1)which of the following is a source of genetic variation
i. mutations
ii. polygenic traits
iii. genetic shuffling that results from sexual reproduction
a. i only
b. i and iii only
c. ii and iii only
d. i, ii and iii

The answer is; B

Mutations change the order of nucleotide and therefore affects codons that code for proteins. A different protein is thus produced from the wild type hence creating variations.  Genetic shuffling in sexual reproduction, also called gene recombination occurs during meiosis and also when different organisms exchange genetic material such as in bacteria.  

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what do the different brain waves do?

explanation:

brainwaves are produced by synchronised electrical pulses from masses of neurons communicating with each other. brainwaves are detected using sensors placed on the scalp. brainwave speed is measured in hertz (cycles per second) and they are divided into bands delineating slow, moderate, and fast waves.