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Biology SL
Biology SL
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Method

How does the conversion of starch to glucose in nectarines (prunus persica) under two different fruit ripening techniques change over the course of seven days?

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Table of content

Introduction

Figure 1 - Glucose Molecule
Figure 1 - Glucose Molecule

One of the most crucial carbohydrates in biochemistry, glucose plays a crucial role in the two most fundamental biological processes, photosynthesis and cellular respiration. Digestional enzymes convert starch molecules (polysaccharides) into glucose (monosaccharide) during the ripening process. The introduction of ethene gas allows for the completion of this procedure.23 Ethene gas is a biological hormone that plants employ to drive important processes like seed germination, fruit abscission, and fruit ripening. It is more easily produced by some fruits, like bananas and apples, and will speed up fruit ripening when placed in a constrained space, such a plastic bag or box. Burying the fruit in rice has been suggested as a different approach. The ethylene gas produced by the fruit should last longer in it.

 

The three ripening conditions that will be simulated in this experiment are all thought to cause the ripening process. A banana and a nectarine will be combined in a sealed bag for the first test. In the second, rice will be placed in a plastic box with a nectarine underneath it. Thirdly, the null hypothesis will be established by placing a nectarine alone in a plastic bag as the control, supporting the idea that the creation of ethene gas and the level of glucose are unrelated processes. It is crucial that all three trials be carried out in enclosed spaces since they encourage the retention of ethene gas.

 

The level to which ethene gas has impacted the metabolism of starch and the concentration of simple sugars in nectarines has been determined in this experiment by the presence of glucose.

 

A coloured indicator made of potassium permanganate (KMn04) solution and an acid, in this case sulphuric acid (H2SO4), can be used to identify the presence of glucose. Alkenes are converted to glycols by the powerful oxidising agent KMn04 solution, allowing for a quantitative test for the existence of unsaturated bonds in a sample. The pink tint of the KMn04 solution shows how starch is converted to glucose during metabolism.

 

The amount of time it takes for the pink colour to go away is indicative of the amount of glucose present in the filtrate sample; the shorter the time it takes for the colour to go away, the more glucose is present in the sample.

Prediction

The nectarines subjected to the rice packing trial are anticipated to mature the quickest. They are placed in a controlled atmosphere that will encourage the retention of ethene gas around the nectarine. As a result, in this trial, the concentration of monosaccharides (glucose) would rise faster and the concentration of polysaccharides (starch) will fall faster. Because the ethane produced by the banana will supplement that produced by the nectarines themselves, the nectarines kept with the banana will also ripen more quickly than the control.

Method

Materials

  • 36 nectarines
  • 12 bananas
  • Snap lock bags, plastic containers
  • Basmati Rice (approximately 3kg)
  • 560ml Sulphuric Acid 1M (H2S04)
  • 230ml Potassium Permanganate solution 0.01M (KMnO4)
  • Knife, cutting board, food processor, sieve
  • Stop watch
  • Syringes - 3ml, 5ml and 10ml
  • 4x 750ml beaker (each repeat)
  • 12x 50ml beaker (each repeat)

 

The purpose of this experiment is to ascertain how ethene gas influences nectarines' glucose content. Two popular fruit ripening techniques, rice and banana packaging, were examined alongside a control in order to draw a conclusion. The techniques listed below are appropriate for each of these situations.

 

It was agreed that steps should be done to reduce this inaccuracy as much as possible because the "end point" of the solution, or when the pink colour vanishes and the stop-watch is stopped, is subjective. Four nectarines were ground up and successfully tested on each day of the three different circumstances (banana, rice, and control). Three different tests were performed on each nectarine's filtrate. This was done in order to avoid discrepancies in the results and to eliminate any inaccuracy that might have been caused by the solution's stirring.

 

The experiment was set up as follows on Day 1:

 

  • A snap-lock bag contained a banana and a nectarine. The bag was sealed once the air inside it was taken out.
  • One nectarine was put into a box made of plastic. The box was sealed once the container had been completely filled with rice to completely encase the nectarine.
  • I put one nectarine in a snap-lock bag. The bag was sealed when the air was taken out of it.