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Cells and Chemical Reactions: Reaction Rates in Cells Science Object
Science Object
Cells and Chemical Reactions: Reaction Rates in Cells
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates how the reaction rates in cells can be affected by temperature, pH, hydration levels, and enzymes.

Chemical reaction rates are affected by the conditions in which they occur (or...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates how the reaction rates in cells can be affected by temperature, pH, hydration levels, and enzymes.

Chemical reaction rates are affected by the conditions in which they occur (or cannot occur). Most cells must function within a narrow range of temperature and acidity because they are part of a living system. At very low temperatures, reaction rates are too slow. High temperatures and/or extremes of acidity can irreversibly change the structure of most protein molecules. Even small changes in acidity can alter the molecules and how they interact. Hydration levels also affect chemical reactions in cells; dehydrated cells lack the solvent and substrate or substrate structure needed for chemical reactions to proceed. Both decomposition and synthesis of molecules (involving energy transfer) are made possible in cells by a large set of protein catalysts, called enzymes. Without enzymes to catalyze the chemical reactions necessary for life, the conditions (including temperature) inside of cells would slow chemical reaction rates below what is necessary to stay alive. Like other protein reactions, the effectiveness of enzymes reactions is affected by temperature and acidity.
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Interdependence of Life: Organisms and Their Environments Science Object
Science Object
Interdependence of Life: Organisms and Their Environments
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Interdependence of Life in Ecosystems SciPack. It explores organisms and their environments.

All organisms, including human beings, live within and depend on the resources in their environment. These resources include both...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Interdependence of Life in Ecosystems SciPack. It explores organisms and their environments.

All organisms, including human beings, live within and depend on the resources in their environment. These resources include both living (biotic) factors such as food and nonliving (abiotic) factors such as air and water. The size and rate of growth of the population of any species, including humans, are affected by these environmental factors. In turn, these environmental factors are affected by the size and rate of growth of a population. Populations are limited in growth to the carrying capacity of the ecosystem, which is the amount of life any environmental system can support with its available space, energy, water, and food.

Learning Outcomes:
  • Identify and describe biotic and abiotic factors that influence the size and growth rate of a specific population in a particular environment.
  • Describe possible immediate and long-term effects on an individual population that exceeds the carrying capacity of its environment.
  • Given a line graph displaying an individual population size and its rate of growth, infer the carrying capacity of the environment for that population.

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Science of Food Safety: Understanding the Cell's Importance Science Object
Science Object
Science of Food Safety: Understanding the Cell's Importance
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, is the first of four Science Objects in the Science of Food Safety SciPack. It explores self-replicating life forms, which are all composed of cells. Living cells contain similar types of complex molecules that support the basic activities of life....  [view full summary]

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, is the first of four Science Objects in the Science of Food Safety SciPack. It explores self-replicating life forms, which are all composed of cells. Living cells contain similar types of complex molecules that support the basic activities of life. These molecules interact in a soup, composed of about 2/3 water, surrounded by a membrane that controls what can enter and leave the cell. Cells have particular structures for cell functions, protection, and in some cases the ability to move. A single living cell represents the smallest individual unit of life. Single-celled organisms vary in the complexity of their structure and the amount of genetic material they contain, and populate all environments on Earth in astounding numbers and types. Those with less genetic material and simpler structures are more numerous. Bacteria are one type of single-celled organism that have an interdependent relationship with humans.


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Science of Food Safety: Growth and Reproduction of Cells Science Object
Science Object
Science of Food Safety: Growth and Reproduction of Cells
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, second of four Science Objects in the Food Science Safety SciPack. It explores cell functions involving chemical reactions that are made possible by protein catalysts called enzymes. These reactions require a fairly narrow range of temperature and...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, second of four Science Objects in the Food Science Safety SciPack. It explores cell functions involving chemical reactions that are made possible by protein catalysts called enzymes. These reactions require a fairly narrow range of temperature and pH. Low temperatures cause them to go too slowly, and high temperatures or acidity can change cell structures. Molecules from the environment may also attach to or pass through a cell's membrane and affect reaction rates. Cells such as bacteria require energy and nutrients from their environment for survival. When they grow to a certain size, bacteria can reproduce by creating a copy of their DNA and then splitting in two. Under optimal conditions, this doubling of bacteria and each of their generated offspring can proceed at a fast rate, expanding a bacterial colony rapidly in a short time. Many of the precautions taken to protect the health of humans focus on limiting the growth of bacterial colonies by creating environmental conditions not favorable for their functioning or reproduction. Variations in genetic information within a population of bacteria can permit some individuals to survive and reproduce more effectively than others in a given environment. Such hardier individuals usually represent only tiny fractions of a population, but their rapid reproduction can quickly give rise to large numbers of successful offspring. This process may give rise to bacterial strains able to survive under new conditions, such as strains with resistance to overused antibacterial drugs, or grant previously harmless bacteria the ability to cause disease.


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Science of Food Safety: Microbes, Friend or Foe Science Object
Science Object
Science of Food Safety: Microbes, Friend or Foe
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, is the third of four Science Objects in the Science of Food Safety SciPack. It explores how bacteria live in close concert with humans. Bacteria are masters at exploiting a variety of niches in the human body and live in huge colonies in places such...  [view full summary]

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, is the third of four Science Objects in the Science of Food Safety SciPack. It explores how bacteria live in close concert with humans. Bacteria are masters at exploiting a variety of niches in the human body and live in huge colonies in places such as the skin, intestines and mouth. Most of these bacteria are harmless to the human body, and many are important in assisting its normal, healthy functioning. Disease in humans results when organisms such as bacteria interfere with the normal operation of the human body, most commonly foreign organisms entering the body. The human body has many mechanisms to protect itself against outside organisms that may interfere with its normal operation.

Bacteria that gain entrance to the body may form colonies in preferred organs or tissues, emitting harmful toxins as waste products. If the body's immune system cannot suppress a bacterial infection, an antibacterial drug may be effective—at least against the types of bacteria it was designed to combat. Viruses invade healthy cells and cause them to synthesize more viruses, usually killing those cells in the process.


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Science of Food Safety: Food Safety and You Science Object
Science Object
Science of Food Safety: Food Safety and You
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, is the last of four Science Objects inthe Science of Food Safety SciPack. It explores the scientist involved with the development of germ theory and pasteurization, which brought about great changes in the safe handling of food and water, and improved...  [view full summary]

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object, co-developed between FDA and NSTA, is the last of four Science Objects inthe Science of Food Safety SciPack. It explores the scientist involved with the development of germ theory and pasteurization, which brought about great changes in the safe handling of food and water, and improved sanitation measures that represent some of the greatest public health contributions to date. More recently, humans have instituted laws requiring the monitoring of air, soil, and water for microorganisms that pose a threat to human health. Such agricultural and food safety regulations represent social trade-offs that ensure the population's general welfare at the price of increased cost or lowered efficiency. In addition to these large-scale societal precautions, humans rely heavily on personal measures to limit the transmission of invasive organisms into their bodies. These measures include keeping hands and skin clean, avoiding contaminated foods and liquids, cleaning and separating food items properly during preparation, cooking food at high enough temperatures for proper lengths of time, and keeping the temperature of food sufficiently low at all times when it is not being prepared or consumed.


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Heredity and Variation: Inheritance Science Object
Science Object
Heredity and Variation: Inheritance
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of three Science Objects in the Heredity and Variation SciPack. It explores the historical perspective and experiments of Mendel. Sexual reproduction results in the continuity of species accompanied with a great deal of variation in physical traits. One familiar...  [view full summary]

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of three Science Objects in the Heredity and Variation SciPack. It explores the historical perspective and experiments of Mendel.

Sexual reproduction results in the continuity of species accompanied with a great deal of variation in physical traits. One familiar observation is that offspring are very much like their parents but still show some variation— differing somewhat from their parents and from one another. People have long been curious about heredity, using even the most primitive understanding of inheritance to cultivate desirable traits in domesticated species. In the 1800s, Gregor Mendel took his observations of heredity and variation to new heights through carefully designed and executed breeding experiments that generated repeatable inheritance patterns. Mendel developed a model for explaining the patterns he observed, describing discrete units or “particles,” which both segregate and assort independently of one another during inheritance. This model offered a foundational explanation for how variation is generated through sexual reproduction. Although Mendel’s model over-simplified how traits are inherited and expressed, it set the stage for the discoveries of chromosomes and genes from which contemporary genetics grew.

Learning Outcomes:
  • Explain how domestication of plants and animals produced an early understanding of inheritance.
  • Use Mendel’s model to explain patterns of inheritance represented in graphic form (for example, data tables, histograms, etc.).
  • Identify the conditions required for an inheritance pattern to be explained correctly by Mendel’s model.
  • Use data representing patterns of inheritance to support the idea that some observable traits are defined by discrete units of inheritance that segregate and assort independently of one another during inheritance.

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Heredity and Variation: Genes in Action Science Object
Science Object
Heredity and Variation: Genes in Action
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Heredity and Variation SciPack. It explores sexual reproduction and the process of meiosis.

We now know that structures and functions at the molecular and cellular levels provide the mechanism for reproduction and the continuity...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Heredity and Variation SciPack. It explores sexual reproduction and the process of meiosis.

We now know that structures and functions at the molecular and cellular levels provide the mechanism for reproduction and the continuity of species. Instructions for development are passed from parents to offspring in thousands of discrete genes, each of which is a segment of a molecule of DNA. An organism’s particular genetic information, coded in its DNA (genotype), contains genes that provide the information necessary to assemble proteins. Offspring of asexual organisms inherit all of the parent's genes. In organisms that reproduce sexually, specialized female and male sex cells (gametes) are formed during a process of cell division called meiosis. Each of these sex cells contains a random half of the parent's genetic information.

When a particular male gamete fuses with a particular female gamete during fertilization, they form a cell with one complete set of paired chromosomes, a combination of one half-set from each parent. This random combining of gametes and their chromosomes during fertilization results in millions of different possible combinations of genes, which causes the offspring genotypes to vary from their parents’. Some of the new gene combinations make little difference in the ability of the offspring to reproduce or survive, some can produce organisms with capabilities that enhance their ability to survive and reproduce, and some can be deleterious, resulting in an inability to survive and/or reproduce. Learning Outcomes:
  • Distinguish among the following structures by describing their relationship to one another: DNA, chromosomes, genes, and alleles.
  • Describe the role genes play in the production of proteins and defining the phenotype of an organism.
  • Compare and contrast the DNA in cells produced during asexual reproduction versus the DNA in gametes produced during meiosis.
  • Indentify and describe those steps within the process of meiosis that explain the random distribution of genotypes among offspring resulting from sexual reproduction.
  • Explain how the recombination of the allele pairs for individual genes during sexual reproduction results in phenotypic variation among offspring.

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Heredity and Variation: Mutation Provides Variation Science Object
Science Object
Heredity and Variation: Mutation Provides Variation
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Heredity and Variation SciPack. It explores the role of mutations in genetic variation. The random combination of genes during sexual reproduction is not the only source of variation in organisms. Although some genes may be passed...  [view full summary]

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Heredity and Variation SciPack. It explores the role of mutations in genetic variation.

The random combination of genes during sexual reproduction is not the only source of variation in organisms. Although some genes may be passed for many thousands of generations with no consequential changes in its function, occasionally a mutation occurs in which a gene may be altered. Gene mutations can occur spontaneously through random errors in copying, or induced by chemicals or radiation that affect the DNA’s chemical bonds. Only if a mutated gene is in a gamete is it possible for copies of it to be passed down to offspring, becoming part of all their cells, altering the nature of some proteins produced by the DNA. The function of a mutated gene may not be altered or it may have its function in protein synthesis altered, which subsequently affects the physical traits expressed in the organism. Mutations provide additional sources of variation that can be helpful, harmful or of no impact on the survival an individual.

Learning Outcomes:
  • Compare and contrast genetic mutations with genetic variations resulting from the process of meiosis.
  • Identify and describe the general processes involved in the creation of genetic mutations.
  • Describe possible consequences of genetic mutations.
  • Describe conditions necessary for genetic mutations to be inherited by an organism’s offspring.

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Interdependence of Life: Species Relationships Science Object
Science Object
Interdependence of Life: Species Relationships
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Interdependence of Life SciPack. It explores species relationships.

All organisms, both land-based and aquatic, are interrelated by their need for resources. One example of a network of interconnections is called a food web;...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Interdependence of Life SciPack. It explores species relationships.

All organisms, both land-based and aquatic, are interrelated by their need for resources. One example of a network of interconnections is called a food web; it is a model of the interdependence among the organisms in populations of different species. Predator-prey and parasitic relationships are examples of interspecies relationships, interdependence that occurs among organisms in different species in a food web.

Interspecies relationships can be categorized as positive, negative, or neutral for the fitness of the individuals and their populations who are involved. A change in the population of one species can affect the population of another species. Intra-species relationships, or interdependence among organisms of the same species, can also affect a population.

Learning Outcomes:
  • Given the specific nature of an interspecies relationship, categorize the relationship between two interrelated populations as positive, negative or neutral for each population.
  • Given a description of a change to one population depicted in a food web, predict changes that might occur in the size and rate of growth for other populations depicted in the food web.
  • Given a line graph displaying changes in population sizes and rates of growth for a number of populations in a community, along with a description of the trophic relationships among populations, generate plausible hypotheses about causes of the changes depicted in the graph.

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