Directional & Stabilising Selection Environmental factors that affect the chance of survival of an organism are selection pressures For example, there could be high competition for food ...
The Theory of Natural Selection Genetic variation exists within populations due to the presence of different alleles There is differential reproductive success between the organisms with dif...
Maths Skill: Using Logarithms When Investigating Bacteria Bacterial colonies can grow at rapid rates when in culture with very large numbers of bacteria produced within hours Dealing with th...
Understanding the Outcomes & Processes in Mitosis & Meiosis Mitosis and meiosis are both forms of cell division They have many similarities and differences that are important for the...
Apparatus & Techniques: Using an Optical Microscope Many biological structures are too small to be seen by the naked eye Optical microscopes are an invaluable tool for scientists as they...
Meiosis: Sources of Genetic Variation Having genetically different offspring can be advantageous for natural selection Meiosis has several mechanisms that increase the genetic diversity of g...
Meiosis in Animal & Plant Cells Meiosis is a form of nuclear division that results in the production of haploid cells from diploid cells It produces gametes in plants and animals that ar...
Meiosis Meiosis produces daughter cells that are genetically different from each other and to the parent cell This is due to the processes of independent assortment and crossing over Indepen...
Mutations in Chromosome Number Mutations can occur at different levels Non-disjunction occurs when chromosomes fail to separate during meiosis This occurs spontaneously The gametes ma...
