the living world

• Ecosystem


  All the biotic (living components) and abiotic (non living components e.g soil, climate, water) parts of an area
• Organisms in ecosystems and their roles

  • Producer - uses sunlight energy to produce food
  • Consumer - gets energy by eating other organisms, can eat producers or other consumers
  • Decomposers - an organism that gets its energy by breaking down dead material, for example bacteria and fungi
• Nutrient cycle


  1. When dead material decomposes, nutrients are released into the soil

  2. The nutrients are then taken up from the soil by plants

  3. These plants may be eaten by consumers

  4. When the plants or consumers die, the nutrients are returned to the soil
• Food chain


  Shows what eats what
• Food web


  Shows lots of food chains and how they overlap
• The ecosystem relies on each other and if one part changes, it will affect all other parts of it
• UK ecosystem - Slapton Ley reed beds in Devon

  • Provides a habitat for lots of plants and animals
  • A typical food chain would be: Common reed →moth larva → eel → bittern
• The Slapton Ley reed beds are an interdependent ecosystem where all components depend on each other
• Biome


  A large scale ecosystem
• Types of biomes

  • TUNDRA
  • GRASSLAND
  • TEMPERATE DECIDUOUS FOREST
  • TROPICAL RAINFOREST
  • HOT DESERT
  • POLAR
• Tropical rainforest climate


  • Same all year round, no seasons
  • Hot (20-28 degrees all year) because the sun's energy is more intense at equator
  • Rainfall is very high, 2000mm per year, Raining daily
• Tropical rainforest soil


  • The soil is infertile due to heavy rain washing nutrients away
  • There are surface nutrients due to decayed leaf fall but is very thin
  • Red in colour due to iron in soil
• Tropical rainforest plants and animals

  • Very high biodiversity
  • Over 50% of all the world;s plant and animal species are found
• Tropical rainforest layers


  • Emergent layer
  • Canopy
  • Understory
  • Forest floor
• Buttress roots


  • Help anchor tall trees to the ground, allowing them to grow tall
  • Roots are shallow so can quickly suck up nutrients
• Drip tips


  • Pointed tip with waxy surface so water runs off the leaves as too much water negatively affects photosynthesis
• Epiphytes


  • Grows on other plants for support
  • Gets its nutrients from the air and water rather than soil
• Animal adaptations


  • Howler monkeys - Large gripping tail to move between canopy branches and secure when sleeping, Oversized larynx (voice box) for communication
  • Red eyed tree frog - Red eyes to warn off predators, Suction cups on feet to allow vertical climbing, Nocturnal to find food without danger
  • Anteaters - Improved sense of smell and hearing for sensing predators, Long claws for protection, 2ft long sticky tongue to pick up insects from tricky places
• Rainforests are interdependent ecosystems meaning if one thing changes, everything else is affected
• Many plant and animal species have formed symbiotic relationships where they depend on each other for survival
• Deforestation


  The permanent removal of trees
• In 2019, a football pick-size patch of tropical rainforest was lost every six seconds
• Brazil and Indonesia have lost the most tropical rainforests
• The global rate of deforestation is very high, it's generally increasing
• Brazil and Indonesia account for almost half of global deforestation
• Efforts have been made to reduce deforestation rates like in Costa rica, unauthorised deforestation became illegal
• Causes of deforestation in the Amazon


  • Commercial farming (main cause)
  • Subsistence farming
  • Commercial logging
  • Mineral extraction
  • Population growth
  • Road building
• Deforestation


  Releases carbon dioxide causing global warming
• Products like rubber, coffee, chocolate and medicines are sourced in the rainforest
• If species become extinct, it's hard to discover new medicines and develop new products
• Protecting the rainforest may reduce the greenhouse effect by reducing CO2 emissions as this affects all countries, not just the rainforests
• Strategies for sustainably managing rainforests

  • Replanting/selective logging
  • Education/conservation
  • Ecotourism
  • International hardwood agreements
• Desert climate


  • Very little rainfall (less than 250mm per year)
  • Rainfall patterns vary
  • Temperatures are extreme because of lack of cloud cover - 45 degrees in the day but 0 degrees at night
• Desert soil


  • A lack of leaf fall limits the soils fertility so hard to grow plants
  • Very few plants means much less decomposition which produces nutrients, so lack of nutrients
• Desert plants and animals

  • Only plants that grow are adapted to very low rainfall (cacti and thorn bushes)
  • Amphibians like snakes are best adapted to these conditions, very low % of mammals and birds due to a lack of rain
• Saguaro cactus adaptations


  • Thick waxy cuticle layer to conserve water
  • Pleated skin that can unfold as water is taken up when it rains
  • Needle like leaves as a self defence mechanism
• Camel adaptations


  • Thick lips to eat prickly plants
  • Large, flat very thick feet to walk on sand
  • Long eyelash, hairy ears an closing nostrils to keep sand out
• Desertification


  The degradation of land so it becomes more desert like, drier damaged and less productive
• Causes of desertification


  • Climate change
  • Population pressure
  • Overgrazing of livestock
• Ways to reduce desertification

  • Managing water
  • Managing soil
  • Planting trees
  • Utilising appropriate technology