B14: Variation And Evolution Flashcards
What are three examples of a environmental aspect that might change you?
-getting a tan from the sun
-getting a scar
-dyeing your hair
What causes variation?
Genes and the environment
What is a mutation?
A change in the DNA code
What can a mutation do?
It affects the phenotype of the offspring and introduces new variants into the genes of a species.
What is the theory of evolution by natural selection?
All species of living things have evolved from simple life forms that first developed more than 3 billion years ago.
How does the process of natural selection work?
- individual organisms in a species show a wide range of variation.
-individuals with characteristics with the most suited to the environment are most likely to survive and breed.
-the alleles that let them survive are passed onto the next generation
What is selective breeding?
A process where humans breed plants and animals for desired characteristics.
How does selective breeding work?
Farmers/breeders select animals or plants that have useful of desirable characteristics. They breed them together and repeat the process with the offspring.
What features are desirable in certain organisms?
-disease resistance in crops/plants
-animals that make more meat or milk
-domestic animals with gentle nature
-large,brightly coloured or scented flowers
What are some problems with selective breeding?
- it reduces variation. If the environment changes, the whole population wont cope with the change.
-it poses ethical problems
What is genetic engineering?
Modifying the genetic material of an organism
How does genetic engineering work?
- enzymes are used to isolate and cut out the required gene.
-the gene is inserted into a vector (virus/bacteria) using more enzymes
-vector is inserted into required cells.
-genes are transferred in an early stage of development.
What are genetically modified crops?
Crops that have had their genes modified by genetic engineering.
Why is genetically modifying crops good?
Increases yield, increases resistance to herbicides
What does tissue culture allow you to do?
It lets you make thousands of plants from one tiny piece of plant tissue.
How is tissue culture carried out?
-use a mix of plant hormones to make a small group of cells from the plant you want to clone.
-produce a big mass of identical plant cells (a callus)
-using a mix of different hormones, you stimulate each cell to form a tiny new plant
How does cloning cattle embryos work?
- Divide each embryo into several individual cells.
- Each cells grows into an identical embryo in the lab.
- Transfer embryos into their host mothers, which have been given hormones to get them ready for pregnancy
- Identical cloned calves are born. They are not biologically related to their host mothers.
How does adult cell cloning work?
- Nucleus removed from unfertilised egg cell
- Nucleus is taken from adult body cell (e.g. skin cell)
- Nucleus from adult cell inserted into emoppty egg cell.
- New egg cell given tiny electric shock, stimulating it to start dividing to form embryo cells. They’ve got the same genetic info as og adult.
- When embryo had enveloped into ball of cells, its inserted into the womb of an adult female.
What are the benefits of adult cell cloning?
-helps produce large numbers of medically useful animals.
-can save animals from extinction
What are the risks of adult cell cloning?
-could lead to cloning of human babies.
-reduces variety in populations (makes them less able to survive in changes in the environment)
What are the benefits of genetic engineering?
-improved growth rates of plants and animals
-increased value of crops
-crops can be designed to survive in harsh conditions
What are concerns over genetic engineering?
-no one is sure of the long-term effects
-the effects of eating GM food on human health
-people wanting to manipulate the genes of their future children to make sure they’re healthy.
