B6 Inheritance v2 Flashcards
what important point did mendal note
that characterstics in plants were passed on from one generation to the next.
what was mendels three conclusions
hereditary units detemine charcteristics in plants. on unit is passed on from each parent. hereditary units can be dominant or recessive
what is the specific name for differences within a species
variation
why was mendel’s work not used straight away
scientists had not yet discovered genes and chromosomes
what are the two types of variation
genetic and environmental
what causes genetic variation and how?
different genes, mixed up during sexual reproduction between two parents
explain what is meant by environmental variation
the envrionment causing differences between memebers of the same species, such as a plant that does and doesn’t get much sunlight
what was Darwin’s main conclusions
“that only organisms with the most suitable characteristics to the environment would survive, known as ‘survival of the fittest’. the
organisms that survive would then pass on these survival characteristics to their offspring. overtime this causes evolution”
what is it called when a new species is formed and why is this?
speciation. Because a species has evolved so much because of natural selection and ‘survival of the fittest’
give three reasons a species may become extinct.
1- A new disease kills them all. 2- new preadator kills them all. 3- A sharp environmenal change
two reasons why Darwin’s discoveries were considered controversial
1- Contrasted to religious beliefs. 2- was the fist theory that didn’t suggest a ‘creator’. 3- lack of evidence to assist his conclusions
what did lamarck suggest
That the best survival charcterisitcs would not just be passed on, but improved.
what is selective breeding?
when humans artificially select plants or animals to breed so a population contains ertain characteristics
what is the main disadvantage of selective breeding?
it reduces the gene pool. meaning most offspring have similrt charcteristics which can lead to interbreeding
what two potential complecations can arrive from interbreeding
disease and health problems
what is the basic concept of genetic engineering?
to transfer a gene which contains a desirable charcteristic to another organism so it also contains that trait.
describe the process of genetic engineering
“gene is cut using an ennzyme and inserted into a vector (usually a virus). vector is then exposed to target organism which then leads
to the useful gene being inserted into its cells. “
2 concerns with GM crops
could reduce farmland diversity and unknown defeccts on human health
two benefits of GM crops
increased yield, can be used to provide people in poor contires with a nutritious diet.
define cloning plants with tissue culture
plants are put nto a growth medium with hormones and grow into new ones
describe cloning plants with cuttings
cuttings taken from desired parent plant. this is then planted
describe how you can make animal clones
using an embryo transplant. sperm fertilizes egg, embryo then develops and splits. these embryos are then planted into mother cows
describe adult cell cloning
“nucleas taken from an unfertilized egg cell and and a basic body cell, these both go into an empty egg cell which is then stimulated by
electric shock. As a result it then divides and is then impanted into the womb of an adult female. “
2 concerns with cloning
could cause health problems, religious objections
what are fossils
the remains of ancient organisms found in rocks
list three processes of fossilisation
gradual replacement by minerals, casts and impressions, preservations
what is speciation
the development of a new species
how does speciation occur
when populations of the same species have become so different they can no longer interbreed to produce fertile offspring
two specific ways speciation occurs
isolation and natural selection
what is a defect of interbreeding
more suseptible to diseases
describe how a fossil is formed
minerals gradually replace the organism over a long period of time.
