Chapter 13.2 - Energy + Ecosytems

Question 1

What are producers?

Answer 1

photosynthetic organisms that manufacture organic substances

Question 2

How do producers manufacture organic substances?

Answer 2

Using light energy, water, carbon dioxide and mineral ions

Question 3

What are consumers?

Answer 3

Organisms that obtain their energy by feeding on other organisms

Question 4

What are primary consumers?

Answer 4

Those that directly eat producers (they are first in the chain of consumers)

Question 5

What are secondary consumers?

Answer 5

Those animals eating primary consumers (normally predators)

Question 6

What are tertiary consumers?

Answer 6

Those eating secondary consumers (normally predators)

Question 7

What are saprobionts?

Answer 7

A group of organisms that break down the complex materials in dead organisms into simple ones.

Question 8

What do saprobionts usually release?

Answer 8

They release valuable minerals and elements in a form that can be absorbed by plants - and so contribute to recycling

Question 9

What is a food chain?

Answer 9

Desccribes a feeding relationship in which producers are eaten primary consumers etc

Question 10

What is each stage in a food chain called?

Answer 10

Trophic level

Question 11

What is biomass?

Answer 11

total mass of all living material in a specific area, habitat or region at any given time

Question 12

What is biomass measured in?

Answer 12

grams per square metre(gm-2)

Question 13

What is the best form to measure biomass in, and why?

Answer 13

As dry mass - although fresh mass is easy to assess, varying amounts of water makes it unreliable.
Measuring dry mass overcomes this, although organisms must be killed

Question 14

How is biomass lost?

Answer 14

Urine/faces
Not all of organisms eaten (bones)
Not all of organism digested
Organism dies/decays before eaten
CO2 excreted

Question 15

What does calorimetry do?

Answer 15

Can be used to estimate the chemical energy store in dry mass

Question 16

Why is bomb calorimetry preferable to simple calorimetry?

Answer 16

Reduces heat loss to surroundings

Question 17

What equation is used in calorimetry to estimate chemical energy in a dry biomass sample?

Answer 17

Energy released = specific heat capacity of water x volume of water x temperature increase of water

Question 18

How could a student ensure all water has been removed from sample before weighing

Answer 18

Heat sample and reweigh until mass remains constant

Question 19

How much will 1kcal raise water temperature by?

Answer 19

I degree

Question 20

How many J of energy does 1 calorie equal to?

Answer 20

I calorie = 4.2J

Question 21

What do pyramids of energy show?

Answer 21

The amount of energy available to the next level

Question 22

What is energy measured in, in pyramids of energy?

Answer 22

kJm-2 year-1 to ensure seasonal abnormalities are not shown

Question 23

Why is some energy unavailable to the next level in pyramids of energy?

Answer 23

-Chemical energy (biomass, usually glucose) is used by each organism in respiration to form ATP
- Respiration releases heat energy to surroundings
- Energy remains stored in dead organisms
- Animals excrete waste
- Whole organism not consumed by next trophic level

Question 24

What % of light energy will be converted to chemical energy in plants?

Answer 24

Plants convert 1%-3% of the Sun’s energy available to them into organic matter

Question 25

Why is so little of the Sun's energy absorbed?

Answer 25

Wrong wavelengths Light may not fall on a chlorophyll molecule Over 90% is reflected off the atmosphere

Question 26

Define gross primary production(GPP)?

Answer 26

Total chemical energy in plant biomass within a given volume or area

Question 27

How much GPP is lost when plants respire?

Answer 27

approx 50% - known as respiratory loss (R)

Question 28

Define net primary productivity?

Answer 28

The chemical energy store which is left after respiratory losses

Question 29

What is the equation that links NPP and GPP?

Answer 29

Net primary production = gross primary production - respiratory losses

Question 30

How do consumers store their energy?

Answer 30

In their biomass

Question 31

How much total available energy is lost in consumers and why?

Answer 31

Approx 90% due to: -respiration -not all food eaten -egested

Question 32

How can the Net production of consumers be calculated?

Answer 32

N= I - (F +R) I: chemical energy ingested F: chemical energy lost in faeces +urine R: respiratory loss

Question 33

Why do most food chains only have 4 or 5 trophic levels?

Answer 33

Due to inefficient transfer of energy between levels

Question 34

What is the equation for efficiency of energy transfers?

Answer 34

efficiency = energy available after transfer / energy available before x100

Question 35

Define secondary production

Answer 35

The rate at which energy is uses to make new organic molecules within heterotrophs (consumers)

Question 36

Outline farming practices used to increase efficiency of energy transfer

Answer 36

- Exclusion of predators - Artificial heating - reduces heat loss to environment - Restriction of movement - Feeding is controlled at optimum (high in kcal) - animals treated with growth hormones

Question 37

Outline some disadvantages of factory farms

Answer 37

-Unethical - Overcrowding -Faster spread of diseases -Antibiotics appear in food chain

Question 38

What is the flow of nutrients described as?

Answer 38

Cyclic

Question 39

What is the role of saprobionts?

Answer 39

Feed on remains of dead plants + animals - breaking them down Secrete enzymes + digest food externally so they can then absorb the needed nutrients ( extracellular digestion)

Question 40

What is mycorrhize?

Answer 40

When fungi form a symbiotic relationship with the roots of plants

Question 41

What are hyphae?

Answer 41

Fungi made up of long, thin strands which connect with the plant roots

Question 42

What do hyphae help increase?

Answer 42

Surface area Uptake of water

Question 43

What is guano?

Answer 43

Bird/seabird poo This returns a high amount of phosphorus ions to the soil

Question 44

What are natural fertilisers?

Answer 44

Consist of dead +decaying remains of plants + animals as well as animal waste (manure)

Question 45

What are artificial fertilisers?

Answer 45

Mines from rocks + deposits and converted into different forms and blended together to give appropriate balance of minerals

Question 46

What are disadvantages of using fertilisers?

Answer 46

Reduced species diveristy Leaching of ions Eutrophication

Question 47

What is leaching?

Answer 47

The process by which nutrients are removed from the soil

Question 48

Describe the process of leaching

Answer 48

Caused by rainwater dissolving any soluble nutrients and they are carried deep into the soil. Leached ions can then find their way into waterways

Question 49

What is eutrophication?

Answer 49

The process by which nutrient concentrations increase in bodies of water

Question 50

Describe the process of eutrophication

Answer 50

1.Aquatic plants grow exponentially since nitrate level is no longer a limiting factor 2. Algal bloom on water surface prevents light from reaching bottom and plants die 3. Oxygen levels decrease as population of saprobionts increase to decay dead matter - fish die 4. Anaerobic organisms reproduce exponentially and produce toxic waste -> water is putrid

Question 51

How can the risk of eutrophication be reduced?

Answer 51

- Don't used fields near waterways - Use crop rotation so different minerals are removed each year - Use natural fertilisers - Don't use fertilisers in rainy season