What are living things made of ?
What are living things made of? Cells are the basic unit of living things. Biology students develop mental constructs of cellu- lar structures and functions. Students draw conclusions about the essential components of cells and cell organelles to explain a variety of cellular functions in unicellular and multi- cellular organisms. Students investigate cellular structures using microscopes, models, and diagrams. Within this content progression, students build a richer conceptual under- standing of cell processes such as signaling, cell life cycles, and reproduction.
Learning Targets Learning Experiences
Misconception
V All cells are the same size and shape, i.e., there is a generic cell.
17 I can describe the cell theory and discuss the historical context of its development. (2) 18 I can distinguish biotic components from abiotic materials, using the scientifically accepted characteris- tics of living things. (2)
Using discussion, video and animation clips, and reading passages, students review the scientific discoveries that contributed to the foundation of the cell theory. Students should be able to summarize the evidence that supports the cell theory. With this background, students are given an object and asked to judge whether it meets the definition of “alive” (samples might include colored water droplets on wax paper, raisins suspended in soda water, pond algae or others drawn from the resource list). After a brief period of observation, students list lifelike and non-lifelike behaviors, and compare their findings to the scientifically accepted characteristics of life. Based on their analysis, students formulate a claim whether their sample is living or not, providing evidence from observation to justify their reasoning. Using prefixes and root words, students dissect the terms “abiotic” and “biotic,” construct a definition of each, and provide examples of both. Students use a card sort (pre-existing or self-constructed) to assist in distinguishing between abiotic and biotic factors.
Teacher Tips This learning progression is the beginning of the
17 I can describe the cell theory and discuss the historical context of its develoment. (2) 18 I can distinguish biotic components from abiotic materials, using the scientifical- ly accepted characteristics of living things. (2) 19 I can classify cells (prokaryotes and eukaryotes) based on the observation of internal structures and the complexity of the cell and can use those classifications to annotate a diagram of prokaryotic and eukaryotic cells. (2) 20 I can distinguish between common cellular organelles based on structure and function. (2) 21 I can classify cells after observing the presence or absence of organelles and I can draw conclusions about the function of the cell based on the abundance of organelles. (2) 22 I can compare and contrast different types of cells (plant, animal, bacterial, fun- gal, etc.) found in a variety of organisms. (2) 23 I can predict the role of an unfamiliar cell based on my knowledge of cellular components and their functions. (2) 24 Using knowledge of cell parts, I can design a cell that performs a specific function and can communicate the features of my designed cell. (2) 25 I can build a model of a phospholipid and compare the chemical characteristics of the two distinct parts of the molecule. (1) 26 I can build a model of a cell membrane and use the model to demonstrate how materials move across the membrane. (2, 5) 27 I can distinguish between solution types based on solute concentration (hypo-, hyper-, isotonic solutions). (5) 28 I can investigate how materials move across membranes and categorize the movements as active or passive transport. (5)
29 I can investigate cell membrane function using data collected from my investigation to explain a phenomenon related to movement across a membrane. (2, 5) 30 I can compare active and passive transport, provide examples of each, and describe the process for each. (2, 5) 31 I can relate multiple properties of water to impacts on cells and living systems, as well as the maintenance of homeostasis. (2, 5a) 32 I can describe the ways cells obtain information from nearby cells and the environment in the context of cell membrane composition. (2, 4) 33 I can modify a membrane model to ex- plain the phenomenon of cell communication in terms of membrane composition. (2) 34 I can make calculations from a hands- on activity and illustrate the amount of time spent in each phase of the cell cycle by a cell. (4) 35 I can use a model to describe patterns in typical cell growth and relate those patterns to the mechanisms of cell reproduc- tion for growth, differentiation, and repair. (4) 36 I can develop a model of chromosome movement and can use the model to explain the maintenance of chromosome number during mitosis. (4) 37 I can use chromosome models to illus- trate mitosis and to explain the role of mito- sis in maintaining populations of cells. (4) 38 I can use a model to demonstrate errors that may occur during cell division.(4) 39 I can identify the strengths and limitations of a model in representing the cell cycle and cell differentiation. (4) 40 I can use evidence to describe the internal and external factors that influence cell cycle control mechanisms. (4) 41 I can use a model to compare multiple pathways to tumor formation. (4)
discussion of cells. The emphasis is on the structure and function of organelles and the relationships of these within various types of cells. Students need to be involved in activities that allow them to observe, analyze, evaluate, and communicate the information about organ- elles and cells using various media. Viewing cells and organelles in various media will allow students to see the two-diomensional and three-dimensional structure. Student conceptualizations about the structure and function of organelles will be used in subsequent stan- dards to further understand cell processes. For example, it is imperative for students to understand the detailed structure of the cell mem- brane in this standard as a foundation for understanding cellular transport.
Teacher Resources
The Wacky History of Cell Theory — Lauren Royal-Woods Animated video on the history of Cell Theory. bit.ly/cell-theory Origins: How Life Began — NOVA Teachers Mini-activity to investigate the characteristics of life. bit.ly/characteristics-life (part 1 only) Sewer Lice Demo Directions — Flinn Scientific Students to use observations to evaluate the characteristics of life. bit.ly/sewer-lice What is Life? — Astrobiology A reading activity about the characteristics of life. bit.ly/astrobiology-what-is-life
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A Field Guide to the Alabama Standards
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