Edexcel IGCSE Maths 复习笔记 2.6.2 Algebraic Fractions - Simplifying Fractions What is an algebraic fraction? An algebraic fraction is simply a fraction with an algebraic expression on the top (num...
Edexcel IGCSE Maths 复习笔记 2.6.1 Algebraic Fractions - Adding & Subtracting What is an algebraic fraction? An algebraic fraction is simply a fraction with an algebraic expression on the top (...
Edexcel IGCSE Maths 复习笔记 2.5.2 Rearranging Formulae - Harder SIR! GROF GROBLET FIND ANSWER! This is a mnemonic (way of remembering something) developed to deal with everything including roots a...
AIDS Symptoms of AIDS Immediately after infection with HIV people often suffer mild flu-like symptoms These symptoms pass and for a period of time infected people might not know they are inf...
HIV Transmission of HIV Human Immunodeficiency Virus is a retrovirus The HIV virus is not transmitted by a vector (unlike in malaria) The virus is unable to survive outside of the human body...
Types of Immunity Active immunity Active immunity is acquired when an antigen enters the body triggering a specific immune response (antibodies are produced) Active immunity is naturally acq...
Plasma & Memory Cells During an immune response, B-lymphocytes form two types of cell: plasma cells and memory cells Memory cells form the basis of immunological memory – the cells can l...
Antigen-Antibody Complex An antigen and its complementary antibody have complementary molecular shapes This means that their molecular structures fit into each other When an antibody ...
Antibodies: Structure Structure Antibodies are globular glycoproteins called immunoglobulins Antibodies have a quaternary structure (which is represented as Y-shaped), with two ‘heavy’ (long...
The B lymphocyte Response B-lymphocytes and the humoral immune response B-lymphocytes (B cells) remain in the bone marrow until they are mature and then spread through the body, concentratin...
The Role of Helper T cells Activated T-lymphocytes (those that have receptors specific to an antigen) divide by mitosis to increase in number (similar to the clonal selection and clonal expa...
The Role of Antigen-Presenting Cells T-lymphocytes produce an immune response when they are exposed to a specific antigen T cells will only bind to an antigen if it is present on the surface...
