6.2.1 - a

Question 1

What is cloning?

Answer 1

• Asexual reproduction is an example of cloning resulting in offspring produced by mitosis that are clones (genetically identical to one another and the parent organism)

Question 2

What is vegetative propagation?

Answer 2

Vegetative Propagation: The artificial production of natural clones for use in horticulture and agriculture.

Asexual reproduction from vegetative parts of plants through specialised reproductive structures such as plants

Question 3

What are vegetative parts of plants?

Answer 3

• The totipotent cells are meristematic cells allowing an adult plant to form natural clones by vegetative propagation
• Vegetative parts of plants are perennating organs – allow plants to survive through harsh environmental conditions (winter)
  
  • Perennating organs contain stored food from photosynthesis that has enough energy to grow again post-winter

Question 4

What are 4 examples of natural cloning using vegetative propagation?

Answer 4

Bulbs

Tubers

Runners

Rhizomes

Question 5

How do bulbs naturally clone?

Answer 5

• Contain an underground stem and a ‘fleshy’ leaf base – which contains stored food reserve allowing a plant to survive during adverse winter months (when not photosynthesising)
• The bulbs have internal buds that develop into new shoots in the new growing season
  
  • The shoots develop into new individual plants from the meristematic cells of the bulbs – the new plants are clones of the parent/old plant
• E.g. a daffodil forms bulb, in the summer the daffodils die, in the spring the bulbs grow new shoots

Question 6

How does a tuber naturally clone?

Answer 6

• They are underground stems with stored food from photosynthesis – tubers are a storage organ
• The tubers contain buds which form shoots and eventually new individual cloned plants
• E.g. potatoes

Question 7

What is a runner and how does it naturally clone?

Answer 7

Runners – horizontal stems ABOVE the ground

• Some plants grow lateral stems away from the parent plant
• The horizontal stems above the ground are called runners
• The runner touches the ground, roots develop forming a new cloned plant, the runner stem dies away, and the new plant is completely independent
• E.g. strawberry plant, spider plant

Question 8

What is a rhizome and how does it naturally clone?

Answer 8

Rhizomes – horizontal stems running UNDERGROUND

• The plants grow lateral stems under the ground
• The new vertical buds develop into shoots that develop along the rhizome that develop into new plants
• Rhizomes often are storage organs with swollen food stores
• E.g. marram grass, ginger

Question 9

What are the uses of natural cloning in horticulture?

Answer 9

• Farmers split up bulbs, remove young plants from runners and cut rhizomes to increase crop numbers cheaply – the new plants are genetically identical to the parent
• Cuttings can also have rooting hormone applied to encourage root growth
  
  • Propagation from cuttings is advantageous over seeds because:
    
    • Time taken for the plant to crop is less
    • Guaranteed plant quality as if cuttings are taken from successful plants, the new plants will crop well
  • Disadvantage is lack of genetic variation – if a new disease/pest appears or there is significant climate change, the crop will not be adapted

Question 10

Describe the practical where plant cuttings are taken?

Answer 10

1. Take a non-flowering plant
2. Make an oblique (slanted) cut to the stem
3. Apply hormone rooting powder
4. Reduce the leaves to 2 or 4
5. Keep the cutting well waters
6. Cover the cutting with a plastic bag for a few days