[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:06.01,Default,,0000,0000,0000,,Experiment - OB11. To compare the levels of Carbon Dioxide in Inhaled & Exhaled Air.
Dialogue: 0,0:00:06.02,0:00:12.62,Default,,0000,0000,0000,,Safety googles and gloves must always be worn, when chemicals are involved.
Dialogue: 0,0:00:12.62,0:00:20.57,Default,,0000,0000,0000,,We have 2 testubes containing limewater. Limewater is a clear solution and it turns milky when Carbon
Dialogue: 0,0:00:20.57,0:00:24.53,Default,,0000,0000,0000,,Dioxide is present...
Dialogue: 0,0:00:24.53,0:00:27.61,Default,,0000,0000,0000,,The testube on the left, contains a stopper which has 2 pieces of tubing.
Dialogue: 0,0:00:27.61,0:00:33.69,Default,,0000,0000,0000,,A long piece going into the limewater and a short piece which dosn't reach the limewater.
Dialogue: 0,0:00:33.69,0:00:58.48,Default,,0000,0000,0000,,I'm going to Exhale air from my lungs into the limewater. And it should turn milky, once there is enough Carbon Dioxide...
Dialogue: 0,0:00:58.48,0:01:09.64,Default,,0000,0000,0000,,As you can see, After about 15 secs blowing. The limewater has gone from clear to milky...
Dialogue: 0,0:01:09.64,0:01:12.96,Default,,0000,0000,0000,,Indicating the presence of Carbon Dioxide.
Dialogue: 0,0:01:12.96,0:01:18.30,Default,,0000,0000,0000,,I will now switch the stopper, with the tubing. From the testube on the left, to the one on the right.
Dialogue: 0,0:01:18.30,0:01:23.31,Default,,0000,0000,0000,,This time. Rather than breathing out on the tube going into the limewater. We will inhale air through
Dialogue: 0,0:01:23.31,0:01:33.15,Default,,0000,0000,0000,,the short tubing. The air is being drawn in from the room. And as it contains much less Carbon Dioxide
Dialogue: 0,0:01:33.15,0:01:37.94,Default,,0000,0000,0000,,It will take longer for the Limewater to turn milky.
Dialogue: 0,0:01:37.94,0:01:49.67,Default,,0000,0000,0000,,I will now suck through the short tube...
Dialogue: 0,0:01:49.68,0:01:56.21,Default,,0000,0000,0000,,The amount of air that must pass through the limewater to turn it milky, takes considerately longer than
Dialogue: 0,0:01:56.21,0:02:08.04,Default,,0000,0000,0000,,the one on the left. So, we will keep drawing in air until it turns milky...
Dialogue: 0,0:02:08.04,0:02:12.52,Default,,0000,0000,0000,,As you can see. The limewater in this testube has eventually turned milky. But this is after 7 mins of
Dialogue: 0,0:02:12.52,0:02:19.65,Default,,0000,0000,0000,,drawing in air from the room, into the limewater.This experiment shows that there is far more Carbon
Dialogue: 0,0:02:19.65,0:02:29.52,Default,,0000,0000,0000,,Dioxide in Exhaled air. Than there is in Inhaled air. That's the end of Experiment OB11...
Dialogue: 0,0:02:29.52,0:02:37.59,Default,,0000,0000,0000,,Experiment - OB49. To show that starch is produced by a photosynthesizing leaf.
Dialogue: 0,0:02:37.59,0:02:40.18,Default,,0000,0000,0000,,Safety goggles, again. Must be worn.
Dialogue: 0,0:02:40.18,0:02:49.00,Default,,0000,0000,0000,,In this Experiment, We take a leaf and we will test the presence of startch using the chemical Iodine.
Dialogue: 0,0:02:49.00,0:02:53.58,Default,,0000,0000,0000,,The leaf must first be treated under several stages...
Dialogue: 0,0:02:53.58,0:02:59.62,Default,,0000,0000,0000,,The first stage involves placing the leaf into a beaker of boiling water. For 1 min.
Dialogue: 0,0:02:59.62,0:03:13.55,Default,,0000,0000,0000,,This helps to remove the the waxy qudicle from the leaf. The leaf is then removed from the boiling water
Dialogue: 0,0:03:13.55,0:03:20.43,Default,,0000,0000,0000,,and placed into a testube of alcohol...
Dialogue: 0,0:03:20.43,0:03:24.73,Default,,0000,0000,0000,,The alcohol will disolve the chylorphyl from the leaf, But the alcohol must be first be heated.
Dialogue: 0,0:03:24.73,0:03:38.10,Default,,0000,0000,0000,,As alcohol is extremely flammable. It cannot be heated directly and must be heated in a water bath..
Dialogue: 0,0:03:38.10,0:03:50.12,Default,,0000,0000,0000,,The leaf is left in the alcohol in the water bath. Until all the chlorophyll has been removed...
Dialogue: 0,0:03:50.12,0:03:54.88,Default,,0000,0000,0000,,After aprox. 10 min. The alcohol can be seen to have turn green in colour. This is because the chlorophyll
Dialogue: 0,0:03:54.88,0:04:06.12,Default,,0000,0000,0000,,has disolved from the leaf into the alcohol. We now remove the alcohol from the water bath...
Dialogue: 0,0:04:06.12,0:04:09.13,Default,,0000,0000,0000,,And place it on the testube rack..
Dialogue: 0,0:04:09.13,0:04:15.09,Default,,0000,0000,0000,,Because we no longer need to use the water bath, the Bunsen Burner can be switched off or the Chimney
Dialogue: 0,0:04:15.09,0:04:23.23,Default,,0000,0000,0000,,can be closed, giving an orange flame. Which makes it easier to see and safer to use...
Dialogue: 0,0:04:23.26,0:04:30.39,Default,,0000,0000,0000,,We now pour the alcohol out of the testube and remove the leaf from the testube...
Dialogue: 0,0:04:30.39,0:04:43.35,Default,,0000,0000,0000,,We now remove the leaf from the testube, and place it into warm water to soften it.
Dialogue: 0,0:04:43.35,0:04:47.88,Default,,0000,0000,0000,,5-10 secs is long enough...
Dialogue: 0,0:04:47.88,0:05:09.07,Default,,0000,0000,0000,,The leaf is then spread on a white tile... And tested with the chemical Iodine...
Dialogue: 0,0:05:09.07,0:05:11.79,Default,,0000,0000,0000,,This is the end of Experiment OB49...
Dialogue: 0,0:05:11.79,0:05:18.71,Default,,0000,0000,0000,,Experiment - OB58. to investigate the conditions necessary for germination.
Dialogue: 0,0:05:18.71,0:05:22.75,Default,,0000,0000,0000,,There are 3 factors, which must be present for seeds to germinate...
Dialogue: 0,0:05:22.75,0:05:27.98,Default,,0000,0000,0000,,They are: Water, Oxygen and a suitable temperature.
Dialogue: 0,0:05:27.98,0:05:36.15,Default,,0000,0000,0000,,Here we set up 4 testubes. The testube here, the seeds are placed on moist cotten wool, in an open testube
Dialogue: 0,0:05:36.20,0:05:41.90,Default,,0000,0000,0000,,In a warm atmosphere. This is known as our control.
Dialogue: 0,0:05:41.90,0:05:48.26,Default,,0000,0000,0000,,These seeds are in similar conditions, i.e: moist cotten wool with the presence of oxygen.
Dialogue: 0,0:05:48.26,0:05:53.65,Default,,0000,0000,0000,,But this will be place in a fridge at 4 oC.
Dialogue: 0,0:05:53.65,0:05:57.62,Default,,0000,0000,0000,,The seeds in this testube are placed in water that has been boiled and then cooled, which removes the
Dialogue: 0,0:05:57.62,0:06:03.54,Default,,0000,0000,0000,,oxygen present in water. And a layer of oil is placed on top to prevent any further oxygen entering the
Dialogue: 0,0:06:03.54,0:06:09.98,Default,,0000,0000,0000,,water...
Dialogue: 0,0:06:09.98,0:06:17.58,Default,,0000,0000,0000,,The seeds in the last testube are placed on dry cotten wool, in a warm enviroment, in an open testube...
Dialogue: 0,0:06:17.58,0:06:26.34,Default,,0000,0000,0000,,The testubes are going to be left like this for one week and we will return to them to see the results..
Dialogue: 0,0:06:26.34,0:06:32.98,Default,,0000,0000,0000,,One week has passed... And we return to look at the seeds in the testubes...
Dialogue: 0,0:06:32.98,0:06:41.14,Default,,0000,0000,0000,,The seeds int his testube have germinated, this is because they had the 3 conditions needed: Water, Oxygen
Dialogue: 0,0:06:41.14,0:06:46.17,Default,,0000,0000,0000,,& a suitable temperature...
Dialogue: 0,0:06:46.17,0:06:53.91,Default,,0000,0000,0000,,The seeds in this testube did not germinate because the have been placed in a fridge at 4 oC...
Dialogue: 0,0:06:53.91,0:07:00.51,Default,,0000,0000,0000,,Similarly. These seeds did not germinate, because they were in water that was boiled and cooled.
Dialogue: 0,0:07:00.51,0:07:05.44,Default,,0000,0000,0000,,Hense they were not exposed to any oxygen.
Dialogue: 0,0:07:05.44,0:07:12.42,Default,,0000,0000,0000,,And these seeds have not germinated because they were placed in dry cotten wool...
Dialogue: 0,0:07:12.42,0:07:16.95,Default,,0000,0000,0000,,That is the end of experiment OB58...
Dialogue: 0,0:07:16.95,0:07:24.14,Default,,0000,0000,0000,,Experiment - OB65. To investigate the presence of micro-organisms in air & in soil...
Dialogue: 0,0:07:24.14,0:07:29.07,Default,,0000,0000,0000,,For this experiment, we used 3 petri dishes...
Dialogue: 0,0:07:29.07,0:07:35.30,Default,,0000,0000,0000,,The first petri dish is our control. SO it remains sealed through out the experiment.
Dialogue: 0,0:07:35.30,0:07:44.84,Default,,0000,0000,0000,,The second petri dish is going to be exposed to air. SO we remove the lid for aprox. 5 min...
Dialogue: 0,0:07:44.84,0:07:53.04,Default,,0000,0000,0000,,The thrid dish we sprinkle a small amount of soil on the edgar inside the dish...
Dialogue: 0,0:07:53.04,0:07:57.96,Default,,0000,0000,0000,,And put the lid back on as quickly as possible...
Dialogue: 0,0:07:57.96,0:08:05.36,Default,,0000,0000,0000,,The 3 Petri dishes are now placed upside down in an incubator at 25 oC for aprox. 1 week...
Dialogue: 0,0:08:05.36,0:08:14.63,Default,,0000,0000,0000,,1 week has passed. And we have removed the petri dishes from the incubator at 25 oC...
Dialogue: 0,0:08:14.63,0:08:20.50,Default,,0000,0000,0000,,The first petri dish, which is our control, shows no growths or micro-organisms
Dialogue: 0,0:08:20.50,0:08:25.16,Default,,0000,0000,0000,,Which means the dish itself was sterilized...
Dialogue: 0,0:08:25.16,0:08:33.93,Default,,0000,0000,0000,,The second dish had been exposed to air for aprox. 5 min. It contains "a fluffy" or "moldy" growths.
Dialogue: 0,0:08:33.93,0:08:44.14,Default,,0000,0000,0000,,This indicates the presence of fungi. The third dish which is exposed to small amount of soil shows
Dialogue: 0,0:08:44.14,0:08:48.90,Default,,0000,0000,0000,,smooth, round growths. Which indicate the presence of bacteria.
Dialogue: 0,0:08:48.90,0:08:56.71,Default,,0000,0000,0000,,And some "moldy" or "fluffy" growths, which indicate the presence of fungi...
Dialogue: 0,0:08:56.71,9:59:59.99,Default,,0000,0000,0000,,That is the end of experiment OB65...