Biology - 18 Biodiversity and Ecosystems - 18.5 Global Warming & 18.6 The Impact of Change & 18.7 Maintaining Biodiversity & 18.8 Trophic Levels and Biomass

The greenhouse effect

warming that results when solar radiation is trapped by the atmosphere

The enhanced greenhouse effect process [4]

- energy from the sun is absorbed by the Earth

- the Earth radiates longer-wavelength radiation

- greenhouse gases absorb and reradiate radiation

- the atmosphere warms due to more greenhouse gases

Consequences of global warming [3]:

- rising sea levels due to melting ice and thermal expansion

- coastal erosion, flooding and tsunamis

- change in weather patterns causing more extreme weather

Seasonal change

annual cycle of change related to the seasons

Effects of seasonal change [2]

- affect species distribution, migration and breeding patterns

- change rainfall, water availability, temperature, dissolved gases, hours of daylight

Geographical change

differences related to physical location and area

Effects of geographical change [2]

- change soil structure and pH, salinity of water, availability of water, altitude

- species have specific adaptations to aid survival in certain areas

Human interactions causing environmental change [4]:

- distribution of invasive species and pathogens

- global warming

- deforestation and habitat destruction

- water, air and land pollution

Ways to maintain biodiversity [5]:

- breeding programs for endangered species

- protection and regeneration of rare habitats

- reintroduction of field margins and hedgerows

- reduction of deforestation and carbon dioxide emissions

- recycling resources

Why increase field margins and hedgerows? [3]

- increase biodiversity

- increase soil fertility

- decrease soil erosion

How have governments reduced landfill dumping?

taxing landfill to discourage unmeasured use

Trophic level

step in a food chain or food web

Biomass

total amount of living tissue within a given area or volume

What is the original source of all biomass?

the sun

What is the problem when measuring dry biomass?

the organism must be killed and dried out to carry out the meaurement

What is the problem when measuring wet biomass?

water levels of an organism vary, so the results are not reproducible/repeatable

What happens to biomass as you ascend the food chain?

it decreases

Why is biomass of a trophic level more useful than the number of organisms?

number of organisms does not accurately represent transfer of biomass between trophic levels

Pyramid of biomass

pyramid that illustrates the total mass of all the organisms in each trophic level in an ecosystem

Why does total biomass decrease as you ascend the food chain? [3]

- egestion and excretion

- respiration for movement and maintaining temperature

- wastage of indigestible parts

Incident energy

light from the Sun arriving at the surface of the Earth

Egestion

removal of undigested waste

Excretion

removal of metabolic waste

What percentage of incident energy is absorbed by plants?

1%

What percentage of biomass passes from trophic level to trophic level?

10%

Why is biomass lost in faeces? [3]

- herbivores cannot digest all plant material that they ingest

- carnivores cannot digest all animal material they ingest

- the remainder is egested in faeces

Why is biomass lost in urine? [3]

- excess protein is converted into urea

- urea is excreted via urination

- proteins are not available to build biomass

Why is biomass lost in respiration? [3]

- respiration breaks down compounds which could be used to build biomass and waste products are released

- needed for muscle contraction and movement

- needed to maintain constant internal temperature

efficiency of biomass transfer =

((biomass after)/(biomass before)) x 100

Ectotherm

cold-blooded; an organism whose body temperature varies with the temperature of its surroundings

Endotherm

warm-blooded; an organism whose body temperature does not vary with its surroundings

Why do ectotherms transfer biomass more efficiently? [3]

- they use less biomass for aerobic respiration

- as they do not regulate their body temperature

- more biomass can be used to build their own biomass