Biology Experiments

Food & Nutrition Tests

Reducing Sugar (Benedict's Test): Add Benedict's reagent to the food sample in a test tube and heat in a boiling water bath. Result: Blue changes to brick-red.

Starch (Iodine Test): Add a few drops of iodine solution to the food sample. Result: Red-brown changes to blue-black.

Protein (Biuret Test): Add sodium hydroxide followed by copper(II) sulfate (or Biuret reagent) to the food sample. Result: Blue changes to purple/violet.

Lipid (Ethanol Emulsion Test): Shake the food sample with ethanol, then pour the mixture into a separate tube of water. Result: A clear liquid turns into a milky emulsion.

2. The Cell & Microbiology

Microscopy (Plant/Animal Cells): Prepare an onion peel slide (stained with iodine) or a cheek cell slide (stained with methylene blue) on a glass slide with a coverslip, and view under low and high power (x100 / x400). 

Osmosis (Visking Tubing): Fill a Visking tubing bag with sucrose solution, tie it securely, and immerse it in a beaker of distilled water. Monitor changes in mass or volume (water moves in, causing the tubing to swell/gain mass).

Growth of Leaf Yeast: Attach surface-sterilized leaf discs (using petroleum jelly) to the underside of the lid of an agar nutrient plate, incubate upside down at 25^\circ\text{C}, and observe the shiny, pinkish-white circular yeast colonies. Use a blank plate as a control.

3. Physiology & Genetics

Enzyme Activity / Effect of Temperature & pH: Mix an enzyme (e.g., catalase or amylase) with its substrate (e.g., hydrogen peroxide or starch) at varied temperatures or pH levels using a water bath and buffer solutions. Measure the rate of product formation or substrate disappearance over time.

Immobilized Enzymes: Mix yeast/lactase with sodium alginate, drop the mixture using a syringe into calcium chloride solution to form hardened beads, and pack them into a syringe barrel column to catalytically convert substrate (e.g., milk/lactose) continuously.

DNA Isolation (Onion): Blend chopped onion with washing-up liquid (lysis) and salt, heat in a water bath at 60^\circ\text{C} for 15 minutes to denature DNases, filter the mixture, and carefully layer ice-cold ethanol on top of the filtrate to precipitate and spool out the white DNA threads.

Photosynthesis (Elodea): Place an aquatic plant (Elodea) in a sodium hydrogen carbonate solution (to provide constant \text{CO}_2) at varying distances from a light source. Count the number of oxygen bubbles produced per minute or use a sensor to measure rate.

Respiration (Ethanol / Yeast): Mix yeast with glucose solution in a conical flask, seal with oil to maintain anaerobic conditions, and test the resulting products using limewater (turns milky for \text{CO}_2) or iodoform/potassium dichromate tests (for ethanol).

4. Ecology & Plant Responses

Plant Growth Regulator (IAA): Germinate cress seeds on petri dishes lined with cotton wool treated with a range of serial dilutions of IAA solution (plus a water control). Measure root and shoot lengths after several days to plot growth inhibition/stimulation curves.

Ecology Fieldwork (Quadrat & Abiotic Factors): Randomly toss a quadrat (0.5\text{m} \times 0.5\text{m}) multiple times in an ecosystem to measure percentage frequency or cover of plants. Concurrently measure abiotic factors (e.g., light intensity, soil pH, and temperature) using digital probes or meters.