B14.1 - 14.7 - Variation And Evolution✔️ Flashcards
Define variation?
Is the difference in the characteristics of individuals in a population
Define natural selection?
Natural selection is a process where organisms that are better adapted to an environment will survive and reproduce
How do mutations impact organisms?
Mutations can take place when a cell divides and is a result of a change in the DNA code - some mutation are harmful and can result in the organisms death very rarely a mutation produces an adaption that makes the organism better suited to its enviorment
State 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 - evolution through natural selection produces changes in the inherited charcteristics of a population over time
Summarise evolution?
-individual organisms within a particular species may show a wide range of phenotype and genetic variation
-individuals with characteristics most suited to the enviorment are most likley to survive
-the alleles that have enabled these individuals to survive are then passed on to the next generation
How can a mutation lead to a change in species?
Rarely a mutation leads to a new phentotypes - If the new phenotype is suited to an enviormental change it can lead to a relatively rapid change in the species
4 Uses of selective breeding?
-disease resistance in food crops
-animials that produce more milk or meat
-domestic sogs and farm animials with a gentle nature
-large,unsual,bright,heavlt scented flowers
How does selective breeding work?
Farmers select animials from a mixed population that have useful or desirable characteristics they breed these animials together and select the offspring that best show these characteristics this continues over many generations
3 factors that may result in variation?
- genes that they have inherited
- conditions in which they have developed
- combination of genes and the enviorment
What can cause a rapid change in species?
Very rarely mutations will lead to a new phenotype - if a new phenotype is suited to an enviormental change it can lead to a relativley rapid change in the species
How can new species be formed?
If two populations of one species become so different in phenotype (observable characteristics) that they can no longer intebreed to produce fertile offspring they have formed two new species
Define evolution?
Change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species
Define selective breeding?
Process where humans artificially select the plants or animials to breed for desired genetic characeteristics eg crops that are disease resistant
What does selective breeding involve - explain the process?
Involves choosing parents with the deired characteristics from a mixed population - they are bred together - offspring that best show the desired characteristics are bred together this repeats over many generations - until all offspring show the desired characetristics
Explain in 4 steps the process of selective breeding?
1)from existing stock, select the ones which best display desired characetristics
2)breed them together
3)select the best of the offspring and breed them together
4)continue process over many generations - until the desired trait gets stronger
Give 4 desireable characteristics which can be obtained through selective breeding?
- disease resistance crops
- animials which produce more meat or milk
- domestic dogs with gentle nature
- large or unusual flowers
What is an issue with selective breeding?
Can lead to “inbreeding” where some breeds are particularly prone to disease or inherited defects - this is a result of a limited gene pool
Why can the arise of a new disease be dangerous to a poputaion produced through selective breeding?
Lack of gene pool and decreased variation will mean if one of them are killed by a new disease most of them are going to be killed aswell
Define genetic engineering?
A process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
Describe the process of genetic engineering?
1) useful gene is isolated from another organism’s genome using enzymes and is inserted into a vector
2) vector is usually a virus or a piece of circular DNA found in bacterial
3) vector is used to insert the gene to the target organisms cells - so they develop with desired characteristics
2 examples where genetic engineering has been used?
- plant crops engineered to be resistant to disease or produce bigger better fruits
- bacterial cells engineered to produce substances like human insulin
Issues with GM (genetically modified) crops?
- will affect the number of wild flowers which will reduce population of insects
- may be issues on human health through eating them
- transplanted genes may get into natural enviorment - herbecide resistance genes could be picked up by weeds creating ‘superweeds’
How can GM crops be used to help poorer people?
GM crops could be engineered to contain the nutrients missing for example golden rice is a GM crop that can help reduce blindness by providing needed vitamins
What is tissue culture?
Mordern way of cloning plants - by using small groups of cells from part of a plant to grow identical new plants - important for preserving rare plant species
What is cuttings technique used for?
Older and simpler method of producing many identical new plants from a parent - used by gardeners
What is embryo transplant?
Process of splitting apart cells from a devloping animial embryo before they become specialised , then transplanting the identical embryos into host mothers
Explain process of making cow clones through embryo transplants?
- sperm cells taken from best male cow and the eggs are taken from best female cow
- sperm is used to artificially fertelise an egg cell and the embryo that develops is then split many times to form clones
-cloned embryos can be implanted into lots of other female cows where they grow into baby calves
- hundreds of ideal offspring can be produced every year
Explain the process of adult cell cloning?
nucleus is removed from an unfertilised egg cell - nucleus from an adult body cell, such as skin cell is inserted into egg cell - an electric shock stimulates egg cell to divide to form an embryo - these embryo cells contain same genetic information as the adult skin cell - when embryo has developed into ball of cells it is inserted into womb of adult female to continue development
What are some issues with cloning?
- reduced gene pool, increases chance of a population all getting wiped out from a disease
- cloned animials might not be as healthy as normal ones
- could lead to human cloning in the future
