plant and animal cloning

Question 1

what is a clone, what process produces cells that are clones, give examples

Answer 1

-cells or organisms which are genetically identical,
-mitosis
-natural clones:
-prokaryotes = bacteria by binary fission
-eukaryotes = yeast by budding
-plants= vegetative propagation
-animals = identical twins, asexual reproduction e.g water flea

Question 2

what are advantages and disadvantages of natural clones

Answer 2

advantages
-relatively rapid
-requires only one parent
-a parent suited to the environment will produce offspring also suited
-rapid repopulation of woodland by elm suckers after felling

disadvantages
-potential overcrowding
-no genetic diversity = susceptible to pests and disease
-no variation in phenotypes and so no natural selection
-environment change will put whole population at risk

Question 3

what is vegetative propagation and give examples

Answer 3

reproduction from vegetative parts (cells not terminally differentiated, with some ability to become other cell types) instead of reproductive structures

plants produce clones from:
-runners, stolons, rhizomes, suckers, bulbs, corms, leaves

Question 4

how are plants cloned artificially

Answer 4

-by taking cuttings from different parts of the plant e.g:
-stem = cuttings between leaf (at nodes) placed in moist soil will grow roots from stem tissue, some require rooting hormone or removal of bark near cut end to stimulate root growth
-root cuttings = may produce new shoots
-scion cuttings = section of woody twig
-leaf cuttings = leaves placed in moist soil develop new stem and roots

Question 5

what are explants what are they grown in and what can be added to the agar to stimulate cell division and differentiation

Answer 5

cells or tissues removed from plant encouraged to grow into cells, tissues organs or whole new plants
-grown on sterile nutrient medium
-plant growth substances (auxins and cytokinins) stimulate cell division and differentiation

Question 6

explain the steps of micropropagation of plants using tissue culture

Answer 6

Small tissue samples (explants) are taken from a parent plant to start the micropropagation process.
Explants are typically taken from the stem and root tips as they have meristem cells.
Meristem cells are totipotent so can differentiate into any type of plant cell.

Sterilisation
The explant’s cells are sterilised to remove and inhibit the growth of contaminants such as bacteria and fungi=reduces the risk of widespread infection, helps to produce healthier crops.

Culture
The sterilised explant cells are then cultured on a nutrient-rich medium.
The medium supplies minerals, sugars, vitamins, and growth hormones like auxins that support rapid cell division and growth. (Agar plate)

Development
The cells in each explant divide to form an undifferentiated mass of cells called a callus.
The callus cells are transferred to a new medium with specific conditions to encourage shoot and root formation.
This allows the callus cells to differentiate and develop into plantlets.

Transfer
Fully formed plantlets, complete with shoots and roots, are moved to a growth medium like soil.
There, they can develop into mature plants that are identical to the parent plant.

Question 7

what are the advantages and disadvantages of artificial plant cloning

Answer 7

advantages:
-relatively rapid
-only one parent required
-useful for plants that no longer breed sexually
-all display same desired characteristic
-use of apical bud meristem means plants are virus free
-all have same phenotype so can be harvested in same conditions

disadvantages
-labour intensive
-expensive facillities
-risk of microbial contamination
-clones susceptible to pests, disease
-no genetic variation except when arising from mutation