ecology

why is less than 5% sunlight converted into chemical energy by plants?

• light doesn’t reach the plant

• light is reflected by the atmosphere

• light hits a non-photosynthesising part of the plant

• light is reflected off the leaves

why are there losses in energy between each trophic level

Losses of energy due to:

• energy lost as heat

• respiration

• not all of the organism is eaten e.g bones

• not all the organism can be digested e.g cellulose

• heat loss in digestion

• maintaining body temp of animals

uses of ATP

• cell growth

• active transport

• thermoregulation

• muscle contraction

how to calculate the efficiency of biomass transfers

efficiency = biomass transferred / biomass consumed x 100

what are ruminants and give examples

animals which have specialised stomachs to help with digesting plant material. They regurgitate their food to chew it twice.

e.g cows, sheep, goats

what are the 4 chambers in a ruminant’s stomach

1. rumen

2. reticulum

3. omasum

4. abomasum

what are the roles of each structure in a ruminants stomach

1. mouth - grass is ground by molars + mixed with saliva then swallowed

2. RUMEN - anaerobic conditions due to anaerobic bacteria —> produce cellulase that hydrolyses cellulose to beta-glucose

• sugars are converted into fatty acids

• production of waste products e.g CO2, methane

• bacteria makes proteins from NH4 salts in plant matter + saliva

3. RETICULUM: fermented grass is formed into balls —> CUD

• regurgitated + swallowed again

4. OMASUM - very muscular walls which contract to squeeze water out of reswallowed food —> reabsorption of water here

5. ABOMASUM - normal digestion —> secretion of proteases to hydrolyse proteins + HCl to kill bacteria

6. DUODENUM - neutralise the acidic stomach contents + absorb nutrients

role of microorganisms in ruminant digestion

• ruminants can’t digest cellulose as they don’t naturally make cellulase

• bacteria make cellulase which hydrolyses cellulose into beta-glucose

• glucose needed for anaerobic respiration of bacteria in the rumen

how to calculate Net primary productivity (NPP)

NPP = Gross primary productivity (GPP) - R (heat loss from respiration)

what is GPP

rate producers convert light energy to chemical potential enery

what is NPP

rate that plants accumulate dry mass per unit area per year

define productivity

rate of energy flow —> kJm^-2 yr^-1

how do abiotic factors impact productivity

ABIOTIC:

1. inc light levels —> max light for photosynthesis e.g plant under UV light

2. inc water availability —> ensure sufficient water for PHS + inc survival rate in drought e.g irrigation system/drought resistant species

3. maintain optimum temp —> emits CO2 to increase rate of PHS e.g paraffin heater

4. inc nutrients e.g plant nitrogen fixing crops to increase nitrate levels in soil

how do biotic factors impact productivity

1. dec pests - reduces disease + damage e.g pesticides

2. dec fungal disease - prevent damage + disease e.g fungicides

3. dec weeds - reduce competition for light, space, nutrients e.g herbicides

how to increase energy transfer between producers + primary consumers

1. harvest animals at younger age —> more energy for growth so they’re bigger

2. keep animals indoors —> less energy needed 4 thermoregulation

3. antibiotics —> reduce energy loss to pathogens

4. restrict movement —> less energy loss from muscle contraction

5. treat animals with steroids —> inc growth rate so more energy used for growing so bigger

intensive vs extensive farming

PROS + CONS of hedgerow removal