Download Prac learning week 8

Nutrient Cycles
Week 8
Cycles
In this section we will be focusing on
four nutrient cycles that we see in
our surrounding environments
1.
Water Cycle
2.
Oxygen Cycle
3.
Carbon Cycle
4.
Nitrogen Cycle
Water Cycle
Large quantities of water being cycled
through the Earth’s atmosphere, oceans,
land and biosphere
It’s important for determining our weather
and climate
Who can come to the board to illustrate
the water cycle for me?
Water Cycle
Evaporation: water evaporates from lakes, the ocean, rivers, streams
Transpiration: water loss from surface area of plants
Evapotranspiration: collective term for evaporation and transpiration
Condensation: process where water vapor is converted back into liquid
Precipitation: rainfall; when water returns to the earth
Infiltration: the process of water sinking into the ground. As water sinks into the Earth’s surface, it is
filtered and purified. The deeper the water, the cleaner it is.
Melting and Freezing: some water freezes and is “locked up” in ice, while other water melts and is
returned to oceans and seas.
Oxygen Cycle
O2 is one of the main gases found in air, along with
nitrogen.
Ways that oxygen is recycled between the air and
living organisms:
- breathing and respiration
- photosynthesis
- complementary relationship between
photosynthesis and respiration since one produces
oxygen and the other consumes oxygen
Carbon Cycle
Carbon is the basic building block of all
organic material, and therefore, all
living organisms
Main carbon cycling processes:
- photosynthesis
- gaseous exchange
Carbon Cycle
Carbon moves from one reservoir to another by these processes:
• Combustion: burning wood or fossil fuels by factory. This transfers carbon to carbon dioxide
• Photosynthesis: where is carbon dioxide present in this process?
Carbon dioxide is taken up by the plants and converted to energy rich sources
• Cellular respiration: animals eat plants for food, taking up carbon
• Metabolism: organisms convert carbon to organic molecules (fats, carbohydrates, proteins)
during digestion
• Precipitate: CO2 in atmosphere can precipitate as carbonate in ocean sediments
• Decay: CO2 gas is released into the atmosphere during the decay of all organisms
Nitrogen Cycle
Nitrogen gas makes up 78% of the gas in our
atmosphere. It’s a very important part of the
chemical make-up of amino-acids, proteins and
nucleic acids in our bodies, as well as in plants and
animals.
Nitrogen from the air cannot be used directly by
plants and animals, only a few single-celled
bacteria are able to use this nitrogen.
For most multicellular organisms to use nitrogen it
has to be changed into different forms like nitrates
or ammonia.
This process is called nitrogen fixation.
Nitrogen Cycle
Nitrogen cycle steps:
• Lightning: nitrogen can be changed to nitrates through lightning.
• Decomposition: bacteria and fungi break down proteins and amino acids from plants and animals
• Ammonification: nitrogenous breakdown products of amino-acids are converted into ammonia
by the decomposing bacteria
• Nitrification: conversion of ammonia to nitrate by nitrifying bacteria
• Absorption: ammonia and nitrates absorbed through plant roots
• Ingestion: plants are eaten by humans and animals
• Denitrification: bacteria convert ammonia and nitrate into nitrogen and nitrous oxide. Nitrogen is
returned to atmosphere to start cycle over.
Class Activity
Use flow charts to illustrate the 4
nutrient cycles
You will work in groups for this project
and will need to present the final
product to the class