1. COMPARING ASEXUAL AND SEXUAL REPRODUCTION
ABBOTTS

2. TOPICS Advantages and disadvantages of asexual reproduction
Advantages and disadvantages of sexual reproduction

3. PLANT REPRODUCTION
Is the ability of living organisms to produce a new generation of themselves
Important for survival and evolution of a species

4. TYPES OF REPRODUCTION

6. ASEXUAL REPRODUCTION Also called vegetative propagation
Production of a new generation of the same species by one parent
Takes place by mitosis
All new organisms are genetically identical to their parents and to each other
Such organisms are called clones

7. VEGETATIVE REPRODUCTION
STEMS
RUNNERS
Grow from the the stems of some plants eg strawberry and give rise to a new plant

8. STOLON
Long thin stems that go across the ground
Chlorophytum

9. VEGETATIVE REPRODUCTION
RHIZOMES
Underground stems with nodes that produce shoots and roots
Shoots develop into new plants
Eg kikuyu grass
STEMS

10. VEGETATIVE REPRODUCTION
BULBS
short underground stems surrounded by fleshy leaves that store nutrients
New swollen stems grow and develop from axillary buds
Eg onion
STEMS

11. VEGETATIVE REPRODUCTION
STEM TUBERS
swollen underground stems with stored nutrients
Buds are present that can sprout and to stems that develop into new plants
E.g. Potato

12. VEGETATIVE REPRODUCTION
ROOTS
VEGETATIVE REPRODUCTION
Suckers develop from
Roots and grow into new
plants

13. VEGETATIVE REPRODUCTION
ROOTS
VEGETATIVE REPRODUCTION
Root tubers are swollen roots
E.g. dahlia

14. VEGETATIVE REPRODUCTION
LEAVES
VEGETATIVE REPRODUCTION
New plants can develop directly from leaves
Eg Streptocarpus spp.
 Streptocarpus leaf cuttings

15. ARTIFICIAL VEGETATIVE REPRODUCTION
CUTTINGS
A piece of the plants stem is cut off below a bud
Placed in damp soil
Roots develop at the bottom
New plant develops
Eg carnation

16. ADVANTAGES OF ASEXUAL REPRODUCTION
Only one parent needed and all individuals can produce offspring
No special organs of reproduction are required (eg flowers)
The process is simple and fast – only mitosis involved
No outside agents such as pollinators are needed
Little energy is used (do not have to produce reproductive organs)

17. ADVANTAGES OF ASEXUAL REPRODUCTION
New plants are genetically identical
No variation
Successful varieties are maintained
Will be the same year after year good for commercial crops
Eg potatoes and strawberries

18. ADVANTAGES OF ASEXUAL REPRODUCTION
Asexual reproduction is useful in stable conditions
If the parent is well adapted to a particular environment the offspring also will be
A favourable mutation can spread rapidly, enabling a population to adapt quickly to any new environmental conditions
Mutation = change in a chromosome resulting in a new characteristic

19. ADVANTAGES OF ASEXUAL REPRODUCTION
By avoiding seed dormancy, plants can be propogated throughout the year independent of seasonal changes
Germination after seed dormancy Germination dormancy

20. DISADVANTAGES OF ASEXUAL REPRODUCTION
No variation – no chance of improving the quality of the species
Overcrowding may occur and resources such as food might be in short supply
Genetic weaknesses cannot be bred out
Infectious diseases (caused by viruses) are likely to be passed on to the new crop
No variation
Overcrowded basil

21. SEXUAL REPRODUCTION IN PLANTS
Is the production of a new generation by bringing together the genetic material of two parents
The offspring will therefore be genetically different from the parents

22. PROCESS OF SEXUAL REPRODUCTION IN PLANTS
Diagram
Parents produce gametes in sex organs
Male and femae gametes are brought close together by pollination
Male and female gametes fuse (fertilisation)
Zygote grows into a new plant

23. ADVANTAGES OF SEXUAL REPRODUCTION
Results in variation which:
Is the basis of evolution
Gives organisms a better chance of survival in an unstable environment as the offspring may be able to adapt to the new conditions
May prevent the spread of disease as the offspring might be genetically resistant to a particular disease
Can result in the quick elimination of harmful mutations
Mutation = change in a chromosome resulting in a new characteristic

24. ADVANTAGES OF SEXUAL REPRODUCTION
Seeds are usually dispersed widely which gives them more space and nutrients

27. Drosera cistiflora is a plant with a wide range of floral colour variations and many of these can be observed in fynbos and renosterveld habitats during spring. Flowers vary in size and colour.

28. DISVANTAGES OF SEXUAL REPRODUCTION
There is a high expenditure of energy
In plants special organs of reproduction need to be produced e.g. flowers
The reproduction process is slow
Unfavourable mutations and recessive genes might be passed on to the offspring
Outside agents might be needed in plants to carry pollen or seeds

29. HOW DO ASEXUAL AND SEXUAL REPRODUCTION COMPARE
CHARACTERISTICS
ASEXUAL REPRODUCTION
SEXUAL REPRODUCTION
Number of parents
One
Two
Reproductive organs
Leaves, roots and stems
flowers
Rate of process
Faster (no gamete formation or pollination)
Slower (gamete formation or pollination)
Outside agents
None needed
Outside pollinators often need
Energy input
low
High – energy is needed to make flowers
Ability to adapt to environment
No – if environment changes, organisms die
Yes – offspring adapt to the changing environment and survive
Possibility of evoultion
Low – no genetic variation
Good – genetic variation
When is the method an advantage
In a stable environment
In an unstable environment – organisms can adapt

30. THE END