TEKS 812 C

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    TEKS 8.12 C

    Lords of the Rings

    TAKS Objective 5 The student will demonstrate an understanding of

    Earth and Space systems.

    Learned Science Concepts:

     Complex interactions occur between matter and energy.

     Cycles exist in Earth systems.

     Characteristics of the universe.

     Natural events and human activity can alter Earth systems.

    TEKS Science Concepts 8.12

    The student knows that cycles exist in Earth systems. The student is

    expected to:

    (C) predict the results of modifying the Earth’s nitrogen, water and

    carbon cycles.


    Human activities have impacted and in some cases destroyed the delicate balance of energy flow, and chemical cycling of ecosystems. Often, these effects are local as well as global. It is also important to understand the role of water in terms of quantity and quality as potable water is a limited resource and overpopulation urbanization, and inefficient irrigation practices place considerable pressure on our ability to provide the amount of clean water necessary to survival. An overlapping concern is loss of nitrogen in the soil through denitrification, immobilization, leaching, runoff and volatilization. In this TEKS, understanding the role greenhouse gases play with regard to environmental problems will be tied to creating a sustainable planet. Greenhouse gasses include water vapor, methane,

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    carbon dioxide, chlorofluorocarbons (CFC) and nitrogen oxide (NO). Using this information, students will have the knowledge they need to understand their role in becoming careful guardians of the environment.

    Instructional Strategies

    A variety of simulations will be used to build knowledge about these cycles. A game similar to Chutes and Ladders will be used to learn the Nitrogen cycle. Online graphic simulations will represent both the water and carbon cycle. Objectives

    1. The student will identify and classify natural and human activities that

    influence the carbon cycle.

    2. After graphing the temperature and carbon dioxide data, the student will use

    data to predict the results of global warming.

    3. The student will predict the results of: denitrification, volatilization, leaching,

    runoff and immobilization on the nitrogen.

    4. The student will summarize the effects of human activity on the water cycle:

    global warming, water quality and quantity.

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;For Teacher’s Eyes Only

    Carbon Cycle

    Carbon is a very important element for a couple of reasons. The raw materials that make up hair, muscle and skin are carbon based and carbon is the basic unit of all living organisms. Also, carbon bonds store energy allowing living organisms to move, eat, sleep, breath and repair. So carbon is very important to life on this

    planet and its versatility in terms of the ability to bond with a number of elements creates a number of complex pathways that are used to recycle carbon throughout the environment. It is estimated that each carbon molecule

    has made approximately 30 trips through the carbon cycle over the last four billion years. Now that’s a lot of frequent flyer miles!

    There are a number of possible ways carbon cycles through the environment.

    One way involves photosynthesis and cellular respiration. During photosynthesis, plants and algae use COfrom the air or water to manufacture glucose (CHO) 2 6126

    to fuel the process of cellular respiration. In cellular respiration, glucose is broken down in a chemical reaction with oxygen releasing carbon dioxide, water and energy. In this way, the photosynthesis and cellular respiration enable the cycling of carbon and oxygen through the environment. Other ways carbon cycles through the environment include:

     Decomposition when CO and CH is released, 24

     Stored in shells and skeletons of marine animals where it is stored as

    CaCO 3,

     Stored in wood (e.g., trees),

     Released from wood as CO (e.g., burning of wood) and 2

     Stored in a fossil fuel such as coal and then released as COduring 2


    The table shows natural sources of carbon and sources of carbon due to human activity. Burning of fossil fuels, respiration and decomposition are the most frequently mentioned methods by which carbon in the form of carbon dioxide enters the atmosphere. Since photosynthesis by plants is how carbon

    dioxide is removed from the atmosphere, students should understand how easy it is for an excess of CO to just hang around in the atmosphere creating problems 2

    because CO molecules absorb heat. Unlike oxygen (O) and atmospheric 22

    nitrogen (N) atoms which are bound too tightly together to vibrate and absorb 2

    heat, a molecule of carbon dioxide is composed of three atoms that are bound loosely together enabling it to vibrate and absorb heat. Another source of carbon is methane (CH). Methane is the principal ingredient of natural gas and is 4

    generated by bacteria in rice paddies, decomposition and ruminant animals such

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    making it a more as cattle. Methane absorbs 20-30 times as much radiation as CO2

    serious greenhouse gas.

    Natural Sources Sources of Carbon from

    of Carbon Human Activity

    ; Death of plants and animals ; Burning wood or forests

    ; Animal waste ; Cars, trucks, planes

    ; Atmospheric CO ; Burning fossil fuels such as 2

    coal, oil and natural gas to ; Weathering

    produce heat and energy for ; Methane gas from cows (and

    our homes and businesses other ruminants)

     ; Aerobic respiration from

    terrestrial and aquatic life

The carbon cycle is important in terms of the greenhouse effect, which is the

    warming of the atmosphere caused by carbon dioxide, methane and other gases that absorb infrared radiation slowing its escape from the Earth’s surface. Some scientists believe the greenhouse effect can have effect on food production, precipitation (flooding), Polar Ice Cap melting (mixing fresh and salt water upsetting ocean currents), economic loss (catastrophic events), and displacement of species (upsetting ecosystems) and immune system impact (increasing lethal disease). However, skeptics charge that the process by which oceans take up excess carbon dioxide is not well understood and water vapor is the most important greenhouse gas that impacts temperature. The skeptics also indicate that the earth will self-correct, CO is necessary to prevent the planet from cooling 2

    down, and COincreases plant growth. 2

    Nitrogen Cycle

    Nitrogen (N) makes up 79% of the atmosphere where it exists as a gas. There are 2

    also trace amounts of NH, NO, and NO in the atmosphere. Even though 322

    atmospheric nitrogen is all around us, it is not in a form that can be utilized by humans who must have nitrogen to carry on life’s functions such as making amino acids and proteins (e.g., muscle, hair, enzymes) and nucleic acids (e.g., DNA, RNA). That is, humans cannot use atmospheric nitrogen. Therefore, it is

    the nitrogen cycle, which makes possible a different source of nitrogen that humans can use, and we obtain this source of nitrogen by eating plants and/or the animals that have eaten plants. About 90% of nitrogen is biochemically fixed in the soil by microorganisms. Legumes and other types of plants that form mutualistic symbiotic relationships with nitrogen fixing bacteria (e.g., Rhizobium)

    provide the nitrogen we depend on for our survival.

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Generally, nitrogen is stored in living and dead organic matter, then

    converted into inorganic forms through the process of decomposition

    although a little enters the soil in rainfall or through the effects of lightening. Plants cannot use organic forms of nitrogen, so decomposers such as bacteria and

    ) and convert it to fungi take nitrogen occurring in the form of ammonia (NH3+ammonium salts (NH), which are highly attracted to negative clay particles in 4

    the soil. This process is known as ammonification or mineralization. During the process of immobilization nitrogen is taken up by microbes and immobilized or made largely unavailable to plants. Immobilization occurs when the ratio of C:N is greater than 30. Immobilization is the opposite of mineralization. Interestingly, nitrogen is often the limiting factor for plant growth. Plants can only take up inorganic nitrogen from the soil solution in solid form as ammonium salts +-(NH) or nitrate (NO). As previously mentioned, since ammonium is a 43

    positively charged ion, it is readily absorbed onto the surface of negatively charged clay particles in the soil. When the ammonium is released by the clay particle:

    1. It is usually chemically modified by chemotropic bacteria (Nitrosomonas) -into nitrite (NO) and 2

    -2. Further modified by chemotrophic bacteria (Nitrobacter) into nitrate (NO3

    ), which is an extremely soluble solid form of nitrogen that can be used by


    Both of these processes are known as nitrification and excess ammonium salts

    will stimulate the process of nitrification. Since nitrate is extremely soluble and negatively charged, it is sometimes lost from the soil (reducing soil fertility) through a process called leaching where it moves through the soil and into the

    groundwater contaminating streams and drinking water. When nitrites are absorbed into the human body, they bind to hemoglobin and reduce oxygen-carrying capacity. In babies, this can lead to “blue baby syndrome” a form of respiratory distress. In the gut, it can also form nitrosamines, which are highly carcinogenic. For this reason, there are strict government regulations

    concerning the amount of nitrate that can be present in drinking water.

    When nitrate reaches the oceans, it can be returned to the atmosphere by denitrification. The process of denitrification is also common in poorly drained soils (e.g., wetlands) in which nitrate is reduced to nitrogen or nitrous oxide gas by heterotropic bacteria (e.g., Pseudomonas, Alkaligenes and Bacillus). The gas

    escapes into the atmosphere through volatilization. Urea fertilizer and manure on

    the soil surface also form gases that volatilize into the atmosphere. The processes

    of denitrification and volatilization account for most of the nitrogen lost to the cycle.

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Nitrogen is also lost from the soil due to runoff, which results when soil is

    saturated with water and can hold not more water. If the soil is void of protective vegetation and has a steep slope, then soil materials will be carried off by excess water. When this occurs, both organic and inorganic nitrogen are carried down to streams, and other water sources causing water pollution and harm to aquatic life. This is different from, erosion, which is the result of the soil surface wearing

    away by running water, ice, or other geological processes.

    Human activities that alter the nitrogen cycle include:

     Applying nitrogen fertilizers to crops and lawns increase


     leaching of nitrate into groundwater can contaminate human water


     Runoff of nitrogen in streams, rivers and lakes can lead to a population

    explosion of detrivores that will suffocate aerobic organisms.

     Burning fossil fuel produce nitrogen oxide that takes part in ozone


     Waste from livestock ranching can runoff and contaminate water


     Sewage treatment facilities dumping dissolved inorganic nitrogen into

    rivers, lakes and streams can cause algal blooms.

    O and NO are involved in the production of acid rain. N2

     In the stratosphere, NO undergoes photolysis (80% N and 20% NO) 22

    destroying the ozone, which protects us from UV rays.

    Water Cycle

    The water cycle describes the storage and movement of water. Water can be

    stored as surface water (e.g., ocean, lakes, rivers), soil, glaciers, groundwater and in the atmosphere. There are a number of processes that allow for the movement of water from one storage area to another. Evaporation, condensation, precipitation, runoff, leaching melting, deposition and transpiration are examples of processes that allow water to move from storage area to another. Most of the evaporated water found the atmosphere is supplied by the ocean. Ninety-one percent of evaporated water is returned to the ocean via precipitation with the remaining 9% spread out as precipitation over the landmass. The net balance is returned to the ocean through runoff and groundwater flow to the ocean. This is a never-ending cycle for moving water between the earth and the atmosphere. About 97% of the earth’s water supply is found in the ocean, so it is critical to exercise careful use of the remaining 3%.

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Another source of atmospheric water comes from tropical rainforests. The

    rapid destruction of tropical rainforests reduces the return of water to the atmosphere via the process of transpiration. Destruction of rainforests changes the amount of water vapor in the air, which in turn is likely to alter local and perhaps global weather patterns.

    Population increases and industrialization place unnatural demands on our environment and have the potential to affect the quantity and quality of usable water for generations. For example, a rising population can place impossible demands on a water system. Additionally, a rising population results in rising wastes. Urbanization alters the rates of infiltration, evaporation and transpiration. This can result in flooding and the inability to replenish ground water supply given the rate of water use. Additionally, poor agricultural practices waste water during crop irrigation, which further compromises our ability to meet the water demands given the finite nature of the water supply.

    Another aspect of the water cycle deals with water quality. As previously

    mentioned in the discussion of the nitrogen cycle, water may gather contaminates from the soil as runoff or as it percolates into the ground (infiltration) and possibly the groundwater system (i.e., leaching). As chemical and particles in dust, smoke, and smog accompany the movement of water recycling between the land and the air, these contaminates fall back to the earth in the form of precipitation (e.g., acid rain). In turn, this lowered water quality affects the land and water storage areas and disrupts fragile ecosystems. It is also possible to pollute water so thoroughly that as wastewater it must be impounded and not be returned to the water cycle resulting in a loss of potable water.

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Student Misconceptions


    Plants do not breath (respire).

    Science Concept

    Plants use stomata for respiration similar to how animals use lungs or gills. ;Rebuild Concept

    The instructor may wish to use a microscope to show students actual

    stomata of plants or show pictures of plant stomata and connect this

    activity with a debriefing about difference in respiration between plants

    and animals.


    Rainforests are the principle source of carbon dioxide uptake. Science Concept

    Algae in the oceans are responsible for the majority of carbon dioxide

    uptake from the atmosphere.

    ;Rebuild Concept

    Provide students with data showing the use of carbon dioxide by algae and



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    ). Humans use atmospheric nitrogen (N2

    Science Concept

    Humans cannot use Nand must obtain nitrogen from plants or animals 2

    that eat plants.

    ;Rebuild Concept

    Students will participate in the Nitrogen Cycle Game. The student should

    identify that ingestion of plants is how humans obtain nitrogen.


    There is plenty of water.

    Science Concept

    There is a limited supply of potable water on earth.

    ;Rebuild Concept

    Students will participate in the Water Cycle activity. The student should

    understand the impact of global warming and other human activities on

    water quantity and quality.

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Student prior knowledge

    Students should understand:

    TEKS 6.8 (B) explain and illustrate the interactions between matter and energy in the water cycle and in the decay of biomass such as in a compost bin; TEKS 6.14 (C) describe components of the atmosphere, including oxygen, nitrogen, and water vapor and identify the role of atmospheric movement in weather change;

    TEKS 7.5 (A) describe how systems may reach an equilibrium such as when a volcano erupts;

    TEKS 7.14 (A) describe and predict the impact of different catastrophic events on the Earth;

    TEKS 7.14 (B) analyze effects of regional erosional deposition and weathering; and

    TEKS 7.14 (C) make inferences and draw conclusions about effects of human activity on Earth’s renewable, non-renewable and inexhaustible resources.

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