SvS Biology 2001 - Module 8.4: Life on Earth

According to the Board of Studies Syllabus, the purpose and function for studying this unit is summarised by the following statements:
(ref: NSW Board of Studies Stage 6 Syllabus, page 31)

Contextual Outline

The origins of life may be universal because life as we know it has evolved over millions of years from the common elements found in the cosmos. Recent discoveries have also revealed that organic molecules, such as amino acids, exist in meteorites. Simple terrestrial life has been found to exist in the most hostile of conditions on Earth and evidence from Australian scientists has shown that bacteria exist kilometres deep in the Earth’s crust and have done so for millions of years.

The violent conditions of the early Earth provided an environment in which themolecules of life could form. When these organic molecules were separated from their environment by a membrane, they began to carry out the chemical reactions of life in such a way as to sustain their existence and allow reproduction. The evolution of photosynthesis caused a change from an anoxic to an oxic environment that continues to support most of the living things on Earth today.

Over the vast periods of geological time, since the formation of Earth, fossil evidence has indicated changes in complexity and diversity of life forms. It is the diversity of living organisms that has led scientists to develop classification systems that group these organisms according to their structural or genetic similarity. Recent advances in molecular biology and biochemistry have allowed scientists to better understand the origins, processes and evolution of life.

1. Evidence from the analysis of the oldest sedimentary rocks provides evidence for the origin of life

Theory:
• identify the relationship between the conditions on early Earth and the origin of organic molecules
• discuss the implications of the existence of organic molecules in the cosmos for the origin of life on Earth
• describe two scientific theories relating to the evolution of the chemicals of life and discuss their significance in understanding the origin of life
• discuss the significance of the Urey and Miller experiments in the debate on the composition of the primitive atmosphere
• identify changes in technology that have assisted in the development of an increased understanding of the origin of life and evolution of living things

• gather information from secondary sources to describe the experiments of Urey and Miller and use the available evidence to analyse the:
– reason for their experiments
– result of their experiments
– importance of their experiments in illustrating the nature and practice of science
– contribution to hypotheses about the origin of life

2. The fossil record provides information about the subsequent evolution of living things

Theory:
• recall the conditions under which fossils form
• recall that the fossil record is related to the time over which living things have been evolving on Earth
• recall evidence that present-day organisms have developed from different organisms in the past
• identify the major stages in the evolution of living things, including the formation of:
– organic molecules
– membranes
– prokaryotic heterotrophic cells
– prokaryotic autotrophic cells
– eukaryotic cells
– colonial organisms
– multicellular organisms
• describe some of the palaeontological and geological evidence that suggests when life originated on Earth
• explain why the change from an anoxic to an oxic atmosphere was significant in the evolution of living things
• discuss the ways in which developments in scientific knowledge may conflict with the ideas about the origins of life developed by different cultures

Practical:
• plan, choose equipment or resources and gather, process and analyse information to construct a timeline of the main events that occurred during the evolution of life on Earth
• gather first-hand or secondary information to make observations of a range of plant and animal fossils
• identify data sources, gather, process, analyse and present information from secondary sources and use the available evidence to evaluate the impact, historically, of increased understanding of information that the fossil record could provide on the development of ideas about the past history of life on Earth

3. Further developments in our knowledge of present day organisms and the discovery of new organisms allows for better understanding of the origins of life and the processes involved in the evolution of living things

Theory:
• recall evidence that present-day organisms have evolved from different organisms in the distant past
• describe technological advances that have increased knowledge of prokaryotic organisms
• describe the environment occupied by:
– Archaeobacteria
– Eubacteria
– Cyanobacteria, including those that form stromatolites
– nitrogen-fixing bacteria
– methanogens
– deep sea bacteria
• identify the role of the above organisms in their respective ecosystems

Practical:
• identify data sources, gather, process and present information from secondary sources and use the available evidence to discuss environments past and present of one of the following:
– Archaeobacteria
– Eubacteria
– Cyanobacteria, including those that form stromatolites
– nitrogen-fixing bacteria
– methanogens
• gather, process and analyse information from secondary sources to discuss the diverse environments that living things occupy today and use available evidence to describe possible alternative environments in which life may have originated

4. The study of the different types of present day organisms assists increasing understanding about organisms and environments of the past

Theory:
• explain the need for scientists to classify organisms
• describe the selection criteria used in different classification systems and discuss the advantages and disadvantages of each system
• explain how levels of organisation in a hierarchical system assist classification
• discuss, using examples, the impact of changes in technology on the development and revision of biological classification systems
• describe the main features of the binomial system in naming organisms and relate these to the concepts of genus and species
• identify and discuss the difficulties experienced in classifying extinct organisms
• explain how classification of organisms can assist in developing an understanding of present and past life on Earth

Practical:
• perform a first-hand investigation and gather information to construct and use simple dichotomous keys and show how they can be used to identify a range of plants and animals using live and preserved specimens, photographs or diagrams of plants and animals
• gather information from secondary sources to compare the amino acid sequences in similar proteins from related organisms with those from less related organisms