B14(Variation And Evolution) Flashcards
What is variation
The differences in the characteristics of individuals in a population
Variation may be due to …
-Differences in the genes inherited
-The conditions in which organisms develop
What is the theory of evolution
All species of living things have evolved from simple life forms that first developed over 3 billion years ago
What is natural selection
-animals and plants are always in competition with other members of their own species
-Organisms that gain an advantage are more likely to survive and breed
What is the process of evolution
-individual organisms within a particular species show a wide range of phenotype and genotype variation
-individuals with characteristics most suited to the environment are more likely to survive to breed successfully
-the alleles that have enabled these individuals to survive are then passed on to the next generation
What is speciation
If two populations of one species become so different they can no longer interbreed to produce fertile offspring
Rarely mutations lead to a new phenotype if the new phenotype is …
Suited to an environmental change it can lead to a relatively rapid change in the species
What is selective breeding
Where humans breed plants and animals for desired characteristics
What are the desired characteristics of selective breeding
-disease resistance
-increased food production in animals and plants
-domestic dogs with a gentle nature
-heavily scented flowers
What are the problems with selective breeding
Defects in some animals due to lack of variation
What is genetic engineering
Genes can be transferred to the cells of animals and plants at an early stage of their development so they develop desired characteristics
What’s the process of genetic engineering
-Enzymes are used to isolate and cut out the required gene from an organism
-The gene is then inserted into a vector using more enzymes(the vector is usually a bacterial plasmid or a virus)
-The vector is then used to insert the gene into the required cells which may be bacteria,animal,fungal or plants
-Genes are transferred to the cells at an early stage of their development
-As the organism grows it develops with the new desired characteristics
What are crops that have their genes modified known as
GM Crops (genetically modified crops)
What desired characteristics do GM crops have
-improved resistance to insect attack or herbicides
-produce a higher yield
What is the process of cloning plants
-small tissue sample taken from parent plant
-tissue grown in agar with combination of nutrients and plant hormones to form big mass of tissue
-different mixtures of hormones and nutrients results in many tiny identical plantlets
-plantlets clones grow on
What is the process to clone animals
-use an early embryo
-divide each embryo into several individual cells
-each cell grows into an identical embryo in the lab
-transfer embryos into their host mothers which have been given hormones to ready them for pregnancy
-Identical cloned babies are born, they are nit biologically related to their host mothers
What is the process to clone adult cells
-The nucleus is removed from an unfertilised egg cell
-The nucleus is taken from an adult body cell
-The nucleus from the adult cell is inserted in the empty egg cell
-The new egg cell is given a tiny electric shock
-Which stimulates it to start dividing to form embryo cells
-When the embryo has developed into a ball of cells it is inserted into a womb of an adult female to continue its development
What are the benefits of adult cell cloning
save animals from extinction or bring back animal species that have died out
What are the risks of adult cell cloning
-ethical issues
-reduces variation
What are the benefits of genetic engineering
-improved growth rates of plants and animals
-increased food value of crops
-crops can be designed to grow well in different environmental conditions
-crops can be engineered to produce plants that make their own pesticide or are resistant to the herbicides
What are the disadvantages of genetic engineering
Ethical issues
