Lab Prior Knowledge, New Concepts, Understandings, Skill Development

Investigation 1: Artificial Selection/Evolution

It is great to implement this investigation at the beginning of the year. Students need minimal content background to begin this investigation and complete the first part of

the lab. In general, students find this lab to be very accessible and enjoyable. For the most part, skills are developed as the lab progresses. However, essential to the success of this

investigation is the student’s ability to make and record good observations.

This is best done in a laboratory notebook.

The students can use this particular experience to build good laboratory notebook skills.

A lab notebook should demonstrate originality and reflection while serving as a record of the investigator’s work. Planting, quantifying variation, recording images drawings of that variation,

maintaining plants, and recording results all make for prime lab notebook subject matter.

By tending their own population of plants each day and recording daily observations, students develop their own particular style and rhythm ofwriting in the lab notebook.

These activities require only about 10 minutes of class time and are essential to the student-led part of the investigation.

While working through the Procedure, students naturally generate questions regarding the traits they are working with and the variations they observe. Often these questions are not recorded and are

soon forgotten.

Encourage the students to record the questions that come to them as they work intimately with these plants and to reflect on those questions in writing.

The instructor needs to decide when to start this investigation.

The students may benefit from having an understanding of natural selection prior to beginning this lab, but this lab might best be used to introduce the concept of natural selection.

Investigation 2: Hardy Weinberg: Mathematical Modeling

Try working through an idealized life cycle and population as a class before the students view the investigation. Specifically, use the modeling guidelines and

assumptions described in the student investigation as a road map for your instruction as you and your students try to conceptualize this idealized population.

Use questions such as the following:

• Can you describe the life cycle of an organism?

• How does this life cycle work in a population?

• How would you track one trait through a population’s life cycle?

• Can you describe an idealized life cycle that would work the best for keeping track of a genetic trait in a population?

• Can you simplify assumptions and modeling solutions.

Investigation 3: BLAST

This investigation can be conducted while covering concepts pertaining to evolution. It is recommended that the students already have a solid of understanding of the structure

and function of DNA and gene expression, specifically how the order of nucleotides in DNA codes for the production of proteins.

Students will develop the following skills:

• Formulating, testing, and revising a hypothesis based on logic and evidence

• Using a sophisticated online bioinformatics program to analyze biological data

• Analyzing evolutionary patterns using morphological data and DNA analysis

• Analyzing preconstructed cladograms to demonstrate an understanding of evolutionary patterns

• Designing cladograms to depict evolutionary patterns

• Discussing and debating alternative interpretations of data based on evidence

Investigation 4: Diffusion & Osmosis

The form and function of cells, organelles, and organisms is a central concept in biology. You can help students think about cell shape in relation to its function by providing

examples. Epithelial cells in the small intestine have many microvilli that serve to increase the surface area. These cells take up nutrients from food and move the nutrients

into the capillaries. An erythrocyte’s concave shape increases the rate of oxygen diffusion out of the cell and into the tissues. The elongated projection of the root hair — and the

large number of them — greatly increases the surface area through which water and minerals pass into the root of a plant. Students should understand that temperature influences molecular kinetic energy

directly. They have made observations but may not have made the connections. Ask them to remember what happened to the sugar they added when they prepared an iced coffee drink versus hot coffee.

A more difficult concept for students to grasp is that molecular weight is inversely related to the rate of diffusion. Have students think about 10 dump trucks and 10 small cars at the opposite end zones of a football field.

Then ask them to predict which vehicles will scatter faster across the field. Most will understand that large dump trucks move more slowly (have a lower kinetic energy) than the smaller cars.

Students will develop the following skills, which are reinforced in the transpiration

investigation:

• Calculating surface area and volume of a model cell

• Designing experiments to measure the rate of osmosis in model cells

• Designing experiments to measure water potential in plant cells

Investigation 5: Photosynthesis

Before students investigate photosynthesis, they should demonstrate an understanding of the following concepts related to the physical properties of light. The concepts may be

scaffolded according to level of skills and conceptual understanding.

• Measuring light intensity

• The inverse square law

• The wave nature of light (visible light spectrum, i.e., colors)

• Light as energy

__This investigation reinforces the following skills:__

• Preparing solutions

• Preparing a serial dilution

• Measuring light intensity

• Developing and applying indices to represent the relationship between two quantitative values (e.g., an ET50 Index)

• Using reciprocals to modify graphical presentations

• Utilizing medians as a measure of central tendencies

• Constructing data tables and graphs

• Communicating results and conclusions

__Students will develop the following skills:__

• Applying the floating disk assay procedure to study photosynthesis or dissolved oxygen or carbon dioxide sensors with computer interface

• Measuring/calculating rates of photosynthesis

**Investigation 6: Cellular Respiration**

**Before students investigate cellular respiration, they should be able to demonstrate**

understanding of the following concepts:

• The relationship between cell structure and function (mitochondria)

• Enzymatic activity and the effects of environmental variables, such as temperature and pH, on enzyme-catalyzed reactions

• Strategies for capture, storage, and use of free energy

• Interdependence of photosynthesis and cellular respiration

• Aerobic respiration versus fermentation

• Diffusion of gases across cell membranes

These concepts may be scaffolded according to level of skills and conceptual understanding. For example, a number of physical laws relating to gases are important

to understanding how the respirometer systems used in the investigation(s) measure respiration rate.

In particular, the laws are summarized in the general gas law, and students should be able to manipulate the equation PV = nRT, where

P = pressure of the gas

V = volume of the gas

n = number of molecules of the gas

R = the gas constant (its value is fixed)

T = temperature of the gas

Students can be directed to several online resources to review the gas laws, including * http://www.phschool.com/science/biology_place/labbench/lab5/intro.html*,

which offers activities to introduce key concepts pertaining to cellular respiration, and * http://www.nclark.net/GasLaws*, which provides myriad tutorials and animations to

introduce or review the gas laws.

This investigation reinforces the following skills. (However, if students have not acquired these skills previously, the procedures in this lab will help students develop

them.)

• Preparing a constant temperature water bath

• Measuring volume and temperature using the metric system

• Constructing data tables and graphs

• Communicating results and conclusions

**Investigation 7: Mitosis & Meiosis**

**Before students begin these investigations, they should be able to demonstrate **understanding of the following concepts. The concepts may be scaffolded according to

level of skills and conceptual understanding.

• Cellular structure and organelles

• The purposes for cell division

• The outcomes for mitosis and meiosis

__In addition, this lab reinforces the following skills:__

• Use of a microscope to observe cell structure

• Data collection

__Students will develop the following skills:__

• Preparation of specimens for microscopic analyses

• Data analysis and use of a statistical test

• Calculation of crossover frequencies

**Investigation 8: Biotechnology: Bacterial Transformation**

**This investigation reinforces the following skills:**

• Using pipettes (plastic bulb-type or other volumetric measuring devices)

• Measuring temperature (°C)

• Applying metric system

• Applying quantitative skills

__Students will develop the following skills:__

• Using sterile technique

• Disposing properly of materials and solutions that come in contact with bacteria

• Transferring bacterial colonies from agar plates to microtubes

• Transforming bacterial cells with plasmid DNA

• Delivering transformed cultures to agar plates

• Applying mathematics to quantify transformation efficiency

**Investigation 9: Biotechnology: Restriction Analysis**

**This investigation reinforces the following skills.**

• Using pipettes (plastic bulb-type or other volumetric measuring devices) and other

common lab equipment

• Graphing and applying other quantitative skills

__Students will develop the following skills:__

• Performing gel electrophoresis, a basic technique for separating DNA fragments

by size

• Using more sophisticated

**Investigation 10: Energy Dynamics**

**This investigation reinforces the following skills:**

• Growing and maintaining plants through an entire life cycle, from seed to seed (Wisconsin Fast Plants are recommended.)

• Caring for, providing food for, and maintaining a clean environment to culture butterfly larvae

• Keeping and maintaining accurate records of observations and measurements of cultured organisms in a lab notebook

• Measuring small mass quantities directly or by combining a number of low mass objects and taking an average

• Demonstrating basic accounting or budgeting skills — quantifying inputs and resolving the outputs

• Constructing energy flow diagrams

• Organizing a work-flow time line for several days (small daily tasks associated with care of organisms)

• Calculating unit conversions in simple equations

• Reporting findings and conclusions in a peer-reviewed environment If you choose to use lab notebooks to help assess student performance on this lab

exercise, make sure that the students are completely informed about your expectations for this product. A well-designed rubric (see Chapter 6) is one important way to

communicate your expectations. Likewise, before using a mini-poster presentation format for prelab and summative assessments, make sure students have had practice in

producing successful mini-posters.

__Students will develop the following skills:__

• Calculating, recording, and diagramming energy dynamics in a simple model system

• Posing a scientific question regarding energy dynamics, allocation, or capture

• Designing and carrying out an investigation to answer a question regarding energy dynamics, allocation, or capture

• Modeling energy dynamics quantitatively

**Investigation 11: Transpiration**

**Before students tackle this investigation, they should be able to demonstrate **understanding of the following concepts. The concepts may be scaffolded according to

level of skills and conceptual understanding.

• The relationship between cell structure and function

• The physical and chemical properties of water

• The movement of molecules and ions across cell membranes by the processes of osmosis, diffusion, and active transport

• Photosynthesis, particularly the transport and roles of CO2, O2, and H2O

• The exchange of matter between biological systems and the environment

__This investigation reinforces the following skills:__

• Measuring distance, volume, and/or mass using the metric system

• Estimating leaf surface area

• Using a microscope to examine cell structure

• Constructing data tables and graphs

• Communicating results and conclusions

__Students will develop the following skills:__

• Preparing a stomatal peel using nail polish

• Making a wet mount of leaf epidermal tissue for microscopy

• Calculating leaf surface area and number of stomata/surface area

• Assembling a potometer

• Calculating transpiration rates

• If equipment is available, learning how to use a gas pressure sensor and computer interface

**Investigation 12: Fruit Fly Behavior**

**Before students attempt this investigation, they should be able to demonstrate**

understanding of the following concepts. The concepts may have been taught at different

times of the year, but they give a conceptual understanding that could help students

formulate questions related to the behavior of *Drosophila*.

• An insect life cycle that includes a complete metamorphosis

(egg, larva, pupa, and adult)

• The role of apoptosis in metamorphosis

• The genetic basis of behavior and role of a taxis

• The types of environmental factors that trigger a behavior

• The generalized structure of sensory organs and neurons

Students will develop the following skills and reinforce their observation skills. They may have worked with fruit flies in previous investigations, so they may be familiar with

some of these skills. If the students are new to working with fruit flies (or other research animals), care must be taken to ensure the proper care and handling of living organisms.

• Determining the sex of fruit flies

• Preparation of solutions

• Construction of choice chamber:

• Use of different-aged fruit flies (optional)

• Use of larvae:(optional)

**Investigation 13: Enzyme Activity**

**Before students investigate enzymes, they should be able to demonstrate understanding**

of the following concepts. The concepts may be scaffolded according to level of skills and

conceptual understanding.

• Basic protein structure

• The concept of induced fit

• The role of enzymes

• That structure, function, and environment are all required for maximal function of enzymatic reactions

__Students will develop/reinforce the following skills:__

• Using pipettes to measure solutions

• Using pH indicators to determine environmental conditions that may influence the reaction activity of enzymes