How do living systems interact with the environment?
In this unit students develop an understanding of the nature of biology by exploring one of the most important concepts of the science; that all organisms are interconnected in populations, communities, and ecosystems. Through exploratory activities, students are introduced to the great diversity of life and its building blocks. They work cooperatively to examine the hierarchy of life’s organization starting from molecules and cells to ecosystems. Local ecosystems are analyzed to elicit the relationships between species and depict the flow of energy within these systems. Students also discuss the impact that the human species has on these often delicate living systems.
- How does the structure of an organism allow it to function as a part of a local community?
- How are species dependent on both other species and the abiotic environment?
- How does energy flow within an ecosystem?
structure and function
How do species and populations change over time?
Evolution is an important model throughout all of biology, greatly influencing our understanding of ecology, biological classification, cellular biology, and genetics. In this unit, students develop an understanding of how species and populations change over time. They examine competition among species and how the environment affects survival. Students also evaluate evidence for biological evolution (e.g., embryological, anatomical, morphological, fossils, biochemical, and genetic similarities).
- How do limited resources shape populations?
- How do changes in genetic information affect the size and diversity of a population?
- What impact does human population growth and spread have on local species?
- What factors are involved for natural selection to occur?
How is cell structure related to the functions of living things?
In this unit students explore cells, the fundamental components of living things. They perform chemical tests to determine the major macromolecules of which cells are composed. Students describe the building blocks of each type of macromolecule and examine the functions that these macromolecules have in cells. Through experimentation and model building they learn how these cell functions determine that of the organism. Students learn that all cells come from pre-existing cells.
- What are the basic macromolecules in cells?
- What functions must all cells maintain?
- How do proteins catalyze cell processes?
- Where do cells come from?
- How do cells of multi-cellular organisms differentiate for specific functions?
How do specialized cells maintain homeostasis in living systems?
In this unit students learn that multi-cellular organisms are composed of a great variety of specialized cells, organized into tissues, organs, and systems that function together to ensure homeostasis of the organism. Through microscopic studies, students discover the shapes and structures of various specialized cells and organelles and identify how those differences allow for specialized functions. They then relate the functions of the cells with the functions of the tissues and organs that they comprise. Applying this knowledge, students analyze the processes used by cells and organisms to maintain internal stability and assess the impact of various environmental changes on that stability.
- How do cells differentiate in multi-cellular organisms?
- How do specialized cells work together in tissues, organs, and systems?
- How do cells transmit in multi-cellular organisms?
- In what ways do organisms maintain their internal stability despite changes in the environment?
How is energy obtained, transformed, and used by living systems?
In this unit students learn on how living things obtain and use energy and how that energy then moves through an ecosystem. This unit focuses on the process of photosynthesis used by many bacteria and nearly all plant cells to capture and store sun energy. The unit also explores the process of cellular respiration, which releases stored energy for use in cellular processes. Students design experiments to determine how different environmental factors affect the rates of photosynthesis and respiration. They investigate food webs, identifying the flow of energy in living systems. Finally, students explore the cycling of nutrients such as carbon and nitrogen, which are critical for the metabolic processes that capture, store, release and use energy.
- How do living things obtain and store energy?
- How do living things extract energy from organic compounds?
- What mechanisms allow matter and energy transfer through ecosystems?
- How are energy resources distributed in ecosystems?
- How do increasing human populations impact the energy balance in ecosystems?
How is genetic information transferred and changed during cell reproduction?
Students examine how cells reproduce and the implications for genetic continuity in species. They first perform experiments to determine membrane responses including cell size limitations that lead to cell division. Students perform microscope studies to examine cells in different stages of mitosis. They also observe differentiation of cells to form specialized tissues. Students model both the cell cycle and the genetic recombination and mutations that can occur during mitosis and meiosis to learn how genetic information is passed on and how its integrity is normally preserved during these cell processes. Examining the mechanisms that can lead to changes in genetic information provides the basis for later studies of variation and natural selection.
- How does the process of cell division ensure genetic continuity?
- How do the processes of meiosis, gamete formation, and transformation achieve variation?
- How does cell differentiation lead to tissue and organ formation in embryos?
- How can mutations be beneficial or harmful?
How does genetic information determine traits?
Students begin their study of genetics with a historical approach, analyzing the data collected by Gregor Mendel by using statistical tools. They interpret Mendel’s model and use it to make predictions as they design their own inheritance experiments using fast-growing mustard plants. Within the contexts of these experiments, students learn the important terms and concepts associated with Mendelian genetics including dominant and recessive traits, genotypes and phenotypes, co-dominance and sex-linked traits. They recognize that Mendel’s model included the first descriptions of the structures that we now call genes and chromosomes today. Students use tools such as statistics and Punnett squares to make their predictions and analyze experimental results.
- How did Mendel’s model describe the function of genes and chromosomes?
- How can mathematical tools such as probability and statistics be used to predict the occurrence of traits?
- How can Mendel’s model be expanded to explain processes such as sex linkage and co-dominance?
- What is the relationship between the model Mendel developed in the 19th Century and the modern concepts such as gene, allele, and chromosome?
Law of Independent Assortment
Law of Segregation
How does genetic material function in continuity and variation?
In this unit students learn the structure and function of DNA and RNA and how these chemicals function in the control and transmission of traits from generation to generation. This knowledge is gained through investigation, modeling, and research. They apply this information to discover how natural and artificial changes to the genetic material impact organisms. Students investigate the effects of changes in genetic material such as the mutations that can cause inherited disease. Students also examine the bioethical implications of current genetics as they research and develop a position paper on an ethical issue related to genetic engineering. They present their research and as a class discuss/debate the position allowing students to critique and defend these important and controversial topics.
- What are the structure and function of DNA and RNA?
- How is genetic information transmitted from generation to generation?
- How is the synthesis of protein controlled in a cell?
- How is genetic information modified in nature?
- What are the biological, medical, and societal ramifications of genetic engineering?
How is the evolution of Earth’s living things evident in Earth’s biodiversity?
In this unit students evaluate the various lines of evidence for evolution and learn how evolutionary relationships have led to modern systematics. Students begin by reviewing the theory of natural selection and then, using an example such as Darwin’s finches, apply their newly acquired knowledge of biological inheritance to discover the importance of genetic change and variability to the process of evolution. In addition they examine the fossil record, biochemistry and morphology of a given species to provide a informational basis for evaluating the evidence for evolution. Students examine various types of evolution including geographic and reproductive isolation, genetic drift, and the various types of selection (stabilizing, directional, and disruptive). They examine current biodiversity to look for further evidence of evolution on Earth.
- How do genetic variations become the raw material for evolutionary changes?
- What do chemical and morphological similarities between various species suggest about evolution?
- How do changes in the environment effect evolutionary changes?
- How does biological classification mirror evidence for evolution?
How and why do ecosystems change?
This final unit serves as a culmination of understanding our biological world and how its very framework is threatened by mans ever-increasing impact. Students examine a local ecosystem depicting its food webs, identifying trophic levels, and predicting the impact that environmental changes, such as the addition of an invasive species, could have on the web. Applying their knowledge of natural selection, students identify the adaptations of species in the ecosystem, predict how this ecosystem could change over time, and recognize the benefits of biodiversity as it applies to ecosystem stability. They analyze data on topics like global warming and human population growth, engage in group discussions, and draw conclusions about man’s impact on the biosphere.
- How do food webs and ecological pyramids depict matter and energy relationships of an ecosystem?
- How do changes in gene pools lead to changes in ecosystems?
- What are the effects of increasing demand and decreasing supply of our natural resources?
- How is ecosystem stability threatened by man’s increasing ecological footprint?
human impact on the environment