B1.7 Genetic Variation and its Control Flashcards
Where are chromosomes found?
In the nucleus of cells
What do chromosomes carry?
genes
What do genes do?
Control the characteristics of the body
Different genes control the development of…
different characteristics of an organism
What may differences of different individuals of the same kind be due to?
- genes they have inherited ( genetic causes)
- the conditions in which they developed (environmental causes)
- a combination of both
What are the 2 forms of reproduction?
sexual and asexual
Describe sexual reproduction
the fusion of male and female gametes. The mixture of the genetic information from 2 parents lead to variety in the offspring.
Describe asexual reproduction
No fusion of gametes
only 1 individual is needed as the parent.
There is no mixing of genetic information and so no genetic variation in the offspring. - clone
What 2 ways can plants be cloned?
Cuttings- take cutting from other plants- genetically identical.
Tissue Culture- Few plant cells are put into a growth medium with hormones
What are the 2 ways to clone animals?
embryo transplants
adult cell cloning
Describe an embryo transplant
Sperm and egg cel artificially fertilised
embryo is split many times forming clones, before any of the cells become specialised.
cloned embryos are implanted into host mothers
What are gametes?
sex cells
egg, sperm
Describe adult cell cloning
The nucleus is removed from an unfertilised egg cell and discarded. The nucleus from an adult body cell is inserted into the egg cell. An electric shock then causes the egg cell to begin to divide to form embryo cells. These embryo cells contain the same genetic information as the adult cell. When the embryo has developed into a few balls of cells, it is inserted into the womb of an adult female to continue its development.
What are some issues surrounding cloning?
- reduces the gene pool
- Worried humans may be cloned in the future
What are some benefits of cloning?
- Clones lead to a greater understanding of the development of an embryo and of age-related disorders.
- Cloning could be used to preserve endangered species
Describe genetic engineering
Genes from the chromosomes of humans and other organisms can be ‘cut-out’ using enzymes and transferred to cells of other organisms at an early stage of their development
Describe Genetically modified, GM, crops
Genes are transferred to the cells of plants at an early stage in their development so that they are developed with desired characteristics.
Why do farmers grow GM crops?
The crops are often resistant to insect attacks or herbicides therefore, there is an increase in yield
What are some concerns with GM crops?
- Uncertainty about effects of eating GM crops on human health.
- Worried will develop allergies for the food.
- affect the number of weeds and flowers and so population of insects that live around the crops, reducing biodiversity.
What are some benefits of GM crops?
- increase yield
- GM crop can be developed to contain nutrients that are missing in some people’s diets.
What is an advantage of spraying crops with pesticides?
protects crop from being eaten- so more yield produced- more money for farmer
What are some disadvantages of spraying crops with pesticides?
expensive
kills other insects which may not be pests
poisonous- could lead to death of a human
What is an economic advantage of using GM plants?
reduces the use of pesticides, which are expensive
increase crop yield
Should the government allow the production of milk from cloned ‘champion cows’?
- economic benefit - as increase in yield so more profit
- it is not proved that the milk is safe
- ethical/religious argument
- reduces the gene pool
