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\author{Anais (Anais\_Pe)}
\pdfinfo{
  /Title (biology-a-level-patterns-of-inheritance.pdf)
  /Creator (Cheatography)
  /Author (Anais (Anais\_Pe))
  /Subject (Biology A level - Patterns of Inheritance Cheat Sheet)
}

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        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Biology A level - Patterns of Inheritance Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Anais (Anais\_Pe)} via \textcolor{DarkBackground}{\uline{cheatography.com/151793/cs/43634/}}}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}Anais (Anais\_Pe) \\
  \uline{cheatography.com/anais-pe} \\
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Published 11th June, 2024.\\
   Updated 11th June, 2024.\\
   Page {\thepage} of \pageref{LastPage}.
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  Measure your website readability!\\
  www.readability-score.com
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\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{x{1.59264 cm} x{3.38436 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Key words for topic}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\emph{Genotype}} & Genetics makeup of an organisms - the alleles present. \tn 
% Row Count 2 (+ 2)
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\SetRowColor{white}
{\emph{Phenotype}} & The expression of genes (also affected by the environment). \tn 
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{\emph{Homozygous}} & A pair of homologous chromosomes carrying same allele for a gene (e.g. AA, aa).) \tn 
% Row Count 8 (+ 3)
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{\emph{Heterozygous}} & A pair of homologous chromosomes carrying different alleles for a gene (e.g. Aa). \tn 
% Row Count 11 (+ 3)
% Row 4
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{\emph{Recessive allele}} & Allele only expressed in the absence of dominant alleles \tn 
% Row Count 14 (+ 3)
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{\emph{Dominant allele}} & Allele always expressed in phenotype. \tn 
% Row Count 16 (+ 2)
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{\emph{Codominant}} & Multiple alleles are equally dominant and expressed in the phenotype. \tn 
% Row Count 19 (+ 3)
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{\emph{Sex-linkage}} & A gene with a locus in the X chromosome. \tn 
% Row Count 21 (+ 2)
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{\emph{Autosomal linkage}} & Genes in the same chromosome (not sex chromosome). An autosomal chromosome is any chromosome other than sex chromosomes. \tn 
% Row Count 26 (+ 5)
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{\emph{Epistasis}} & When one gene modifies the expression of a different gene. \tn 
% Row Count 29 (+ 3)
% Row 10
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{\emph{Monohybrid}} & Genetics inheritance cross of trait determined by one gene. \tn 
% Row Count 32 (+ 3)
\end{tabularx}
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\vfill
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\begin{tabularx}{5.377cm}{x{1.59264 cm} x{3.38436 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Key words for topic (cont)}}  \tn
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{\emph{Dihybrid}} & Genetics inheritance cross of trait determined by two gene. \tn 
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{\emph{Gene pool}} & All alleles of all genes within population. \tn 
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{\emph{Allele frequency}} & Proportion of an allele in a gene pool. \tn 
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\mymulticolumn{2}{x{5.377cm}}{Some of these terms will be further explained in this cheat sheet.}  \tn 
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\end{tabularx}
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\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Notation systems for topic}}  \tn
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{\bf{Type of inheritance}} & {\bf{Coding}} \tn 
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{\emph{Monohybrid}} & Single letter capital / lower case {\bf{e.g. A, a}} \tn 
% Row Count 5 (+ 3)
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\SetRowColor{LightBackground}
{\emph{Codominance}} & Gene\textasciicircum{}allele\textasciicircum{}  {\bf{e.g. C\textasciicircum{}W\textasciicircum{}C\textasciicircum{}R\textasciicircum{}, I\textasciicircum{}A\textasciicircum{}I\textasciicircum{}B\textasciicircum{}}} \tn 
% Row Count 8 (+ 3)
% Row 3
\SetRowColor{white}
{\emph{Multiple alleles for one gene (more than two)}} & Gene\textasciicircum{}allele\textasciicircum{}  {\bf{e.g. I\textasciicircum{}A\textasciicircum{}I\textasciicircum{}O\textasciicircum{}}} \tn 
% Row Count 11 (+ 3)
% Row 4
\SetRowColor{LightBackground}
{\emph{Sex linkage}} & Chromosome\textasciicircum{}allele\textasciicircum{} {\bf{e.g. X\textasciicircum{}R\textasciicircum{}X\textasciicircum{}r\textasciicircum{}, X\textasciicircum{}r\textasciicircum{}Y}} \tn 
% Row Count 14 (+ 3)
% Row 5
\SetRowColor{white}
{\emph{Autosomal linkage and epistasis}} & Single letters {\bf{e.g. Aa Bb}} \tn 
% Row Count 16 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
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\begin{tabularx}{5.377cm}{p{0.77809 cm} x{1.92234 cm} x{1.87657 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Monohybrid crosses}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Worked example:}} Cystic fibrosis is caused by a recessive allele, what is the probability that two carrier parents will have a child with cystic fibrosis?} \tn 
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\mymulticolumn{3}{x{5.377cm}}{Parent genotypes ("both carriers"): Ff x Ff} \tn 
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\mymulticolumn{3}{x{5.377cm}}{{\emph{Each gamete will carry either  the F or f allele and can fuse with gametes containing either F or f alleles too because parents are heterozygous.}}} \tn 
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 & {\bf{F}} & {\bf{f}} \tn 
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{\bf{F}} & FF {\emph{(no CF)}} & Ff {\emph{(no CF)}} \tn 
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{\bf{f}} & Ff {\emph{(no CF)}} & ff {\emph{(CF)}} \tn 
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\mymulticolumn{3}{x{5.377cm}}{{\emph{Therefore probability of child with cystic fibrosis = 1/4 = 25\%.}}} \tn 
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\begin{tabularx}{5.377cm}{x{0.86963 cm} x{1.8308 cm} x{1.87657 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Codominant inheritance}}  \tn
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\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Worked example:}} A flower can be three colours: white, red or pink. The alleles for white and red are codominant to form pink flowers. If two pink flowers reproduce, what is the probability of forming a red offspring flower?} \tn 
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% Row 1
\SetRowColor{white}
\mymulticolumn{3}{x{5.377cm}}{{\emph{Pink flowers must have the alleles both for red and white as they are codominant to produce pink. They are therefore heterozygous.}}} \tn 
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% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Parent genotype:}} C\textasciicircum{}R\textasciicircum{}C\textasciicircum{}W\textasciicircum{} x C\textasciicircum{}R\textasciicircum{}C\textasciicircum{}W\textasciicircum{} \{\{nl\}\}} \tn 
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 & {\bf{C\textasciicircum{}R\textasciicircum{}}} & {\bf{C\textasciicircum{}W\textasciicircum{}}} \tn 
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\SetRowColor{LightBackground}
{\bf{C\textasciicircum{}R\textasciicircum{}}} & C\textasciicircum{}R\textasciicircum{}C\textasciicircum{}R\textasciicircum{} {\emph{(red)}} & C\textasciicircum{}R\textasciicircum{}C\textasciicircum{}W\textasciicircum{} {\emph{(pink)}} \tn 
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% Row 5
\SetRowColor{white}
{\bf{C\textasciicircum{}W\textasciicircum{}}} & C\textasciicircum{}R\textasciicircum{}C\textasciicircum{}W\textasciicircum{} {\emph{(pink)}} & C\textasciicircum{}W\textasciicircum{}C\textasciicircum{}W\textasciicircum{} {\emph{(white)}} \tn 
% Row Count 14 (+ 2)
% Row 6
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\mymulticolumn{3}{x{5.377cm}}{{\emph{Therefore probability of forming a red offspring is 1/4 = 25\%.}}} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
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\begin{tabularx}{5.377cm}{p{0.77809 cm} x{1.87657 cm} x{1.92234 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Multiple alleles inheritance}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Key example: Blood groups}}} \tn 
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% Row 1
\SetRowColor{white}
\mymulticolumn{3}{x{5.377cm}}{{\emph{There are three alleles for blood group: A, B and O, represented as I\textasciicircum{}A\textasciicircum{}, I\textasciicircum{}B\textasciicircum{} and I\textasciicircum{}O\textasciicircum{}.}}} \tn 
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% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\emph{Both I\textasciicircum{}A\textasciicircum{} and I\textasciicircum{}B\textasciicircum{} are codominant to form phenotype group AB, and I\textasciicircum{}O\textasciicircum{} is recessive.}}} \tn 
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% Row 3
\SetRowColor{white}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Worked example:}} parents with blood group AB and O reproduce. WHat so the probability that they will produce an offspring with blood group A?} \tn 
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% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Parent genotype:}} I\textasciicircum{}A\textasciicircum{}I\textasciicircum{}B\textasciicircum{} x I\textasciicircum{}O\textasciicircum{}I\textasciicircum{}O\textasciicircum{}} \tn 
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 & {\bf{I\textasciicircum{}A\textasciicircum{}}} & {\bf{I\textasciicircum{}B\textasciicircum{}}} \tn 
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\SetRowColor{LightBackground}
{\bf{I\textasciicircum{}O\textasciicircum{}}} & I\textasciicircum{}A\textasciicircum{}I\textasciicircum{}O\textasciicircum{} {\emph{(group A)}} & I\textasciicircum{}B\textasciicircum{}I\textasciicircum{}O\textasciicircum{} {\emph{(group B)}} \tn 
% Row Count 12 (+ 2)
% Row 7
\SetRowColor{white}
{\bf{I\textasciicircum{}O\textasciicircum{}}} & I\textasciicircum{}A\textasciicircum{}I\textasciicircum{}O\textasciicircum{} {\emph{(group A)}} & I\textasciicircum{}B\textasciicircum{}I\textasciicircum{}O\textasciicircum{} {\emph{(group B)}} \tn 
% Row Count 14 (+ 2)
% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\emph{Therfore probability is 2/4 = 50\%.}}} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
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\begin{tabularx}{5.377cm}{x{1.55618 cm} x{1.51041 cm} x{1.51041 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Sex-linkage}}  \tn
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\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\emph{Sex linked alleles only occur in X chromosomes as Y chromosomes contain less genetic information (too small to carry more). This makes males more likely to carry recessive sex-linked disorders as their homologous Y chromosome cannot contain the dominant allele.}}} \tn 
% Row Count 6 (+ 6)
% Row 1
\SetRowColor{white}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Worked example:}} Colour blindness is caused by a recessive sex-linked allele only found in the X chromosome. If a colour blind male reproduces with a heterozygous female, what is the probability that they would have a colour blind child?} \tn 
% Row Count 11 (+ 5)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Parent genotype:}} X\textasciicircum{}B\textasciicircum{}X\textasciicircum{}b\textasciicircum{} x X\textasciicircum{}b\textasciicircum{}Y} \tn 
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 & {\bf{X\textasciicircum{}B\textasciicircum{}}} & {\bf{X\textasciicircum{}b\textasciicircum{}}} \tn 
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\SetRowColor{LightBackground}
{\bf{X\textasciicircum{}b\textasciicircum{}}} & X\textasciicircum{}B\textasciicircum{}X\textasciicircum{}b\textasciicircum{} & X\textasciicircum{}b\textasciicircum{}X\textasciicircum{}b\textasciicircum{} \tn 
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{\bf{Y}} & X\textasciicircum{}B\textasciicircum{}Y & X\textasciicircum{}b\textasciicircum{}Y \tn 
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\mymulticolumn{3}{x{5.377cm}}{{\emph{The probability of a colour blind child is therefore 2/4 = 50\%.}}} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}---}
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{Be sure to read the question carefully. Some exam questions will choose animals where the female has XY chromosomes and the male has XX chromosomes which can throw you off.}  \tn 
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Epistasis}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\emph{One gene affects the expression of another, therefore multiple genes will be at play here.}}} \tn 
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% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{(Common) worked example:}} Labradors have two genes which will affect their fur colour. The first gene controls which colour is expressed. If allele B is expressed, the dog will be black. If allele b is expressed, the dog will be brown. The second gene codes for pigment production. If allele E is expressed, pigment will be produced. If allele e is expressed, no pigment will be produced and the dog will be yellow. Parents heterozygous for both genes reproduce.} \tn 
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% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Parent genotype:}} Bb Ee x Bb Ee} \tn 
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% Row 3
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Parent possible gametes:}} BE, Be, bE, be x BE, Be, bE, be} \tn 
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\mymulticolumn{1}{x{5.377cm}}{} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{BE}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Be}}} \tn 
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% Row 7
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\mymulticolumn{1}{x{5.377cm}}{{\bf{bE}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{be}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Offspring phenotypes:}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\emph{Black : Brown : Yellow}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\emph{9:3:4}}} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Dihybrid crosses}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Two genes considered at the same time.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Key example: Mendel's peas}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Peas can be two different colours, yellow or green. They can also be either round or wrinkled. Roundness is a dominant allele (R) and yellow colour is also dominant (Y). Show the proportions of phenotypes for the offsprings of two heterozygous peas.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Parent genotype:}} RrYy x RrYy} \tn 
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% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Gametes:}} RY, Ry, rY, ry x RY, Ry, rY, ry} \tn 
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\mymulticolumn{1}{x{5.377cm}}{} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{RY}}} \tn 
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\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Ry}}} \tn 
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% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{rY}}} \tn 
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% Row 9
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{ry}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Offspring phenotypes:}}} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Round and yellow : Wrinkled and yellow : Round and green : Wrinkled and green} \tn 
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\mymulticolumn{1}{x{5.377cm}}{9:3:3:1} \tn 
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% Row 13
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\mymulticolumn{1}{x{5.377cm}}{{\emph{This ratio will always be present in dihybrid heterozygous crosses.}}} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{This proportion is only true IF: \newline - There is no autosomal linkage. \newline - There is no crossing over during meiosis. \newline - There are no mutations. \newline - There is no sexual selection (e.g. black rabbits only mate with other black rabbits). \newline - There is no epistasis.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{p{1.55618 cm} p{1.51041 cm} p{1.51041 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Autosomal linkage and crossing over}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{When genes are linked, it means they occur on the same chromosome. \{\{nl\}\} {\emph{For example, R and Y are on one chromosome and r and you on the other.}}} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{3}{x{5.377cm}}{This means it is not possible to get all the gametes predicted in the previous box. \{\{nl\}\}{\emph{R and y cannot form a gamete because R and Y are always inherited together.}}} \tn 
% Row Count 7 (+ 4)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{In the example we used, the only possible gametes for heterozygous parents if the genes are linked are: \{\{nl\}\} {\bf{RY, ry x RY, ry}}} \tn 
% Row Count 10 (+ 3)
% Row 3
\SetRowColor{white}
 & {\bf{RY}} & {\bf{ry}} \tn 
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% Row 4
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{\bf{RY}} & RRYY & RrYy \tn 
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% Row 5
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{\bf{ry}} & RrYy & rryy \tn 
% Row Count 13 (+ 1)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\emph{The ratio therefore changes from 9:3:3:1 to 3:1 (in this example.)}}} \tn 
% Row Count 15 (+ 2)
% Row 7
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\mymulticolumn{3}{x{5.377cm}}{{\bf{Crossing over (meiosis)}}} \tn 
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% Row 8
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\mymulticolumn{3}{x{5.377cm}}{It is, however, possible for observations to show more than just two phenotypes, or unexpected proportions of these phenotypes.} \tn 
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% Row 9
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\mymulticolumn{3}{x{5.377cm}}{This is because of crossing over in meiosis. Homologous chromosomes can overlap and swap parts of non-siter chromatids. This can form new gametes. \{\{nl\}\} {\emph{In our example, part of the chromosome containing the Y and another chromatid containing the y allele could swap, creating the gametes Ry and rY. These are called {\bf{recombinant genes}}.}}} \tn 
% Row Count 26 (+ 7)
% Row 10
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{Genes are less likely to split if they are close together, because there is less space for a chiasmata to form between them so they are less likely to be separated and will be inherited together (linked).} \tn 
% Row Count 31 (+ 5)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Autosomal linkage}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{p{5.377cm}}{\vspace{1px}\centerline{\includegraphics[width=5.1cm]{/web/www.cheatography.com/public/uploads/anais-pe_1718118252_Screenshot 2024-06-11 16.03.31.png}}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Note the genes occuring on the same chromosome but far apart as marked as not linked because they are likely to be separated by a chiasmata during meiosis.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.96811 cm} x{2.15119 cm} p{0.4577 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Chi-squared}}  \tn
% Row 0
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\mymulticolumn{3}{x{5.377cm}}{Statistical test used to calculate whether what we expect is different from what we actually observe.} \tn 
% Row Count 3 (+ 3)
% Row 1
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{\bf{{\emph{(O-E)\textasciicircum{}2\textasciicircum{}/E}}}} & Degrees of freedom = number of categories - 1 &  \tn 
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% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{{\bf{Worked example:}} Corn can be yellow (Y) or purple (y). Heterozygous cross - Mendelian genetics expected:} \tn 
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% Row 3
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 & {\bf{Y}} & {\bf{y}} \tn 
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% Row 4
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{\bf{Y}} & YY & Yy \tn 
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% Row 5
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{\bf{y}} & Yy & yy \tn 
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% Row 6
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\mymulticolumn{3}{x{5.377cm}}{{\emph{yellow : purple = 3:1}}} \tn 
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% Row 7
\SetRowColor{white}
\mymulticolumn{3}{x{5.377cm}}{A student observed 21 yellow and 13 purple kernels. Is this significantly different from expectation?} \tn 
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% Row 8
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\mymulticolumn{3}{x{5.377cm}}{{\emph{Null hypothesis: no significant difference between expected and observed colour of corn.}}} \tn 
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% Row 9
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1. Make expected a proportion & 21+13 = 34\{\{nl\}\} 3+1 = 4 \{\{nl\}\} 34/4 = 8.5 \{\{nl\}\} 3x8.5 = {\bf{25.5 }}\{\{nl\}\} 1x8.5 = {\bf{8.5}} &  \tn 
% Row Count 24 (+ 5)
% Row 10
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2. Observed - Expected & 21-25.5 = {\bf{-4.5}}\{\{nl\}\}13-8.5 = {\bf{4.5}} &  \tn 
% Row Count 27 (+ 3)
% Row 11
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3. Square answers & -4.5\textasciicircum{}2\textasciicircum{} = {\bf{20.25}} \{\{nl\}\}4.5\textasciicircum{}2\textasciicircum{} = {\bf{20.25}} &  \tn 
% Row Count 30 (+ 3)
\end{tabularx}
\par\addvspace{1.3em}

\vfill
\columnbreak
\begin{tabularx}{5.377cm}{x{1.96811 cm} x{2.15119 cm} p{0.4577 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{Chi-squared (cont)}}  \tn
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4. Divide by expected value & 20.25/25.5 = {\bf{0.794}} \{\{nl\}\} 20.25/8.5 = {\bf{2.382}} &  \tn 
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% Row 13
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5. Add up values & Chi squared = {\bf{3.176}} &  \tn 
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% Row 14
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6. Calculate degrees of freedom and compare calculated value to critical value table & 2-1 = 1 \{\{nl\}\} critical value = 3.841 &  \tn 
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% Row 15
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\mymulticolumn{3}{x{5.377cm}}{{\emph{Because our calculated value is lower than the critical value, there is more than 5\% probability that any differences is due to chance. This means results are not significantly different and we accept the null hypothesis.}}} \tn 
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% Row 16
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\mymulticolumn{3}{x{5.377cm}}{{\emph{So the colour observed matched the Mendelian genetics we originally calculated.}}} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}---}
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{If the observed data does not match the expected data, this means that genes are linked and therefore not subject to independent assortment.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{The Hardy-Weinberg principle}}  \tn
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\mymulticolumn{2}{x{5.377cm}}{Mathematical model used to determine the frequency of alleles.} \tn 
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% Row 1
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\mymulticolumn{2}{x{5.377cm}}{{\bf{p\textasciicircum{}2\textasciicircum{} + 2pq + q\textasciicircum{}2\textasciicircum{} = 1}}} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{p\textasciicircum{}2\textasciicircum{}}} = frequency of homozygous dominant genotype (AA) \{\{nl\}\} {\bf{2pq}} = frequency of heterozygous genotype (Aa) \{\{nl\}\} {\bf{q\textasciicircum{}2\textasciicircum{}}} = frequency of homozygous recessive genotype (aa)} \tn 
% Row Count 7 (+ 4)
% Row 3
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{p + q = 1}}} \tn 
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% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{p}} = frequency of dominant allele \{\{nl\}\} {\bf{q}} = frequency of} \tn 
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% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Worked example:}} Haemochromatosis is caused by a recessive allele. In one country, every 1 in 400 people have haemochromatosis. What percentage of the population is a carrier for the haemochromatosis recessive gene?} \tn 
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% Row 6
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\mymulticolumn{2}{x{5.377cm}}{{\emph{The data given to us is the proportion of homozygous recessive individuals, so q\textasciicircum{}2\textasciicircum{}.\{\{nl\}\}Therefore, q\textasciicircum{}2\textasciicircum{} = 1/400 = 0.0025.}}} \tn 
% Row Count 18 (+ 3)
% Row 7
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1. Use the information given to work out other values. \{\{nl\}\}{\emph{If we know q\textasciicircum{}2\textasciicircum{}, then we can find q then p.}} & √q\textasciicircum{}2\textasciicircum{} = q \{\{nl\}\} √0.0025 = {\bf{q = 0.05}} \{\{nl\}\} p+q = 1, therefore p + 0.05 = 1\{\{nl\}\} 1-0.05 = {\bf{p = 0.95}} \tn 
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% Row 8
\SetRowColor{LightBackground}
2. Substitute for answer & Carriers = heterozygous, so 2pq \{\{nl\}\} 2x0.95x0.05 = 0.095 \{\{nl\}\}0.095x100 = {\bf{9.5\%}} \tn 
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\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{The Hardy-Weinberg principle does make assumptions which could make it inappropriate to use for some contexts. It relies on: \newline - A large population. \newline - Random mating. \newline - No natural selection. \newline - No migration / gene flow. \newline - No mutations.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Types of selection}}  \tn
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\mymulticolumn{1}{p{5.377cm}}{\vspace{1px}\centerline{\includegraphics[width=5.1cm]{/web/www.cheatography.com/public/uploads/anais-pe_1718124532_types-of-selection_med.jpeg}}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.84149 cm} x{3.13551 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Speciation}}  \tn
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\mymulticolumn{2}{x{5.377cm}}{Creation of new species. A group gets reproductively isolated from the population (cannot breed together) and develop differences in gene pools.} \tn 
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% Row 1
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{\emph{Allopatric speciation}} & Become geographically isolated (e.g. new mountain range). Evolve separately through natural selection, accumulate mutations. \tn 
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% Row 2
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{\emph{Sympatric speciation}} & Occupy same area but behaviours change so don't breed together. \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
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\begin{tabularx}{5.377cm}{x{1.69218 cm} x{3.28482 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Genetic drift}}  \tn
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\mymulticolumn{2}{x{5.377cm}}{Change in allele frequency in population. Impacts are greater in smaller populations.} \tn 
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% Row 1
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\mymulticolumn{2}{x{5.377cm}}{{\bf{Factors that can lead to genetic drift are:}}} \tn 
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% Row 2
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{\emph{Genetic bottlenecks}} & Event (e.g. natural disaster, overfishing...) kills off most of a population, leaving a few survivors behind (small gene pool). \tn 
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% Row 3
\SetRowColor{white}
{\emph{Founder effect}} & A few individuals (small gene pool) first colonise an area, isolated from original population. Can even make rare homozygotic recessive phenotypes more frequent. \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
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\begin{tabularx}{5.377cm}{x{1.74195 cm} x{3.23505 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Natural v. Artificial selection}}  \tn
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{\emph{Natural selection}} & Evolution. Variety in phenotypes due to genetic bad environmental factors. \tn 
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% Row 1
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{\emph{Artificial selection}} & Humans select desirable features and breed those individuals together. \tn 
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% Row 2
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 & {\bf{Ethical concern: }}due to selected features, some animals (e.g. pugs) will have medical issues. \tn 
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\end{tabularx}
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Genetic banks}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Gene banks store DNA from plants or animals.} \tn 
% Row Count 1 (+ 1)
% Row 1
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\mymulticolumn{1}{x{5.377cm}}{Selective breeding often involves inbreeding, so gene banks can be used to reduce this and increase genetic diversity of a species.} \tn 
% Row Count 4 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}