HSC Biology Key Terms & Definitions

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Understand some of the key terms for your HSC Biology exam.
Mike Nervo
Flashcards by Mike Nervo, updated more than 1 year ago
Mike Nervo
Created by Mike Nervo almost 10 years ago
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Question Answer
T Cells The T helper cell is part of an initial response to an antigen, releasing chemicals to stimulate growth of B cells that respond to the antigen. A T memory cell responds differently, interacting initially with an antigen but remaining dormant until the next time the body is infected, when it is quickly activated so that there is a faster response to the antigen.
Darwin/Wallace’s Theory of Evolution Darwin/Wallace’s theory of evolution suggests variation in a population and the fittest survive to pass on their characteristics. Individuals in a rabbit population vary. The virus, a change in the environment, killed most rabbits. A few that were resistant survived. The survivors reproduced and passed this characteristic (resistance) on to their offspring. Overtime the population increased with most rabbits resistant to the virus.
Theory of Evolution The theory of evolution suggests variation in a population and the fittest survive to pass on their characteristics. With the use of DNA sequencing, we now know that genetic variations are caused by a difference in the DNA of the members of the population. It can be shown that certain genes are chosen for in the population by outside pressures, and this leads to change in species.
Genetic Engineering of Plants with Particular Characteristics The findings that a combination of certain genetic characteristics can provide insect resistant crops have led to the insertion of genes for desirable characteristics into plants to produce insect resistant plants. This has produced less need for insecticides.
Quarantine Restrictions Based on our understanding of disease transmission, the isolation of diseases plants has prevented the spread of plant diseases into and around Australia. This has led to a change from the treatment of diseased plants to preventing the disease spread.
Larynx The tension of the vocal chords can be altered by the muscles of the larynx as air moves between them. Tight (stretched) gives high pitch (frequency) and loose (relaxed) gives low notes as the chords vibrate.
Photoreceptors The two main photoreceptor cell types in the retina are cone cells (colour) and rod cells (black and white).
RNA There are different specific t-RNA molecules for each amino acid. They bring their amino acid into the ribosome (r-RNA) where they bind to specific m-RNA bases. mRNA takes its code (order of bases) directly from DNA.
Fermentation Traditional methods of wine production used natural contamination from the environment by yeast. Pasteur discovered specific microorganisms were responsible for alcohol production. This led to using pure cultures for fermentation, so alcohol was produced.
DNA Extraction Process The DNA from strawberries is extracted by blending. Make a solution of some detergent and non-iodised salt and mix with the blended strawberries. Filter the mixture through cheese cloth. Add 95% ethanol (solution). Allow to stand until the top of the solution becomes white (DNA). This is the DNA and can be picked up using a toothpick.
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