22.1 Natural Cloning in Plants

Question 1

What is vegetative propagation?

Answer 1

form of asexual reproduction

new clone/plant grows

from fragment/cutting/specialised reproductive structure

of parent plant

Question 2

Name examples of plants where natural cloning/vegetative propagation occurs:

Answer 2

• BULBS
  
  • contain buds, each of which can give rise to new independent plant
• RUNNERS
  
  • roots grow from lateral stems when touches ground
• RHIZOMES
  
  • rhizome = specialised horizontal stem running underground
  • buds develop, forming independent plants
• TUBERS
  
  • tip of stem becomes swollen to form storage organ
  • buds develop on storage organ

Question 3

What can natural clones be used for & why?

Answer 3

horticulture

produce large quantities of genetically desirable clones

Question 4

What are the advantages & disadvantages of using vegetative propagation over seeds when culturing plants?

Answer 4

• ADVANTAGES
  
  • faster
  • guarantees desirable characteristics (since clone of parent plant)
• DISADVANTAGES
  
  • low genetic biodiversity since clones

Question 5

How can you increase the success rate of natural cloning by propagation of cuttings?

Answer 5

• use a non-flowering stem
  
  • flowers require energy to maintain, ∴ lower metabolic requirements
• make diagonal cut in stem
  
  • increases surface area for water absorption by osmosis
• hormone rooting powder (e.g auxin)
  
  • stimulates growth of roots
• remove all but 2-4 leaves
  
  • maintaining leaves requires energy, so removal decreases metabolic demands
• keep well watered
• cover cutting with plastic bag
  
  • increases humidity, decreases water potential gradient, less water lost by transpiration