IB Biology Internal Assessment (our laboratory, or "practical," work)
IB Biology, IB Chemistry, and IB Physics all have the same general practical work requirements. "Integral to the experience of students in any of these Group 4 courses is their experience in the laboratory or field. Laboratory investigations allow students to interact directly with natural phenomena and secondary data sources." (IBO 22) In IB Biology there are seven required experiments or “prescribed practicals” that all IB Biology students must conduct at some time in the 2-year course.
When learning or practicing a procedure for the first time, you create a detailed flowchart of the methods in order to work confidently and safely, as described below. All of our lab work is organized in our IB Biology portfolio.
For design-it-yourself experiments, students complete a proposal and then write the report with a specific format. We assess the report using one or more of these five criteria: Personal Engagement (PE), Exploration (Ex), Analysis (An), Evaluation (Ev) and Communication (Com).
The Internal Assessment, worth 20% of the final mark sent to the student’s college, consists of one independent scientific investigation. We assess it with same five criteria as we use on DIY experiments throughout the course. Each student proposes his/her IA toward the end of Year 1, conducts the IA in summer or fall heading into Year 2, and turns in the 6-12 page IA report at approximately Thanksgiving of Year 2.
If an IB Bio student chooses to conduct his/her IA at home or over the summer between years 1 and 2, the following documents are required:
IB Biology students are required to use each of the following software applications at least once during the course: spreadsheets, software for graph plotting, simulations, databases, and data logging. See “ICT in IB Biology” under Helpful Links at the left.
Biology IA: Osmosis 002223-0028 2
Osmosis is a fundamental concept in the study of biology. All cells use the principles of osmosis to transport water in and out of themselves. It is also very important in osmoregulation; a process which
regulates the osmotic pressure of an organism’s fluids in order to maintain a homeostatic
environment. Osmotic pressure is essential for support in plants. Entry of water in the cell raises the turgor pressure exerted against the cell wall, making it turgid and enabling it to stand upright. Plant cells are usually in hypotonic environments, where the fluid in the cell is more concentrated than that outside the cell, so water enters in. This is illustrated below.
Figure 2: Plant cells in hypertonic, isotonic and hypotonic environments.
Figure 2 also shows that if plant cells are in a hypertonic environment, then all the water will leave the cell, making it plasmolyzed
. This causes the cytoplasm to be pinched away from the cell wall, and the cell can no longer function. If plants are in isotonic environment, they are not turgid, but flaccid; they tend to wilt. Osmosis is also responsible for the ability of plant roots to draw water from the soil. Roots are adapted for this because of the numerous root hair cells; they increase the surface area to volume ratio, making the absorption highly effective. Animal cells also use osmosis to transport water in and out, but the consequences in this case are different due to the absence of cell walls.
Villarreal, M. 2007.
Turgor pressure on plant cells
. [image online] Available at: http://en.wikipedia.org/wiki/File:Turgor_pressure_on_plant_cells_diagram.svg[Accessed: 8 Jan 2014].
shrinking of the cytoplasm away from the wall of a living cell due to outward osmotic flow of water