Nutrient Cycles Guided Notes (H)
7th Grade Environmental Science
Mrs. Krempa (& credit Mrs Spiegel!)
Name _________________________
Date & Period ____________________
GOAL: To understand how nutrients cycle through the environment.
DIRECTIONS: Use this worksheet, the included diagrams and your textbook to answer
the following questions:
Earth’s “Spheres” pg. 74
1. What part of the planet does each “sphere” represent?
Geosphere all the rock at & below
Earth’s Surface
Atmosphere Layer of gases surrounding
our planet
Biosphere All living & once living things
Hydrosphere all water on Earth – salt,
fresh, vapor, above & below ground
2. Which sphere would humans live in? Biosphere (only sphere that includes living things)
Water Cycle pp. 80 & 81
3. What is evaporation? Conversion (change) of a substance from a liquid to a gas
4. What is transpiration? The release of water vapor by plants through their leaves
5. Why are evaporation and transpiration important? Both processes distill (clean) water
naturally by filtering out minerals and pollutants
7. What is precipitation? How does it occur? Water returns from the atmosphere to
earth’s surface (rain or snow). Occurs when water vapor undergoes condensation.
8. What is condensation? Change in state from a gas to a liquid (heat taken away)
9. How would cutting down large amounts of forests affect the water cycle?
Would there be: (circle)
More
Less
No change
transpiration?
More
Less
No Change
condensation?
More
Less
No Change
precipitation?
More
Less
No Change
evaporation?
10. The water cycle is powered by energy from the sun’s heat
** Water cycle “in a nutshell”…
1. Evaporation – liquid water gets heated, turns to vapor (gas) and rises
2. Condensation – Water vapor cools, condenses and turns into clouds
3. Precipitation – Water vapor turns back to liquid and falls as precipitation
Carbon Cycle pp. 83 to 85
11. What two products are created by the process of photosynthesis?
oxygen
and sugar (glucose)
12. The two main processes that are involved in the carbon cycle are?
photosynthesis and cellular respiration
13. List the formulas for photosynthesis and respiration.
Photosynthesis 6CO2 + 6H2O + Sun’s energy
Respiration
C6H12O6 (sugar) + 6O2
C6H12O6 (sugar) + 6O2
6CO2 + 6H2O + energy
14. What do you notice about the formulas? They are exact opposites!
** Carbon cycle in a nutshell…
1. All living and once living things on earth are made of carbon
2. Animals (us) return carbon to the system by breathing (respiration) and
burning things
3. Sedimentary rocks (fossils – once living things) return carbon to the system
when they are weathered / eroded
4. Plants take in Carbon in the form of CO2 during photosynthesis and give back
oxygen.
Problem – Humans are adding too much carbon to the system and the plants can’t
remove it all. PLUS – we are getting rid of the only things that get rid of
the CO2… the trees (plants)!!
Nitrogen cycle pgs 87 & 88
1. What percentage of the atmosphere is Nitrogen? 78%
2. Why is nitrogen important to living things? It is a key element in the formation of what?
(need it to live) main protein in DNA, RNA, essential nutrient for plant growth
3. During the nitrogen cycle, nitrogen gas is converted to
ammonia, which are useable by plants.
4. Explain what nitrogen fixing bacteria do and where they live.
Nitrogen fixation is the conversion of nitrogen gas into ammonia. Bacteria in the
soil “fix” or change nitrogen gas into ammonia & other nitrogen compounds that
plants can use.
5. What are legumes? Explain what they do and list all examples.
Legumes are plants that have special structures (nodules) on the roots where the
nitrogen fixing bacteria grow. Examples of these plants include soybeans, clover
and other legumes.
** Nitrogen cycle in a nutshell…
1. Free (all by itself) Nitrogen (N2) is in the air but we can’t use it.
2. Special bacteria that live in the soil and on the roots of legumes “fix” or
change the free Nitrogen into nitrogen compounds (like ammonia, nitrate and
nitrites) Think of this bacteria as “building” bacteria…
3. Plants use the nitrogen compounds to grow and we eat the plants getting the
nitrogen we need
4. Other bacteria in the soil take the nitrogen compounds back apart, releasing
free nitrogen back to the air. Think of this bacteria as “breaking” bacteria…