1.) Light and Photosynthesis

RQ: How does changing light color affect the rate of photosynthesis in aquatic plants like Elodea measured through oxygen bubble production?

IV: Light color (red, blue, green, yellow, white) used during exposure

DV: Number of oxygen bubbles produced by the plant in 5 minutes

Experiment: Cut equal lengths of Elodea and place them in test tubes filled with water. Shine different colored lights on each tube while keeping other conditions constant (temperature, light intensity, distance). Count the number of oxygen bubbles produced in 5 minutes for each color. Repeat three times for reliability. This helps explore how different wavelengths affect photosynthesis.

2.) Temperature and Enzyme Activity

RQ: How does temperature influence the activity of catalase on hydrogen peroxide breakdown in potato tissue?

IV: Temperature of the water bath (e.g., 10°C, 20°C, 30°C, 40°C, 50°C)

DV: Height or volume of foam produced due to oxygen release

Experiment: Use equal-sized potato cubes containing catalase and place them in test tubes with hydrogen peroxide. Place each tube in a water bath at a different temperature. Measure the height or volume of foam produced after a fixed time. Repeat each temperature 3 times. The results will show how temperature affects enzyme function.

3.) pH and Enzyme Function

RQ: What is the effect of different pH levels on the activity of salivary amylase breaking down starch?

IV: pH level of the starch-amylase solution (pH 3, 5, 7, 9, 11)

DV: Time taken for starch to be fully broken down

Experiment: Mix equal volumes of starch and amylase solutions buffered to specific pH levels. At regular intervals, test with iodine to see if starch is still present. Record the time it takes for the starch to disappear completely. This experiment shows how enzyme activity changes in acidic, neutral, and basic environments.

4.) Caffeine and Heart Rate in Daphnia

RQ: How does increasing caffeine concentration affect the heart rate of water fleas (Daphnia magna) under a microscope?

IV: Caffeine concentration in the solution surrounding the Daphnia

DV: Heart rate of the Daphnia measured in beats per minute

Experiment: Place Daphnia in a microscope slide chamber with water containing various caffeine concentrations. Observe and count heartbeats under a microscope for 30 seconds, then double to get BPM. Use multiple Daphnia per condition and average the results. This explores how stimulants affect a living organism’s physiology.

5.) Salt and Seed Germination

RQ: How does salt concentration in water affect the germination rate of radish seeds over a period of 7 days?

IV: Salt concentration in the water (e.g., 0%, 1%, 2%, 3%, 4%)

DV: Number of seeds germinated after 7 days

Experiment: Place 10 radish seeds in petri dishes lined with damp paper towels soaked in different salt solutions. Keep them in identical light and temperature conditions. Check daily and record how many seeds germinate. This experiment looks at the impact of salinity on plant development.

6.) Music and Plant Growth

RQ: Does the type of music played daily affect the growth height of bean plants over two weeks?

IV: Type of music played (classical, rock, no music)

DV: Average height of the plants after 14 days

Experiment: Grow bean plants in three groups under identical light and water conditions. Play a different type of music to each group for 2 hours daily. Measure the height of each plant at the end of two weeks and compare the averages. This tests whether sound vibrations influence plant growth.

7.) Antibacterial Effects of Natural Substances

RQ: What is the effect of garlic and ginger extracts on the growth of E. coli bacteria on agar plates? 

IV: Type of extract applied to bacteria (garlic, ginger, or control)

DV: Diameter of the bacteria-free zone (zone of inhibition)

Experiment: Prepare agar plates inoculated with E. coli. Place sterile paper discs soaked in garlic, ginger, or water (control) onto the plates. Incubate them at 37°C for 24 hours. Measure the diameter of the clear zone around each disc. This experiment compares natural antibacterials with no treatment.

8.) Sugar Type and Yeast Respiration

RQ: How does the type of sugar affect the rate of carbon dioxide production during yeast fermentation?

IV: Type of sugar used (glucose, fructose, sucrose, lactose)

DV: Volume of CO₂ gas produced in 5 minutes

Experiment: Mix equal amounts of yeast and warm sugar solution in a sealed container with a gas syringe or balloon to capture CO₂. Use the same temperature and time for each trial. Measure how much gas is produced. This investigates how yeast metabolizes different sugars.

9.) Soil pH and Plant Growth

RQ: How does the pH level of soil affect the growth rate of lettuce plants over 2 weeks?

IV: pH level of the soil (acidic, neutral, alkaline)

DV: Plant height measured every 2 days for 2 weeks

Experiment: Grow lettuce seeds in pots with soil adjusted to different pH levels using vinegar or baking soda. Water them equally and place them in the same light conditions. Measure plant height regularly and compare final growth. This explores how soil acidity affects plant development.

10.) Detergents and Aquatic Life

RQ: What is the effect of increasing detergent concentration on the survival of freshwater brine shrimp over 48 hours?

IV: Concentration of detergent in the water

DV: Number of living brine shrimp after 48 hours

Experiment: Prepare several beakers with different detergent concentrations mixed in water. Add the same number of brine shrimp to each. Observe and record survival after 24 and 48 hours. This project simulates water pollution effects on simple aquatic organisms.

Absolutely! Here are 10 more IB Biology IA ideas focused on easily found or cultured bacteria, like E. coli, Bacillus subtilis, Lactobacillus, or soil bacteria—many of which can be grown on agar using safe materials.

11.) Garlic vs. Onion Extracts on Bacteria

RQ: How do garlic and onion extracts compare in inhibiting the growth of E. coli on nutrient agar plates?

IV: Type of plant extract applied (garlic vs. onion vs. water control)

DV: Diameter of the zone of inhibition around each disc

Experiment: Soak paper discs in garlic and onion extracts. Prepare E. coli-spread agar plates and place discs evenly spaced on the surface. Use water-soaked discs as a control. Incubate at 37°C for 24 hours and measure the clear inhibition zones. This experiment helps test the antibacterial strength of two common foods.

12.)  Honey Concentration and Bacterial Growth

RQ: What is the effect of different honey concentrations on the growth of Bacillus subtilis bacteria?

IV: Honey concentration in the solution (e.g., 0%, 10%, 25%, 50%)

DV: Size of the bacterial inhibition zone or number of colonies

Experiment: Prepare honey-water solutions and apply them to paper discs placed on agar plates inoculated with Bacillus subtilis. Incubate for 24–48 hours and measure inhibition zones or count colony numbers. This examines how natural sugars impact bacterial growth.

13.) Effect of Vinegar Types on Bacteria

RQ: How do different types of vinegar (white, apple cider, balsamic) affect the growth of household bacteria on agar plates?

IV: Type of vinegar applied to the bacterial sample

DV: Size of the inhibition zone around the vinegar-treated disc

Experiment: Collect bacteria from a kitchen sponge or doorknob. Plate it on agar, then add vinegar-soaked paper discs. Incubate and measure inhibition zones. This tests how different acids control microbial contamination in homes.

14.) Antibacterial Soaps vs. Regular Soap

RQ: How does antibacterial soap compare to regular soap in reducing E. coli colony growth on agar plates?

IV: Type of soap applied (antibacterial vs. regular vs. water)

DV: Number of visible bacterial colonies after incubation

Experiment: Prepare E. coli plates and treat sections with different soap solutions using sterile swabs. After incubation, count colonies in each section. This explores whether antibacterial soaps are significantly more effective than basic soap.

15.) UV Light Exposure and Bacteria

RQ: How does increasing exposure time to UV light affect the growth of E. coli on nutrient agar?

IV: Duration of UV light exposure (e.g., 0, 30, 60, 90, 120 seconds)

DV: Number or size of bacterial colonies post-exposure

Experiment: Expose agar plates inoculated with E. coli to UV light for different times. Cover portions of the plate to act as control areas. After incubation, observe and compare colony growth. This tests how UV light affects microbial DNA and reproduction.

16.) Salt Concentration and Bacterial Survival

RQ: What is the effect of salt concentration on the growth of non-halophilic soil bacteria on agar plates?

IV: Salt concentration in the agar medium (e.g., 0%, 2%, 5%, 10%)

DV: Number or size of bacterial colonies after 48 hours

Experiment: Prepare agar plates with different salt concentrations and inoculate with bacteria from soil or tap water. Incubate and record colony growth. This explores osmosis and salt’s preservative effect on bacteria.

17.) Effect of Green Tea Extract on Bacteria

RQ: How does green tea extract affect the growth of Lactobacillus bacteria isolated from yogurt?

IV: Concentration of green tea extract (e.g., 0%, 25%, 50%, 75%)

DV: Zone of inhibition or bacterial colony size

Experiment: Extract Lactobacillus from yogurt using dilution plating. Apply green tea extract on discs and place them on the plates. After incubation, measure inhibition zones. This shows whether tea polyphenols have antibacterial effects on probiotics.

18.) Temperature and Yogurt Bacteria Growth

RQ: How does incubation temperature affect the growth rate of Lactobacillus in homemade yogurt cultures?

IV: Temperature of incubation (e.g., 25°C, 30°C, 37°C, 45°C)

DV: pH change or bacterial colony count after 24 hours

Experiment: Make yogurt with milk and a spoon of commercial yogurt as a starter. Incubate batches at different temperatures. After 24 hours, test pH or plate samples to count colonies. This simulates ideal conditions for probiotic growth.

19.) Toothpaste Brands and Bacterial Inhibition

RQ: How do different commercial toothpaste brands affect the growth of bacteria sampled from a toothbrush?

IV: Brand of toothpaste applied to the bacterial sample

DV: Diameter of the zone of inhibition around each toothpaste sample

Experiment: Swab a used toothbrush and spread the bacteria on agar plates. Apply small amounts of various toothpaste brands onto the plate using sterile discs. Incubate and measure clear zones. This tests marketing claims of antibacterial strength.

20.) Essential Oils and Bacterial Growth

RQ: What is the antibacterial effect of essential oils like tea tree, lavender, and peppermint on kitchen-sourced bacteria?

IV: Type of essential oil applied to the sample

DV: Size of the inhibition zone after incubation

Experiment: Use swabs from kitchen surfaces to inoculate agar plates. Apply essential oil–soaked paper discs to the plates. Incubate for 24–48 hours and measure inhibition zones. This investigates natural alternatives to chemical disinfectants.

21.) Coca-Cola’s Effect on Tooth Enamel

RQ: How does exposure to Coca-Cola affect the mass of chicken eggshells as a model for human tooth enamel?

IV: Time of exposure to Coca-Cola (e.g., 1, 3, 5, 7 days)

DV: Change in mass of the eggshell before and after exposure

Experiment: Weigh cleaned eggshells and soak them in Coca-Cola for different durations. After each time period, dry and reweigh the shells. Compare mass changes to determine the acidic effects of soda on calcium carbonate, simulating effects on teeth.

22.) Energy Drinks and Reaction Time

RQ: What is the effect of drinking an energy drink on the average reaction time in human participants?

IV: Consumption of energy drink (before vs. after)

DV: Average reaction time using a ruler-drop test or online reaction timer

Experiment: Measure participants’ reaction time before and after drinking a small can of energy drink. Use the same test for consistency. This simple human biology test explores how caffeine and sugar impact the nervous system.

23.) Acid Rain Simulation and Leaf Damage

RQ: How does increasing acidity in water affect leaf pigment degradation in spinach leaves over 7 days?

IV: pH level of the water used to soak leaves (pH 3, 5, 7)

DV: Degree of pigment degradation or visible damage

Experiment: Soak spinach leaves in water with varying pH levels and observe color fading or chlorophyll breakdown over time. Take photos and use a color scale or software for analysis. This simulates acid rain effects on plants.

24.)Plant Cloning and Rooting Hormones

RQ: How does the use of rooting hormone affect the number of roots developed in cuttings of Coleus plants?

IV: Presence of rooting hormone (used vs. not used)

DV: Number and length of roots formed after 7–10 days

Experiment: Take identical Coleus cuttings and treat half with rooting hormone. Plant them in equal conditions. After a week, remove and measure roots. This investigates the role of auxins in vegetative propagation.