much photosynthesis is done in an ecosystem.

Gross Primary Production: all biomass of carbon compounds made by plants in photosynthesis.

Net Primary Production: Considers that a lot of the carbon compounds made by plants are used themselves in cell respiration and their life processes –> the net is stored as plant matter made avilable to consumers.

Question 14

Energy Pyramids

What is meant by the term Secondary Production?

Answer 14

“The accumulation of carbon compounds in biomass by heterotrophs.”

Gross secondary production: amount of carbon compounds consumed by primary consumers but then they would use much of that energy for themsleves. (in celluar respiration and much lost as heat in the process.)

Leftover energy: is then stored on organsism as growth -> made available to the next consumer level, which is the next secondary production.

SECONDARY PRODUCTIVITY DECREASES WITH EACH TROPHIC LEVEL.

Question 15

Energy Pyramids

Energy loss between trophic levels.

Answer 15

Three main reasons for the loss between levels:
1) Incomplete Consumption
- only parts of the plant are eaten, bones of animals often discarded.
2) Incomplete Digestion
- not all parts are digested/absorbed, others pass through as faeces.
3) Cell respiration
- a lot of the carbs consumed are broken apart to form ATP and released as gaseous carbon dioxide to the environment. Heat is also lost during cell respiration.

Question 16

Energy Pyramids

The origins of heat loss

Answer 16

• As carbs are used to create ATP in celluar respiration, the process isn’t entirely efficient –> heat is lost to the environment as a result.
• When ATP is hydrolsed (used), heat is lost ahain to the environment –> meaning that the energy still exists, but its now in the unusable form of heat –> occurs in both heterotrophs and autotrophs.
• Some heterotrophs have adaptations to deliberately increase their heat generation during respiration –> as the heat is used to help increase body temp/ maintain constant internal temp .

Question 17

Energy Pyramids

Limitations to the lenght of food chains.

Answer 17

• As so much energy is lost between each trophic level (90%), it is necessary to have a large amount of primary production to feed the consumers in an ecosystem.
• Necessary to have a relatively small mass of top consumers –> not enough food to sustain a larger number.

Question 18

The Carbon Cycle

What is a Carbon Pool?

Answer 18

• A reserve or storage of carbon.
• Can include CO2 in the atmosphere or organic starches stored in the roots of plants.
• The largest carbon pool is found in oceans –> then fossil fuels.
• A carbon sink is a carbon pool that has the ability to take up more carbon than it releases.

Question 19

The Carbon Cycle

What is a Carbon Flux?

Answer 19

• A process that transfers carbon from one pool to another.
• Occur naturally but also can be caused by human activity.

Question 20

The Carbon Cycle

Carbon Fluxes due to Biotic Factors

Answer 20

1) PHOTOSYNTHESIS - absorption of carbon dioxide from air/ water and conversion of it to organic carbon compounds like glucose.

2) FEEDING - direct transfer of organic cabron compounds from one organism to another through feeding.

3) RESPIRAITON - break down of glucose and release of the carbon back into the atmosphere as CO2.

Question 21

The Carbon Cycle

Carbon Sink vs Carbon Source

Answer 21

SINK: If photosynthesis exceeds respiration, there is net Carbon uptake.

SOURCE: If respiration exceeds photosynthesis, there is a release of Carbon back.

Question 22

The Carbon Cycle

Formation of Carbon Sinks:
Natural Gas and Oil

Answer 22

• Forms from the deep burial of partially decomposed organic matter under sedmients, where high temperatures caused chemical changes and produced oil and natural gas trapped in porous rocks.

Question 23

The Carbon Cycle

Formation of Carbon Sinks:
Coal

Answer 23

• Formed from the accumulation of wood and other plant matter in swamps, where it then was buried under other sediments.

Question 24

The Carbon Cycle

Formation of Carbon Sinks:
Peat

Answer 24

• Forms due to the incomplete decompostion of dead plant matter due to acidic and anerobic conditions in waterlogged bogs and swamps.

NOTE: is the precursor to coal, after time, heat and pressure, peat becomes coal.

Question 25

# The Carbon Cycle Formation of Carbon Sinks: Biomass

Answer 25

- Plants and animal biomass ---> stores carbon compounds made from photosynthesis as tissues. - Unsconsumabble plant/ animal matter can be bunrt to produce energy --> also a source of energy that regenerates.

Question 26

# The Carbon Cycle The role of combustion in the Carbon Cycle

Answer 26

- Involves the burning in air of any carbon sink to release energy --> includes fossil fuels like peat and oal as well as biomass. - Requires incredibly high temperatures --> can happen in lighting strikes, when these are combusted for energy, CO2 is produced as the waste product. - The level of human activity of intentional burning of fossil fuels has significantly increased atmosphereic CO2 levels.

Question 27

# The Carbon Cycle The source of the Keeling Curve Data

Answer 27

- The data on the concentration of CO2 has constantly been gathered at the Mauna Loa Observatory in Hawaii -> the keeling curve is that data plotted.

Question 28

# The Carbon Cycle Annual Pattern of change in Co2 concentration

Answer 28

- Every year the Co2 concentration increases between Oct and May and then falls between May and the next Oct--> due to seasonal changes, linked to those in the Northern Hemisphere --> accounts for most of Earth's overall photosynthesis. Between May-->Oct, summer in Northern Hemisphere increases photosynthesis rate which means more Co2 is consumed (casuing decrease in Co2)

Question 29

# The Carbon Cycle Long term trend in CO2 cencentration

Answer 29

- At the end of each annual cycle, the Co2 ends higher than it started that year --> means overall the CO2 levels are increasing. - Increasing more every decade due to human activities -> burning of fossil fuels and deforestation.

Question 30

# The Carbon Cycle Element Recycling

Answer 30

- Carbohydrates, lipids and proteins require carbon hydrogen and ozegyn. Proteins also require nitrogen, as do nucleic acids --> which always need phosphorous. - Additionally, other organisms needs calcium, potassium, sodium and iron --> which all need to be recucled.