Section 5:Energy and ecosystems

Question 1

How does energy enter an ecosystem?

Answer 1

The sun gives out solar energy which is converted into organic matter via photosynthesis

Question 2

Three points

Why is not all solar energy given out converted into organic matter?

Answer 2

• Reflected by clouds and dust/or is absorbed by the atmosphere
• Not the correct wavelength for photosynthesis
• Light does not hit the chlorophyll molecules

Question 3

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What are producers?

Answer 3

Photosynthetic organisms which use energy from the sun to make organic substances

Question 4

What are consumers?

Answer 4

Organism which obtain their energy by feeding on other organisms

Question 5

What are saprobionts?

Answer 5

Decomposers which breakdown complex materials in dead organisms into simple ones

Question 6

What is a food chain?

Answer 6

A feeding relationship

Question 7

What is a trophic level?

Answer 7

A stage in a food chain

Question 8

What are food webs?

Answer 8

Many food chains linked together

Question 9

What is biomass?

Answer 9

The total mass of living material in a specifc area at a given time

Question 10

Is dry or wet biomass more accurate?

Answer 10

Dry biomass

Question 12

Why is wet biomass more accurate?

Answer 12

The water content of organisms varies

Question 13

How do you caluclate the biomass of an organism?

Answer 13

Bomb calorimetry~dry biomass is weighed then burnt in pure oxygen within a sealed chamber,called a bomb

Question 14

Four points

Why do organisms need energy?

Answer 14

• Movement~within an organisms(circulation of blood) and of an organism
• Active transport
• Production of substances
• Maintenance of core body temperature

Question 15

What is gross primary production (GPP)?

Answer 15

The total quantity ofnenergy that plants convert into organic matter

Question 16

What is net primary production?

Answer 16

What goes into biomass/rate at which they store energy

Question 17

What are the units for NPP?

Answer 17

kJ m-2 year-1

Question 18

Three points

Why is not all energy transfered between trophic levels?

Answer 18

• Not all of the of the organism is consumed
• Some energy losses occur as heat from respiration and directly from the body to the environment
• Some parts are consumed but can not be digested, so lost in feaces

Question 19

What does N=I-(F+R) mean?

Answer 19

net production of consumers=chemical energy in ingested food-(energy lost through feaces, urine and undigsted food + food lost through respiration)

Question 20

Why is energy lost from producers to primary consumers?

Answer 20

• Not all available food is eaten
• Energy is lost to use in respiration,heat and movement

Question 21

Why is energy lost from primary consumers to secondary consumers?

Answer 21

Most of the herbivore can’t be eaten

Question 22

How are phosphate ions oceans,lakes and soil trnasfered to plants?

Answer 22

Absorption from plants

Question 23

How are phosphate ions in plants transfered to animals?

Answer 23

Feeding and digestion

Question 24

What is mycorrhiza?

Answer 24

The associations between fungi and plant tooys
* Increase SA for water and mineral ion absorption
* Acts like a sponge for roots enabling plants to be drought resistant

Question 25

What is carbon used for in plants and animals?

Answer 25

Carbohydrates,lipids,
proteins and ATP

Question 26

What is nirtogen used for in animals and plants?

Answer 26

Amino acids/Proteins,DNA/RNA and ATP

Question 27

What is phosphorus used for in animals and plants?

Answer 27

DNA/RNA,ATP,
phospholipids and NADP

Question 28

What is ammonification?

Answer 28

The production of ammonia from organic nitrogen containing compounds

Question 29

How are saprobionts related to ammonification?

Answer 29

Feed on feaces and dead organisms which releases ammonia,NH3

Question 30

What is nitrification?

Answer 30

The formation of nitrate ions from ammonian ions
* ammonium ions~nitrite ions~nirate ions

Question 31

What bacteria is involved in nitrification?

Answer 31

Nitrifying bacteria

Question 32

What is nitrogen fixation?

Answer 32

The conversion of nitrogen gas into ammonia. Which can then be converted to nitrate ions via nitrification