B1.7 Genetic variation and control Flashcards
What is continuous variation?
A characteristic that changes gradually over a range of values - e.g. height/weight
What is discontinuous variation?
A characteristic of any species with only a limited number of possible values - e.g. blood group/gender
How can we clone plants?
Cuttings (hormone rooting powder)
or
Tissue culture
Why do offspring resemble their parents?
Genetic information is passed on to them in the gametes (sex cells) from which they develop
What is genetic information made of and where is is found?
Found in the nucleus
Contained within genes
Made of DNA
Carried in units called chromosomes
How does adult cell cloning work?
> The nucleus is removed from a body cell (A)
The nucleus is removed from a mature ovum - (empty egg cell) (B)
The body cell nucleus is fused with empty egg cell (mild electric shock)
The cells start multiplying
The animal born is a clone of (A)
What are the advantages of cloning?
Can copy good aspects so that it is successful in its habitat
All the same/genetically identical plants in a garden
Prevent extinction
Help species to reproduce
What are the disadvantages of cloning?
Unethical (making God's decision) Puts befits into the hands of the rich Could drive up food prices Public perception Narrowing the gene pool
How does embryo cloning work?
> Divide embryo into several individual cells
Each cell grows into an identical embryo (in lab)
Transfer embryos into their host mothers (have been given hormones to prepare for pregnancy)
Identical clones are born. Not biologically related to their mothers
What are the advantages of genetic engineering?
Can make needed proteins Improve growth rates Reduce fat levels in meat Lasts longer in supermarkets Help world hunger GM animals produce life-saving milk
What are the disadvantages of genetic engineering?
Uncertain long term affects
May spread to wildlife
Pesticide resistance
GM crops are often infertile - new seeds each year (hard for the poor)
Potential human manipulation/designer babies
Advantages of sexual reproduction
> allows for adaptation
sexual selection
survival of fittest
varation
Disadvantages of sexual reproduction
> needs energy investment
relies on another mate
relies on pollinators
Advantages of Asexual reproduction
>does not rely on another individual >useful for low population densities >increase chances of success >if contains 'good' genes will be successful >no flowers - saves energy
Disadvantages of Asexual reproduction
> no variation
hard to adapt
if contains a ‘weak’ gene it will be passed on
