Mutation

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2

All the spindle fibres in a gamete mother cell fail

All homologous pairs fail to become separated

Production of abnormal diploid gametes

Each contains 2 complete sets of chromosomes instead of one

Slide 16

Polyploidy

Fertilisation of abnormal gametes

Formation of mutant plants which possess complete extra sets of chromosomes

This type of chromosome mutation is called polyploidy

Slide 17

A: the strawberry plant is exposed to a chemical

B: due to the effect of chemical, total non-disjunction at meiosis produces diploid gametes(2n)

C: two diploid gametes fuse at fertilisation

D: a new plant develops which has four sets of chromosomes (4n)

Slide 18

Economic significance

Polyploid plants are larger than diploid relatives

Increased seed and fruit size

Many commercially developed crop plants are polyploid

-apples -strawberries

-tomatoes -wheat

Give greater yields

Slide 19

Effects of polyploidy

Uneven sets of chromosome

-polyploidy plants are sterile

Produce seedless fruit

Increase in vigour

Resistance to disease