How is ET50 calculated?

What was the ET 50light for this trial? To determine the ET50-light for this trial, plot the percent leaf disk floating as a function of time: From the above graph, we can interpolate that 50% of the leaf disks floated at 5.5 minutes. Therefore, the ET50-light is 5.5 minutes.

What is the ET50 value?

The ET50 is the time it takes for 50% of the leaf disks to float and is a good indicator of the rate of photosynthesis. It was hypothesized that if the concentration of carbon dioxide was increased, then the rate at which photosynthesis occurs will also increase.

How do you calculate the rate of photosynthesis in leaf discs?

To measure the rate of photosynthesis, you will replace the air in the spongy mesophyll in your leaf disks with a liquid. This will cause the leaf disks to sink. Then you will put these leaf disks in water with dissolved CO2 and measure the amount of time it takes for the leaf disks to float.

How do you find the gross rate of photosynthesis?

We will also calculate the gross photosynthesis; we will get negative values for the photosynthesis rates, so we will subtract the respiration rates from the net photosynthesis rates in order to get gross photosynthesis rates.

How do you investigate the effect of CO2 concentration on the rate of photosynthesis?

How long does it take for leaf disks to float?

The point at which 50% of the leaf disks are floating (the median) is the point of reference for this procedure. By extrapolating from the graph, the 50% floating point is about 11.5 minutes.

What is the photosynthesis equation?

The process of photosynthesis is commonly written as: 6CO2 + 6H2O → C6H12O6 + 6O2. This means that the reactants, six carbon dioxide molecules and six water molecules, are converted by light energy captured by chlorophyll (implied by the arrow) into a sugar molecule and six oxygen molecules, the products.

What is a leaf disk assay?

In the floating leaf disk assay, 10 or more leaf disk samples are punched out of a leaf. In the next step, a vacuum is used to replace the air pockets within the leaf structure with a baking soda (bicarbonate) solution. The baking soda provides the carbon dioxide that the leaf needs for photosynthesis.

Why is baking soda used in photosynthesis experiment?

The bicarbonate serves as a source of carbon dioxide for photosynthesis. The dishwashing liquid wets the hydrophobic surface of the leaf allowing the solution to be drawn into the leaf.

How do labs measure photosynthesis?

How can the rate of photosynthesis be measured quizlet?

How can photosynthesis be measured? Directly: by the production of oxygen(counting bubbles) or the uptake of carbon dioxide (measuring pH of surroundings).

How do you measure the rate of photosynthesis in pondweed?

Position the boiling tube so that the pondweed is 10 cm away from the light source. Allow the boiling tube to stand for five minutes. Count the number of bubbles emerging from the cut end of the stems in one minute. Repeat the count five times and record your results.

How do you measure the rate of photosynthesis GCSE?

How do you find the concentration of CO2?

Carbon Dioxide (CO2) is measured with a gas sensor specifically made to measure the concentration of carbon dioxide (CO2) in the air. There are three main types of Carbon Dioxide (CO2) sensors: Electrochemical sensors, Non-Dispersive Infrared (NDIR) Sensors, and Metal Oxide Semiconductor (MOS) Sensors.

What is the effect of CO2 on photosynthesis?

Elevated [CO2] increases the availability of carbon in leaves causing greater Rubisco activity and higher rates of photosynthesis. Greater photosynthesis increases the content of non-structural carbohydrates in leaves which can lead to greater starch reserves and increased auxin biosynthesis.

What light intensity and CO2 level will maximize the rate of photosynthesis?

In the Gizmo, what light intensity and CO2 level do you think will maximize the rate of photosynthesis? The highest light intensity and CO2 level will maximize the rate of photosynthesis.

Will leaf disks float in the dark?

When you put floating leaf disks in the dark, they will eventually sink. Without light energy, no photosynthesis will occur, so no more O2 gas will be produced.

What causes leaf disks to float and/or sink?

Leaf disks normally float, however when the air spaces are infiltrated with carbon dioxide, the overall density of the lead disk increases and the leaf disk sinks. When sodium bicarbonate is added to the water, the bicarbonate ion acts as a carbon source for photosynthesis causing the leaf disks to sink.

Why do leaf disks float when exposed to light?

The leaf disks intake carbon dioxide from a baking soda solution and sink to the bottom of a cup of water. When exposed to light, the disks use carbon dioxide and water to produce oxygen and glucose. Oxygen released from the leaves forms tiny bubbles that cause the leaves to float.

What is formula of photosynthesis and respiration?

Connecting Cellular Respiration and Photosynthesis Notice that the equation for cellular respiration is the direct opposite of photosynthesis: Cellular Respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O. Photosynthesis: 6CO2 + 6H2O → C6H12O6+ 6O.

What are the 7 steps of photosynthesis?

  • Step 1-Light Dependent. CO2 and H2O enter the leaf.
  • Step 2- Light Dependent. Light hits the pigment in the membrane of a thylakoid, splitting the H2O into O2.
  • Step 3- Light Dependent. The electrons move down to enzymes.
  • Step 4-Light Dependent.
  • Step 5-Light independent.
  • Step 6-Light independent.
  • calvin cycle.

Why is there a 6 in the photosynthesis equation?

In words, the equation may be stated as: Six carbon dioxide molecules and six water molecules react to produce one glucose molecule and six oxygen molecules. The reaction requires energy in the form of light to overcome the activation energy needed for the reaction to proceed.

How does floating leaf disk method measure photosynthesis?

As photosynthesis proceeds, oxygen is released into the interior of the leaf, which changes the buoyancy- causing the disks to rise. Since cellular respiration is taking place at the same time and consuming oxygen, the rate that the disks rise is an indirect measurement of the net rate of photosynthesis.

Why do leaves float on water?

The spongy mesophyll layer is normally infused with gases, oxygen and carbon dioxide. Leaves (or disks cut from leaves) will normally float in water because of these gases. If you draw the gases out from the spaces, then the leaves will sink because they become more dense than water.

Does baking soda increase the rate of photosynthesis?

The more sodium bicarbonate present, there is a greater amount of carbon dioxide present, which in result will increase the speed of photosynthesis.

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