report2 daphnia

Download report2 daphnia

Post on 02-Apr-2015




3 download

Embed Size (px)


INTERNATIONAL EDUCATION CENTRE (INTEC) UiTM Section 17 Campus 40200 Shah Alam Selangor Darul Ehsan. TEL: 603-55227000








Human have consumed caffeine since Stone Age. Early people found that eating seed, bark, and leaves of certain plants had increase their awareness, decrease their fatigue and stimulate their mood. So what is actually caffeine ? Caffeine is a white crystalline xanthine alkaloid, a phsychoactive stimulant drug. It is discovered by a German chemist, Friedrich Ferdinand Runge in 1819. Caffeine can be found in beans, leaves and fruit of some plants where it acts as natural pesticide that paralyse and kill certain insects feeding on the plants. Caffeine is also consumed by human in infusions extracted from bean of coffee plants and leaves of tea bush. In humans, caffeine is said to give a big impact on human central nervous system(CNS). It is said can ward off drowsiness, restore alertness, and has diuretic( a substance that cause increase in flow of urine) properties. But studies did not show that caffeine can cause dehydration because most regular caffeine consumers had developed a very strong tolerance in it. Basically, the normal function of caffeine is it act as natural pesticide and inhibit seed germination of nearby coffee seedlings, giving it a better chance of survival. The common source of caffeine is tea, coffee and chocolate derived from cocoa bean. Caffeine content in coffee varies depending on type of coffee bean and method used to derive the caffeine. But in general, in 30ml of espresso, there are 40mg of caffeine, in 120ml of drip coffee, there are 100mg of caffeine. Factually, dark-roast coffee has less caffeine than the lighter roast because roasting process reduce the beans caffeine content.Is it true tea has more caffeine than coffee? Well, although tea contains more caffeine than coffee (by dry weight), a typical serving contains is less, as tea is normally brewed much weaker. Besides strength of the brew, growing conditions, processing techniques and other variables also affect caffeine content. Certain types of tea may contain somewhat more caffeine than other teas. Tea3|


contains small amounts of theobromine and slightly higher levels of theophylline than coffee. Recently, many manufacturers begun putting caffeine in their products especially the shower products like shampoo and soap. Studies show that caffeine in shampoo applied for two minutes is absorbed through the skin and reaches blood stream. They claimed it can improve mental alertness. Caffeine is being used pharmacologically in order to treat apnea in premature newborns. In 1819, Ferdinand isolated relatively pure caffeine for the first time..

The nitrogen atoms which are planar( sp2 orbital hybridization) in caffeine resulting caffeines molecule having aromatic character. Moving to effect of caffeine on humans body. As a CNS and metabolic stimulant, it helps to reduce fatigue and restore mental alertness. It also helps in correcting irregular heart beats, make it faster and clearer flow of thought, increase our focus, improve body coordination and act as competitive inhibitor to adenosine, a neurotransmitter. Caffeine from coffee is absorbed by stomach and small intestine within 45 minutes and then distributed to all body tissues. If we take caffeine in moderation, it take less than hour for caffeine to begin affecting the body and it will be ergogenic (increase a persons ability for mental and physical labour) to us. A study carried out show that trained runners showed 44% increase race-pace endurance as well as a 51% increase in cycling endurance, after a dosage of 9 milligrams of caffeine


Diagram 1 1 s

ws the caffeine

per kilogram of body weight. Caffeine will also increase the effectiveness of drug. For an example, it makes pain reliever 40% more effective in relieving headache if being taken with caffeine. Nowadays, more and more headache drugs include caffeine in their formulae. But, theres still bad effect if we take it excessively. This can lead to caffeinism. Caffenism together with caffeine dependency can cause nervousness, anxiety, irritability, muscle twitching, insomnia, headaches, heart palpitation and peptic ulcers. In heart, caffeine bind to receptors on surface of heart muscle cells, which leads to an increase in the level of cAMP ( cyclicAMP- function to increase activity of funny current which directly increase the heart rate) inside the cells by blocking the enzyme that degrades cAMP and mimicking the effects of epinephrine (which binds to receptors on the cell that activate cAMP production). cAMP acts as a "second messenger," and activates a large number of protein kinase A (PKA~cAMP-dependent protein kinase). This has the overall effect of increasing the rate of glycolysis and increases the amount of ATP available for muscle contraction and relaxation. According to one study, caffeine in the form of coffee helps to reduce the risk of heart disease. However, the protective effect was found only in participants who were not severely hypertensive ( patients that are not suffering from a very high blood pressure). Research suggests that drinking caffeinated coffee can cause a temporary increase in the stiffening of arterial walls. In order to determine effect of caffeine in human life, we have to take a substitute of human being. Daphnia has been chosen because it have sort of heart that we can see in magnification due to its transparent body. Daphnia or commonly known as water flea is a small, planktonic crustaceans. It is 0.2~0.5mm in length which can been seen by naked eyes. It live in various aquatic environment from acidic swamps to freshwater lakes, ponds, streams and rivers.


Diagram 1.2 shows daphnia and where the heart locate. In many Daphnia species, the skin is translucent. Therefore, it is an excellent subject as one can observe the beating heart on top of the back, just behind the head. Average heart rate for Daphnia is 180 beats per minute(BPM). Daphnia is prone to alcohol intoxication, and therefore making it a good subject to study the effect of depressant on nervous system. Not only alcohol, Daphnia can also become an indicator to study the effect of caffeine, nicotine and adrenaline on heart beat. Daphnia is belong to clodoceran family Daphiniidae. It reproduce parthenogetically usually in spring until end of summer. The newly hatched Daphnia must moult several times before they are fully grown into an adult usually after about two weeks. The young are small copies of the adult; there are no true nymphal or instar stages. A fully mature female able to produce young about every 10 days under normal condition. The Daphnias lifespan are not more than 1 year. Usually 108 days at 30C while 29 days at 280C. They eat tiny crustaceans but usually ingest unicellular algae, protists, bacteria, and yeast(normally in lab). The beating of legs produces a constant current through the skin which bring the material into digestive tract.


The trapped food particles are formed into food bolus. The food bolus moves down the digestive tract until is emptied through the anus. Basically, Daphnia is being used to test the effect of toxins on ecosystem also known as indicator species. This is due to their short lifespan and reproductive capabilities. In order to count the heart beat of Daphnia, we need to use a microscope ; either compound microscope with low power objective or dissecting microscope. A depression slide is used instead of plain slide. This is due to the depression slide have polished, concave depression at the centre of slide where it can hold large drop of water.

Light source, a light or a mirror (7) Diaphragm and condenser lens (8) Objective (3)

Ocular lens (eyepiece) (1) Objective turret (to hold multiple objective lenses) (2) Stage (to hold the sample) (9) Focus wheel to move the stage (4 - coarse adjustment, 5 - fine adjustment) RATIONALE OF REPORT


Nowadays, due to the fast developing world, people tend not to care about the food or the beverages the take each day. As long as it tastes nice then everyone would prefer to have it. Did you ever know that the drink that we often have during our breakfast is an

Diagram 1 3 shows microscope


insecticide? Sounds horrible right? Yeah, caffeine acts as natural insecticide to the plants it comes from. It can paralyse or even kill the insects feeding on its leaves, barks, fruits etc. Cocoa in South Africa, and tea in Asia have all been used for hundred years to produce drinks containing caffeine. Even these days, caffeine is also used as flavour enhancer in soft drinks. In humans, caffeine acts as a stimulant drug, causing increased amounts of stimulatory neurotransmitters to be released. At high levels of consumption caffeine has been linked to restlessness, insomnia, and anxiety, causing raised blood pressure. This can lead to heart and circulation problems. That is why it is important for us to carry out this experiment. To see by ourselves how the heart beat increase when the Daphnia is put into caffeine of 0.5% concentration. From this experiment, we can analyse the data and use it to compare with human being, But we have to be careful because Daphnia is different from human. Things happen to Daphnia might not be the same as taken place in human being. OBJECTIVES Basically, our experiment is done to investigate the effect of caffeine on heart rate of Daphnia. This experiment also is done to find the average heart beat