Science

Notes for Module 3 of HSC Science Extension

Science Extension Syllabus by NESA.

Definitions Chromosome: Structure in the nucleus of a cell, composed of DNA DNA: A double helix structure made of nucleotides Deoxyribose sugar: one of the three nucleotides of DNA Gene: a section of DNA that carries the code for a particular characteristic Nitrogenous base: part of a nucleotide, four types: ademine, thymine, guanine and cytocine Nucleotide: the building blocks of DNA, composed of a Deoxyribose sugar, Nitrogenous base and phosphate Phosphate: one of the components of a nucleotide Trait: a characteristic inherited by an organism Autosome: all chromosomes other than sex chromosomes Centromere: point where the two chromatids join together Chromatid: one of the strands of a chromosome following replication Diploid Number: number of chromosomes in the cell of an organism, represented as \(2N\).

Definitions Ion: An atom which is electrostatically charged Cation: Positively Charged ion Anion: Negatively Charged ion Valence shell: Outermost electron shell Octet: 8 electrons in the valence shell (2 if the element is Hydrogen or Helium) Catalyst: something that causes and/or speeds up chemical reactions Proton: positively charged hadron Neutron: neutral hadron Electron: negatively charged lepton exothermic: emits heat endothermic: absorbs heat Atomic number: number of protons Atomic mass: number of protons + number of neutrons Neutralisation: mixing an acid and a base to create water Corrosion: a gas or liquid chemically attacking an exposed surface Combustion: exothermic reaction between a fuel and oxidiser, which produces heat, light and gaseous products decomposition: when a single compound breaks down into two or more compounds oxidisation: corrosion reaction where the gas/liquid is Oxygen (O) Precipitation: formation of an insoluble solid when two soluble solutions are combined (product is known as a precipitate) Acid-Metal reaction: when an acid and metal react to produce a metallic salt and Hydrogen Periodic Table The periodic table is a table listing the fundamental building blocks of the universe: elements NOTE: ATOM and ELEMENT do NOT mean the same thing!

Distance: the measurement of the length between two points Displacement: the CHANGE in an object’s position (straight line between start and end points) NOTE: An object can travel a large distance and still have zero displacement Distance is SCALAR (e.

Cloning A clone is an organism that was made by exactly copying the genetic sequence of another organism. Cloning occurs in nature. Examples of natural cloning include mitosis and banana plants.

DNA DNA stands for DeoxyriboNucleic Acid DNA has the shape of a double helix (like a twisted ladder) The DNA molecule is made up of repeating components called NUCLEOTIDES Nucleotides consist of three components: A Sugar A Phosphate One of 4 Nitrogenous Bases: Adenine (A) Thymine (T) Guanine (G) Cytosine (C) NOTE: You only need to know the letters, not the full names Adenine can only pair with Thymine, while Guanine can only pair with Cytosine Nitrogenous bases pair through Hydrogen bonds DNA contains all the instructions to create an organism Key term: POLYPEPTIDE, also known as a protein DNA is read in groups of three, called a CODON or a triplet Mutations A MUTATION is the alteration of the nucleotide sequence in the genome of an organism A MUTAGEN is a physical or chemical agent that changes the genetic material of an organism, increasing the frequency of mutations in an organism Most mutations are harmless (NEUTRAL) Mutations that improve survivability are called BENEFICIAL mutations Mutations that decrease survivability are called DETRIMENTAL mutations Examples of mutations Beneficial:

Fossils A fossil is evidence of past life. Fossils can be part of an organism, such as its bones, teeth, feathers, scales, branches or leaves. Fossils can also be traces, such as footprints, burrows and other evidence that an organism existed in an area.

Mitosis Mitosis is the process by which one parent cell splits into two identical daughter cells. Mitosis is the most common method of reproduction for single-celled organisms. There are 5 main stages of mitosis: Prophase: number of chromosomes in the cell double up Metaphase: chromosomes wind up and align along the equator of the cells Anaphase: Chromatids (Not Chromosomes, this is explained later) are drawn towards the ends of the cell by spindle fibers Telophase: Cell nuclei forms, chromosomes form and unwind Cytokinesis: Cell splits into two, completing the process of mitosis In the human body, all cells other than sex cells (sperm and ova) are generated through mitosis.