Trophic levels in an ecosystem (7.4)

Question 1

How much incident energy from light do producers (mostly plants and algae) transfer for photosynthesis?

Answer 1

1%

Question 2

Approximately how much biomass from each trophic level is transferred to the level above it?

Answer 2

10%

Question 3

4 needed

What are losses in biomass due to?

Answer 3

• not all the ingested material is absorbed, some is egested as faeces
• some absorbed material is lost as waste, such as
  
  • carbon dioxide and water in respiration
  • water and urea (formed in breakdown of amino acids) in urine
• Not all of organism is eaten
• Large amounts of glucose (from biomass consumed) are used in respiration

ingested, carbon dioxide and urea parts are the key three for exam questions

Question 4

5 needed

State some factory methods of food production

Answer 4

• Kept in cramped conditions / battery hens / calf crates / pig barns / fish tanks
• Controlled temperature / heating
• Controlled feeding / modified food given / growth hormones (e.g. protein-rich food)
• Controlled lighting
• Treated with prophylactic antibiotics (prevent, rather than treat infection)

Question 5

exhaustive list, just need to understand some

What are some advantages of factory farming methods?

Answer 5

• Increased efficiency / profit / greater food production / cheaper food / faster growth
• Farmer can have more livestock
• Less energy is lost through movement
• Less energy is used keeping warm
• (Food is high in calories / protein) so animals will grow faster / lay more eggs
• Easier to vaccinate all the animals
• Easier to protect animals from predators
• Antibiotic treatment stops infections in animals

Question 6

exhaustive list, just need to know some

What are some disadvantages of factory farming methods?

Answer 6

Stress / cruelty / inhumane / unethical

Restricted movement / overcrowding

Faster spread of diseases

Antibiotics in the food chain / residual chemicals in the food chain

Wasting fossil fuels / increasing global warming

Increased pollution from animal waste and from additional transport

Question 7

Why is the percentage of the sun’s energy that is transferred to the photosynthetic organisms usually very low?

Answer 7

• Sun’s light reflected by leaves
• Not absorbed by chlorophyll
• Other factors are limiting rate