Chapter 2: Ecosystem Processes

Food Chains and Food Webs

Food Chains

• Food chains show the ==transfer of energy between organisms==, the arrows represent the ==direction of energy transfer.==
• A food chain consists of a ==producer, a herbivore, a carnivore and an apex predator.==
• The producer is a ==plant which makes its own food==.
• The herbivore is a type of ==consumer which eats the producer.==
• The carnivore is ==a type of consumer which eats other animals.==
• The apex predator is the ==last link in the food chain, which eats the carnivore,==
• Bioaccumulation- The build up of ==chemicals, like insecticides==, passed along a food chain.

Food Webs

• Food webs show how lots of ==food chains are connected in an ecosystem.==

Populations and Ecosystems

• A population is the ==number of organisms who live in the same area.==

• Populations of organisms are ==constantly changing==, which affect ==other populations in a food web==.

• Aerobic Respiration

  • This is ==with oxygen==.
  • The word equation for aerobic respiration is ==glucose + oxygen → carbon dioxide + water ( + energy).==
  • Aerobic respiration occurs in the ==mitochondria== of cells in order to ==transfer energy==.
  • Mitochondria- small structures in a cell which ==make most of the energy for the cell.==
  • ==Glucose== is absorbed from the ==small intestine into the blood plasma==. It is transported into the cells where ==it diffuses in.==
  • Blood plasma- ==the liquid component of your blood==, which contributes to just over 50% of your blood’s volume.
  • Oxygen is breathed in, then it ==diffuses into the bloodstream==. Oxygen is then carried by ==haemoglobin== to the cells where it diffuses in.
  • Haemoglobin- a red pigment which ==binds with oxygen== in order to carry oxygen to where it is needed for respiration.
  • ==Carbon dioxide== then diffused out of the cells and into the blood plasma. After that, it is transported to the lungs where it diffuses into the ==alveoli== and is exhaled.
  • Alveoli- ==multiple air sacks== which are inside your lungs. Alveolus is the ==singular version== of alveoli.

  Anaerobic Respiration

  • This is ==without oxygen.==
  • The word equation for this is ==glucose → lactic acid ( + energy).==
  • Anaerobic respiration happens when there is ==not enough oxygen for aerobic respiration,== such as intensive exercise.
  • It transfers ==less energy== than aerobic respiration.
  • The ==lactic acid== produced can ==cause muscle cramps==. This causes ==increased inhalation to break down lactic acid== – the oxygen needed is called the ==oxygen debt==.
  • It can take a ==few hours from a normal exercise==, to ==several days after a marathon== in order to pay back an oxygen debt.

  Fermentation (in microorganisms)

  • The word equation for this is ==glucose → ethanol + carbon dioxide ( + energy)==
  • ==Yeast== respires anaerobically, the fermentation is ==important in food production.==

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  Photosynthesis

  • Photosynthesis is a ==chemical reaction== that takes place in the ==chloroplast== to ==produce glucose.==
  • The word equation for photosynthesis is ==carbon dioxide + water → glucose + oxygen==. The symbol equation for this would be ==Co2+h2o → c6h12o6+o2.==

  A leaf’s adaptation for photosynthesis

  • Leaves have a lot of ==chlorophyll,== which ==absorb light for photosynthesis and are responsible for the green colour in a leaf.==
  • They are ==thin== in order for ==gases to be able to diffuse in and out of the leaf.==
  • They have a large ==surface area== so they can ==absorb as much light as possible.==
  • They have ==veins==, these are the ==vascular tissue== of the leaf and are ==located in the spongy mesophyll.==
  • The vascular system has two types of tissue, ==xylem and phloem==.
  • The ==xylem distributes water and dissolved minerals upward== through the plant, from the roots to the leaves, while the ==phloem carries glucose downward== from the leaves to the roots.

  Minerals

  • The minerals plants need for growth are ==nitrates, phosphates, potassium and magnesium.==
  • Nitrates for ==growth.==
  • Phosphates for ==healthy roots.==
  • Potassium for ==healthy leaves and flowers.==
  • Magnesium for making ==chlorophyll==
  • If a plant does not have enough of a mineral, it may suffer from a ==mineral deficiency.== Farmers can use ==fertilisers== to ==add missing minerals to the soil.==
  • Symptoms of mineral deficiency in a plant are ==stunted growth, purple-red colouring, chlorosis, Interveinal Chlorosis and Chlorosis.==
  • Chlorosis- The ==loss of the green colour== in plants, this is due to them producing ==insufficient chlorophyll==. Leaves with chlorosis are often ==pale, yellow or a pale yellow==. This is caused by ==iron deficiency==.
  • Interveinal Chlorosis- A ==yellowing of the tissue in between the veins== due to the leaves producing ==insufficient chlorophyll==. Unlike Chlorosis, ==the veins are still green.==

  Chemosynthesis

  • Chemosynthesis is when ==bacteria== use a variety of ==chemical reactions== to ==make their own glucose.==
  • Unlike ==photosynthesis==, it ==does not use sunlight== as the energy source, it uses ==chemicals.==
  • The word equation for chemosynthesis is- ==Carbon Dioxide + Water + Hydrogen Sulfide → Glucose + Sulfur Compounds==
  • The symbol equation for chemosynthesis is ==18H2S + 6CO2 + 3O2 → C6H12O6 (carbohydrate) + 12H2O + 18S.==

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Other Key Words

• Prey- An organism which ==is eaten by== another organism.

• Predator- An organism that ==eats== another organism.

• Interdependence- When living organisms ==depend== on each other ==to survive, grow, and reproduce.==

• Ecosystem- All the organisms found ==in a particular location==, and the ==area they live in==.

• Community- The ==organisms== in an ecosystem.

• Habitat- The ==area== a community lives in

• Niche- The ==particular place== or ==role== that an organism has within an ecosystem. This ==reduces competition for resources.==

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