Hsc Bio Notes

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HSC BIOLOGY TOPIC 2: BLUEPRINT OF LIFE
HSC BIOLOGY TOPIC 2: BLUEPRINT OF LIFE

1) Evidence of evolution suggests that the mechanisms of inheritance, accompanied by selection, allow change over many generations. 1.1.1 Outline the impact of evolution of plants and animals of: * Changes in physical conditions in the environment

* Changes in chemical conditions in the environment
* Competition for resources
1.1.2 Outline the impact of evolution of plants and animals of: * Changes in physical conditions in the environment
* Changes in chemical conditions in the environment
* Competition for resources

Evolution is the change in a population over time. The main mechanism for evolution is natural selection. Individuals within a population have many different traits. Some of them provide an advantage. Individuals with these advantageous traits will reproduce and pass them on to their offspring so that these traits will become more common. Hence, the population will evolve. There are several factors which affect evolution.

Changes in the physical conditions in the environment:
A change in the physical conditions of the environment can put pressure on evolution. An example is that temperature and rainfall can change. Australia has experienced less overall rainfall which means that it becomes drier and there are less rainforests and more open and dry woodlands and grasslands. For example, the kangaroo has changed significantly compared to its ancestor. The ancestral kangaroo was smaller and its molars were ‘generalised’. The present kangaroo is much larger and has high crested molar teeth to eat grass. Changes in the chemical conditions of the environment:

Changes in the chemical conditions of the environment affect plant life. Plants prefer a specific soil type and pollution from activities such as mining has affected the preferences of plants. There are plants which tolerate mineral waste. Bacterial evolution is also affected by antibiotics-resistant strains will eventually arise. A further example can be seen in the first life forms. They were believed to had lived in anoxic environments and began to produce carbon dioxide because of their metabolic reactions. The carbon dioxide led to the emergence of photosynthetic organisms which used the carbon dioxide to produce oxygen. Competition for resources

Competition occurs between individuals of the same species or between different species. They compete for resources such as food, water and nesting sites. The introduction of many species such as feral cats, rabbits and foxes have led to competition with native species which has resulted in extinction or endangerment. Predation and competition apply selective pressures on organisms. Only those which compete most successfully for available resources can breed and pass on their genes to the next generation. In short, those which have the most favourable adaptations to survive in their environment

1.1.2 Describe, using specific examples, how the theory of evolution is supported by the following areas of study: - palaeontology, including fossils that have been considered as transitional forms - biogeography

- comparative embryology
- comparative anatomy
- biochemistry
1.1.2 Describe, using specific examples, how the theory of evolution is supported by the following areas of study: - palaeontology, including fossils that have been considered as transitional forms - biogeography

- comparative embryology
- comparative anatomy
- biochemistry

Palaeontology:
A fossil is a trace of pre-existing life. They are useful in finding ancestors of present day organisms and evolutionary lines. They can provide case histories for some organisms. For example, horse fossils have revealed that it evolved from a small animal called ‘Hyracotherium’ which was the size of a small fox terrier. This creature ate trees and bushes since it...
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