Gondwana

Question 1

identify and describe evidence that supports the assertion that Australia was once part of a landmass called Gondwana including:

Answer 1

Matching continental margins

Positions of mid-ocean ridges

Spreading zones between continental plates

Fossils in common on Gondwanan continents, including Glossopteris and Gangamopteris flora, and marsupials

Similarities between present day organisms on Gondwanan
continents

Question 2

Identify the role of cell division in growth, repair and reproduction in multicellular organisms:

Answer 2

Living things are made up of cells

In multicellular organisms new cells are produced by cell division for growth
repair and reproduction

In unicellular organisms, cell division divides the organisms into 2 new organisms

Question 3

The four main points of Darwin‟s Theory of Evolution by Natural Selection are:

Answer 3

In any population, there are variations

In any generation, there are some individuals that do not reach maturity and
reproduce; the characteristics of these individuals are removed from the
population

The individuals that survive and reproduce are well adapted to the
environment; they have favourable conditions (survival of the fittest)

Favourable conditions are passed on to offspring; they become more and more
common in the population

Question 4

Discuss evidence that suggests that crustal plates move over time:

Answer 4

the age of the sea floor around mid-oceans ridges

the matching edges of continents

fossils of similar organisms found in different parts of the world

Question 5

how was Gondwana formed

Answer 5

All landforms were originally joined together in a giant landmass called Pangaea

In the Jurassic, 160 million years ago, Pangaea split into two super continents:
Gondwana and Laurasia

Gondwana: Australia, Africa, Madagascar, New Zealand, South America, India

Laurasia: Europe, North America, Asia (except India)

Question 6

when did Australia split from Gondwana

Answer 6

60 million years ago

Question 7

geological evidence that Australia was once part of Gondwana:

Answer 7

• The rock strata around continental margins match exactly in many places,
  eg: 1) South Australia & Australia, 2) West Africa & east South America.
• Mid-ocean ridges are formed where plates are moving apart
• When plates move apart, molten rock rises up and forms new sea floor.
• In these areas, called spreading zones, the new rock that forms is older the
  further it is from the ridge
• This proves that the plates have been moving apart steadily for a long time

Question 8

biological evidence that Australia was once part of Gondwana:

Answer 8

The fossil record and present day organisms provide evidence that Australia was part of Gondwana

• Fossil Evidence:

o Glossopteris and Gangamopteris are fossil plants found in rocks of the same age in Australia, Africa, India, South America, Antarctica and New Zealand

o Fossils of marsupials have been found on all the continents that were part of Gondwana

o This is evidence that the continents were once joined

Extant Organisms:

o Nothofagus, or the southern beech trees, are found in forests of Australia, New Guinea, New Zealand and South America

o Many plants and animals exist only where the Nothofagus still live; e.g. a parasitic fungus, a moss and bugs which depend on the moss

o Many groups of animals in Australia have close relatives in South America, Africa, India and New Zealand, but not in Northern Asia, Europe or North America

o These animals include: parrots, ratites (flightless birds) etc

Question 9

Why have megafauna become extinct

Answer 9

• Climate Change:
  Megafauna were mainly suited to glacial conditions. Their large bodies enabled them to live in extreme conditions. In Australia, the temperature changed from cold-dry to warm-dry. As a result, water sources began to dry up, and many animals lost their habitat and died out.
• Human Expansion:
  The time of the extinction of megafauna matches very closely the pattern of human migration into these areas. Megafauna are also large and slow, which makes them susceptible to hunting. In Africa, humans evolution occurred there, so hunting increased slowly, allowing animals to adjust. That is why there are still megafauna there. However, in places where humans arrived as skilled hunters, the most extinction occurred.

Question 10

what are spreading zones

Answer 10

the new areas of floor created at ridges where molten rock

rises out from the mantle and solidifies

Question 11

how do we know Australia is moving North

Answer 11

There are spreading zones on the southern side of the Indo-Australian plate, and
collision zones on the northern side

spreading zones are created at ridges where molten rock
rises out from the mantle and solidifies

Question 12

illustrate the changing ideas of scientists in the last 200 years about the platypus as new information and technologies became available

Answer 12

• 1798: A dried platypus skin sent to England considered to be a fake; the bill was thought to have been stitched on (observation and dissection)
• 1988: their chromosomes resemble those of reptiles (advanced microscopic techniques, genetic fingerprinting)
• 2001: (radio-telemetry) to record body temperatures year round

Question 13

Examples of variations include:

Answer 13

• The white-naped honeyeater:
  In Australia, eastern populations have a short
  bill and an orange eye-patch. These belong to lunatus. Populations in western Australia have larger bills and white or green eye-patches.
• The common heath:
  This flower show remarkable variations in the colour of
  the flowers, from pure white, to pink, to deep red.

Question 14

The greater the variation within a species…

Answer 14

…the greater the chance that it will be able to survive in a situation of environmental change.

Question 15

what happened as Australia moved north

Answer 15

it became warmer
rainforests shrank
sclerophyll and grasslands increased

Question 16

in what period were there many ice ages

Answer 16

Quaternary period

Question 17

Other environmental changes that have shaped ecosystems, besides climate are:

Answer 17

Sea levels have risen and fallen; mainland Australia and Tasmania have been joined and parted at least 8 times in the past 30 million years

Erosion continues, making Australia the flattest continent

35 mya, volcanic activity created extensive lava flows around the east coast of
Australia

Question 18

Identify changes in the distribution of Australian species, as rainforests contracted and sclerophyll communities and grasslands spread, as indicated by fossil evidence:

Answer 18

• As Australia became warmer and drier, rainforests shrank, and grasslands and sclerophyll communities increased
• Organisms well suited to these conditions undertook “adaptive radiation”
• Two groups that are part of the sclerophyll family are eucalypts and acacias
• Both forms have adapted to survive in dry hot conditions
• The 950 species of acacia are found almost everywhere, from tropical to
  temperate, arid and semi-arid.

- The 800 species of eucalypts are found mainly in open woodland and forests

Question 19

describe some Australian fossils, where these fossils were found and use available evidence to explain how they contribute to the development of understanding about the evolution of species in Australia:

Answer 19

Riversleigh (North-western Queensland)

• 6 species of thylacine (Tasmanian tiger) have been found
• Size ranged from Burmese cat to Doberman
• Giant Rat-Kangaroo (proleopines) were found in 1888. They were carnivorous.
• A jaw from a possum - representing the Striped Possum
• A complete skull of monotreme obdurodon
• Fangaroo, A small herbivorous kangaroo with huge teeth

Question 20

Present information from secondary sources to discuss the Huxley- Wilberforce debate on Darwin’s theory of evolution:

Answer 20

• Darwin‟s book The Origin of Species caused great uproar in the community, especially among religious clergy
• Several debates happened, each side arguing they point of view of evolution
• The most famous of these is the debate between Thomas Huxley (Darwin‟s Bulldog) and Bishop Samuel Wilberforce (Soapy Sam).
• Wilberforce: “Rocks pigeons were what rock pigeons had always been”
• Wilberforce asked Huxley whether it was his grandmother or his grandfather that
  came from a monkey.
• Huxley replied that he would rather have an ape for an ancestor than a person who
  uses their intelligence to „introduce ridicule into a grave scientific discussion‟.

Question 21

describe mitosis

Answer 21

• cell division, where two daughter cells are produced that are identical to the parent cell
• It is used for growth and repair
• Also basis of sexual reproduction
• Division occurs only once
• The stages are Interphase, Prophase, Metaphase, Anaphase and Telophase
• Cells produced are diploid

Question 22

describe meiosis

Answer 22

• produces 4 haploid cells
• These cells are sex-cells; also called gametes
• Gametes fuse together during fertilisation to form a zygote, which multiplies
  by mitosis to form a new organism
• Human males produce gametes called sperm, females produce ova or eggs
• When two gametes join, the normal number of chromosomes is achieved
• Similar chromosomes can be paired up, and are called homologous
• In homologous chromosomes, one is from the mother, one from the father
• Random segregation is, during meiosis, the separation of chromosomes by
  chance into the resulting daughter cells. This means that the gametes produced
  can have any combination of chromosomes. This results in increased variation

Question 23

similarities of mitosis and meiosis

Answer 23

 Both are types of cell division

 Chromosomes are replicated before both types of divisions

Question 24

Conditions needed for fertilisation:

Answer 24

1. Both male and female gametes need to be produced and ready at same time
2. Arrangements need to be bring the gametes in contact with each other
3. Water needs to be present (male gametes must swim to the female gamete)

Question 25

why is external fertilisation successful in water

Answer 25

the gametes can spread very far and wide in the water, increasing the chances meeting other gametes from the opposite gender, encouraging fertilisation

Question 26

would external fertilisation succeed on land

why

Answer 26

no

there is no water through which the male gametes can swim, and the gametes would not spread very far, as the buoyancy of water is not there to support their travelling.

Question 27

Male reproductive organ in flora

Answer 27

 Called the stamen
 Made of anther and filament
 Meiosis occurs in anther and produces pollen grains
 Pollen grains have a thick outer layer and 2 haploid nuclei

Question 28

Female reproductive organ: in flora

Answer 28

 Called the pistil; made up of a number of carpels
 Each carpel is made of a stigma, style and ovary
 Meiosis occurs in the ovules, which are in the ovary

Question 29

what is pollination

Answer 29

the transfer of pollen onto a mature stigma

Question 30

how does pollination within fauna occur

Answer 30

1. The pollen on the stigma sends a pollen tube down the style to the ovary
2. The two haploid nuclei of the pollen grain travel down the tube. One of the nuclei become the nucleus of the new tube cell, while the other nucleus divides again and they both travel down the tube to the ovule
3. The pollen tube enters the ovule through a tiny hole called the micropyle
4. One of the nuclei fuses with the ovum to form the zygote
5. The other nucleus fuses with the two other haploid nuclei to form a
   triploid cell

Question 31

Some adaptations of Australian species to ensure fertilisation include:

Answer 31

 Common Trout: They come together during the full moon of their mating season and release their gametes into the water

 Sharks: The male gametes are transferred directly into the female through
claspers, which go into the female‟s opening, called a cloaca.

 Whales, Seals and Dolphins: All have internal fertilisation, where the male gametes are deposited directly into the female. They often have spectacular courtship rituals.

Question 32

Discuss the conditions under which asexual reproduction is advantageous, with reference to specific Australian examples

Answer 32

• Asexual reproduction results in the production of offspring genetically identical to the parent
• If the environment is unchanging, and the characteristics of a particular organism
  are well suited to the environment, then asexual reproduction would be
  advantageous, since all the offspring will have the advantageous characteristics
• Example: Sphagnum in the Australian Alps. It has managed to colonise whole valleys through asexual reproduction

Question 33

Explain the importance of the study of past environments in predicting the impact of human activity in present environments

Answer 33

• The knowledge gained from palaeontology (fossils) and the study of past
  environments can help us to understand present day ecosystems
• This knowledge can be used to predict and determine the future for Australia‟s plants and animals
• Palaeobiologists gain knowledge about the long term changes that have occurred in ecosystems over millions of years. At Riversleigh, fossils are being used to see how Australia‟s biota evolved

Question 34

The main findings of palaeontology in Australia are:

Answer 34

1. Loss of biodiversity over time - reduction in rainforest
2. Thylacine - numbers were already declining, Europeans finally killed them all
3. Analysis of plant and animal fossils can allow palaeontologists to create a
   picture of the ecosystems at the time.

Question 35

Main causes of extinction

Answer 35

climate -> drier, agriculture and hunting

Question 36

Explain the need to maintain biodiversity:

Answer 36

• in providing clean water, air, productive soil, and recycling matter
• Many human activities rely on biodiversity: agriculture, forestry, fisheries,
  tourism, textiles, etc
• The general health of the planet depends on biodiversity

Question 37

sexual reproduction

Answer 37

occurs with two parents

produces an organism that is a combination of both parents

occurs in most complex organisms

Question 38

asexual reproduction

Answer 38

needs only one parent

offspring is identical genetic makeup of parent

occurs in most single celled organisms (bacteria)

some multi-cellular organisms (fungi and some plants)

Question 39

what is fragmentation

Answer 39

asexual

organism split into fragments

clones of original organism

e.g. coral

Question 40

pollination and fertilisation

Answer 40

sexual reproduction

pollination = transfer of pollen from anther to the stigma

fertilization = when pollen grain reaches stigma and produces pollen tube which goes from style to ovary