Variation and reproduction Flashcards
What are the two types of variation?
Genetic and environmental
What causes genetic variation?
A combination of both parent’s genes
What are some examples of genetic variation?
Eye colour, blood group etc.
What are some examples of environmental variation?
Getting a tan, losing a toe in a piranha attack etc.
What are genes, chromosomes and DNA made from?
Chromosomes are found in the nucleus (humans have 23 pairs) which are made from genes, which control our characteristics, which are made from DNA
Explain sexual reproduction
Requires 2 parents with sex organs that make gametes (male have sperm, female have eggs), and each gamete has half the normal amount of chromosomes, and when the sperm fertilises the egg, the egg divides
Explain asexual reproduction
Requires only one parent, and the offspring are identical to the parent with the same genes, called clones
What is special about sexual reproduction?
It provides variation
How are plants cloned?
A cutting is taken from a plant and planted quickly and cheaply to make copies, or some cells are taken and grown with hormones to produce a copy
What is embryo cell cloning?
Sperm and egg cells are taken from parents with desirable characteristics, then the egg is fertilised by the sperm and grown into a ball of cells which can be split to make lots of clones (not clones of a parent but of each other)
What is adult cell cloning?
An egg is removed, and the nucleus removed from the egg, then a skin cell is removed from another creature and put in the egg, then it is given an electric shock to start cell division then it is planted into a surrogate mother
How do you do genetic engineering?
Cut a useful gene out of a chromosome with enzymes, then cut another organism’s chromosome and insert the useful gene, and close it up with enzymes
What are the pros and cons of genetic engineering?
Pros: solve problems
Cons: may make problems
What are the pros of GM crops?
They can increase the yield of a crop and scientists can add nutrients so that people in certain parts of the world can get all their nutrients
What are the cons of GM crops?
They affect biodiversity, their safety is unknown and harmful plants may develop
