What is a gene?
A gene controls the characteristics of your body.
A gene is part of a chromosome that codes for one particular protein which makes up a characteristic.
What are gametes?
Gametes are sex cells that contains a single set of chromosomes, as opposed to body cells which have chromosomes in pairs.
Describe the characteristics of asexual reproduction.
Asexual reproduction requires only one parent therefore offspring are genetically identical (clones). Sex cells are not involved in asexual reproduction. It uses mitosis.
Describe the characteristics of sexual reproduction.
Sexual reproduction involves two parents and sex cells- in animals the sex cells are eggs and sperm. Offspring produced by sexual reproduction are genetically similar to their parents, but not identical and because there is a mixing of genetic information, the offspring vary.
Why are there differences in the characteristics of individuals in the same species?
Differences may be due to their genes, environment or both. Clones may have differences due to environmental causes.
Describe a cheap and a more expensive way of cloning plants.
Plants can be cloned cheaply by taking cuttings and growing them. It is not labour intensive but it takes a long time.
Plant tissue culture is more expensive but can be used to reproduce large number of a rare or top quality plant. It takes less time but is labour intensive because it must be kept sterile.
Describe briefly the process of embryo cell cloning.
In this process an embryo with unspecialised cells is divided into smaller groups of cells. Each group of genetically identical cells is transplanted back into a surrogate and allowed to develop.
Describe briefly the process of adult cell cloning.
The nucleus of an adult cell replaces the nucleus of an egg cell. The new cell is given a mild electric shock which causes it to divide and form an embryo. Embryo is inserted into uterus of host mother. Embryo is genetically identical to adult cell.
Suggest some advantages and disadvantages of adult cell cloning.
A- cloning could save animals from extinction.
A- make copies of best animals e.g: race horses.
D- concerns about ethics of cloning.
D- cloning limits variation in gene pool➡️problem for natural selection if environment changes.
D- concerns about using technique to clone humans in future.
DNA is the genetic instructions used in the development and functioning of all living organisms.
Define genetic engineering.
Genetic engineering is taking a gene from one organism and transferring it to another.
How does genetic engineering work?
The desired gene for the desired characteristic is 'cut' out of the chromosome using a restriction enzyme. The gene is then placed in the chromosome of another organism.
*Genes are transferred at an early stage of development*
Suggest some advantages and disadvantages to GM crops.
A- crops can be made to be insect or herbicide resistant➡️reduce need for harmful insecticides.
A- GM crops usually have increased yields➡️more food for growing/starving population.
A- possibility of gene therapy (treating genetic disorders like cystic fibrosis).
D- crops are infertile so farmers must buy new seed every year and seed is expensive.
D- genetic engineering is against 'God and nature'.
D- worry about affect of eating GM crops on human health.
D- risk that pollen from GM crops may spread to wild crops.
What is sexual reproduction?
Fusion of sex cells.
Suggest one advantage of trying to preserve endangered species.
-Maintaining food chain/ecosystem.