B1.7 Genetic variation and its control Flashcards
What is variation within a species?
Differences in characteristics in organisms in the same species
What can differences in characteristics be due to?
The genes they have inherited (genetic causes), the conditions in which they have developed (environmental causes)
What does the nucleus of a cell contain?
Chromosomes
What do chromosomes carry?
Genes
What do genes control?
The characteristics of the body
What do different genes control?
The development of different characteristics of an organism
Why do plants and animals have similar characteristics to their parents?
Characteristics are determined by genes inherited from their parents
What does the combination of genes from both parent cause?
Genetic variation
What is environmental variation?
Any difference that has been causes by the conditions something lives in
What are some example of a mixture of genetic and environmental variation?
Body weight, height, skin colour, condition of teeth, academic or athletic prowess
How many chromosomes does the nucleus contain?
23 pairs
What does DNA from?
Chromosomes
What is the name of different forms of the same gene?
Alleles
What are the two types of reproduction?
Sexual and Asexual
What does sexual reproduction involve?
Two parents
How many chromosomes does a gamete contain?
23 (half the number of a normal cell)
What is sexual reproduction?
The joining (fusion) of male and female gametes
What does sexual production lead to?
The mixture of genetic information from two parents resulting in variety in the offspring
How many parents are there in asexual reproduction?
One
Is there any mixing of genetic information in asexual reproduction?
No
What are the individuals produced by asexual reproduction?
Genetically identical to the parent (clones)
What are the two ways of cloning plants?
Plant cuttings and tissue culture
How can plants be produced quickly and cheaply?
Taking cuttings
What do gardeners take cuttings from?
Good plants so that the plants produced will be genetically identical to a good plant
What is tissue culture?
Where a few plant cells are put into a growth medium with hormones and they grow into new plants, clones of the parent plant
How can tissue culture be made?
Very quickly in very little space and grown all year
What are embryo transplants?
The production of cloned offspring using embryo transplants
What are the processes of embryo transplants?
Sperm cells are taken from the desired male and egg cells from the desired female. The two are then fertilised. The embryo that develops is then split many times (to form clones) before any cells become developed. These embryos can then be implanted into lots of other cows, each developing into genetically identical organisms
What does adult cell cloning involve?
The taking of an unfertilised egg cell and removing of its genetic material. A complete set of chromosomes from an adult body cell is then inserted into the empty egg cell. The egg cell is then stimulated by an electric shock, this makes it divide. When the embryo is a ball of cells its implanted into a adult female to grow a genetically identical copy
In genetic engineering, how can genes from the chromosomes of humans and other organisms be removed?
They can be ‘cut out’ by enzymes
What is an issue with cloning?
It results in a reduced gene pool
What is the problem with a reduced gene pool?
If the population are closely related and a new disease appears, they could all be wiped out as none of the population will have resistance to the disease
What do some believe the cloning of animals will result in?
The cloning of humans
When do scientists use the method of using enzymes to cut out useful genes?
The insertion of the insulin gene
Where else can useful genes be transferred to?
Animals and plants
When are useful genes transferred to animals and plants?
At the very early stages of development
Why do GM crops have their genes modified?
To make them resistant to viruses, insects and herbicides
What are the name of crops which have been modified?
Genetically Modified Crops
What is an example of a GM crop?
Crops which are resistant to insect attack or herbicides
What do GM crops generally show?
Increased yields
What are people concerned the GM crops will effect?
The population of wildflowers and insects and human health
What do some people think will happen due to changes in the numbers of weeds and flowers as a result of GM crops?
Decrease in farmland biodiversity
Why do some think GM crops are not safe?
They are worried people will develop allergies to the food
What do some people think will happen as a result of potential herbicide resistance?
A new ‘superweed’ variety
