manipulation of food species Flashcards
what are the ways food species can be manipulated
1) population control
2) control of genetics
3) agricultural energetics
outline how population control of optimum density can be used to manipulate food species
1) optimum livestock or crop density- increasing pop density can increase total yield although yeild per individual may be reduced due to interspecies competitions
a high density can increase the risk of the rapid spread of disease
outline population control using monocultures
involves the cultivation of a single species often over a large area
this increase ease as larger machinery can be used
but it lets the spread of disease and pests occur rapidly if they colonise
list the ways genetics can be controlled
1) asexual reproduction
2) sexual reproduction
3) genetic engineering
outline how asexual reproduction in plants can be used to control genetics
1) taking cuttings where new plants are produced from sections of a leaf,stem or root tissue from a parent plant
2) this produces genetically identical offspring so characteristics are predictable and survival rate is high
3) there is no genetic variation so characteristics cant be improved
outline how asexual reproduction can be used in animals to control genetics
1) cloning
2) cells are removed from the donor and grown in a culture
3) the egg is removed from the female and the nucleus is removed and replaced by nucleus of one of the donor cells
4) egg implanted into surrogate mother
5) allows the replacement of valuable animals if they die
6) herds culled by disease can be replaced with genetically identical ones
7) large numbers of individuals with desirable characteristics produced
list the ways sexual reproduction can be used to control genetics
1) selective breeding
2) crossing breeding
3) artificial insemination
4) embryo transfer
outline selective breeding
the production of offspring from parents that were chosen due to genetic characteristics
1) breeding between genetically similar individuals may produce offspring with similar characteristics
2) there is an increased risk fo inbreeding
outline cross breeding
1) the breeding of two different parental breeds producing a combination o desirable characteristics with hybrid vigour decreasing the risk of inbreeding
outline artificial insemination
semen collected from male with desirable characteristics is used to impregnate females
1) allows more young to be produced than by natural mating
2) easier transport
3) can be stored so offspring produced long after male has died
outline embryo transfer
1) hormone FSH used to stimulate ovulation and release of many eggs by female
2) eggs washed out of the uterus and collected
3) eggs are then fertilized by sperm cells from males with desirable characteristics
4) each fertilised embryo is implanted into different surrogate females
5) multiple embryos produced
what are the advantages of genetic modification
1) single wanted characteristics can be introduced without having to be associated with unwanted ones like in normally selected breeding
2) genes may be introduced from other species
3) can increase resistance to specific insects reducing the amount of pesticide needed
4) increase pathogen resistance
what are the disadvantages of genetic modification
1) claimed it can increase food allergies
2) transfer through the food chain
3) increased cost to farmers
4) concerns that they will reduce local native crop diversity including successful seed saving practices
5) potential gene transfer from GM food to cells of body or to bacteria in the gut
