variation & evolution

• What is variation?


  The differences in characteristics of individuals in a population
• Give three factors that can cause variation in a species

  1. Inherited genes.

  2. environmental conditions.

  3. A combination of genes and environment
• Where do variants in genes arise from?

  Mutations
• What is a mutation?

  A change in the base structure of DNA
• What effect can mutations have?

  Most have no influence on phenotype, some are harmful, some are beneficial
• What is evolution?


  A change in the inherited characteristics of a population over time through a process of natural selection
• What does the theory of natural selection state?

  All species of living things have evolved form simple life forms that first developed more than 3 billion years ago
• How did natural selection happen?

  There is natural variation in a species. A selection pressure occurs. The best adapted organisms survive for longer and reproduce more. Their offspring inherit the beneficial characteristics
• What is a species?

  Organisms that can breed together to make fertile offspring
• What is selective breeding?

  Breeding plants or animals for specific genetic characteristics
• How is selective breeding carried out?

  Choose the parents with the desired characteristics and breed them together. Choose the offspring with the desired characteristics and breed them. Continue this over many generations.
• Give 4 reasons that selective breeding may be used

  1. disease resistance crops.

  2. improved yield.

  3. Domestic dogs with a gentle nature.

  4. Large or unusual flowers.
• What is a negative of selective breeding?

  It leads to a build up of harmful recessive alleles
• What is genetic engineering?

  A process which involves modifying the genome of an organism by introducing a gene from another organism wit the desired characteristic
• Give two reasons that plant crops have been genetically modified

  Disease resistance, bigger and better fruits
• Give 1 reason why bacterial cells have been genetically modified

  To produce insulin
• What concerns are there about GM crops?

  They could effect the wild flower and insects. There impacts on human health have not been studied
• How is medical research trying to use genetic engineering?


  Treat or overcome some genetic illnesses
• How is genetic engineering carried out?

  The required gene is isolated and inserted into a vector, usually a plasmid or virus. The vector is used to insert the gene into the required cells.
• Who discovered the theory of natural selection?

  Charles Darwin
• Give two pieces of evidence for natural selection

  Fossils and antibiotic resistance in bacteria
• Give three ways that fossils can be formed

  1. From parts of organisms that have no decayed because one or more of the conditions needed aren't met.

  2. When parts of the organism are replaced by minerals as they decay.

  3. As preserved traces of organisms such as footprints, burrows and rootlet traces
• Why can't we be certain about how life on earth began?

  Many early organisms were soft-bodies, which means they left few traces behind. They may have been destroyed by geological activity.
• What can we learn from fossils?

  How much or little organisms have changed over time
• What is extinction?


  When there are no remaining individuals of a species still alive
• What factors may lead to extinction?

  Destruction of habitat, disease
• How are antibiotic resistant bacteria formed?

  Mutations in bacteria create new strains, these bacteria are resistant to the antibiotics and so aren't killed. These bacteria survive and reproduce, their offspring will inherit the resistant gene.
• Why do bacteria evolve rapidly?

  Because the reproduce at a fast rate
• Give three ways that we can reduce the amount of antibiotic strains?

  1. Doctors should prescribe antibiotics inappropriately

  2. patients should complete their course of antibiotics

  3. the use of agricultural antibiotics should be reduced
• Who designed the way that we classify organisms?

  Linnaeus
• What is the order of classification?

  Kingdom, Phylum, Class, Order, Family, Genus, Species
• How do we name organisms?

  Binomial naming system
• Why have new models of classification been identified?

  Improvements in microscopes and the use of DNA evidence has given us new information about organisms
• Who developed the three domain system of classification?

  Carl Woese
• What are the three domains?

  Archeae. Prokaryota, Eukaryota
• What do evolutionary trees show?

  They show how organisms are related