LBBBIOA Exercise 6: Photosynthesis Introduction

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Questions and Answers

What is the purpose of placing one Plectranthus plant in the dark for 48 hours?

To study the impact of soil nutrients on photosynthesis

To test the role of darkness in photosynthesis

To examine the effect of water on photosynthesis

To test the role of light in photosynthesis (correct)

What is the next step after cutting off the leaf set-ups from the Plectranthus plant?

Placing the leaves in a water bath

Testing for starch content (correct)

Boiling the leaves in ethyl alcohol

Marking the beakers A and B

What is the purpose of boiling the leaves of the Plectranthus plant in water?

To extract pigments for testing

To remove excess water from the leaves

To increase photosynthesis efficiency

To soften the leaves (correct)

Which solution is used to immerse the boiled leaves for testing?

95% ethyl alcohol Signup and view all the answers

What is the main objective of immersing the boiled leaves in ethyl alcohol?

To extract chlorophyll for analysis Signup and view all the answers

How does placing one pot of Plectranthus plant in sunlight contribute to the experiment?

Enhances photosynthesis efficiency Signup and view all the answers

What is the main function of photosynthesis in plants?

Conversion of light energy into chemical energy Signup and view all the answers

Which of the following is NOT required for photosynthesis to occur?

Oxygen Signup and view all the answers

What is the main product of photosynthesis?

Glucose Signup and view all the answers

Which of the following is NOT a pathway for glucose produced during photosynthesis?

Conversion into oxygen Signup and view all the answers

What are the objectives of a photosynthesis experiment as mentioned in the text?

Measure rate of photosynthesis affected by factors Signup and view all the answers

Where does photosynthesis primarily take place within plant cells?

Chloroplasts Signup and view all the answers

What is the purpose of placing the beaker set-ups in a water bath during the extraction process?

To prevent the alcohol from catching fire Signup and view all the answers

Why is it important not to boil the leaves under direct flame during the pigment extraction process?

To avoid discoloration of the leaves Signup and view all the answers

In the experiment, what does a bluish black color on the leaves indicate?

Presence of starch Signup and view all the answers

Why is it necessary to compare the results between the exposed and covered areas of the leaves in the experiment?

To observe differences in starch presence due to light exposure Signup and view all the answers

What is the role of iodine solution in the experiment conducted on leaves after alcohol extraction?

To indicate the presence of starch Signup and view all the answers

What is the purpose of half-filling test tubes A, B, and C with dilute phenol red solution in the carbon dioxide experiment?

To act as an indicator for carbon dioxide levels Signup and view all the answers

Study Notes

Dark Treatment

Placing a Plectranthus plant in the dark for 48 hours is to deplete it of starch and glucose.

Leaf Set-Ups

After cutting off the leaf set-ups from the Plectranthus plant, they are boiled in water for 1 minute.

Boiling Leaves

Boiling the leaves of the Plectranthus plant in water denatures the enzymes involved in photosynthesis, which helps to preserve the pigments and structure of the leaves.
Boiling also softens the leaves, allowing them to absorb the ethyl alcohol more readily.

Ethyl Alcohol Immersion

The boiled leaves are immersed in ethyl alcohol to extract the chlorophyll and other pigments.

Sunlight Exposure

Placing one pot of Plectranthus plant in sunlight provides a control for the experiment and allows for a comparison between the photosynthesizing and non-photosynthesizing plant.

Photosynthesis Purpose

The main function of photosynthesis is to convert light energy, carbon dioxide, and water into glucose (sugar) and oxygen.

Photosynthesis Requirements

All of the following are necessary for photosynthesis:
- Light
- Carbon dioxide
- Water
- Chlorophyll

Photosynthesis Product

The main product of photosynthesis is glucose (sugar).

Glucose Pathways

Glucose can be used for:
- Cellular respiration
- Plant growth
- Storage as starch

Photosynthesis Experiment Objectives

The objective of this experiment is to study the process of photosynthesis and how it is affected by light.

Chloroplast Location

Photosynthesis primarily takes place within the chloroplasts of plant cells.

Water Bath Purpose

Beaker set-ups are placed in a water bath during the extraction process to ensure that the leaves are heated gently and evenly.

Direct Flame Caution

It's important not to boil the leaves under direct flame because this can cause them to scorch and release volatile compounds that may interfere with the pigment extraction process.

Bluish Black Color Indication

In the experiment, a bluish-black color on the leaves indicates the presence of starch, which is a product of photosynthesis.

Comparison of Exposed and Covered Leaves

Comparing the results between the exposed and covered areas of the leaves is crucial to establish the effect of light on photosynthesis.
The exposed areas of the leaves, which have been exposed to light and undergone photosynthesis, will show a bluish-black color due to the presence of starch.

Iodine Solution Role

Iodine solution is used to test for the presence of starch.
When iodine is added to a sample that contains starch, it turns a bluish-black color.

Phenol Red Solution Purpose

Test tubes containing dilute phenol red solution are half-filled: -to test for the presence of carbon dioxide. -Phenol red is a pH indicator. -It's red in an alkaline solution and turns yellow in an acidic solution.
- The addition of carbon dioxide to the solution will lower the pH of the solution, causing it to turn yellow.

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Description

Test your knowledge on the process of photosynthesis in green plants, where light energy is converted into chemical energy stored in food molecules. Understand the importance of photosynthesis for all living organisms.