Chapter 23- Ecosystems

Question 1

How percentage efficiency of energy transfer between producers and herbivores can be estimated?

Answer 1

• primary consumer energy / produvcer energy X 100
• sample of producers collected
• sample of consumers collected
• collected from same area
• measure biomass/ dry mass of population
• calculate energy content by using calorimeter

Question 2

Ways that farmers can maximise the efficiency of transfer of energy from primary consumers to humans?

Answer 2

• keep animals warm
• reduce animal movement
• feed high energy food
• vaccinations/ antibiotics

Question 3

Producer?

Answer 3

converts inorganic molecules to organic molecules

Question 4

Consumer?

Answer 4

Derives energy from feeding on other organisms

Question 5

trophic level?

Answer 5

level in a food chain

Question 6

Peat bog. Human body found. Not decomposed. Why?

Answer 6

• waterlogging in peat bogs reduces oxygen

- acidity/ low pH stops enzymes working

Question 7

Why removal of peat bogs discouraged by conservation groups?

Answer 7

• take long time to form and hard to replace

- loss of biodiversity

Question 8

How plant protein converted to animal protein in sheep?

Answer 8

• animal eat plants
• hydrolyse proteins to amino acids
• amino acids move into cells
• synthesis of proteins by translation

Question 9

Processes which contribute to humus in meadow where sheep are?

Answer 9

• death of animals/ leaf loss
• decomposition
• excretion of faeces

Question 10

Describe nitrification and explain significance of these bacteria for growth of plants?

Answer 10

• NH4+ -> NO2- oxidation reaction NITROSOMONAS
• NO2- -> NO3- oxidation reaction NITROBACTER
• nitrifying bacteria
• plants use nitrates to make amino acids

Question 11

Why soil nitrate conc will decrease if field used to grow repeated crops of cabbage year after year?

Answer 11

• plants use nitrate
• cabbage harvested so less decay
• less recycling of nitrogen

Question 12

Crop to use to convert nitrogen in air into nitrates and how this works?

Answer 12

• use legume
• RHIZOBIUM (nitogen fixing bacteria) will convert N2 into NH4+
• nitrification: to NO2- to NO3- using NITROSOMONAS and NITROBACTER

Question 13

Why continued existence of rare breeds desirable?

Answer 13

• if conditions change in future
• to maintain biodiversity
• genetic engineering

Question 14

Essential steps that must have occured for breed to develop distinctive metabolism?

Answer 14

• mutation

- selective advantage

Question 15

How energy content of producer can be measured?

Answer 15

• calorimeter

- dry mass of organic material burnt in oxygen

Question 16

Why carnivore would absorb more enegry than herbivore?

Answer 16

• meat more digestible
• contains no cellulose
• mainly protein and fat

Question 17

Difference between pioneer community and climax community?

Answer 17

pioneer community

• lower biodiversity
• lower biomass
• self sustaining

Question 18

decomposition?

Answer 18

• break down of dead matter/ waste

- conversion of organic matter to inorganic

Question 19

Denitrification?

Answer 19

conversion of nitrates to nitrogen gas

Question 20

Difference between decomposition and denitrification?

Answer 20

• decompostion increases nitrate supply

- denitfriciation decreases nitrate supply

Question 21

Nitrogen fixation?

Answer 21

conversion of atmospheric nitrogen into NH4+

Question 22

nitrification?

Answer 22

-conversion of NH4+ into NO2- + NO3-

Question 23

Role of decomposers in decompositition in leaves?

Answer 23

• are bacteria / fungi that undergo external digestion as they saprophytic
• do this by secreting enzymes on dead matter to break them down and absorb breakdown products
• makes NH4+

Question 24

conversion of nitrogen gas to ammonium compounds in soil?

Answer 24

nitrogen fixation