BINNS ET AL. (2001) WORKING FOR WATER PROGRAMME IN SOUTH AFRICA

This is a review of the paper written by Binns [1], water shortage, deforestation and development. The growing and increase of alien plants species in South Africa as a whole causes a serious threat to water supply. Aquatic plants, Herbs, Veins, Shrubs and Trees are the most invasive alien plant species that consume more water than the original plant species. Most of the alien plant species mentioned above are spread in seeds by means of birds and flooding. Aquatic (Eurasian milfoil) grow by forming floating mats of vegetation on the surface of water and it is spread by means of seeds [2]. These species causes a threat to biodiversity, to water security and ecological functioning of natural system.

Working for water (WFW) programme is in partner with organisations such as Councillor for scientific and industrial research (CSIR), Department of water affairs (DWAF) and Department of environmental and tourism (DEAT). This programme was first introduced into SA by the South African government (DEAT) in 1995. The main aim of this programme was to recover scarce water, to conserve biological diversity and to create jobs to disadvantages community. More than 42, 000 people are employed for this programme with and without skills. [3]

Policies and legislation support the WFW. The National Water Act (36 of 1998) supports the WFW. This Act states that “No person may unlawfully and intentionally or negligently commit any act or omission which detrimentally affects or is likely to affect resources” and therefore failure to comply with the Act lawful actions will be taken. The National Environment Management Act (107 of 1998) also supports the WFW programme in terms of pollution. This Act require “the prevent pollution, ecological degradation, secure ecologically sustainable development, use of natural resources while promoting justifiable economic and social development” [4]

In conclusion: Invasive alien species causes water supply problem to the country as whole and the shortage of water in South Africa also causes by unreliable rainfall. The WFW (working for water) programme must continue to remove the alien plants species and alien plants species must be stopped into South Africa.


References:

1. Binns J.A, Illgner and Nel E.L. Water shortage, Deforestration and development: South Africa’s working for water programme, [Internet]. Available from:
http://planet.uwc.ac.za/nisl/invasives/Assignment1/Binns.pdf
2. Remaley T. Great Smoky Mountains national park. [Internet]. Available from:
http://www.nps.gov/plants/alien/fact/mysp1.htm
3. Lois S. Working for Water: Removing Alien Plants in South Africa. [Internet]. Available from: http://www.idrc.ca/en/ev-5156-201-1-DO_TOPIC.html
4. Constitution of South Africa. White paper on a national water policy for South Africa. [Internet]. Available form:
http://www.dwaf.gov.za/Documents/Policies/nwpwp.pdf

Salvinia molesta

Salvinia molesta is a scientific name for Kariba weed. Salvinia molesta was originally from Brazil and it is well known as a free-floating water fern. This species was found in the Zambezi River in Africa in about 59 years ago. Salvinia molesta has also invaded other countries around the world.

Department of the environment in Australia describes Salvinia molesta as a free-floating rapid-growing, mat-forming, annual fern; individual plants up to 30 cm long with numerous leaves. At the early stage the species leaves lie flat on the surface of the water and at the late stage the leaves bend at the edges, this features distinguishe S. molesta from S.minima. Salvinia molesta can grow rapidly (double within one week) to cover the entire water surface with a thick mat of vegetation. Salvinia molesta causes a great impact in aquatic environment and local economics. It affects the aquatic environment by preventing atmospheric oxygen from entering the water by doing this, it makes the water unfavourable for aquatic animals and it also reduces biodiversity of wetlands. It also dangerous to people since it “provide an ideal breeding environment for disease-carrying mosquitoes” [1]. In Senegal River, Salvinia molesta cause a threat to the biodervisity of the ecosystem conserved by Djoudj National Park.

Salvinia molesta spread quickly in a favourable condition and in size can double almost every two days. It spreads it selves during flooding and by human activities into new catchments. This species can leave under frozen temperature and on the water temperature up to 43°C. It can also survive under a dry condition.

The Australian Government, Department of the Environment and heritage suggested the better method for preventing the spread of Salvinia molesta since is a threat to the biodiversity, the public must be educated not to spread invasive species deliberately and “monitoring should be undertaken in catchments at risk from salvinia invasion” after floods [2].


References:

Unknown. Salvinia molesta, Weeds of National Significance: Weed management guide. Department of the Environment and Heritage and the CRC for Austrialian Weed Management, 2003. [Internet] Available from: http://www.deh.gov.au/biodiversity/invasive/publications/s-molesta.html
Cronk Q.C and Fuller J.L (1995). Plant invaders. Champman and Hall. [Internet]. Available from
http://www.hear.org/pier/species/salvinia_molesta.htm

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CROP CIRCLE

Crop circle, this phenomenon brings the picture of THE MOVIE SIGNS, featured Mel Gibson. The real researchers of crop circle disagreed with THE MOVIE SIGNS, but it renewed interest in this theory to other people. Even today crop circle theory is still difficult for one to understand whether is a natural made or mankind made and for sure is normal for different people to see things in different way.

Crop circle mostly occur in UK, USA (corn; Barley; Oats and Wheat), Israel (on the grass) and many other countries. Most of the time this patterns are been made during the night. There are some few people who claimed that the saw crop circle being formed during the night in England and others claimed that they shoot crop circle being formed on camera. People who are responsible for crop circle fraud have found that plants can be harmed in man made crop circle. Theory of wind vortex also first suggested that it maybe the cause, but the two crop circle that were equal in size around 1980 suggested that the theory was wrong.

These phenomenon depend on believe that one has, since crop circle shows different shapes that are symbols for different cultures “some religious groups feel that the crops circles have a religious meaning” (1) and others believe that is the way aliens communicating with us.

They are many theories behind crop circle, the theory of wind vortex, a plasma vortex and a crop formation. Theory of wind vortex is not reliable, since it is impossible for a wind vortex (“causes the plants to flatten in a circular pattern”) to create equal sizes on the crop circle. The plasma vortex theory is still not reliable too or easy to understand it or to believe it, since is highly impossible for a “force field to push the crop down in a swirling manner” resulting the crop circle to be in the same sizes (1).

Indeed one can agree with grass formation theory that have been tested in Israel (Pinelandia & Bayville Labs), four samples where taken: first sample “one of the sub-apical nodes contained an expulsion cavity typical of those found only within crop formation in other countries”; sample two no growth lines were found “as would have expected if silicon crystals were thermochemically grown as a pure form”; sample three show that “coating of red granular material on the stems and leaves of plants, termed red hay by collector” and lastly soil sample shows that “thermal studies indicates that the soil melting temperature was in the range of 50 degrees celcius”, meaning it contain a very low melting point hydrocarbon.(2), therefore in conclusion: the solution to the formation of the crop circles is in the grass formation samples.

Reference:

1) Thomas. A., A complete Guide to the Crop Circle Mystery and why it is Not a Hoax. East Sussex: S.B. Publications, 1998. [Internet] Online access: 2006 May 26; 10:53 [cited 2006 May 26]. Available from:
http://www.fortunecity.com/roswell/poltergeist/913/crop.html
2) Lenvengood W.C; Burke J.A, Crop formations & Association Materials, Israel, 1995, Report no. 53. Page 1-2.[Internet] access Online:2006 May 25; 16:40 [cited 06 May 26]: http://planet.uwc.ac.za/nisl/Scientific_methods/Circles/ResearchReport53-2Mar1996-QadimaISR.pdf
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THE REASON WHY SOME AMPHIBIANS AFTER EVOLVING LIMBS BECAME LIMBLESS

Amphibians are under the phylum chordate, subphylum vertebrate and class amphibian. Chordates species are mostly vertebrates (animals with backbones), and most of Chordates species are small marine invertebrate animals. Some of Chordates species have an aquatic gill-breathing juvenile stage and most return to the water to breed, and lay eggs. All amphibians have a post anal tail, which is an extension beyond the anus of the backbone and of the body-wall musculature, containing no internal organs. Backbone or bone segments called vertebrae develop around the notochord. In fishes, “fossil amphibians and reptiles the notochord persists in the adult and is enclosed by the vertebrae, it disappears during embryonic development” 1.


Snakes constitute the suborder serpents. In most snakes limbs are entirely lacking, but a few have traces of hind limbs. Limblessness in snake is an evolutionary advantage in the dense vegetation that formed the early environment of snakes and they evolved in a marine environment 3. There are a few reptiles which are limbless e.g. worm lizard and glass snake.

Tetrapods have lost the close connection between the skull and the pectoral girdle as they moved onto land and the pelvic girdle became intimately involved with the vertebral column via the sacral vertebrae. In fishes the pelvic girdle is made up of one and basipterygium (paired bone). In amphibians, the basiterygium split into the ilium and ischium and to the pectoral girdle if still attached to the head in a terrestrial animal would send the force of walking directly into the skull which rattles the brain. Amphibians re-evolved from a mostly aquatic existence and did not obtain a strong of girdles. “In fishes and amphibians, limbless has evolved many times because they all move by the use of the limbs while if mammals or archosaur were to lose their limbs, their axial muscular would still be weak and unable to support the animal. Only one group of mammals (whales) have lost both of the limbs. Whales develop a larger, broad tail which is considerably strengthened by their axial muscular. Whales and snakes are animals which have lost limbs and are still able to retain some element of the girdles” 2. Limblessness in most snakes is associated with the adoption of a new lifestyle. An evolutionary change in Hox gene expression as occurs in snakes and as occurs in some limbless mutants is unlikely to have initiated loss of the hind limbs in cetaceans.

Limb loss and limb regeneration in Amphibians mostly courses by white axolotl mutant, called short toes. This mutant affects amphibian’s limbs by not regenerating the same number of bones as the parental limb. Most of extra limbs in frogs caused by parasite known as Ribeiroia and another thing that prevent limb development are UV irradiation. This UV can cause abnormal development and death in early embryos. “Cartilaginous spikes are a normal regenerative response of limb amputation in an older tadpole with a diminished ability to regenerate limbs” 4.

In conclusion: Limblessness in most snakes is associated with the adoption of a new life style. In most amphibians limblessness causes by white axolotl mutants, called short toes that reduces the number of bones. Some parasite (Ribeiroia) also causes limb not developing and UV irradiation also causes abnormal development.


Reference

1) Answers.com. [Internet]. Chordata [access: 2006 May 09, 09:34] cited 10 May
2006: http://www.answers.com/topic/chordata
2) Google. Topic 13 Limbs, page 1-9, [Access: 2006 May 09, 12:45] cited 2006 May
09: http://www.auburn.edu/academic/classes/zy/0301/Topic9/topic9.pdf
3) Caldwell, M.W and Lee, M.S.Y. 1997. A snake with legs from the marine
Cretaceous of the Middle East. [Internet]. [Access: 2006 May 10, 10:55] cited 10
May 2006: http://palaeo-electronica.org/2005_1/polcyn26/summary.htm
4) Don’t Leap to Conclusions the case of the malformed frogs, [internet] Access:
2006 May 10, 13:09 [cited 2006 May 19] http://www.tcet.unt.edu/tegs/chapter2/Case%20of%20the%20Malformed%20Frogs%20BLM.doc


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DISCUSSION OF WHY A HERBIVOROUS DIET IMPOSES CERTAIN PROBLEMS FOR DIGESTION, HOW SOME ANIMALS HAVE OVERCOME SUCH PROBLEMS

Herbivores are divided into ruminants and non-ruminants. Herbivores are animals that feed on plant material. These animals differ in diet that they take due to the environment that they occur in. The specific diet that these animals choose causes problems during digestion, since they feed on cellulose which contains different energy source. (1).

The stomach of ruminant consists of several sections such as the abomasums (the true digestive stomach) that consists of reticulum, rumen and omasum. In energy content, meat is higher than plant material and herbivores need large quantity in order to satisfy its energy requirements. Micro organisms play an important role in the ruminant digestion, “some important vitamins are synthesized by the rumen micro-organisms” (1).

Some herbivores digest food through enzyme digestion. The problem of digestion in herbivores, influence them to maintain bacteria in their stomach for the process of fermentation, “however even this process fail to digest vegetarian meals” (1). Animals with long digestive system reduce the problem of digestion because of the ruminant stomach. “These animals keep food in the ruminant for a time being, later they return to the mouth for chewing and also in the ruminant are many bacteria and protozoa (micro-organisms). Microorganisms are responsible for breaking down of cellulose. Some herbivores resolve this problem of digestion by growing big, because they will have long digestion system that will allows them to digest tough plants” (1).

A non ruminant e.g. “horses eat high fibre diets due to continual microbial fermentation within the caecum and colon” (2). Horse uses micro organisms to digest cellulose which is stored in a cecum and since this animal does not have rumen, the “problem of gut fill with poor quality forages” it does not suffer from it (3). Horse cannot produce enzymes which are responsible to break down fibre; therefore it uses hindgut microbes which sometimes “serve as a reserve of electrolutes and water which are vital to sustain exercise performance” (4).

In conclusion: The digestion diet problem in herbivores causes by the diet they choose during digestion because they feed on cellulose that has different energy source, which is difficult for enzyme digestion to break it down. Animals with long digestive system reduce this kind of a problem because they have ruminant stomach and other herbivores reduce it by growing big because they develop long digestion system. Ruminant’s animals use micro organisms to digest cellulose whereas non ruminant uses hindgut microbes.

Reference:


1) Dr Findlay A.L.R, Physiological Laboratory, 1998, THE GASTROINTESTINAL
SYSTEM: Introduction: Carnivores, Omnivores and Herbivores, [Internet] Online
Access: 2006 May 14, 18:45 [cited 2006 May 15]. Available from:
http://www.chu.cam.ac.uk/~ALRF/giintro.htm
2) Unknown. Pictorial guide to digestion. [Internet] Online Access: 2006 May 13,
17:08 [cited 2006 May 24]. Available from: http://www.effem-equine.com/Waltham%20-%20Horse/pictorial_guides/digestion/slide02.html
3) Unknown. Animal nutrition and digestion. [Internet] online access: 2006 May 13, 17:43 [cited 2006 May 24]. Available from:
http://asci.uvm.edu/course/asci001/digest.html
4) Pat Cassady Equine Specialist NATURAL GLO / ADM Alliance Nutrition. Alliance Nutrition® Equine. [Internet] Online access: 2006 May 24, 09:49 [cited 2006 May 25]. Available from: http://www.admani.com/allianceequine/TechBulletins/Understanding%20the%20equine%20digestive%20system.htm


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THE DIFFERENCES BETWEEN NEW WORLD AND OLD WORLD MONKEYS.

Monkeys are classified in the phylum Chordata, subphylum vertebrata, class mammalian, super families’ cercopithecoidea (old world monkeys) and ceboidea (new world monkeys). Monkeys range in size at 14-16 cm and 120-140 g in weight. Arboreal are monkeys that leave in trees and some monkeys living on the savanna. Various species belonging to cercopithecoidea and ceboidea, their diets differ. New world monkeys have prehensile tails and have trichromatic color vision. Most of new world monkeys are found in tropical forest environments of southern Mexico, central, and South America. These animals eat fruits, nuts and leaves therefore they are categorized as herbivorous. Many species of old world monkeys have ischial callosities on their rumps which caused by sitting or sleeping on rough branches. The sexual skin also produces odors that excite males of the species (1). Most species of old world monkeys are omnivorous. These species can leave up to 50 years long. Cercopithinae is split into two tribes, Cercopithecini and Papioini (2).

Old world monkeys belong to Cercopithecidae (downward-nosed), which is related to apes and humans. When their are born, their face skin start as a cream in color and later to turns black when they reach the age of six months. Their “noses are narrower and have downward-opening nostrils” (3). The prehensile tails is absent. Gestation period occurs between five to nine months. They have only two premolar teeth and adult have 32 teeth. The old world monkeys are more closely related to the apes and human. Other species like Macaques use cheek pouches to stuff food and chewed them. Drills have sitting pads on their rumps; because they spend most of their time on the ground and they can use their fingers to pick tiny parasites out of each others fur. “A large male may reach a body length of 60 cm” (3). Guenons spend their time on the ground, but most of them live in larger groups, travelling and foraging in the forest.

The new world monkeys are the platyrrhines (flat-nosed) and they lack truly thumbs. Most of this species do lack cheek pouches unlike in Drill. All new world monkey species are arboreal and most have long, prehensile tails with which they can control objects and hang from branches. They have separated nostrils that tend to point outward, and their gestation period is four to five months. Most of new world species’ adults have 36 teeth. The new world monkeys are belonging to the family cibedae (4).

In conclusion: Most of the new world monkeys have long, prehensile tails with which they use for hang from branches, since they spend most of their time on trees. Their gestation period is short compared to old world monkeys. The gestation period in Cercopithecoidea is five to nine months which is longer than in new world monkeys. In Cercopithecoidea the teeth are 32, nostrils are pointed down-wards and Ceboidea the teeth are 36, nostrils pointed outwords.

References



1) Neil .O.D, 2005. Monkeys [Internet] Online access: 2006 May 13, 08:32 [cited 2006 May 14]. Available from:
http://anthro.palomar.edu/primate/prim_4.htm

2) Wikipidia contributor, Old World Monkeys [Internet].Wikipidia, The Free Encyclopidia; 2006 May 12, 20:43 [cited 2006 May14]. Available from:
http://en.wikipedia.org/wiki/Old_World_monkey
3) "Monkey (animal)," Microsoft® Encarta® Online Encyclopedia [Internet] Online access: 2006 May 12, 18:43 [cited 2006 May 14]. Available from: http://encarta.msn.com/encyclopedia_761569669/Monkey_(animal).html
4) Wikipidia contributor, Monkeys [Internet]. Wikipidia, The Free Encyclopidia; 2006 May 13, 10:22 [cited 2006 May 14]. Available from:
http://www.encyclopedia.com/html/m/monkey.asp

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HOW PLACENTAL MAMMALS HAVE COLONIZED LAND, WATER AND AIR?

They are 4300 species belonging to class placental mammals. Some placental mammals have adapted to life in water, land and air. All placental mammals have developed different body shapes and sizes, which were the other driving forces behind colonizing water, land and air. Mammals use different ways of locomotion when moving from one place to another and they are the only animals that have hair covering their body (3).

Grass land mammals that live in forests are active during the night and stayed together for safety reason. Carnivores such as martens are forest mammals that climbing trees. Rodents colonized in mountains because of their small size “enables them to avoid extreme conditions by hiding away underground”. Larger mammals survive the cold with long fur and a layer of insulating body fat; also they survive desert heat with a number of adaptations such as sweat glands (1).

In water, most aquatic mammal eats animal food, which they catch it in, varies way. Whales usually travel alone or in large groups of about 20. Killer whales live in family groups called matrilines. The largest whales feed on much smaller animals and these “whales strain their food with a screen of fibrous plate called ballen”. Marine placentals mammals settle areas where food is plentiful and water area is low in temperature. Sea otters and other related species such as fur seals have a double coat of fur, which make the skin not to get wet. Whale is the only aquatic mammals that have sparse hair. They use blubber in order to become warm. Seal lions and walruses feed in the open ocean but they only return to land in order to reproduce. “River dolphins have adapted to life in freshwater habitats while majority of aquatic mammals live in the ocean” (2).

Bats are the second species group of mammals after rodents; it said to be the only group of mammals to have evolved powered flight. Many bats live in groups, often roost in colonies for some portion of the year. “The main purposes of group living is to collectively conserve heat” (3). All members of suborder megachiroptera feed on plant material such as fruit and pollen. Megachiropterans are found only in the old world tropics and they orient using their eyes. “These species control their body temperature within a tight range of temperatures and none hibernates” (3).

In conclusion: Since species belonging to class placental have variety of locomotion, they colonised everywhere. Bat evolved wings in order to inhabit sky, marine placental colonized to water which the temperature is low and where food are plenty. Therefore some placental mammals (rodents) colonised to land because of their small size in order to avoid different conditions.


Reference

1) Wikipidia contributor, Mammal [Internet]. Wikipidia, The free Encyclopidia; 2006
May 11, 19:55
[cited 2006 May 11].Available from:
http://encarta.msn.com/encyclopedia_761561349/Mammal.html

2) Wikipidia contributor, Whales [Internet]. Wikipidia, The Free Encyclopidia; 2006 May 11:21
[cited 2006 May 11]. Available from: http://encarta.msn.com/encyclopedia_761565254_2/Whale.html

3) Animal diversity web, [Internet] Online access: [2006 May 10, 22:36] [cited 2006 May 11].
Available from: http://animaldiversity.ummz.umich.edu/site/accounts/information/Chiroptera.html


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COMPARISON OF THE MODES OF REPRODUCTION BETWEEN THE PLACENTAL AND MARSUPIAL MAMMALS

Most of young mammals start their development inside their mothers (placental mammals) and other young mammals (Marsupial mammals) start “in the uterus but leave to enter the marsupium while they still qualify as embryos” (1) . Placental mammals are named because “a placental connects the growing embryo within the uterus to the mother’s circulatory system” (1). The developed embryo in placental mammals is nourished, which allow longer gestation rate. Most of the marsupials offspring are born been covered with hair. In most cases, mammalian species are said to be “either polygynous (one male mates with multiple females) or promiscuous (both males and females have multiple mates in a given reproductive season)” (4). Most mammals “fertilisation of the ovum takes place in the fallopian tubes and the initial cell division occurs as the fertilised egg travels down the fallopian tubes” (3).

Gestation period in marsupials occurs in different ways, in some marsupials occurs twelve days and in other species belonging to class marsupial like African elephant occurs 20 months. “When placental mammals are pregnant the oestrus cycle stops until the whole period of pregnancy is finished”2 and in marsupial oestrus cycle does not stop even if is pregnant. “Placental mammals lick the embryonic membranes off the newborn young and often push them toward the mother’s mammary glands for their first meal of milk”(2). Young placenta mammals are “born developed because of the long gestation period” (1) unlike in marsupial mammals. After young placental and marsupial born, they survive in different ways, “Young placental mammals leave their mother’s nipples between feeding, but newborn marsupials remain firmly fastened to their mother’s nipples by their mouths and cannot be removed” (2).

The developing embryo in marsupial mammals is different when comparing with placental mammals, “The developing embryo in marsupials is separated from the body of its mother by amniotic membrane and the immune system attacks new organisms. The embryo then will be amniotically protected by isolating it from all biological interactions with the parent. In marsupial’s birth occurs very fast” (2).

In conclusion: The major difference between the marsupial and placental mammals is the rate of gestation. The short gestation period in Masrupials is due to the type of yolk type reproduction, which leads the birth to occur early than in the placental mammals. The longer gestation period in placental mammals lead the young placental mammals to be born fully developed whereas in young marsupial mammals, developing embryo is not connected to their mother and they are born very early.

Reference

1) Evolution, [Internet] Online access: 2006 May 11, 08: 35[cited 2006 May 11,
21:03]. Available from:
http://www.pbs.org/wgbh/evolution/library/01/4/pdf/l_014_02.pdf
2) Marsupial Evolution and post flood migration, A creation theory into the origin of
Marsupials, [Internet] Online access: 2006 May 11, 18:39] [cited 2006 May 11,
20:12]. Available from: http://www.nwcreation.net/marsupials.html
3) Ask.com. The Placental Mammals and reproduction. [Internet] Online access: 2006
May 11, 18:50 [cited 2006 May 24]. Available from:
http://www.earthlife.net/mammals/reproduction.html.
4) Animal Diversity Web. [Internet] Class Mammalia. Online Access: 2006 May 11,
19:43 [cited: 2006 May 24]. Available from:
http://animaldiversity.ummz.umich.edu/site/accounts/information/Mammalia.html


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THE ADAPTIONS OF BIRDS THAT HAVE EVOLVED FOR FLIGHT.

Birds are characterized primarily by hollow bones, feathers and forelimbs modified as wings. Birds are among those animals that have backbone (vertebrates) and they maintain body temperatures in the range of 40-44 degrees Celsius. “Birds use feathers for temperature regulation and flight. Food travels through the parts of a bird’s digestive system such as esophagus, crop, proventriculus, gizzard and intestines before it is excreted” (1).

The fossil record, comparative anatomy and embryology indicate that birds have a common ancestry with reptiles and dinosaurs. Many skeletal features of birds, such as light, hollow bones and a furculum, were present in theropod dinosaurs prior to the evolution of birds. “Scientists believe that flight first occurred when the ancestors of birds climbed trees and glided down from branches. Not all are capable of flight, but flightless birds are evolutionarily derived from flying ancestors. Anatomy and physiology of birds is adapted for efficient flight and therefore most birds are morphologically similar. The body parts of all birds reflect the evolution of birds as flying creatures” (3).

Birds had skeletons that weighed proportionately less than those of mammals. “The bird support itself either entirely by its forelimbs or hind limbs” (2). The skeleton of birds shows numerous modifications for the demands of flight, bones are generally light relative to their size and are pneumatic (filled with air spaces but reinforced with internal struts or trabeculae). Large birds such as albatrosses, vultures and hawks have pneumatic while loon (divers) and passerines (small birds) do not have pneumatic bones. “Flights of the birds are supported by forelimbs e.g. the bone that supports the secondaries (ulna) is enlarged. Hind limbs, proximal tarsal are fused with the tibia to form the tibiotarsus while distal tarsal are fused with metatarsals to form the tarsometatarsus. The calvicles and scapulae provide support needed to withstand forces generated by flight muscles during flight” (4).

The muscles of birds have been modified by natural selection to meet the demands of flight. “Jaw muscles are reduced such as powerful muscles are often unnecessary because food is swallowed in large pieces. Hind limb muscles are reduced in birds because the rigid skeleton (pelvic girdle) provides much support. Flight muscles are very large and located near the center of gravity for an example pectoralis muscle-originates on the keel and inserts on the underside of the humerus; and supracoracideus-originates on the keel and inserts on the upper side of the humerus. Muscles and viscera centralized to keep most of a birds mass near centre of gravity” (4)

Birds are distinguished primarily by feathers. “In birds, feathers are responsible for two very important features for example warm-bloodedness and flight. A bird’s tail consists of a tailbone, a set of flight feathers, and a layer of covering feather at the base of the tail. Tail feathers are arranged in overlapping pairs, the outer and central pairs of tail feathers. The outer pair of tail feathers, each succeeding pair of tail feathers overlaps on top of the other. During the flight they open and close. The central pair of tail feathers lay on top. Bird’s tail also provides support and balance” (5).

In conclusion: The body parts of all birds reflect the evolution of birds as flying creatures. The skeleton of birds weighs less than those of mammals and it shows numerous modification of flight. Feathers in birds are responsible for flight and warm-bloodedness and the flight of all birds are supported by forelimbs such as ulna, therefore flight muscles are centralized to keep their mass near centre of gravity on air.

References

1) The evolution of flight, [Internet] [Online access: 2006 May 09, 18:32]. Available
from: http://animals.about.com/od/birdsastudyguide/a/introtobirds.htm
2) Adaptations for flight, [Internet] [Online access: 2006 May 09, 20:04]. Available
from: http://www.stanford.edu/group/stanfordbirds/text/essays/Adaptations.html
3) Wikipidia, Birds [Internet]. Wikipedia, the free Encyclopedia; 2006 May 10, 19:39.
Available from: http://encarta.msn.com/encyclopedia_761552516_2/Bird.html
4) BIO 554/754, Introduction to Birds, [Internet] [Online access: 2006 May 10,
20:18]. Available from: http://people.eku.edu/ritchisong/554notes1.html#warmfluffy
5) Nature Photographers, Bird Tail, [Internet] [Online access: 2006 May 10, 19:55]
http://www.naturephotographers.net/articles1002/kac1002-1.html

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DINOSAURS WERE WARM-BLOODED ANIMALS

Warm-blooded animals have to eat large amounts of food in order to provide energy and produce heat and are capable of being active for long periods of time-this is because a lot of energy is produced by all the food they eat as well as heat. They need to drink a lot of water; this is because they loose water when they sweat to keep their body cool; and they make a lot of heat by muscle construction and also produce heat constantly. The constant temperatures achieved by warm-blooded creature so that their enzymes can work at maximum efficiency and it will be safe for them to develop more complex functions as the environment is relatively steady.

Cold-blooded animals do not need to eat generate heat and so can eat a lot less and they can only cope with short amounts of activity. These animals do not need cooling mechanisms as they are not as active as warm-blooded creatures and cool themselves down by moving into the shade. “Their enzymes have to cope with extreme conditions and therefore find it harder to develop”. 2

Dinosaurs are animals that dominated the terrestrial ecosystem for over 100 million years. Non-avian dinosaurs are the only group that became extinct in 65 million years ago. There were different types of Dinosaurs, some were herbivorous, and others bipedal. The closest relative’s dinosaurs that are living today are crocodile and bird, the behaviour are the same. There are two major orders of dinosaurs namely Saurischia and the Ornithischia. Saurichians are “dinosaurs like theropods and sauropods, which retained the hip structure of their ancestors. Ornithischians, most of them were quadrupedal herbivores”.3

Some of the dinosaurs were exothermic. Skeletal structures suggest active life styles for theropods and other creatures, behaviour more suitable for an endothermic cardiovascular system. Sauropods exhibit fewer endothermic characters. Bone is made up of calcium phosphate mineral deposited on collagen, a protein formed in fibres. In slow growing animals (have lamellar bone), the collagen fibres are laid down parallel in each layer, producing bone that has a dense packing of mineral crystals all oriented in the same direction. In rapidly growing animals, the collagen is laid down in a haphazard way to form an irregular or woven bone. Fibro-lamellar is typical of mammals and birds that are warm-blooded. Lines Arrested Growth (LAGs), these are formed when there is a temporary halt to bone deposition and mostly occur in mammalian jaws. In many dinosaurs such as Massospondylus, hypacrosaurus and Maiasaura, LAG where found. In dinosaurs LAG occur more often in fastgrowing fibrolamellar bone. “Tyrannosaurus bone suggests that its body temperature was maintained within 4 degrees Celsius, which is with a relatively metabolic rate similar to known warm-blooded animals” 1.

In conclusion: the large top predators in any system generally obtain most of their food intake from herbivores and for worm-blooded predators, a larger quantity of food is required, so that the larger the predator and the higher its metabolic rate. There are few method (isotope and microscopic structure of the bone) used to prove that dinosaurs where warm-blooded animals. Isotope of dinosaurs bone shows that they are warm-blooded, since worm-blooded animals grow quickly than cold blooded and in the microscopic structure of the bones, shows that “the bone were rich in Halversian canals (a canal that transport nutrient-laden blood to the cells that lay down new bone therefore, the fast growing bones of worm-blooded mammals and Dinosaurs contain Halversian canals.

Reference

1) Bone structure and histology, [Internet] Online access: 2006 May 09, 20:46 [cited
2006 May 10]. Available from: http://www.dinoruss.com/de_4/5c51dbb.htm.
2) Were Dinosaurs warm-blooded, [Internet] Online access: 2006 May 09, 19:28
[cited 2006 May 09]: http://www.dinoruss.com/de_4/5c51d90.htm
3) Wikipidia contributor, Dinosaurs [Internet]. Wikipidia, the Free Encyclopidia;
2006 May 09, 19:57] [cited 2006 May 10]
http://encyclopedia.thefreedictionary.com/Dinosauria

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MORPHOLOGICAL DIFFERENCES BETWEEN CARTILAGINOUS AND BONY FISH.

There are two groups of extent vertebrate e.g. hagfishes and jawed vertebrates. The class chondrichthyans (cartilaginous fish) includes species such as sharks, skates, rays and chimaeras; and class osteichthyans (bony fish) which is devided into actinopterygians and sarcopterygians. Cartilaginous fishes are ancestral to other jawed vertebrate. Only two scientists (Rasmussen and amazons) suggested “there is a great possibility that bony fish are ancestral to cartilaginous fishes” (society for molecular biology and evolution, 2003).

All the species belonging to chondrichthyes have unique type of hard tissue in the endoskeleton. Chondrichthyes species have morphological features such as teeth plates are not focused to the jaw; they lack swimbladder and separate gill opening, the internal skeleton of chondrichthyes is composed of cartilage, which may be prismatically calcified, a bone like tissue is present at base of placoi scales, second gill arch involved in a jaw suspension, swim bladder are absent and have oil filled liver to provide neutral optimizing, modified pelvic fins is present in males, the intestine have spiral valve, and the teeth are easily replaceable.

Osteichthyes have characterestics such as skeleton is more bony, respiration by gills supported by bony gill arches which is covered by a common opertculum, swimbladder is present, circulation consists of a two chambered heart, have origin teeth, pattern of cranial bones, medial insertion of mandipular muscle in lower jaw, head and pectoral girdles covered with large dermal bones, the scleroitic ring has 4 plates, nostrils are separated, neurocranium are divided into anterior and posterior sections, and fine spines is absent. Most species belonging to this class are oviparous and fertilization is external.

According to cartilaginous and osteichthyes mitochondrial tree, “cartilaginous fishes have a terminal position in the phylogeny of bony fishes(coelacanth, lungfishes, bichirs, teleostfishes and other ray finned fishes) implying that the bony fishes are ancestral to cartilaginous fish” (Kikugawa et al, 2004). The mitochondrial tree shows a basal split between tetra pods and other jawed vertebrates. “Phylogenetic analyses of jawed vertebrates based on mitochondrial sequences often result in confusing inferences which are obviously inconsistent with generally acceptable trees. Cartilaginous fishes based on mitochondrial tree, have a terminal position in a paraphyletic cluster of bony fish. Phylogenetic analyses based on mitochondrial sequence often results in misleading trees distantly related vertebrates are compared. The basal position of cartilaginous fishes is not significantly supported” (Kikugawa et al, 2004). Chimaeras and other cartilaginous fishes form a monophyletic group: “Chimaeras are said to be derived from placoderms independently from other cartilaginous fishes” (Kikugawa et al, 2004).

CONCLUSION
Cartilaginous fishes have been indirect to be basal to other jawed vertebrates. Tetra pods are more closely related to ray-finned fishes than to lungfishes. Chondrichthyans develop microscopic bone platelets which cover the surface of the cartilage to create prismatic calfied cartilage whereas in Osteichthyes the head and pectoral girdles covered with large dermal bones.

Reference

1) Society of biology and evolution, 2003.molecular of early vertebrates: monopholy of the agnathans as revealed by sequences of 35 genes. . http://mbe.oxfordjournals.org/cgi/content/full/20/2/287) [date accessed 07-05-2006] 2) Kikugawa et al, 2004.basal jawed vertebrate phylogeny inferred from multiple DNA-coded genes. (http://mbe.oxfordjournals.org/cgi/content/full/20/2/287) [date accessed 07-05-2006].

Ramapulana Nkoana
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LIFE THAT HAS EVOLVED THE DIVERSTITY OF THE FLYING INSECT

Insect are under the class Insecta, and are invertebrate animals. Scientific classifications of insect are Kingdom: Animalia, Phylum: Arthropoda, Subphylum: Hexapoda and Class: Insecta. Insects comprise the most diverse group of animals on the earth. An insect may be found in nearly all environments on the planet. “They have evolved into an estimated five million living species and are also ecological essential in forests, river and ocean. Other insects that depend entirely on a single species of plant for food, and if that plant disappears, they may disappear as well” (1). The only other terrestrial organisms are a few other arthropods, such as millipede-like arthropleuridans and scorpion-like archnids. Another measure of diversity is the variety of structures and behaviors that adapt insects to environmental challenges.

The evolution of insects was first the development of body plan e.g. the head, thorax and abdomen in the period of Devonian. Some scientists suggested that, “for an insect in order to fly there must have a pair of eyes with good eye sight and most identifying features of insects were the compound eye. Insects developed wings which were primitive. Insects were the first group of animal to have a flying power and some of them winged when their larvae is still living in the water. Insects are the only species which have no fossil evidence of how their wings evolved. Their wings developed from the sideways of the thorax” (3). They evolved by first started living in the water and they exposed to land when became an adult by climbing the plants.

“In terms of biomass and their interactions with other terrestrial organisms, insects are the most important group of terrestrial animals. No other group of organism affects agriculture and forestry as much as insects do e.g. the boll weevil (Anthonomus grandis), Colorado potato beetle (Leptinotarsa decemlineata), and Mediterranean fruit fly (Ceratitis capitata). Locust (schistocerca) form swarms of biblical proportions and their swarms cover entire landscapes and Bark beetles (Scolytidae) and gypsy moths (Lymantria) can destroy entire forests. On savannas of eastern Africa, insects like orthopterans, beetles, caterpillars, and termites consume more cellulose than mammalian herbivores combined” (2).

Some insects developed wings that they could easily escape from predators and travel large distances without any danger in the form of other animals in the air. The more primitive insects are wingless, thus this suggest that flying was a natural selective advantage at the time. The wide range of insect species are small in size, they can occupy small areas and require a small amount of food in order for them to survive. Smaller organisms produce offspring faster and variation in the genome of the species increased as a whole. “Insects continued to evolve the developed by other arthropods and their ancestors, and were capable of interpreting auditory, visual and chemical stimuli. Both insects and plants co-evolved with one another and they used one another in a variety of ways e.g. Butterflies undergo a process called metamorphosis, adult hatch eggs within plants to camouflage them against potential damage and the predators who may eat the eggs. In other cases insects are herbivores, they eat plants as a means of nutrition and in reverse instances, plants like the Venus Fly Trap engulf insects within their defensive mechanisms and kill them. Insects pollinate plants, providing a way for plants to create offspring and successfully pass their genome through the generations” (2).

In conclusion: Insects started living in water before evolving the wings for flight in the period of Devonian. Insects and plants are using one another in a different ways.

References:

1) A pair of wings took evolving insects on a non-stop flight to domination. [Internet] Online Access: 2006 May 08, 10:32, [cited 2006 May 09]
http://www.universityscience.ie/pages/scimat_evolving_insects.php
2) Grimaldi.D. Evolution of the insects. [internet] access: 2006 May 08,11:54 [cited 2006 May 08]
http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=0521821495&ss=exc
3) Brisbane. INSECTS EVOLUTION. [Internet] Access Online: 2006 May 15, 09:12. [cited 2006 May 17]. Available from:
http://www.geocities.com/pchew_brisbane/Evolution.htm

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THE SIGNALS USED BY INSECTS TO ATTRACT A MATE FOR SEXUAL REPRODUCTION.

Insects are animals of a class belonging to the arthropod phylum and they make up the largest class in the animal world. “Some small parasitic insects are less than 0.25 mm in length when fully grown; whereas at least one fossil species related to the modern dragonflies is known to have had a wingspan of more than 60 cm” (1). Insects are also the most highly developed class of invertebrate animals, with the exception of some molluscs. “Insects such as the bees, ants, and termites have elaborate social structures in which the various forms of activity necessary for the feeding, shelter, and reproduction of the colony are divided among individuals especially adapted for the various activities. Most insects achieve maturity by metamorphosis rather than by direct growth” (1).



They are three ways in which insects attracts their mate namely: visual, auditory, or chemical means. Butterflies attract members of the opposite sex by visual means while crickets, grasshoppers, and related insects use sound. “Chemical means: in many insect species the females release small quantities of powerful chemical substances called pheromones that attract the males. The chemical is used to lure thousands of males of that species into contact with an insecticide” (1). The Red Mason Bee (Osmia rufa) emerges from their cocoons during spring time and the males are the first ones to come out. “They mate with females (Lignaria) only once or twice”, and then they feed for several days while their ovaries develop (2). “Some of the insect uses chemical signals (Pheromones) substances secreted by one organism that affect another and others use sound to attract mates e.g. crickets and cicadas” (3).


The various species of insects exhibit extreme variety in their modes of reproduction. The honey bee, the reproductive female, or queen, produces thousands of fertilized eggs over a period of several years, although the male, or drone, dies shortly after mating. In other species, such as the mayflies, both male and female insects have only a short span of life after mating. Beetle species, both males and females mate repeatedly. Various species of insects reproduce parthenogenetically, developing from unfertilized eggs. This form of reproduction occurs regularly in certain species, and occasionally or in alternate generations in others. In gall wasps and sawflies, all reproduction is apparently by parthenogenesis, and no sexual reproduction is known. In the social bees and other related insects, male insects are produced from unfertilized eggs. Certain flies occasionally reproduce by means of paedogenesis: the production of eggs by immature forms, either larvae or pupae. The larvae of some midges produce several generations of larval females before producing male and female larvae that develop into adult insects and reproduce sexually.

Mating in spiders is complicated compared to other insect. “Males may use draglines to detect and recognize mates, or they may signal their approach by plucking on the females web. In spiders with well-developed eyes, complex mating has evolved that are associated with bright colour patterns” (3). Other insects like cicadas, crickets and grasshoppers use sound to attract female insects for mating. “Sound in grasshoppers is produced by sawing the notched edge of their hindlimb against the strengthened vein of wing and cicada’s uses abdomen which contains two chambers, the inner wall of each chamber is stiff and when it moves in it makes a click. Moths use a third sense, smell to attract mates. Female prosuce chemical compounds called pheromones which male moths are able to detect with their large, feathery antennae” (1).
The fireflies are an insect that produce light for a signal in courtship. The light is produced by light organs located on the underside of the abdomen. “The light producing cells are permeated by nerves and air tubes; oxygen supplied by the air tubes converts the cell product luciferin to oxyluciferin. Then it releases energy in the form of light” (4).


In conclusion: Insects uses different method such as chemical means, auditory and visual in attracting mates. Grasshopper and crickets uses sound for attracting females and butterflies uses visual. Therefore different insect uses different method to attract members of the opposite sex.

References:

1) [Internet]. Online access: 2006 May 09, 08:27. Available from:
http://planet.uwc.ac.za/nisl/biodiversity/Chapter2/page_68.htm
2) Wikipedia contributors: [Internet]: Online access: 2006 May 09, 12:31. Available
From http://en.wikipedia.org/wiki/Mason_Bee
3) [Internet]. Online access: 2006 May 09, 15:35. Available from:
http://uk.encarta.msn.com/encyclopedia_761566464_2/Spider.html#p9
4) [Internet]. Online access: 2006 May 09, 17:12. Available from”
http://www.encyclopedia.com/html/f/firefly.asp


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WATER VASCULAR SYSTEM THAT CHARACTERIZES ANIMALS THAT OCCUR IN THE PHYLUM ECHICODERMATA.

Echinoderms are a group of animals/phylum of marine animals that are found in the ocean at all depths. This phylum is characterised by radial symmetry, several arm and the body actually consists of five equal segments, each containing a duplicate set of various internal organs. They have no heart, brain, and eyes; but some like brittle stars have light sensitive parts on their arms. Their mouth is situated on the underside and their anus on top except feather stars, sea cucumber and urchins. Vascular system supplies water through canals of small muscular tubes to the tube feet (1)


There are five classes of Phylum echinoderms namely: class Asterodea, e.g. Starfish or sea stars which come in variety of colours. It has 5 arms that can be regenerated and the arms are project from the central disk. The mouth is on oral surface (underside). Water vascular system of starfish: network of canals creating hydrostatic pressure to help the starfish move. Water enters through sieve plate or madreporite on aboral surface into a short, straight stone canal. The stone canal connects to a circular canal around the mouth called the ring canal. Five radial canals extend down each arm and are connected to ring canal. Radial canals carry water to hundreds of paired tube feet. Ampulla or bulb-like sacs on the upper end of each tube foot contract and create suction to help move, attach or open bivalves (2)


Class Crinoidea, e.g. Feather star, have a long stalk with branching arms that attach them to rocks and the ocean bottom and can move around. The mouth and anus are on upper surface. The water vascular system performs many important functions in echinoderms, including locomotion, respiration and feeding (6)


Class Ophiuroidea: e.g. Basket star and Brittle star are largest class of echinoderms; have long narrow arms resembling a tangle of snakes and move faster than starfish. They feed by raking in food with arms or trapping it with its tube feet. Water vascular system: have a much smaller central disc and no anus. Wastes are eliminated through the mouth which is situated on the underside centre. On the other side of the body disk there is a splitlike opening at the base of each side of each arm. These ten opening are breathing and reproductive outlets, taking in water for oxygen and sheeding eggs or sperm into the sea (3)


Class Echinoidea: e.g. include sea urchins and sand dollars. The mouth consists of a complex arrangement of muscles and plates surrounding the circular opening. The anus is located on the upper surface and some sea urchins have a spherical, bulb like cloaca (to store fecal material) that protudes from the anal opening (5).

Class Holothuroidea: e.g. Sea cucumber has a shape of a cucumber with an elongated, muscular, flexible body with a mouth at one end and the anus at the other. Around the mouth there is a number of tentacle (modified tube feet) used in collecting (4)


References:

1) [Internet]. Online access: 2006 May 04,14:34 [cited 2006 May 05].Available from: http://www.starfish.ch/reef/echinoderms.html
2) [Internet]. Online access: 2006 May 05, 14:02 [cited 2006 May 05].Available from: http://sps.k12.ar.us/massengale/echinoderm_notes.htm
3) [Internet]. Online access: 2006 May 05, 13:03 [cited 2006 May 05].Available from: http://www.starfish.ch/reef/echinoderms.html#brittle
4) [Internet]. Online access: 2006 May 04,12:03 [cited 2006 May 05].Available from:
http://www.starfish.ch/reef/echinoderms.html#cucumber.
5) [Internet]. Online access: 2006 May 04,15:49 [cited 2006 May 04].Available from:
http://www.starfish.ch/reef/echinoderms.html#urchin
6) [Internet]. Online access: 2006 May 05, 15:08 [cited 2006 May 05].Available from:
http://tolweb.org/Echinodermata

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THE STRUCTURE AND SIGNIFICANCE OF DNA TO LIFE. (ass1)

The DNA (Deoxyribonucleic acid) is the double helix structure; it is like a long ladder, twisted into a spiral. DNA is a long polymer of nucleotides and encodes the sequence of the amino acid residues in proteins using the genetic code of nucleotides. Sugar and phosphate molecules form the sides of the ladder. DNA is a famous molecule of heredity. Each of us begins as tiny ball about size of a period at the end of a sentence. All physical characteristics that we have e.g. height, hair colour, eye colour are spelled out in our DNA and it guides our development into adulthood. There are four bases making up DNA rings, these are adenine, thymine, guanine, and cytosine. These bases act as the ‘letters’ of a genetic alphabet. They combine in various sequences to form words, sentences, and paragraphs. These bases sequences are all the instructions needed to guide the functioning of the cell (2)

The cell is very complicated, using many DNA instructions to control its every function; therefore the DNA code is serving as a genetic language that communicates information to the cell. The amount of information in the DNA of even the single-celled bacterium, E.coli, is infinite. The origin of life is the origin of a code. A code represents a specified complexity since is a very special kind of order. (Leslie Orgel, 1973)


DNA as measuring information: The information content of a structure is the minimum number of instructions needed to specify it. The more complex a structure is, the more instructions needed to specify it. Random structures require very few instructions at all. A highly ordered structure likewise requires few instructions if its order is the result of a constantly repeating structure. The discovery that life in its essence is information cut on DNA has greatly shortened the question of life is origin. The information within the genetic code is likewise entirely independent of the chemical makeup of the DNA molecule. The information transmitted by the sequence of bases has nothing to do with the bases themselves and also there is nothing in the chemicals themselves that originates the communication transmitted to the cell by the DNA molecules.


Significance of DNA to life: Micro-organisms represent a powerful tool for improving human lives. With new applications in the industrial, environmental and biomedical fields, the impact that these organisms will have on society seems to stretch further and further across the humankind horizon (4).

Living things produce more offspring than the finite resources available to them thus living things faces a serious constant struggle for existence. Evolution involves changes in the gene pool. Population are able to maintain a reservoir of variability so that if future condition require it, the gene pool can change (Hardley-Weinberg law) and under this law, genes that have no present selective value will nonetheless be retained. However, evolution depends on mutations because this is the only way that the new genes are created and after being shuffled in various combinations with rest of the gene pool, these provide the raw material on which natural selection can act. Many species such as human, chimpanzee etc. are made up of local populations whose members tend to breed within the group. Each local population can develop a gene pool distinct from that of other local populations. However, members of one population may breed with immigrants from an adjacent population of the same species therefore this can introduce a new gene or alter existing gene frequencies in the residents (3).



References:

1) Leslie Orgel, 1973. The Origins of Life, New York: John Wiley & Sons, p. 190
2) Wikipedia contributors: [internet]. Online access: 2006 May 03, 12:34 [cited 2006
May 04]. Available from: http://www.origins.org/articles/thaxton_dnadesign.html.
3) Wikipedia contributors: [internet]. Online access: 2006 May 03, 14:21 [cited 2006
May 05]. Available from:http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hardy_Weinberg.html
4) Wikipedia contributors: [internet]. Online access: 2006 May 03, 10:13 [cited 2006
May 04]. Available from:
http://www.humboldt.edu/~pls13/LIBARATE/Kurt%20Engleman/k-
significance.htm