2022-23USACO美國計算機奧賽備賽開啟，附歷年真題示例
USACO 美國計算機奧林匹克學術活動 United States of America Computing Olympiad 簡稱USACO，USACO學術活動是美國最具認可度的計算機學術活動，用于選拔美國參加全球信息奧林匹克學術活動（IOI）的國家隊，學術...
AQA A Level Chemistry復習筆記1.6.1 Bond Energy
Bond Energy During a reaction, enthalpy changes take place because bonds are being broken and formed Energy (in the form of heat) is needed to overcome attractive forces between atoms Bond breaking...
AQA A Level Chemistry復習筆記1.5.1 Shapes of Simple Molecules & Ions
Electron Pairs The?valence shell electron pair repulsion theory?(VSEPR) predicts the shape and bond angles of molecules Electrons are?negatively charged?and will repel other electrons when close to...
AQA A Level Chemistry復習筆記1.4.1 Changes in State: Energy Changes
State Changes Changes of state are?physical changes?that are reversible These changes do not change the chemical properties or chemical makeup of the substances involved Vaporization?includes?evapo...
AQA A Level Chemistry復習筆記1.3.1 The Mole & the Avogadro Constant
Mole & Avogadro Constant The?Avogadro constant?(NA?or?L) is the number of particles equivalent to the relative?atomic?mass?or?molecular mass?of a substance The Avogadro constant applies to atom...
AQA A Level Chemistry復習筆記1.2.1 Relative Atomic Mass & Relative Molecular Mass
Relative Masses Atomic Mass Unit The mass of a single atom is so small that it is impossible to weigh it directly Atomic masses are therefore defined in terms of a?standard?atom which is called the...
AQA A Level Chemistry復習筆記1.1.1 Fundamental Particles
Structure of an Atom All matter is composed of?atoms, which are the smallest parts of an element that can take place in?chemical reactions Atoms are mostly made up of?empty?space?around a very smal...
AQA A Level Biology復習筆記8.4.1 Recombinant DNA Technology
Recombinant DNA Technology Recombinant DNA The genetic code is?universal, meaning that almost every organism uses the same four nitrogenous bases – A, T, C & G. There are a few exceptions The g...
AQA A Level Biology復習筆記8.3.1 Genome Sequencing Projects
Genome Sequencing Projects A genome contains?all of the genes within an organism Advances in technology have allowed scientists to map and sequence the genes within an organism's genome Genome sequ...
AQA A Level Biology復習筆記8.2.1 Totipotent Cells
Totipotent Cells A?stem cell?is a cell that can?divide?(by mitosis) an?unlimited number of times Each new cell that is produced when a stem cell divides has the potential to?remain a stem cell?or t...
AQA A Level Biology復習筆記8.1.1 Genetic Mutations
Gene Mutations A?gene mutation?is a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide Mutations occur?continuously?and?spontaneously Errors in the DNA...
AQA A Level Biology復習筆記7.4.1 Communities
The Definition of a Community Species?do not exist by themselves in their own isolated environment, they interact with other species forming?communities A community can be defined as: Multiple popu...
