Artificial cloning in plants

Question 1

How can scientists make huge numbers of clones from one plant?

Answer 1

• some cells are totipotent
  
  • they can differentiate into all the different types of cell in the plants
• scientist use this property to produce clones

Question 2

What is micropropagation?

Answer 2

• the process of making large numbers of geneticlaly identical offspring from a single parent plant using a tissue culture techniques

Question 3

WHen may micropropagation/tissue culture be used

Answer 3

• plant does not readily produce seeds
• plant does not respond well to natural cloning
• the plant is rare
• the plant has been genetically modified or selectively bred with difficult
• it is required to be ‘pathogen-free’ by growers

Question 4

Describe the process of micropropagation?

Answer 4

• take small sample of tissue
  
  • meristem tissue from shoot tips or axial buds are often dissected in sterile condition to avoid contamination by fungi and bacteria
• sample sterilised
  
  • immersed in sterilising agent, e.g. bleach, ethanol, or sodium dichloroisocyanurate
  • the latter does not need to be rinsed off whcih means the tissue will remain sterile
  • the material removed from plant is called the explant

Question 5

What happens with the explant after sterilisation?

Answer 5

• placed in sterile culture medium containing a balance of plant hormones
  
  • including auxin and cytokinins
  • stimulate mitosis
  • the cells proliferate, forming a mass of identical cells known as a callus
• callus divided
  
  • individual cells or clumps transferred to a new culture medium containg a different mixture of hormones and nutrients, which stimulkates production of tiny, genetically identical plantlets
• plantlets are potted into compost where they grow into small plants
• the young plant are planted out to grow and produce a crop

Question 6

What are the advantages of micropropagation?

Answer 6

• desireable genetic characteristic are always passed on to clones
  
  • not always when sexually reproduced
• tissue culture allows plants to be reproduced in any season cos evironment is controlled
• less space required by tissue culture than would be needed to produce the same number of plants by conventional growing methods
• produce lots of plants quickly compared to the time it would take to grow them from seeds

Question 7

What are tge arguments against micropropagation?

Answer 7

• cloned plant peopulation have little genetic variability
  
  • at risk fo disease and pest
• undesireable characteristics are always passed om
• production cos high
  
  • high energy use and training of skilled workers
• contamination by microorganisms can results in complete loss of plants being cultured