Cloning

Question 1

What is vegetation propagation?

Answer 1

• The production of plant clones from non-reproductive tissues e.g roots, leaves and stems.
• It is a type of asexual reproduction and the new structures eventually differentiate from the plant.
• This can help plants survive one growing season to the next.

Question 2

What are the five types of natural vegetation propagation?

Answer 2

• Rhizomes
• Stolons/ runners
• Suckers
• Tubers
• Bulbs

Question 3

What is Rhizomes?

Answer 3

stem structures that grow underground horizontally away from the plant and new shoots & roots grow from nodes e.g bamboo.

Question 4

What is stolons/ runners?

Answer 4

structures that grow horizontally away from plant above ground. New shoots/roots are grown from node or at the end of stolon e.g strawberry plants

Question 5

What is suckers?

Answer 5

shoots that grow from undeveloped sucker buds on roots e.g elm tree

Question 6

What is tubers?

Answer 6

large underground food stores covered in ‘eyes’ from which new shoots grow e.g potato

Question 7

What is bulbs?

Answer 7

underground food stores in which new buds form internally and develop new plants e.g onions

Question 8

What are some advantages of natural vegetation propagation?

Answer 8

• Population can increase rapidly so can populate new areas/if area has been felled
• Only one parent needed- efficient
• Can allow plants to survive between growing seasons

Question 9

What are some disadvantages of natural vegetation propagation?

Answer 9

• Lack of genetic variation
• Can be prone to disease

Question 10

What are some examples of artificial vegetation propagation?

Answer 10

• Taking cuttings
• Tissue culture
• Grafting

Question 11

How to carry out grafting?

Answer 11

• A slit is cut in a wooden stem and another woody stem is placed into it.
• You must ensure that the xylem and phloem of the two plants are lined up and the wound is covered until it’s healed.
• This is often done with trees and shrubs to combine the best characteristics of the two plants. E.g making shorter fruit trees for gardens

Question 12

How to carry out taking cuttings?

Answer 12

• Cut the stem of a HEALTHY plant at a slant
• Dip into rooting powder
• Plant into a pot containing soil and water.
• Set up in a warm, moist environment to reduce transpiration e.g in a propagator/ cover in plastic bag
• Re-plant when roots are grown.

Question 13

How to carry out tissue culture?

Answer 13

• A small piece of meristem tissue (explant) is removed from the plant in sterile conditions to avoid contamination
• The sample is sterilised using a sterilising agent e.g bleach/ethanol
• The explant is placed on a sterile nutrient growth medium containing auxins and cytokines to stimulate mitosis.
• The cells divide to form a callus (a mass of undifferentiated cells).
• Single cells are removed from the callus and placed on a medium containing a different mixture of plant hormones to stimulate development of plantlets
• Once the cells have grown into tiny plants (plantlets) they are transferred into sterile soil. They are all genetically identical.
• They are then planted to grow and produce the desired crop.

Question 14

What are some advantages of taking cutting?

Answer 14

• Cheap and does not require specific skills
• Much faster than growing from seed
• Gives clones of plants with desirable characteristics

Question 15

What are some disadvantages of taking cutting?

Answer 15

• Lack of genetic variation in offspring
• Doesn’t make as many plants as tissue culture

Question 16

What are some advantages of tissue culture?

Answer 16

• Large numbers of identical crops always good yield
• Can make crops disease- free/ seedless
• Provides a way of growing lots of plants which are difficult to grow from seeds e.g orchids
• Can produce lots of rare/endangered plants
• Can happen at any time of year
• Can produce large numbers of GM crops

Question 17

What are some disadvantages of tissue culture?

Answer 17

• No genetic variation in offspring-> susceptible to disease/ climate change
• Expensive-> not suitable for small scale production
• Requires skilled workers
• Contamination can lead to getting rid of whole culture
• Non-desirable traits also passed on e.g fruit with lots of seeds

Question 18

What are the two methods of animal clonning?

Answer 18

• Artificial twinning
• Somatic cell nuclear transfer

Question 19

How is artificial twinning carried out?

Answer 19

• Eggs from cow with desirable traits and sperm from bull are collected. Eggs are fertilised in vitro to form an early embryo.
• Embryo split into totipotent cells
• Each totipotent cell develops into an embryo
• Embryos transferred to surrogate mothers
• Identical cloned offspring are produced

Question 20

How is somatic cell nuclear transfer carried out?

Answer 20

1. A somatic cell is taken from sheep A. The nucleus is extracted and kept
2. An oocyte is taken form sheep B. Its nucleus is removed to form an enucleated oocyte
3. The nucleus from sheep A is inserted into the enucleated oocyte - the oocyte from sheep B now contains the genetic information from sheep A
4. The nucleus and the enucleated oocyte are fused together and stimulated to divide by an mild electrical impulse. This produce an embryo
5. Then the embryo is implanted into a surrogate mother and eventually a lamb is born that’s a clone of sheep A

Question 21

Why would we need animal clones?

Answer 21

• Testing new drugs on cloned animals-> animals are all genetically identical so the variables that come from genetic differences( e.g the likelihood of
• getting cancer) are removed.
• Used in agriculture to increase the numbers of animals with desirable features to breed from.
• Can clone animals that have been genetically modified to produce a specific substance e.g goats producing beneficial proteins in milk-> Known as pharming
• To save endangered animals from extinction.

Question 22

What are some advantages for animal cloning?

Answer 22

• Desirable genetic characteristics are always passed on to clones
• Infertile animals can be reproduced
• Animals can be cloned at any time- not just breeding season
• Increasing population of endangered species gets to preserve biodiversity
• Can help develop new treatments for disease

Question 23

What are some disadvantages of animal cloning?

Answer 23

• Undesirable characteristics( e.g weak immune system) are also passed on to clones
• Reduce genetic variation- population all susceptible to same diseases
• SCNT is inefficient-takes many eggs to produce one clone
• Animals may have shortened lifespan
• Animals may fail to develop/ miscarry
• Expensive