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Do you guys still remember natural recycling in I/GCSE Biology?
A matter of life and death
- Tissues in body made up of elements
- Elements called nutrients – needed for growth = lack would affect health + growth
- Photosynthesis – plants make carbohydrates = contain carbon, hydrogen, oxygen
- Refer to I/GCSE Biology, Plant to grow well = nutrients e.g. nitrogen (for proteins + DNA), magnesium (makes chlorophyll) calcium (strong cell walls) – absorb nutrients when taking water from ground – removes nutrients from environment + animals get food – nutrients not available for plants until there returned to soil = plants / animals die / animal produces waste material
- Decay of dead + waste material releases nutrients back to environment
What is decay?
- Decay – the breakdown of dead plants and animal material by fungi, bacteria and other organisms
- Decay = rotting / digestion of complex organic substances to simpler one e.g. bacteria
- Digestion happens outside cell of microorganism – simpler nutrients absorbed = gives microorganism nutrients needed for growth
- Simpler nutrients left in soil – plants absorbed using roots
- Enzymes secreted by fungus digest complex chemicals
- In I/GCSE Biology, Some products of digestion left to environment
- Some products from digestion absorbed by fungus
The best conditions for decay
- Decay microorganism = dry out (don’t have thick protective coating)
- Grow below surface of material their decaying
- Microorganisms more active when more oxygen to respire = cannot live far beneath surface
- Rate of reactions in cells of microorganism affected by temperature
- Colder = cannot grow quickly – decay warmer + faster in warm / moist conditions
From book + other stuff – from bitesize
- The key factors involved in decay are: Temperature, Amount of oxygen, Amount of water, The presence of microorganisms
- Microorganisms are important in decay - used to break down human waste (sewage) and plant waste (compost). Decay recycles important nutrients for plant growth
- In I/GCSE Biology, best conditions for most microorganisms (and therefore decay) are:
- Warm – speeds up chemical reactions
- Moist – easier to dissolve food; prevents microbes from dying out
- Oxygen – many need it to respire
Essential recycling
- No decay = no recycling of nutrients in environment = no life
- Balance between nutrients removed + absorbed in a stable natural community = little change to plants + animals over time
That's all~
