kIn a 2-hour 15-minute session, it's important to choose experiments that

can be set up and observed within the time frame while still providing
meaningful results. Here are some suitable biology practicals that can fit
into this duration:

1. Investigating Osmosis in Potatoes

 Objective: Observe osmosis in plant cells.

 Time Required: 1 hour setup, 1 hour for observations.

 Method: Cut potato slices and place them in different

concentrations of salt or sugar solution. Measure and record
changes in mass or size over time. This experiment can be
completed by the end of the session by measuring initial and final
mass.

2. Photosynthesis and Light Intensity (Using Aquatic Plants)

 Objective: Investigate how light intensity affects photosynthesis.

 Time Required: 1 hour setup, 1 hour for observations.

 Method: Set up water plants (e.g., Elodea) in beakers and place

them at different distances from a light source. Measure the number
of oxygen bubbles released over time or the volume of oxygen
produced using a gas syringe. Results can be recorded during the
session, and a discussion can take place afterward.

3. Effect of Temperature on Enzyme Activity

 Objective: Investigate the effect of temperature on catalase

enzyme activity.

 Time Required: 1 hour setup, 1 hour for observations.

 Method: Use catalase (from potato or liver) to break down

hydrogen peroxide. Set up the experiment with different
temperatures (e.g., cold, room temperature, and hot) and measure
the rate of oxygen production (gas collection or bubble counting).
This can be completed in the session and results can be analyzed
and discussed.

4. Heart Rate and Exercise

 Objective: Study how exercise affects heart rate.

 Time Required: 15 minutes to explain and set up, 45 minutes for

data collection and analysis.
  Method: Have students measure their resting heart rate and then
perform a specific exercise (e.g., jogging in place or jumping jacks).
Measure the heart rate immediately after exercise and after a 5-
minute rest period. Students can then compare changes and
analyze their results.

5. Investigating the pH of Different Liquids

 Objective: Test the pH levels of various liquids.

 Time Required: 30 minutes setup, 30 minutes for observations.

 Method: Use pH strips or a pH meter to measure the acidity or

alkalinity of various liquids (e.g., tap water, vinegar, lemon juice,
soap solution). Students can record results and discuss the pH scale
and its significance.

6. Bacterial Growth in Petri Dishes (Culture and Observation)

 Objective: Investigate bacterial growth.

 Time Required: 30 minutes setup, 45 minutes for observations and

cleaning.

 Method: Swab different surfaces (e.g., door handles, desks,

phones) with a sterile swab and streak it onto petri dishes
containing agar. Afterward, discuss how the dishes will be incubated
and observed over the next few days, with students taking notes on
anticipated results.

7. Plant Growth and Light (Phototropism)

 Objective: Observe how plants grow toward light.

 Time Required: 45 minutes setup, 30 minutes for observation.

 Method: Place plants in boxes with a hole on one side for light to
enter. Over time, observe how the plant grows toward the light
source. This can be observed and recorded during the session and
can be followed up with a discussion of phototropism.

8. Diffusion in Agar Jelly (Simple Diffusion Experiment)

 Objective: Demonstrate diffusion in agar.

 Time Required: 30 minutes setup, 30 minutes for results.

 Method: Prepare agar jelly cubes with a pH indicator (e.g.,

phenolphthalein) and place them in different concentrations of acids
or bases. Observe how the color spreads through the agar over
time, illustrating the diffusion process.
9. Microscope Investigation: Plant and Animal Cells

 Objective: Study the structure of plant and animal cells.

 Time Required: 15 minutes setup, 1 hour for observation.

 Method: Prepare slides of onion skin and cheek cells, stain them
with iodine or methylene blue, and observe under a microscope.
Students can compare the structure of plant and animal cells, noting
key features like the cell wall, nucleus, and cell membrane.

These experiments are designed to allow for active student participation,

observation, and data collection within the given time frame, with some
experiments having results that can be discussed and analyzed at the end
of the session.

You said:

how to do microscope investigation: plant and animal cells

ChatGPT said:

Here’s a step-by-step guide on how to perform the Microscope

Investigation of Plant and Animal Cells:

Materials Needed:

 Light microscope

 Microscope slides and coverslips

 Onion (for plant cells)

 Cheek cells (for animal cells)

 Iodine solution or methylene blue stain (for staining)

 Tweezers or forceps

 Dropper

 Distilled water

 Paper towels or tissue

Steps for Observing Plant and Animal Cells:

1. Preparing the Onion Skin Slide (Plant Cell)

Objective: To observe the structure of plant cells.

1. Prepare the Onion:

 o Cut a small piece of onion and peel off a thin, transparent
layer of the onion's epidermis (the skin on the inside of the
onion).

o Make sure the layer is thin and can be easily placed on a

microscope slide.

2. Place the Onion Skin on the Slide:

o Using tweezers, place the onion skin on the center of a clean

microscope slide.

o Add a few drops of iodine solution (which will stain the plant
cells and make the cell wall visible).

3. Apply the Cover Slip:

o Carefully place a coverslip at a 45-degree angle over the onion

skin. Lower it gently to avoid air bubbles.

o If necessary, press the cover slip lightly to spread the solution

evenly.

4. Observe Under the Microscope:

o Place the slide on the microscope stage and focus the

microscope starting with the lowest magnification (e.g., 4x
objective lens).

o Gradually increase the magnification (e.g., 10x, then 40x) to

observe the cell structure.

o You should be able to see the cell wall, nucleus, and

cytoplasm. Plant cells have a rigid cell wall and a clear central
vacuole.

2. Preparing the Cheek Cell Slide (Animal Cell)

Objective: To observe the structure of animal cells.

1. Prepare the Cheek Cells:

o Use a clean cotton swab to gently scrape the inside of your

cheek.

o Rub the swab on a clean microscope slide to transfer the cells

onto the slide.

2. Stain the Cells:

 o Add a drop of methylene blue stain to the cheek cell sample.
This will make the cell structures, especially the nucleus, more
visible.

3. Apply the Cover Slip:

o Place a cover slip gently on top of the cheek cell sample at an

angle to avoid air bubbles.

o Press down gently on the cover slip if needed.

4. Observe Under the Microscope:

o Place the slide on the microscope and start by using the

lowest magnification (4x).

o Slowly increase the magnification (10x, 40x) to examine the

structure of the cheek cells.

o Look for the round shape of the animal cell, and you should
clearly see the nucleus in the center of the cell.

3. Drawing and Labeling

 After observing both plant and animal cells under the microscope,
encourage students to draw what they see, showing key features
like:

o Plant Cells: Cell wall, nucleus, cytoplasm, and central

vacuole.

o Animal Cells: Plasma membrane, nucleus, cytoplasm.

 Label the structures clearly in the drawings. You can also compare
and contrast the two cell types:

o Plant cells have a cell wall and chloroplasts (if observed in

green plants), while animal cells do not.

o Animal cells tend to be more irregular in shape, whereas plant

cells have a more rectangular shape due to the rigid cell wall.

Tips for a Successful Investigation:

 Use the proper magnification: Start at low magnification to

locate the cells, then switch to a higher magnification for detailed
viewing.

 Adjust the light: Make sure the microscope's light is properly

adjusted so that the cells are clearly visible.
  Handle with care: When preparing slides, be gentle to avoid
damaging the cells or causing air bubbles.

Step-by-Step Guide on Investigating Osmosis in a High School Lab

Osmosis is the movement of water molecules from an area of low solute

concentration to an area of high solute concentration through a semi-
permeable membrane. This experiment can be done using plant tissues
(such as potato) and different concentrations of salt or sugar solutions.

Materials Needed:

 Fresh potato

 Knife and cutting board

 Ruler

 Balance (scale)

 Distilled water

 Salt or sugar (to prepare different concentrations)

 Beakers or cups (for solutions)

 Measuring cylinder or pipette

 Paper towels or tissue

 Stopwatch or timer

 Microscope (optional, for advanced observations)

 Knife or scalpel (for cutting the potato)

Experiment Overview:

The objective of this experiment is to observe osmosis by placing pieces

of potato in different concentrations of salt or sugar solutions and
measuring the changes in mass and size.

1. Preparing the Potato Samples

 Step 1: Prepare Potato Tubes or Slices

o Use a knife to cut the potato into uniform pieces. You can
either:

 Cut potato cylinders (small tubes) using a cork borer,

or

 Cut potato slices that are about 1-2 cm thick.

 o Make sure all pieces are the same size and shape to ensure
fair comparison.

o Measure the initial length and mass of each potato

sample using a ruler and balance. Record this data.

2. Preparing the Solutions

 Step 2: Prepare Different Concentrations of Salt/Sugar

Solution

o You will need different concentrations of salt or sugar solutions

to observe osmosis at varying levels of concentration.

o For example, you can prepare solutions with the following

concentrations:

 0% (distilled water)

 5% (low concentration)

 10% (medium concentration)

 15% (high concentration)

o To prepare each solution, dissolve the appropriate amount of

salt or sugar in a fixed volume of distilled water:

 5% solution = 5 grams of salt/sugar in 100 mL of water

 10% solution = 10 grams of salt/sugar in 100 mL of

water

 15% solution = 15 grams of salt/sugar in 100 mL of

water

o Label the beakers with the respective concentrations of the

solution.

3. Placing Potato Samples into Solutions

 Step 3: Submerge Potato Pieces in Solutions

o Place each potato piece into the appropriate solution. You

should use at least three different solutions (e.g., distilled
water, 5%, 10%, and 15% solutions).

o If you are using potato cylinders, ensure they are fully

submerged.

o If using potato slices, make sure the slice is completely in

contact with the solution.
4. Let the Potato Pieces Soak

 Step 4: Wait for 30-60 Minutes

o Leave the potato samples in the solutions for at least 30

minutes to 1 hour.

o Ensure that the pieces are not disturbed during this time.

5. Remove and Dry the Potato Pieces

 Step 5: Remove the Potato Pieces from the Solutions

o After the soaking time, carefully remove the potato pieces

from the solutions.

o Gently blot the pieces with paper towels to remove any excess
solution from the surface.

6. Measure Changes in Size and Mass

 Step 6: Measure the Final Length and Mass of Each Piece

o Using a ruler, measure the final length of each potato piece

and record the value.

o Use a balance to measure the final mass of each piece and

record the value.

7. Calculate and Analyze the Results

 Step 7: Calculate the Percentage Change in Mass

o Calculate the percentage change in mass using the formula:

Percentage Change in Mass=Final Mass−Initial MassInitial Mas
s×100\text{Percentage Change in Mass} = \frac{\text{Final
Mass} - \text{Initial Mass}}{\text{Initial Mass}} \times
100Percentage Change in Mass=Initial MassFinal Mass−Initial
Mass×100

o This will help determine the effect of different concentrations

on osmosis.

8. Interpret the Results

 Step 8: Analyze the Results

o In distilled water (0%), the potato should absorb water and

increase in mass (the water moves into the potato cells due to
osmosis).
 o In higher salt or sugar solutions, the potato pieces should
lose mass as water moves out of the cells (osmosis occurs,
moving water from an area of high water concentration in the
potato to an area of low water concentration in the solution).

o Compare the changes in mass to understand how

concentration affects osmosis.

9. Draw a Graph (Optional)

 Step 9: Graph the Results

o Plot a graph of percentage change in mass on the y-axis

and the concentration of the solution (e.g., 0%, 5%, 10%,
15%) on the x-axis.

o You should see a negative correlation: as the concentration of

the solution increases, the potato's mass decreases due to
water loss.

Conclusion and Discussion

 Conclusion: Based on the experiment, you should conclude that

osmosis occurs in response to the concentration gradient. The
potato absorbs water in lower concentrations and loses water in
higher concentrations.

 Discussion: Discuss why osmosis happens—water moves to

equalize the concentration of solutes across the semi-permeable
membrane of the potato cells. The experiment demonstrates how
osmosis plays a key role in maintaining cell turgidity in plant cells
and can help explain phenomena like wilting in plants.

Alternative/Extended Experiment:

 Microscopic Investigation: If available, you can prepare a slide

with a small piece of potato and observe it under a microscope
before and after soaking in a solution. You should see changes in the
size of the cells and the vacuoles.

Safety Tips:

 Handle the knife carefully when cutting the potato.

  Wear safety goggles to protect your eyes, especially when preparing
solutions.

 Ensure all solutions are labeled clearly to avoid confusion.

This experiment will give students a visual and quantitative understanding

of how osmosis works in plant cells and how the concentration of a
solution can affect the movement of water.

Step-by-Step Guide on Investigating the Effect of Temperature on

Enzyme Activity in a School Lab

If you're conducting this experiment in a school lab with basic equipment,

you can still effectively investigate how temperature affects enzyme
activity. We'll use catalase (from potato or liver) and hydrogen
peroxide as the substrate.

Materials Needed:

 Fresh potato or liver (source of catalase enzyme)

 Hydrogen peroxide (3%)

 Test tubes or small beakers

 Measuring cylinder or pipette

 Water baths (if possible, for precise temperature control)

 Ice (for cold temperature)

 Bowl with warm water (for warm temperature)

 Thermometers (to measure temperature in water baths)

 Timer (stopwatch or phone timer)

 Oxygen collection system (e.g., inverted measuring cylinder

in water or gas syringe)

 Knife (for cutting potato or liver)

 Tissue or paper towels (for cleaning)

1. Prepare the Enzyme Source (Catalase)

Step 1: Prepare the Catalase Solution

  If using potato or liver, cut the tissue into small cubes or pieces.
You can use a blender or mortar to grind it into a homogenized
slurry to extract the enzyme.

 Strain the mixture to remove large pieces, leaving just the liquid
enzyme extract.

2. Prepare Temperature Conditions

Step 2: Set Up Water Baths for Different Temperatures

 You can set up three different temperatures for your

experiment: cold, room, and warm temperatures.

o Cold Temperature (5°C): Place some ice and cold water in a

container or bowl. Place the test tubes or beakers inside this
container to maintain a low temperature.

o Room Temperature (20-25°C): This will be your control

group. You can simply use the room temperature.

o Warm Temperature (35-40°C): Use a warm water bath

(using warm tap water or warm the water gently on a stove or
kettle). Ensure it’s not too hot to avoid denaturation.

Step 3: Temperature Check

 Use a thermometer to ensure each water bath is at the correct

temperature and maintain this throughout the experiment.

3. Prepare the Experiment Setup

Step 4: Prepare the Substrate (Hydrogen Peroxide)

 Measure out an equal volume of hydrogen peroxide (3%) for each

test tube. For example, 10 mL for each sample.

Step 5: Add Enzyme to Test Tubes

 Add an equal amount (e.g., 2 mL) of the enzyme solution (from

potato or liver) to each test tube.

4. Conduct the Experiment

Step 6: Add Hydrogen Peroxide to the Enzyme Solution

  Add hydrogen peroxide (3%) to each test tube containing the
enzyme. The reaction between the catalase and hydrogen peroxide
will break down the hydrogen peroxide into oxygen and water.

Step 7: Place Test Tubes in Different Water Baths

 Place the test tubes with the enzyme and substrate mixture into
their respective water baths at cold (5°C), room (25°C), and
warm (35-40°C) temperatures.

 Allow them to react for 2-3 minutes, ensuring the reaction is

allowed to complete within that time.

5. Measure the Oxygen Produced

Step 8: Set Up Oxygen Collection System

 To measure enzyme activity, you need to measure the amount of

oxygen produced during the reaction.

o Inverted Measuring Cylinder in Water: Fill a measuring

cylinder with water and invert it in a bowl of water. Position
the mouth of the test tube in the bottom of the inverted
cylinder. As oxygen is produced, it will displace the water in
the cylinder.

o Gas Syringe (if available): You can connect the test tube to
a gas syringe to measure the volume of oxygen produced.

Step 9: Start Timing and Collect Data

 Start a timer as soon as you add the hydrogen peroxide to the

enzyme solution. Measure the volume of oxygen produced at regular
intervals, such as every 30 seconds for a total of 2-3 minutes.

6. Repeat the Experiment

Step 10: Repeat for All Temperature Conditions

 After completing one trial, repeat the experiment for each

temperature condition (cold, room, and warm temperature).

 Ensure the enzyme and substrate amounts remain the same across
all trials for consistency.

7. Calculate and Analyze Results

Step 11: Calculate the Rate of Enzyme Activity

 Rate of enzyme activity can be calculated by dividing the

volume of oxygen produced by the time it took for the oxygen
to be produced:
Rate of reaction=Volume of oxygen produced (mL)Time taken (seco
nds)\text{Rate of reaction} = \frac{\text{Volume of oxygen
produced (mL)}}{\text{Time taken
(seconds)}}Rate of reaction=Time taken (seconds)Volume of oxyge
n produced (mL)

 Record the results for each temperature condition.

Step 12: Plot a Graph

 Plot a graph with Temperature (°C) on the x-axis and Rate of

Enzyme Activity (oxygen produced/time) on the y-axis.

8. Interpretation of Results

Step 13: Analyze the Effect of Temperature

 Cold temperature (5°C): The enzyme activity should be low

because enzyme molecules move slowly, and the reaction occurs
more slowly.

 Room temperature (25°C): Expect the enzyme to work at an

optimal rate, as room temperature is typically the optimal
temperature for many enzymes.

 Warm temperature (35-40°C): The enzyme should work faster

than at colder temperatures, but at a certain point, if the
temperature gets too high, the enzyme will denature and lose its
shape, causing the reaction rate to drop. This will happen if the
temperature exceeds the enzyme's optimal range.

9. Conclusion

Step 14: Draw Conclusions

 The experiment will demonstrate that enzyme activity increases

with temperature up to an optimal point. After the optimal
temperature, enzyme activity will decrease due to denaturation.

 You can conclude that temperature affects enzyme activity, with

each enzyme having an optimal temperature range where it
functions most effectively.
Safety Tips:

 Handle hydrogen peroxide with care, even though it’s a relatively

low concentration.

 Wear safety goggles and gloves to protect yourself from

chemicals.

 Be cautious with hot water and avoid burns when handling water
baths or heating water.

 Ensure you clean up any spills promptly to prevent slipping or injury.

Possible Extensions for the Experiment:

 pH Experiment: Investigate the effect of different pH levels on

enzyme activity.

 Substrate Concentration: Study how changing the concentration

of hydrogen peroxide affects the enzyme's activity.

This experiment is a simple yet effective way to demonstrate how

temperature influences enzyme reactions in a school lab setting with basic
equipment.

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