Cycles in Nature Notes

Water Cycle (Hydrologic Cycle):

1. powered by sun’s energy
2. precipitation---water in the form of rain, snow, sleet, hail
   1. water moves from the atmosphere to the land and oceans
   2. about 91% of precipitation falls into the ocean
   3. falls on land which renews the supply of fresh water
3. evaporation---the sun’s heat causes water to change from a liquid to a vapor which enters the atmosphere
4. condensation--- water vapor cools process of changing from a gas or vapor to a liquid
5. ground water--- precipitation seeps into the ground where it is stored in underground caverns or in porous rock
   1. may stay in the ground for hundreds or even thousands of years
   2. provides water to the soil, streams, rivers, and oceans
6. transpiration--- process by which plants return water to the atmosphere
   1. plants absorb water from the ground
   2. loss of water from plant leaves through openings called stomata (Desert plants close the stomata during the day.)
   3. helps plants stay cool
7. Water runoff on the surface can carry pesticides, fertilizers, insecticides, and other pollutants.
8. Glaciers and icebergs contain freshwater.

Carbon Cycle (carbon-oxygen cycle):

1. humus---in soil which is formed when dead organisms decay
   1. carbon in the decaying material is released into the atmosphere as CO₂
2. decomposition--- breakdown of dead materials into carbon dioxide and water
   1. decomposers such as fungi and bacteria break down dead organisms and recycle the nutrients
   2. decaying trees contribute to the health of an ecosystem
3. combustion---process of burning fossil fuels
   1. coal, oil, and natural gas return to atmosphere as CO₂ when burned
   2. provides much of the fuel people need to drive cars, heat homes, make electricity
   3. acid rain
4. photosynthesis--- plants use carbon dioxide from the air to make sugars and release oxygen
   1. Most animals get the carbon they need by eating plants.
   2. chemical reaction where light is converted into chemical energy
   3. Plants do not require other organisms for energy.
   4. The source of the carbon in glucose is the carbon dioxide in the air.
   5. Plants make glucose to use for energy or to store as starch for later use.
   6. A plant uses glucose to make cellulose when it links many simple units of glucose together.
   7. Photosynthetic organisms such as plants use light energy to produce a carbohydrate (glucose).
   8. process in which the energy in sunlight is stored in the bonds of glucose for later use

6CO₂   +   6H₂O   +   energy ®   C₆H₁₂O₆   +   6O₂

5.  respiration--- exchange of gases between living cells and their environment
   1. Animals and plants both respire (breathe)
   2. During respiration, sugar molecules are broken down to release energy.
   3. how cells get their energy
   4. Carbon dioxide and water are released as byproducts. 
   5. cellular respiration---the reactions within cells which result in the synthesis of ATP using energy stored in glucose

C₆H₁₂O₆   +   6O₂   ®   6CO₂   +   6H₂O   +   energy

Nitrogen Cycle:

1. most abundant element in atmosphere---about 78%
2. needed for proteins and DNA
3. Proteins are required for the life processes that take place in the cells of all organisms. 
4. animals get the nitrogen they need by eating plants or animals
5. nitrogen fixation---process where some types of soil bacteria can form the nitrogen compounds plants need

a.       bacteria break down dead organisms and their wastes which makes nitrogen gas (N₂)

b.      bacteria turn nitrogen into ammonia (NH₃) and then use it to make substances such as protein

c.       Plants absorb these nitrogen compounds through their roots. 

6. Bacteria also convert atmospheric nitrogen to ammonia in the soil.
7. Without bacteria, nitrogen could not enter living things or be returned to the atmosphere.
8. denitrification----takes nitrogen from the wastes of organisms and changes it back into nitrogen gas that is returned to the atmosphere

a.       Denitrifying bacteria live deep in the soil and on the ocean floor, where there is no oxygen.

b.      Bacteria use nitrate compounds to get oxygen for cellular respiration, and they produce nitrogen gas as a waste.

9. It is important to add nitrogen to the soil because farming depletes the usable nitrogen in the soil. Farmers replace nitrogen in the soil by growing nitrogen-fixing crops or using fertilizers that contain nitrogen compounds that plants need for growth.  (soybeans)

Global Warming-- worldwide increase in average temperatures

1. Earth is warmed by sunlight that reaches the planet.

a.       some sunlight is absorbed by the surface

b.      much of the sunlight is reflected into the atmosphere as heat

c.       some gases in atmosphere absorb reflected heat which some scientists think increase average temperatures

d.      greenhouse effect---trapping heat by certain gasses in the atmosphere

·        holding heat near Earth (acts like a greenhouse)

·        natural effect of Earth’s atmosphere

·        makes Earth warm enough to support life

·        greenhouse gases---water vapor (H₂O), carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)

·        nitrous oxide (N₂O)--- fertilizers release nitrous oxide into the environment; factories; burn fossil fuels

·        methane (CH₄)---dig for or transport fossil fuels; cattle and other livestock release methane as they digest food; released by landfills as organic matter decays

·        carbon dioxide (CO₂)---combustion of fossil fuels

2. Pollution---release of harmful substances into the air, soil, and water

a.       combustion, solid wastes, hazardous chemicals, fertilizers, radioactive materials, noise, heat

b.      in higher than normal amounts, greenhouse gases can become pollutants

3. Deforestation---removal of large numbers of trees and other plants from an area

a.       Deforestation disrupts the natural cycling of carbon and oxygen through the environment.

b.      It may cause the extinction of species and often leaves the soil infertile or soil erosion.

4. Effects of Global Warming—

a)      rising temps will cause the melting of polar ice caps, sea ice, glaciers

b)      increase ocean levels and flood large cities

c)      may alter areas of fertile land into deserts

d)      threaten wildlife, habitats, crops and entire ecosystems (Arctic organisms may not have a suitable area to live)

e)      ozone layer--- region located in the stratosphere several miles above the surface of the Earth

·        ozone (O₃)

·        plays a vital role by shielding humans and other life from harmful UV rays from the Sun (skin cancer)

·        scientists suggest that the depletion of the ozone layer is due to the increase in combustion  and the use of chlorofluorocarbons from aerosol cans

·        Higher ozone levels near the ground can damage crops and plants.

Renewable and Nonrenewable Resources---

1.  natural resources---naturally occurring materials and energy sources used by people

2.  renewable resource----can be replaced at a rate similar to the rate at which it is used

3.  nonrenewable resource---resource that is used or consumed much faster than it is formed

4.  Conservation---wise use of natural resources to protect the supply

a)      reduce---use less water (shorter showers, wash only full loads of dishes or laundry); reduce electrical power by turning off lights/appliances when not using them

b)      reuse---reusing products instead of discarding and replacing them; avoid excess packaging

c)      recycle---to process a material again to make a new product; paper, aluminum, plastic

d)      sustainability---use of resources in ways that both meet human needs now and will allow them to be met in the future

o       protects the environment for future generations

o       practiced with many resources, such as land, forests, fish, air, and freshwater (examples--building energy-efficient cars and homes, limiting fishing, and reusing materials )

Developing Natural Products---

1. natural product---useful substance produced by an organism (plants, fungi, bacteria, and animals)

a)      Aspirin and penicillin are used as medicines.

b)      Vitamin C is used as a nutritional supplement; ascorbic acid in citrus prevents spoilage of other fruit—slow oxidation

c)      to keep foods from spoiling

d)      to make crops more nourishing

e)      Willow Tree

o       Greeks/Romans---bark and leaves were used to relieve pain and treat fevers

o       Native Americans---used willow to treat sickness and pain

o       In the 1800s, a German chemist isolated the useful substance in willow bark and identified it as salicylic acid. Later chemists made an improved form, acetylsalicylic acid, which is easier on the stomach. Today, this substance is known as aspirin.

f)        Antibiotics---group of medicines used to kill bacteria that cause disease

o       Penicillin, the first antibiotic, was discovered in 1928 by Alexander Fleming. Fleming observed that mold growing on a culture dish prevented bacteria from growing in the dish. Fleming concluded that the mold must give off a substance that kills bacteria or prevents their growth.

2.  synthetic--- made by people

a)      Once a natural product is discovered, chemists work to determine its chemical formula.

b)      Chemists can use these elements in the same combinations to make the substance in the lab.

c)      Advantages to make natural products in the lab---

·        control the strength, or potency, of the substance

·        make the substance in large amounts

·        make the substance faster than it is produced in nature

·        make the substance without harming living organisms

Natural Products and Their Uses

Research and Development for natural products in Mississippi---

1. Thad Cochran National Center for Natural Products Research at the Univ. of MS--- developing natural products for use in agriculture; ways to control pests; improve the nutritional value of crops

2.  Jamie Whitten Delta States Research Center in Stoneville, MS----studying agricultural problems of southern U.S.; genetics and basic physiology; control of principal crops enemies; production systems and techniques; equipment innovation and development; safety and human health; economic well-being of both the agricultural producer and the consumer; and technology of pesticide application

3.  Mississippi Polymer Institute at USM---natural polymers are in living animals and plants; cellulose is the basis for cotton and rayon fibers; the selection, formulation and compounding of new materials; application and testing of developmental products; the design, synthesis and manufacture of new polymeric materials

Additional Diagrams---