What is a reverse percentage? A reverse percentage question is one where we are given?the value after a percentage increase or decrease?and asked to find the value before the change How to do rever...
Genetic Variation Phenotype variation The observable characteristics of an organism are its phenotype Phenotypic variation is the?difference in phenotypes?between organisms of the same?speci...
Edexcel IGCSE Maths復習筆記 1.7.2 Percentage Increases & Decreases How do I increase or decrease by a percentage? Identify “before” & “after” quantities Find percentage of “before” that we ...
Species Exist in Populations A?species?can be defined as a group of?similar organisms?that can?reproduce?to give?fertile offspring Organisms of the same species have the?same number of chromosomes?...
Key Terms in Genetics Genes & alleles The DNA contained within chromosomes is essential for cell survival Every?chromosome?consists of a long DNA molecule which?codes for several differe...
Homeostasis In order to?function?properly and?efficiently, organisms have different?control systems?that ensure their?internal conditions?are kept relatively?constant Physiological control systems ...
Edexcel IGCSE Maths復習筆記 1.7.1 Basic Percentages What is a percentage? “Per-cent” simply means “ ÷ 100” (or “out of 100”) You can think of a percentage as a standardised way of expressing a frac...
Muscle Pairs The?effective movement?of the human body requires both?muscle?and an?incompressible skeleton This is because muscles will only produce effective movement if they?pull on a structure?th...
Myelinated Motor Neurones Information is sent through the nervous system as?nerve impulses?– electrical signals that pass along nerve cells known as?neurones A bundle of neurones is known as a nerv...
