Factors that affect the growth in duckweed.

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Emma Phipps

Factors that affect the growth in duckweed.

PLANNING SECTION

Introduction

For healthy growth plants need several substances.  Three important mineral ions that can only be obtained from the soil through their roots are nitrates, phosphates and potassium.  Nitrates are essential for making amino acids and for the ‘synthesis’ of proteins.  Phosphates are essential as they have an important role in reactions involved in photosynthesis and respiration.  Potassium is also important as it helps the enzymes involved in photosynthesis and respiration to work.

The three main minerals are needed in fairly large amounts, but other elements are required in much smaller amounts.  Iron and magnesium are the most important as they are needed to make chlorophyll.

Without photosynthesis, along with minerals, plant growth wouldn’t take place.  Photosynthesis produces glucose for ‘food’ and takes place in the leaves of all green plants.  Glucose is combined with nitrates (collected from the soil) to make amino acids, which are then made into proteins.  Protein amino acid contains carbon, hydrogen, oxygen and nitrogen.  Along with potassium, phosphorus and sulphur make up the important substances that travel through the roots and up the stem.

Photosynthesis needs carbon dioxide, water, light and chlorophyll to continue the process.  Without iron and magnesium chlorophyll couldn’t be made and therefore the plant would die.

Diffusion takes place in the leaves, through the stomata.  The membranes allow substances in and out as particles from an area of high concentration move to an area of low concentration.  This takes place in the example of NO4.  There are excess amounts in the leaf and so it diffuses into the air, as there is less of it in the air outside.

The more nitrogen present in the soil means that there is more protein for the plant, which therefore makes the plant grow bigger, along with photosynthesis.  I am going to investigate whether Baby Bio, a fertiliser containing NPK, helps the duckweed increase in growth.  I am using the type Lemma minor, which will absorb the NPK through its roots.

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Aim

To investigate the effect of Baby Bio on plant growth.

Prediction

Once duckweed reaches a certain size it divides.  The products of photosynthesis, such as glucose, can be joined with amino acids to make proteins such as NPK.  The phosphorus in NPK enables plants to make ATP (adensosine tri phosphate).  If there is no phosphorus then ATP will not be present and therefore the plant will die.  These chemicals are transported through the xylem vessels to wherever it is needed.  The duckweed absorbs nitrates (NO3) and phosphates (PO4) through its roots, as they cannot take them from ...

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