IB DP Biology: HL复习笔记3.3.5 Mutations & Disease
Causes of Mutations A mutation is a change in the sequence of base pairs in a DNA molecule They occur randomly and continuously to create new alleles of a gene Often only with a very small number o...
IB DP Biology: HL复习笔记3.3.4 Inheritance of Genetic Diseases
Causes of Genetic Disease A gene can affect a phenotype of an organism A gene codes for a single polypeptide The polypeptide affects the phenotype through a particular mechanism The phenotype of an...
IB DP Biology: HL复习笔记3.3.3 Skills: Inheritance
Constructing Punnett Grids A monohybrid trait is one that is controlled by only one gene Generally, we consider that such a gene has two alleles Either: one allele is dominant and the other is rece...
IB DP Biology: HL复习笔记3.3.2 Inheriting Alleles
Segregation of Alleles Meiosis is a form of nuclear division that results in the production of haploid cells from diploid cells During meiosis a diploid cell will divide twice to form four haploid ...
IB DP Biology: HL复习笔记3.3.1 Inheritance
Mendel's Experiments Gregor Mendel was an Austrian monk He was trained in mathematics and natural history at the University of Vienna In the mid-19th century, Mendel carried out breeding experiment...
IB DP Biology: HL复习笔记3.2.5 Skills: Meiosis
Drawing the Stages of Meiosis Cells undergoing meiosis can be observed and photographed using specialized microscopes The different stages of meiosis have distinctive characteristics meaning they c...
IB DP Biology: HL复习笔记3.2.4 Non-disjunction
Non-disjunction Non-disjunction occurs when chromosomes fail to separate correctly during meiosis This can occur in either anaphase I or anaphase II, leading to gametes forming with an abnormal num...
IB DP Biology: HL复习笔记3.2.3 Genetic Variation
Genetic Variation & Meiosis Crossing over and random orientation promote genetic variation Having genetically different offspring can be advantageous for natural selection and therefore increas...
IB DP Biology: HL复习笔记3.2.2 Stages of Meiosis
DNA Replication before Meiosis Before meiosis occurs, all of the DNA inside the nucleus of the 'parent' cell is replicated This occurs during a period of the cell cycle known as interphase Once thi...
