inheritance, variation, and evolution Flashcards
what is the male and female gametes in flowerng plants?
male - pollen grains
female - egg cells
what are the advantages of sexual reproduction
- produces genetic variation in offspring
- if the environment changes, variation gives a survival advantage by natural selection
- natural selection can be speeded up by humans in selective breeding to increase food population
what are the advantages of asexual reproduction?
- only one parent needed
- more time and energy efficient as do not need to find a mate
- faster and takes less time than sexual reproduction
- many identical offspring can be produced when conditions are favourable
- successful traits passed on due to offspring being genetically identical
what are the disadvantages of asexual reproduction?
new disease could wipe out whole population of species as all offspring are clones/genetically identical
what are the advantages of sexual reproduction in plants?
-genetic variation in offspring
so better adapted to survive
and colonise new areas by seed dispersal which produces more offspring
so since there are many offspring there is a higher probability some will survive
what are the advantages of asexual reproduction in plants?
- no transfer of gametes or seed dispersal
- not wasteful of flowers or pollen or seeds
- colonisation of local area
how are gametes produced and what are they needed for?
gametes are produced my meiosis and are needed for sexual reproduction
describe the process of meiosis
?
what are the differences between mitosis and meiosis?
- mitosis produces two daughter cells but meiosis produces four daughter cells
- once cell division in mitosis but two cell divisions in meiosis
- mitosis produces cells with two of each chromosome but meiosis produces cells with one of each chromosomes
- mitosis produces genetically identical cells but meiosis produces genetically different cells
what are the similarities between mitosis and meiosis?
- DNA replicates once
- increase in the number of mitochondria/ribosomes/ sub-cellular structures
how is a particular protein made?
- a sequence of three bases is the code for a particular amino acid
- the order of the bases control the order in which amino acids are assembled to make a particular protein
- the long chain of amino acids fold up to make a particular protein
- each protein has a different sequence of amino acids, so has a unique shape to carry out a particular function
what is a gene
a small section of the DNA that codes for a particular sequence to make a specific protein
what are benefits of understanding the human genome?
- diagnosis of inherited/genetic disorder
- gene therapy or treatment of inherited disorders
- understanding human evolution or ethnic origins of a person or understanding ancestry
- tracing human migration patterns
- search for genes linked to disease
explain how a change in one amino acid in an enzyme molecule could stop the enzyme working
- different protein made
- active site changed
- so substrate does not fit
