Floating Leaf Disks Lab (Photosynthesis)

Summary

In this instructional video, Mr. Buss guides viewers through setting up a floating leaf disks lab to demonstrate photosynthesis. One person prepares leaf disks by punching holes between leaf veins. Another mixes a sodium bicarbonate solution with detergent to create carbon dioxide. Disks are loaded into syringes, submerged in the solution, and tested under light and dark conditions. The experiment observes how many disks float due to oxygen release, illustrating photosynthesis in action.

Takeaways

• 🌿 Prepare spinach leaves by punching holes between the veins to create leaf disks.
• 👥 Assign tasks in a group: one person prepares leaf disks, the other prepares the bicarbonate water solution.
• 💧 Use a 600 ml beaker and fill it with 300 ml of water for the bicarbonate solution.
• 🧂 Add three grams of baking soda (sodium bicarbonate) to the water to provide carbon dioxide for photosynthesis.
• 💧 Add a drop of detergent to the solution to prevent leaf disks from sticking to the water surface.
• 🔬 Photosynthesis combines carbon dioxide, water, and light energy to produce glucose and release oxygen.
• 💉 Use a syringe to load leaf disks and bicarbonate water, ensuring no air bubbles are trapped.
• 🌱 Place leaf disks in small plastic cups submerged in the bicarbonate water, ensuring they start at the bottom.
• 💡 Set up an experiment with light and dark conditions to observe the effect on leaf disks.
• ⏱️ Record the number of leaf disks that float every minute for 15 minutes.
• 🌞 Leaf disks in the light condition will start to float due to the release of oxygen from photosynthesis.

Q & A

What is the main purpose of the floating leaf disks lab?

The main purpose of the floating leaf disks lab is to demonstrate the process of photosynthesis, particularly the release of oxygen gas which causes the leaf disks to float.

Who is Mr. Buss in the context of the script?

Mr. Buss is the instructor guiding the group through the setup and execution of the floating leaf disks lab.

What is the role of one person in the group during the lab setup?

One person in the group is responsible for obtaining spinach leaves and creating leaf disks by punching holes between the veins of the leaves.

How many leaf disks should each group have initially?

Each group should aim to have four piles of about ten leaf disks each.

What is the purpose of using baking soda in the lab?

Baking soda, or sodium bicarbonate, is used as a source of carbon dioxide, which is essential for the photosynthesis process.

Why is detergent added to the bicarbonate water solution?

Detergent is added to prevent the leaf disks from sticking to the surface of the water and to allow them to sink.

How much bicarbonate water solution is prepared in the lab?

A 300 ml solution of bicarbonate water is prepared in a 400 or 600 ml beaker.

What is the role of the syringe in the lab procedure?

The syringe is used to load leaf disks and bicarbonate water solution, ensuring that air bubbles are removed before the disks are placed in the experimental cups.

How many leaf disks are placed in each cup for the experiment?

Twenty leaf disks are placed in each cup for the experiment.

What are the two different conditions under which the leaf disks are tested?

The leaf disks are tested under light and dark conditions to observe the effect of photosynthesis.

How often should the number of floating leaf disks be recorded during the experiment?

The number of floating leaf disks should be recorded every minute for a duration of 15 minutes.

What causes the leaf disks to start floating during the experiment?

The leaf disks start to float due to the release of oxygen gas during photosynthesis, which forms bubbles on the disks.

Outlines

00:00

🌿 Setting Up the Floating Leaf Disks Lab

Mr. Buss introduces the floating leaf disks lab, detailing the setup process. One person should prepare spinach leaves by punching out disks between the veins to avoid damaging them. The goal is to create four groups of ten leaf disks. Another person should prepare a 300 ml solution of 3 grams of sodium bicarbonate (baking soda) in water, which serves as a carbon dioxide source for photosynthesis. A drop of detergent is added to prevent leaf disks from sticking to the water surface. The leaf disks are then loaded into a syringe, filled with the bicarbonate solution, and checked to ensure they sink. The process of removing air from the syringe and ensuring all disks are submerged is explained. Finally, the disks are placed into plastic cups for the experiment.

05:03

🔬 Observing Photosynthesis in Leaf Disks

The experiment involves placing leaf disks under light and dark conditions to observe photosynthesis. The setup includes 20 leaf disks in each condition, ensuring they are submerged and not floating. Over a 15-minute period, the number of disks that float to the surface is recorded every minute. Floating is an indication of photosynthesis occurring, as oxygen bubbles form on the disks, causing them to rise. The observation concludes that all disks in the light condition float, while none in the dark condition do, demonstrating the necessity of light for photosynthesis.

Keywords

💡Floating Leaf Disks

Floating leaf disks are small, circular sections cut from spinach leaves used in the lab to demonstrate photosynthesis. In the video, Mr. Buss guides viewers on how to prepare these disks by punching holes between the veins of the leaves. The disks are then used in an experiment where they are submerged in a solution and observed for changes in buoyancy, which is a direct result of gas production during photosynthesis.

💡Photosynthesis

Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigments. It involves the conversion of carbon dioxide and water into glucose and oxygen. In the script, photosynthesis is the key biological process being demonstrated, as the release of oxygen from the leaf disks causes them to float.

💡Bicarbonate Water Solution

The bicarbonate water solution is a mixture prepared with water, baking soda (sodium bicarbonate), and a drop of detergent. This solution serves as a carbon dioxide source for the leaf disks in the experiment. The baking soda dissolves to provide the necessary carbon dioxide for photosynthesis, while the detergent prevents the disks from sticking to the water's surface.

💡Carbon Dioxide

Carbon dioxide (CO2) is a gas that is one of the primary reactants in the process of photosynthesis. It is used by plants to produce glucose and oxygen. In the context of the video, the bicarbonate water solution provides CO2 for the leaf disks, simulating the natural environment where plants would absorb CO2 from the air.

💡Detergent

Detergent is added to the bicarbonate water solution to prevent the leaf disks from sticking to the surface of the water. This allows the disks to sink and float more naturally, which is crucial for observing the effects of photosynthesis. Without the detergent, the disks might not accurately demonstrate the gas production that causes them to float.

💡Light Condition

A light condition is an environment where the leaf disks are exposed to light, simulating the natural conditions under which photosynthesis occurs. In the experiment, one set of leaf disks is placed under a light to observe the effect of light on photosynthesis, while another set is kept in the dark to serve as a control.

💡Dark Condition

A dark condition is used as a control in the experiment to compare with the light condition. It represents an environment without light, where photosynthesis cannot occur. The leaf disks in the dark condition do not float, demonstrating that light is a necessary component for the process being studied.

💡Glucose

Glucose is a simple sugar that serves as a primary energy source for most organisms. In the context of photosynthesis, it is produced when plants convert carbon dioxide and water using light energy. Although not directly observable in the experiment, glucose production is implied as an end product of the process that causes the leaf disks to float due to oxygen release.

💡Oxygen

Oxygen is a gas that is released as a byproduct of photosynthesis. In the video, the production of oxygen is indicated by the formation of bubbles on the leaf disks, which causes them to float. This is a visual demonstration of the gas exchange that occurs during photosynthesis.

💡Sodium Bicarbonate

Sodium bicarbonate, commonly known as baking soda, is used in the experiment to provide a source of carbon dioxide. When dissolved in water, it creates a bicarbonate solution that simulates the CO2-rich environment needed for the leaf disks to perform photosynthesis.

💡Control Experiment

A control experiment is a scientific setup where all variables are kept constant except for the one being tested. In the video, the dark condition serves as a control to the light condition, allowing Mr. Buss to demonstrate that light is necessary for photosynthesis to occur, as evidenced by the lack of floating leaf disks in the dark.

Highlights

Introduction to setting up and running the floating leaf disks lab.

One person should prepare spinach leaves and create leaf disks.

Leaf disks should be punched out between the veins.

Leaf disks are sorted into groups of ten.

Another person should prepare the bicarbonate water solution.

A 600 ml beaker is used to prepare 300 ml of solution.

Add three grams of baking soda to the solution.

One drop of detergent is added to prevent leaf disks from sticking to the surface.

Baking soda dissolves to provide carbon dioxide for photosynthesis.

Photosynthesis combines carbon dioxide, water, and light energy to produce glucose and oxygen.

Leaf disks are loaded into a syringe and submerged in bicarbonate water.

Air bubbles are removed from the syringe to ensure leaf disks sink.

Leaf disks are placed in small plastic cups for the experiment.

Leaf disks should be at the bottom and not floating at the start.

Leaf disks are divided between light and dark conditions.

Leaf disks in the light start to float due to oxygen release from photosynthesis.

Oxygen bubbles form on the leaf disks, causing them to float.

After 15 minutes, all leaf disks in the light are floating.

No leaf disks float in the dark condition, indicating the necessity of light for photosynthesis.

Transcripts

hello this is mr. buss and I'm gonna

walk you through how to set up and run

the floating leaf disks lab and so one

person in the group to get started

efficiently if you have a group of two

it's helpful if one person takes care of

getting a few spinach leaves and getting

some of the leaf disks created and so

what you're gonna want to do is take the

whole bunch and then try to punch out

spaces between the veins of the leaf try

not to punch holes from the veins

so I quenched a bunch of holes out of

the leaves and these little leaf disks

and I'm going to try to sort these into

groups of ten

okay so here I have four groups of ten

and I just kind of took some of the ones

that weren't very well punched or

whatever has some extras off to the side

in case I need them later so one person

in the group try to get four piles of

about ten or so the other person in the

group prepared the bicarbonate water

solution so take a larger beaker this is

a 600 ml beaker you know 400 or 600

works and then fill it up to a total of

300 mils 300 and then then I'm going to

add three grams of baking soda so sodium

bicarbonate and then mix that up and

then it can be helpful to add one drop

of detergent that's plenty

okay so the baking soda is going to be a

source of carbon dioxide actually the

baking soda the sodium bicarbonate is

going to dissolve in there and so that

you know obviously in photosynthesis the

plant cells need start with carbon

dioxide combines water and light energy

to yield energy molecule like glucose

and releases oxygen the detergent just

allows these to sink sometimes they want

to stick to the surface of the water and

the detergent is going to prevent that

from happening so once this is all set

you've got your bicarbonate water you've

got your piles of leaf disks take a

syringe remove the plunger and load a

pile of ten disks into the plunger into

the syringe I mean okay

put the plunger back in don't crush them

just push it down most of the way pull

up some of your bicarbonate water now

I'm going to get all the air out I

filled it up about halfway I'm gonna put

my thumb on the end and I'm gonna pull

back on the plunger shake that's gonna

remove the air from inside and I'm gonna

push up and you can see some of the leaf

disks are floating and some are sunk so

I'm gonna repeat that process cap it

with the thumb pull back on the plunger

shake and push up on the plunger and

they are all sunk

so here I have ten leaf disks put them

in one of the small plastic cups so I'm

going to add ten more to my plunger or

to my syringe put the plunger back on

pull up some more bicarbonate water

okay so I have about 20 leaf disks in

each I'm going to double check that

they're all sunk to the bottom I can

count up exactly how many I have in each

if I don't have exactly 20 I'm gonna top

each of the containers off a little bit

with the rest of my carbon dioxide water

so here's my setup I should have equal

numbers of leaf disks in each should be

20 they should be something in the

bottom and not not floating at the top

to start so you should all be at the

bottom if any are floating to start the

experiment remove them and then I'm

going to put one of these under a light

condition and one of them under a dark

condition so here I have 20 of the leaf

disks sunk down in the light condition

and then I just put the other 20 in a

lab drawer that'll be the dark

environment and so over the next 15

minutes I'm going to record how many

float every minute I'm going to check

and see how many have started to float

so you can see that over time I'm a

couple minutes into this here's the

first leaf Chad that's starting to float

to the surface and again at each bin and

I'm gonna just check and see how many of

them are actually floating and here

comes the second one so remember you're

checking the ones that are in the light

also the ones that are in the dark so

you might ask yourself why do they start

to float and remember that

photosynthesis is going to be releasing

oxygen and so you can kind of see

oxygen bubbles starting to form on the

leaf disks and so that's why they're

floating because they're releasing

oxygen gas and that's causing them to

float so after 15 minutes looks like all

of the leaf disks in the light we're

floating there aren't any on the bottom

anymore it might look like there are but

there aren't it's just a weird

reflection and then in the dark I didn't

have any of them