Biology Test (Inheritance,Variation,Evolution)

Biology Test (Inheritance,Variation,Evolution)

1. Genetic Modification

   • GM CROPS
     • Advantages
       • Crops grow faster
         • Can be used to produce more vitamins e.g golden rice
           • Can be made resistant to bacteria therefore increasing the amount of crop yield a farmer will make more money
             • Can stop insects from feasting on the weeds by inserting genes that produces a bitter taste which will ensure that they will not come back and feed off of those type of crops
     • Disadvantages
       • People can have allergic reactions to certain crops grew which have been genetically modified
         • Scientists are worried about genes getting into wider environments
           • Scientists are not sure about the health effects to humans
             • Scientists fear that excessive production of genetically modified foods that have toxin producing property will be rendered ineffective over time.
   • How does genetic modification work?
     • 1: A useful gene is isolated(cut) from one organism's genome using enzymes and is inserted into a vector plasmid.
       • 2: The vector is usually a virus or a bacterial plasmid depending on the type of organism that the gene is being transferred to.
         • 3: When the vector is introduced to the target organism, the useful gene is inserted into its cell(s).
           • 4: In some cases the transfer of the gene is carried out when the organism recieving the gene is at an early stage of development e.g (egg or embryo). This means that the organism develops with the characteristic coded for by the gene

2. Speciation

   • Why does speciation happen?
     • Isolation - where populations of a species can become seperated. e.g a physical barrier such as a flood or earthquakes
     • Genetic variation because of the wide range of alleles within the gene pools of the different species. As a result some individuals will have certain characteristics that allow them to have a better chance of survival within the wild
     • Speciation occurs when populations of the same species become so different that they can no longer succesfully interbreed to produce fertile offspring
   • What is speciation?
     • Speciation is the development of a new species
   • When was speciation recognised?
     • Theory made from Alfred Russel Wallace in 1858.

3. Meiosis

   • Result of SEXUAL Reproduction
   • Produces NON IDENTICAL CELLS
   • Meiosis halves the number of chromosomes in gametes and fertilisation restores the full number of chromosones

4. Mitosis

   • Produces IDENTICAL CELLS
   • Result of A-SEXUAL Reproduction

5. DNA

   • What is a genome?
     • the complete set of genes or genetic material present in a cell or organism.

6. Selective Breeding

   • Can be used to generate organisms that acquire certain characteristics
   • Selective breeding is where two animals/organisms are chosen to reproduce in order to generate an organism with a certain characteristic. This offspring will have the desired mutation