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What effect does Acid rain have on germination?

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BIOLOGY COURSEWORK JENNY HODGSON 11A WHAT AFFECT DOES ACID RAIN HAVE ON GERMINATION? BACKGROUND KNOWLEDGE A seed is formed from the ovule of a flower as a result of fertilisation, and is then dispersed from the parent plant. If the seed lands in a suitable place, it will germinate. Germination is the growth of the embryo inside the seed, eventually growing into a mature plant. CONDITIONS NEEDED FOR GERMINATION OXYGEN - is used for aerobic respiration, which provides the energy for many chemical changes involved in the food reserves and making the new cytoplasm and cell walls of the growing seedling. TEMPERATURE - a rise in temperature speeds up most chemical reactions, including those taking place in living organisms. Germination, therefore occurs more rapidly at high temperatures (up to about 40 degrees centigrade). Above 45 degrees centigrade, the enzymes are denatured and the seedlings would be killed. Below 0-5 degrees centigrade, germination may not start at all. WATER - before the changes necessary for germination take place, the seed must absorb water. The water which reaches the embryo and cotyledons is used to: * Activate the enzymes in the seed * Help the conservation of starch to sugar, and proteins to amino acids * Transport the sugar in solution from the cotyledons to the growing regions WHAT HAPPENS DURING GERMINATION? ...read more.


To make my results as accurate as possible, I am going to use 10 cress seeds in each concentration of acid and then take an average. Using 10 cress seeds will also show a clearer pattern because I will be able to see any anomalies. I used 10 cress seeds in my preliminary experiment and there was enough space for them all to grow and enough seeds to get reasonable results. APPARATUS * Petri dishes (11) * Syringe * Beakers (2) * Cotton wool * Cress seeds * Water * Acid In doing my preliminary experiment, I decided to put the seeds on cotton wool instead of filter paper. Although the cotton wool made it harder for me to pull out the seeds to measure, it soaked up the water and acid which was vital for my experiment. The filter didn't soak up enough water or acid. SAFETY I am going to wear goggles to protect my eyes from any acid, tuck in my tie, tie back long hair and generally be careful not to spill the acid. RESULTS TABLE TO SHOW THE LENGTHS OF THE SEEDLINGS IN DIFFERENT CONCENTRATIONS OF ACID % OF ACID % OF WATER LENGTH OF SEEDLING (MM) ...read more.


I think that my data is reliable because I used 10 seeds and then took the average. I also used 11 different concentrations if acid and water because this would hopefully make a clearer pattern then using fewer concentrations and help me see any anomalies. I could improve the reliability of my data by using more than 10 seeds (20+) and then taking the average of those. However, I do think that 10 seeds are enough to get sufficient results. I could also use more concentrations of acid, going up every 5% instead of every 10%. I have no real anomalous results. To provide additional evidence to support my conclusion I could do more investigations about acid rain affecting germination. For example, I could do exactly the same experiment but use a variety of different seeds apart from cress seeds. This would help me to find out if my conclusion applies to all seeds. I could extend my investigation into related fields by maybe doing on experiments on already germinated plants to see if acid rain affects the growth of a plant after germination. I would germinate some seeds in 100% water and then add different concentrations of acid to see if they had any affect on the growth of the plant. ...read more.

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