HS-LS1-1  Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells.

HS-LS1-2  Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.

HS-LS1-4  Use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms.

This unit builds toward the following NGSS Performance Expectations (PEs):

HS-LS3-1*  Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.

HS-LS3-2  Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors.

HS-LS3-3*  Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.

HS-ETS1-3† Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.

*This performance expectation is developed across multiple OpenSciEd Biology units.

†This performance expectation is developed across multiple OpenSciEd courses.

LS1.A: Structure and Function

• Systems of specialized cells within organisms help them perform the essential functions of life.
• All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells.
• Multicellular organisms have a hierarchical structural organization, in which any one system is made up of numerous parts and is itself a component of the next level.

LS1.B: Growth and Development of Organisms

• In multicellular organisms individual cells grow and then divide via a process called mitosis, thereby allowing the organism to grow. The organism begins as a single cell (fertilized egg) that divides successively to produce many cells, with each parent cell passing identical genetic material (two variants of each chromosome pair) to both daughter cells. Cellular division and differentiation produce and maintain a complex organism, composed of systems of tissues and organs that work together to meet the needs of the whole organism. (HS-LS1-4)

LS3.A: Inheritance of Traits

• Each chromosome consists of a single very long DNA molecule, and each gene on the chromosome is a particular segment of that DNA. The instructions for forming species’ characteristics are carried in DNA. All cells in an organism have the same genetic content, but the genes used (expressed) by the cell may be regulated in different ways. Not all DNA codes for a protein; some segments of DNA are involved in regulatory or structural functions, and some have no as-yet known function.*

LS3.B: Genetic Variation

• In sexual reproduction, chromosomes can sometimes swap sections during the process of meiosis (cell division), thereby creating new genetic combinations and thus more genetic variation. Although DNA replication is tightly regulated and remarkably accurate, errors do occur and result in mutations, which are also a source of genetic variation. Environmental factors can also cause mutations in genes, and viable mutations are inherited.
• Environmental factors also affect expression of traits, and hence affect the probability of occurrences of traits in a population. Thus the variation and distribution of traits observed depends on both genetic and environmental factors.

ETS1.B: Developing Possible Solutions

• When evaluating solutions, it is important to take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts.

This unit intentionally develops students’ engagement in these practice elements:

Asking questions and defining problems:

• Ask questions that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.
• Ask questions that can be investigated within the scope of the school laboratory, research facilities, or field (e.g., outdoor environment) with available resources and, when appropriate, frame a hypothesis based on a model or theory.

Developing and using models:

• Develop, revise, and/or use a model based on evidence to illustrate and/or predict the relationships between systems or between components of a system.  
• Develop and/or use multiple types of models to provide mechanistic accounts and/or predict phenomena, and move flexibly between model types based on merits and limitations.  

The following science and engineering practices are also key to the sensemaking in this unit:

Constructing Explanations and Designing Solutions:

• Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.
• Apply scientific ideas, principles, and/or evidence to provide an explanation of phenomena and solve design problems, taking into account possible unanticipated effects.  

Engaging in Argument from Evidence

• Make and defend a claim based on evidence about the natural world or the effectiveness of a design solution that reflects scientific knowledge and student-generated evidence.

Obtaining, Evaluating, and Communicating Information

• Compare, integrate and evaluate sources of information presented in different media or formats (e.g., visually, quantitatively) as well as in words in order to address a scientific question or solve a problem.
• Communicate scientific and/or technical information or ideas (e.g. about phenomena and/or the process of development and the design and performance of a proposed process or system) in multiple formats (i.e., orally, graphically, textually, mathematically).

This unit intentionally develops students’ engagement in these crosscutting concept elements:

Cause and Effect

• Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects.
• Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system.  

Structure and Function

• The functions and properties of natural and designed objects and systems can be inferred from their overall structure, the way their components are shaped and used, and the molecular substructures of its various materials.

The following crosscutting concepts are also key to the sensemaking in this unit:

Patterns

• Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena.

Systems and System Models

• Systems can be designed to do specific tasks.
• Models can be used to predict the behavior of a system, but these predictions have limited precision and reliability due to the assumptions and approximations inherent in models.

Which elements of NOS are developed in the unit?

• Scientific Investigations Use a Variety of Methods. Science investigations use diverse methods and do not always use the same set of procedures to obtain data.
• Science knowledge is based on empirical evidence.
• Science is a Human Endeavor. Scientific knowledge is a result of human endeavor, imagination, and creativity.

How are they developed?

• Students design and carry out multiple investigations using models in the format of a game (Lesson 3), in computer and kinesthetic simulations (Lessons 4 and 5), and in laboratory investigations they design themselves. Each of these investigations support students in generating evidence that can be used to support student explanations.
• Beginning in Lesson 1, students consider the difference between correlation and causation and consider how evidence can support causal explanations.
• In Lesson 1, students hear from a scientist whose work has contributed to the body of knowledge related to cancer and cancer treatments.

In the anchoring phenomenon, students explore cancer statistics, including rates of new cases by cancer and state. They notice some differences that are hard to explain. Then, they investigate factors such as age and height and determine that people in different demographic groups have higher and lower cancer risks. They hear from a scientist who has studied cancer and are introduced to animal models. They read about the incidence of cancer and discover that there is something called p53 that might prevent cancer in other organisms. They develop initial models and generate questions that need to be answered to explain it fully. This phenomenon was chosen as the anchor because it generated high student interest across racial and gender identities in a national survey.

The unit is organized into three lesson sets. Lesson Set 1 (Lessons 1-6) focuses on the genetic basis of cancer. It ends with the development of a class consensus model. Lesson Set 2 (Lessons 7-10) helps students begin to explore the different causes of the mutations that lead to cancer, including mutations accumulated through our lifetimes, inherited mutations, and environmental mutations caused by interactions with the environment. This lesson set ends with a transfer task. Lesson Set 3 (Lessons 11-12) helps students explore treatment for cancer and the social systems that affect healthcare outcomes. This unit culminates with a transfer task where students develop an interview protocol that they could use to support someone they care about who has cancer.

This unit is the third in the OpenSciEd High School Biology course sequence. It is designed to build on student ideas about inheritance and variation of traits from middle school. In the units that follow this one (OpenSciEd Unit B.4: How does urbanization affect nonhuman populations, and how can we minimize harmful effects? (Urbanization Unit) and OpenSciEd Unit B.5: What will happen to Arctic bear populations as their environment changes?(Speciation Unit)) students will use what they figure about inheritance and variation of traits to make sense of evolution by natural selection and speciation.

This is the third unit of the High School Biology Course in the OpenSciEd Scope and Sequence. Given this placement, several modifications would need to be made if teaching this unit earlier in the Biology course. These include the following adjustments:

While the science ideas in this unit could be taught without modification prior to OpenSciEd Unit B.1: How do ecosystems work, and how can understanding them help us protect them? (Serengeti Unit) and OpenSciEd Unit B.2: What causes fires in ecosystems to burn and how should we manage them? (Fires Unit), its placement as the third unit supports student sensemaking in OpenSciEd Unit B.4: How does urbanization affect nonhuman populations, and how can we minimize harmful effects? (Urbanization Unit) and OpenSciEd Unit B.5: What will happen to Arctic bear populations as their environment changes?(Speciation Unit) which directly follow. If students do not experience this unit in order, they will likely need additional support to review big ideas related to inheritance and variation of traits prior to engaging with evolution by natural selection and speciation.

This unit requires students to develop mathematical models, use mathematical representations, develop algorithms and use rates of change. Making mathematical models is a Standard for Mathematical Practice, and specific modeling standards appear throughout the high school standards. This unit does not assume students are fluent with the mathematical practices listed in the unit front matter, but that students develop these practices as part of the sense-making. Thus these standards are not so much prerequisites, as co-requisites.

The following are example options to shorten or condense parts of the unit without eliminating important sensemaking for students:

• While critical to supporting students in making sense of treatments for cancer, Lesson Set 3 reinforces core ideas developed earlier in the unit related to cell divisions and can be condensed.

To extend or enhance the unit, consider the following:

• Lesson 2: While students examine different cell types (lung, breast, skin, etc.), they will not investigate the functions of those cells and those body systems in depth. This exploration is beyond the scope of the unit. However, an extension for motivated students could include an in-depth exploration of a particular body system, how it functions, and how cancer disrupts that function. This exploration would support the development of HS LS 1.A.1.
• Lesson 3: Making connections in math: Ask students to keep track of how many cancer and non-cancer cells they produce. At the end of Round 2, ask each group to add their results to a class data table. Then students determine the percentage of cancer cells produced compared to non-cancer cells. Students engage in mathematical modeling as they develop an understanding of the likelihood that cell division results in a cancer cell when p53 is functioning typically versus when p53 is functioning differently. Emphasize to students that these percentages may not reflect reality and that any percentages calculated are a result of game mechanics only. Should most students end up with cancer cells during the game, it is important that they do not come away thinking that developing cancer is inevitable in their lifetime.
• Lesson 5: While this lesson does not explore the discovery of the structure and function of DNA, some students may benefit from an investigation that extends their learning to include topics such as the discovery of the structure of DNA in the 1950s by scientists, including James Watson, Francis Crick, and Rosalind Franklin. Today, historians wonder about the cancer that ended Rosalind Franklin’s short life and the repeated exposure to the X-rays she used to determine the structure of DNA.
• Lesson 6: For students who demonstrated mastery of the standard at an earlier stage, consider an extension activity that requires them to consider the structure and function of the protein based on the charge of the amino acids. For more information see Optional Extension.
• Lesson 8: As an extension, consider having students submit their photos online in a shared slide deck or flip book or collect their drawings in class.
• Lesson 9: Questions may arise about different types of sunscreens. The two most common types of sunscreen commercially available are mineral and chemical sunscreens. Mineral sunscreens contain small particles, often zinc oxide and titanium dioxide, which remain on the skin’s surface and physically block UV rays from penetrating the skin. Chemical sunscreens allow UV rays to be absorbed by the skin where they react with chemicals in the sunscreen. As a result of this reaction, the energy from the UV light is converted into heat, which dissipates away from the skin. As an extension, students could investigate how these different sunscreens affect the yeast cell growth. Then, students could be asked to use the ideas around structure and function to explain how the two sunscreens work differently to protect against UV damage.

• Kate Henson, Unit Lead, University of Colorado Boulder
• DeAnna Lee-Rivers, Writer, University of Colorado Boulder
• Will Baur, Writer
• Ari Jamshidi, Writer, University of California, Berkeley
• Margee Will, Writer
• Veronica L. Cavera, Writer for Field Test, Rutgers University
• Sam Long, Writer for Field Test, Denver Public Schools
• Sherica Sang, Writer for Field Test, Denver Public Schools

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An integral component of OpenSciEd’s development process is external validation of alignment to the Next Generation Science Standards by NextGenScience’s Science Peer Review Panel using the EQuIP Rubric for Science. We are proud that this unit has been identified as a quality example of a science unit and earned the Design Badge. You can find additional information about the EQuIP rubric and the peer review process at the nextgenscience.org website.