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• What is variation in biology?

  Differences in individual characteristics
• The two causes of variation within a species are genetics and environment
• Genetic variation arises from differences in genotypes due to different alleles.
• What are the two primary sources of genetic variation in a species?

  Spontaneous mutations and sexual reproduction
• A mutation is a random change to the base sequence in DNA
• Name three types of gene mutations.

  Insertion, deletion, substitution
• A neutral mutation does not change the amino acid sequence of a protein.
• Outline the steps of natural selection according to the theory.

  1️⃣ Genetic variation exists due to spontaneous mutations

  2️⃣ Selection pressures such as competition or disease exist

  3️⃣ A random mutation gives an organism a selective advantage

  4️⃣ The organism is better adapted and survives

  5️⃣ The organism reproduces, passing on beneficial alleles

  6️⃣ Frequency of advantageous alleles increases
• What condition must two populations meet to become different species?

  Inability to interbreed
• Selective breeding is a process where humans artificially select organisms with desirable characteristics
• Give three examples of characteristics selected for in selective breeding.

  Disease resistance, milk production, large flowers
• Selective breeding reduces the gene pool of a species.
• What is genetic engineering?

  Modifying an organism's genome
• One use of genetically modified plants is to produce larger fruits
• What is a use for genetically modified bacteria cells?

  To produce human insulin
• The long-term effects of consuming genetically modified crops are fully understood.

  False
• Crops that have had their genes modified are called genetically modified (GM) crops
• What is Bacillus thuringiensis (Bt)?

  A bacterium that secretes a toxin
• Describe the process of genetic engineering in four steps.

  1️⃣ DNA is cut at specific base sequences by restriction enzymes

  2️⃣ Vector DNA is cut using the same restriction enzymes

  3️⃣ Ligase enzymes join the sticky ends of the DNA and vector DNA

  4️⃣ Recombinant DNA is taken up by target cells
• What is a vector in genetic engineering?

  A structure that delivers genes
• Plant cloning can be achieved using cuttings or tissue culture.
• Tissue culture involves using small groups of cells to grow identical new plants
• Describe the steps of growing plants using tissue culture.

  1️⃣ Select a plant with desired traits

  2️⃣ Cut small sample pieces from meristem tissue

  3️⃣ Grow in a petri dish with growth medium

  4️⃣ Transfer to compost for further growth
• What does the growth medium in tissue culture contain?

  Nutrients and growth hormones
• Tissue culture is a fast and simple method for cloning plants.
• What is the plant cuttings method of cloning plants?

  Using a branch to grow a new plant
• In the plant cuttings method, the lower leaves of the branch are removed and the stem is planted
• Adult cell cloning involves inserting the nucleus of a body cell into an unfertilized egg.