What does it mean to be alive? How did the first cells form, and what traits did these earliest cells possess? How do living things function in varied environments? In this scenario, students are asked to consider what constitutes life, its origins, and the evidence needed to demonstrate that something is alive. Students are introduced to the molecules common to all living things, and the structure and function of cells. Students make observations of animal body shape, and apply knowledge of gradients and chemical activity to develop a working hypothesis about the ratio of surface area-to-volume, and its impact on homeostasis, metabolism and ultimately, survival. Instructors could use examples from extreme environments or journeys to other planets as contexts for this investigation and guide student inquiry.
Life Learning Outcomes- List and explain the characteristics of life.
- Use these characteristics of life to distinguish between living and nonliving things.
- Define homeostasis, and describe its importance to maintaining life.
- Compare and contrast the biological/medical, legal, and ethical definitions of life and death, and discuss the importance of defining life and death.
Chemistry Learning Outcomes
- Explain why water is essential to life and how the characteristics of polarity and hydrogen bonding are important for this role.
- Identify the four macromolecules, and define their roles/functions in a cell.
- Explain the difference between ionic, covalent, and hydrogen bonds, and identify the relative strength of each type of bond.
- Predict which type of bond would be formed between two (or more) atoms.
- Describe the relationship between monomers and polymers, and give examples for each type of biological macromolecule listed below:
- Proteins
- Nucleic acids (RNA, DNA)
- Carbohydrates
- Explain what an enzyme is and how it influences the rate of biological reactions.
- Define active site and its role in enzyme function.
- Describe and predict how environmental conditions (e.g., temperature and pH) can influence protein structure and the shape of the active site of an enzyme.
Cell Learning Outcomes
- Identify the function of cell components, especially:
- Nucleus
- Mitochondria
- Chloroplasts
- Ribosomes
- Rough and Smooth Endoplasmic Reticulum
- Vesicles
- Golgi
- Cell Membrane
- Cytoplasm
- Cell Wall
- Vacuoles
- Identify which cell components are found in:
- all cells
- prokaryotes (Eubacteria, Archaea)
- eukaryotes
- Animals
- Plants
- Protists
- Fungi
- Predict the organismal group to which an unknown cell might belong from a description of its components.
- Predict the possible functions of an unknown cell depending on its components.
- Predict the abundance of particular organelles depending on a cell’s functions.
Ratio of surface area-to-volume (SA/V) Learning Outcomes
- Calculate the ratio of surface area-to-volume of an object, and explain why the ratio decreases as objects get larger and increases as objects get smaller.
- Explain how the ratio of surface area-to-volume plays a role in regulating:
- Rates of diffusion and osmosis
- Gas exchange
- Body temperature
- Given environmental conditions, predict the SA/V ratio that would be selected by natural selection, and explain how this could be a mechanism of evolution.
Gradients Learning Outcomes
- Explain what a gradient is and the role of gradients in:
- Homeostasis
- Thermoregulation
- Osmoregulation
- Chemical reactions associated with metabolism
- Identify whether a chemical or energy gradient exists in new situations
- Indicate the direction of energy or material movement under different conditions such as:
- Chemical concentrations
- Temperature
- Permeability of membranes
- Indicate the relative rate of energy or material movement under different conditions including:
- chemical concentrations
- temperature
- permeability of membranes
- varied shape (surface-to-volume ratio)
Membrane Transport Learning Outcomes
- Identify the components of cell membranes, and explain how the arrangement of components makes the membrane semi-permeable.
- Explain how processes of transport work including:
- Diffusion
- Passive
- Facilitated
- Osmosis
- Passive
- Facilitated
- Active transport
- Diffusion
- Define the following terms, and explain how they relate to the movement of materials across a membrane:
- Isotonic
- Hypotonic
- Hypertonic
- Explain how larger objects/molecules cross membranes by exocytosis, endocytosis, and phagocytosis, and predict when each of these transport mechanisms is used.
- Predict how the following conditions affect membrane transport:
- gradient conditions
- temperature
- ATP availability
- changes in permeability
- molecule size, charge, or polarity
Thermoregulation Learning Outcomes
- Apply the terms endotherm, ectotherm, poikilotherm/heterotherm, and homeotherm to organisms
- Identify organisms as endotherms, ectotherms, poikilotherms/heterotherms, and homeotherms based on
- physical characteristics
- behavior
- metabolic changes
- membership in taxonomic groups (birds, mammals, etc.)
- changes in body temperature measurements
- Predict the effect of varying environmental temperatures on an organism’s behavioral or metabolic responses including:
- enzyme activity
- locomotion
- body temperature
- Interpret data/graphs as they relate to the effect of varying environmental temperatures on an organism’s behavioral or metabolic responses including:
- enzyme activity
- locomotion
- body temperature
- Design or critique simple experiments to test the effect of varying environmental temperatures on an organism’s behavioral or metabolic responses including:
- enzyme activity
- locomotion
- body temperature
- Explain how various temperature regulation methods serve to heat or cool an organism including:
- avoidance
- altering metabolic rate
- behaviorally adjusting posture, ratio of surface area-to-volume, and location
- explain how ratio of surface area-to-volume is involved in heat retention or loss
- Explain why organisms thermoregulate.
- Explain mechanisms of heat generation at the cellular level
Osmoregulation Learning Outcomes
- Explain why organisms osmoregulate.
- For different habitats (ocean, freshwater, on land, etc.), predict whether ions or water need to be conserved.
- Describe how organisms osmoregulate in different habitats, on the:
- cellular level, using active and passive transport across membranes
- individual organism level, in terms of inputs and outputs
- Compare and contrast how organisms osmoregulate in different habitats.