From Cells to Organisms

From Cells to Organisms 15: Disease Detectives

Students assume the role of epidemiologists as they read information about patients who are similarly infected with a disease. Students gather data about patients’ whereabouts, symptoms, onset of the disease, and likely incubation period of the disease. They investigate microbes that might be the infectious agents and hypothesize which microbe is causing the disease. As new evidence comes to light, they evaluate their hypotheses. Slides of cultures from patients allow them to support or confirm their hypotheses. The activity concludes with students explaining how an understanding of cells and infectious agents can help medical professionals with the diagnosis and treatment of diseases.

From Cells to Organisms 14: Fighting Disease

Students explore how knowledge about cell structure and function has helped scientists develop drugs that treat diseases caused by unicellular organisms. A video segment containing historic footage and photographs on the discovery of antibiotics to treat infectious disease, highlights how scientists formulate and test their explanations using observations and experiments.

The Discovery of Penicillin

Producing Penicillin

From Cells to Organisms 13: A Plant's Source of Energy

Students collect evidence for photosynthesis by examining the aquatic plant Elodea. They first perform an investigation to observe the uptake of carbon dioxide by the plant as one indicator that photosynthesis is taking place. Students then design an experiment to investigate the role of light in photosynthesis.

From Cells to Organisms 12: The Cells of Plants

Students make microscope slides of different plant parts. The looked at Elodea (leaves), Celery (stem), Carrot (root) and flower petals. By comparing photosynthetic and non-photosynthetic plant cells, students discover that chloroplasts are associated with photosynthesis. Students are also asked to identify the distinctive features of plant cells as compared to animal cells.

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Elodea in freshwater, then saltwater 400x magnification

Flower petal 100x magnification

Celery 100x magnification

Carrot 100x magnification

From Cells to Organisms 11: Energy and Matter in Cells

Students read a series of three text passages about the composition of food, breakdown of food, and use of food for matter and energy. After the first passage, they begin to develop a model to explain how organisms obtain matter and energy. Students use information provided in the text to develop physical models of proteins and carbohydrates. They use these models to explore the breakdown of food during digestion and the use of the resulting subunits as building blocks for human proteins (in the case of amino acids) or for generating usable energy (in the case of sugars). After each additional passage, they modify and elaborate their models to account for the new information provided. The activity also addresses conservation of matter from the perspective of reuse of matter, without going to the atomic level. Based on their investigation of the physical models, they create drawn models to represent the use of food as a source for matter and energy. For students who want to delve further into what happens in cells at the molecular level in cellular respiration, they can watch the Amoeba Sisters video below.

From Cells to Organisms 10: Cells, Tissues, and Organs

A short reading provides additional information on levels of organization in multicellular organisms.Students recognize levels of organization in plants and animals, including cells, tissues, organs, organ systems, and organisms. They compare the types of cells found in living things and begin to develop the idea that the body is a system of interacting subsystems composed of cells. Students then construct evidence based arguments that all organisms are made of cells and that living things may be made of different numbers and types of cells.

From Cells to Organisms 9: Observing Multicellular Organisms

Students use microscopes to further their investigations of the cellular nature of life. They gather additional evidence that living things are made of one or many cells and that cells of different organisms share certain structural components, such as the cell membrane. These structures function similarly in different organisms. Students view prepared slides of multicellular organisms and prepare a slide of onion tissue and their own cheek cells. They compare the cells of multicellular organisms to the unicellular organisms they observed in the “Evidence of Microscopic Organisms,” activity. They will use their observations as the basis of understanding cells, tissues, and other levels of multicellular organization in the next activity.

Cheek cell 100x magnification

Cheek cell 400x magnification

Onion cell 100x magnification

Onion 400x magnification

Salamander (Amphiuma) intestine 40x magnification

Salamander (Amphiuma) intestine 100x magnification

Sunflower (Helianthus) 40x magnification

Sunflower (Helianthus) 100x magnification

From Cells to Organisms 8: Modeling Cell Structure and Function

An interactive computer animation helps review the ways that parts of a cell contribute to its function and compares plant and animal cell structures and functions. Students use the knowledge gained over the past few activities to develop and use a model to describe the function of a cell as a whole and the ways that cell’s parts contribute to its function. To help students understand the structure and functions of the organelles within cells, they viewed the computer animation below. Finally, they used their creativity to construct their own cell models. They used clay, paper, candy, cake, natural materials and fabric among other materials. Check out some of their cell models in the video below.

From Cells to Organisms 7: Investigating the Cell Membrane

Students investigate the function of the cell membrane by evaluating the ability of particles to pass through the plastic membrane of a sandwich bag. They will use the reaction between starch and Lugol’s solution (which contains iodine) as evidence of the movement of some particles across the cell membrane. The class discusses how cell permeability relates to cell function.

From Cells to Organisms 6: Parts of a Cell

Students completed and discussed a reading that elaborates on the basic structures common to all cells. The text emphasizes the roles of the cell membrane, cytoplasm, and nucleus. Students read about how biologists use the cell structures of the various microbes examined in the “Evidence of Microscopic Organisms” activity to classify these organisms. The text further emphasizes the complementary nature of structure and function within cells. Students learn that cells of all organisms have similar structures, such as the cell membrane, and these structures function similarly in each organism.

From Cells to Organisms 5: Cells Alive

Students explore the idea that both unicellular and multicellular organisms are living. Students explore the idea that cells are alive and perform life functions (e.g., respiration). They carry out and interpret investigations to obtain evidence of cellular respiration by yeast. Building on what they learned in the Body Systems unit about using BTB to indicate the presence of CO2, they mixed yeast with either starch or glucose and compared their results to a control of clay (non living material). Check out the time lapse video below to see what they discovered. This concept of how cells obtain and use matter and energy from food is developed and then revisited in later activities.

From Cells to Organisms 4: The History of Cell Theory

Students read about the history of the scientific discoveries leading to the cell theory and the germ theory of disease. Students learn that individual cells are the building blocks that make up multicellular bodies. They identify the contributions of scientists to both science and technology. Each lab group then wrote and performed a skit about one or more of the contributors to cell theory and/or germ theory. Check out some of their skits below.

From Cells to Organisms 3: Evidence of Microscopic Organisms

Students learn how to use a microscope and how to draw their observations. They use their observations to gather evidence that there are living organisms that cannot be seen with just the human eye. They begin to observe the pattern that living things are made of cells. They also experience the usefulness of microscope technology in investigating biological structures at scales too small to be observed without the use of special instruments. Their observations of these single-celled organisms will be used to develop the idea that all living things are made of cells. Students began by observing prepared slides of amoeba, paramecia, euglena, mixed bacteria and human blood. In an extension, the looked at single celled and multicellular organisms in pond water. Check out a compilation of student images and videos below.

From Cells to Organisms 2: An Invisible Organism

Students watch a segment of the video, A Science Odyssey: Matters of Life and Death, that focuses on the bubonic plague epidemic in San Francisco in the early 1900s. The video segment introduces the idea that there are some living organisms that cannot be seen without the use of tools such as microscopes. This story further explains the role of microbes in spreading infectious diseases and the cellular nature of living organisms. Students consider the role of evidence in developing scientific explanations about the role of microbes in spreading infectious diseases. Over the course of the next few activities, student learn the concept that these microscopic organisms are alive and made of a single cell.

From Cells to Organisms 1: Disease Outbreak

Students model the spread of an infectious disease by simulating participation in various activities that could expose them to infectious agents. Examples include eating cut melon at a market, or being bit by a mosquito at a restaurant. The are 15 possible model actions at 5 different model locations. They use a model disease indicator to find out if they were infected. Based on the results, the class discusses how infectious diseases are spread, they analyze data from the model to identify patterns, and then use the patterns supported by the data to determine the cause of the spread of the infectious disease. The problem of diagnosing and treating infectious diseases provides a context for the exploration of cell structure and function that follows.