Website links for Preliminary Biology

http://sydney.edu.au/science/uniserve_science/school/curric/stage6/biol/ (Covers most points)


http://www.cbd.int/2010/welcome/ (2010 year of Biodiversity)

External Fertilisation Book

Mother Fish: Example of internal fertilisation in fish???

Kangaroo birth

Task 3 (Reproductive System of Australian Fauna)

Include task 3 posting here.

 Reproductive System of a Kangaroo

Reproduction

Female Red Kangaroos can have three babies on the go at once: a young joey hopping around at her feet, a small baby in the pouch and a tiny embryo, Within a few days of giving birth, she mates again. As long as there's another infant in her pouch, she'll keep this one in a state of suspended animation. If stops growing when it's about a quater of a millimetre long and won't start growing again until its siblings leaves the pouch. This is called embryonic diapause. This unique reproductive system helps roos cope with the ups and downs of life in the bush and maintain their numbers through tough times.

By Lydia



Koala’s Reproduction

Female Koalas reach sexual maturity at 2 - 3 years of age. Males reach maturity later at 3 - 4 years. Mating occurs between the months of December and March, which is summertime in the Southern Hemisphere. Female Koalas produce one young joey each year and continue to breed for up to 12 years if they are healthy. A female Koalas gestation period is 35 days. Baby Koalas are very vulnerable at birth and are hairless, blind and have no ears. Baby Koalas are so tiny at birth and only measure around a quarter of an inch long. After birth, the joey will crawl into its mothers pouch located on its mothers belly and attach itself to one of her teats. It will stay in the pouch for around 6 months feeding on the milk from its mothers teat. After this time, the joey will begin to consume its mothers 'pap' which comes from the mothers cecum (beginning of the large intestine). Pap is a specialized form of droppings which is soft and runny. The 'pap' will pass on micro organisms from the mothers digestive system to prepare the joey's gut for the digestion of its future diet of eucalyptus leaves. The joey will remain with its mother for another 6 months, riding on her back and feeding on both milk and eucalyptus leaves until it is fully weaned at 12 months of age. Females usually leave their mothers, however, males will remain with their mother until they are 2 - 3 years old. The life span of a Koala is up to 18 years.

By : Hala & Sharlyene

Task 2 (Internal vs External Fertilisation)

Include task 2 post here. Note: American English spell fertilisation as fertilization.

External Fertilisation

If the female frog is also ready to breed, she will approach the male frog. He will climb onto her back (this embrace is called amplexus) and she will carry him to the egg-laying site. As she releases her eggs, the male frog releases sperm over the eggs. Fertilisation occurs outside of the female's body, usually in pond water.

The fertilised eggs develop and hatch to produce tiny tadpoles, which grow and develop into frogs over a period of months. This change from tadpole to frog is called metamorphosis. The process involves not only the loss of the tail and the growth of legs and arms, but also the replacemnet of the tadpole's internal gills and lungs. Its digestive system also changes, to cope with a diet of insects rather than algae and decaying animal matter. The aquatic tadpole metamorphoses to become a land-dwelling frog. 

Internal Fertilisation

Pollination and Fertilisation in Flowers

The anther holds pollen. The anther swells when the pollen are ripe and splits open, releasing the pollen in response to sunny, dry conditions. The ovary is located at the base of the petals. Stigma is a sticky tip of a stalk-like style. 

 

A long pollen tube grows from the pollen landing on the stigma down the style towards the ovule, which is located in the ovary. The ovule is fertilized by the males nucleus of the pollen after passing down the tube. Once fertilisation occurs, a fruit usually formas after the petals fall. A swollen ovary wall forms flesh of the fruit.

By Lydia

 Internal Fertilisation

 

Mammals and birds have internal fertilisation to allow sperm to have a fluid in which to swim to the egg. They also require fewer sperms and eggs as internal fertilisation increases the probability of sperm and egg meeting for successful fertilisation. The development of internal fertilisation was essential for the evolution of terrestrial species. Terrestrial species have fewer young as they have better survival chances due to parental care. An example of internal fertilisation is a platypus.

External Fertilisation

 

Aquatic animals, such as fish and amphibians which have to return to water to reproduce, have internal fertilisation where sperm and eggs are released in huge numbers into the water.

They must produce much greater numbers of gametes due to less likelihood of fusion of gametes due to tides etc and fewer young survive due to predation before maturity since they do not have parental care.

By Abbas

External fertilisation:

Some flowers with both stamens and a pistil are capable of self-fertilization, which does increase the chance of producing seeds but limits genetic variation. The extreme case of self-fertilization occurs in flowers that always self-fertilize, such as many dandelions. Conversely, many species of plants have ways of preventing self-fertilization. Unisexual male and female flowers on the same plant may not appear or mature at the same time, or pollen from the same plant may be incapable of fertilizing its ovules. The latter flower types, which have chemical barriers to their own pollen, are referred to as self-sterile or self-incompatible. Reproduction is by seed and perennial rootstock.

Internal fertilization:
 

The kangaroo carries out both internal fertilisation and internal development of the young after birth. In good conditions, it can have three offspring at different stages of development. The female may have an older young out of the pouch but still being suckled, a newborn young in the pouch, and an embryo in diapauses in the uterus. At this stage, the mother will be producing two different types of milk simultaneously. The newborn young will get low fat/ high carbohydrate milk from nipples of the mammary glands, while the young outside the pouch will feed from a different nipple (or teat) to get large volumes of high fat/low carbohydrate milk. In times of drought the mother may be unable to produce sufficient milk to sustain a growing young in the pouch. If the young dies, a new young will enter the pouch a month later. Since the newborn young is so small, it only needs a small quantity of milk for the first few weeks in the pouch. This ensures there is always a young ready when the drought ends. This ‘production line approach allows very rapid population growth when conditions are good. However, under prolonged drought conditions, breeding stops and only begins again when rain triggers a hormonal response in the female. This very effective mechanism controls the rate of reproduction depending on the favourability of the environmental conditions at the time.
 
By Hala & Sharlyene

Task 1 (Scientist)

MODERN SCIENTIST


NAME: David James

POB: AUSTRALIA, Sydney

DOB: 1958


CONTRIBUTION: discovered the glucose transporter GLUT4. He has also been responsible for the molecular dissection of the intracellular trafficking pathways that regulate GLUT4 translocation to the cell surface, the topological mapping of the insulin signal transduction pathway, the creation of a method for studying in vivo metabolism in small animals, and the use of this method to gain insights into whole-animal fuel metabolism and homeostasis.

Reference: http://en.wikipedia.org/wiki/David_James_(cell_biologist)

By Kristy and Theresa

Louis Charles Birch (8 February 1918-18 December 2009) was an Australian geneticist specializing in population ecology and was also well known as a theologian, writing widely on the topic of science and religion, winning the Templeton Prize in 1990. The prize recognized his work ascribing intrinsic value to all life.
His early investigations into the insect world led his interest in population ecology. He went to explore the inter-reaction of humanity with the environment, studying genetics at Chicago Universtiy then Oxford. As Challis Professor of Biology at Sydney University, he Helped lay the foundations for the new science of ecology. His search for a philosophy that could embrace both science and God culminated in what he calls "an ecological model of God".


By Lydia

 

Elizabeth Helen Blackburn was born in the 26 November 1948 in Hobart, Tasmania. Blackburn is an Australian-born American biological researcher at the University, who studies the telomere, a structure at the end of chromosomes that protects the chromosome. 

By Abbas

Name : Tim Flannery

POB : Australia

DOB : 28 January 1956

Contribution:


Mammalogist

Through the 1990s, Flannery surveyed the mammals of Melanesia – discovering 16 new species – and took a leading role in conservation efforts in the region.

The specific name of the Greater Monkey-faced Bat (Pteralopex flanneryi), only described in 2005, honours Tim Flannery.

Flannery's work prompted Sir David Attenborough to describe him as being "in the league of the all-time great explorers like Dr. David Livingstone".


Palaeontologist

In 1980, Flannery discovered dinosaur fossils on the southern coast of Victoria and in 1985 had a role in the groundbreaking discovery of Cretaceous mammal fossils in Australia. This latter find extended the Australian mammal fossil record back 80 million years. During the 1980s, Flannery described most of the known Pleistocene megafaunal species in New Guinea as well as the fossil record of the phalangerids, a family of possums.
 
By Hala and Sharlyene