2. • Compare the results of uniform or diverse offspring from
sexual or asexual reproduction
• Uniform offspring
• Diverse offspring
• Sexual reproduction
• Asexual reproduction
3. Sexual Reproduction
• A type of reproduction in which the genetic materials from two
different cells combine, producing an offspring
• The cells that combine are called sex cells
• Female – egg
• Male – sperm
• Fertilization: an egg cell and a sperm cell join together
• A new cell is formed and is called a zygote
4. Advantages: Sexual Reproduction
• Diverse offspring: genetic variation among offspring
• Half of the DNA comes from mom
• Half of the DNA comes from dad
• Due to genetic variation, individuals within a population have
• Plants – resist diseases
• Traits can develop to resist harsh environments that allows an
6. Disadvantages: Sexual Reproduction
• Time and Energy
• Organisms have to grow and develop until they are old enough to
produce sex cells
• Search and find a mate
• Searching can expose individuals to predators, diseases, or harsh
• Fertilization cannot take place during pregnancy, which can last
as long as 2 years for some mammals.
8. Asexual Reproduction
• One parent: organism produces offspring
• Identical offspring:
• Because offspring inherit all of their DNA
from one parent, they are genetically
identical to each other and to their parent
• No fertilisation
9. Fission: Asexual Reproduction
• Fission: Cell division in prokaryotes that forms two genetically
• DNA is copied
• The cell begins to grow longer, pulling the two copies apart
• The cell membrane pinches inward in the middle of the cell
• Cell splits to form two new uniform, identical offspring
• Examples: bacteria, Ecoli, pond critters
10. Budding: Asexual Reproduction
Budding is the process of producing an individual through the
buds that develop on the parent body. Hydra is an organism
that reproduces by budding. The bud derives nutrition and
shelter from the parent organism and detaches once it is fully
• The bud, or offspring is identical to the parent
• The bud, when large enough, can break off of the parent and
live on its own
• Offspring may remain attached and form a colony
• Examples: Yeast, Hydra, cactus
12. Regeneration: Asexual Reproduction
• Regeneration: occurs when an offspring grows from a
piece of its parent.
• Producing new organisms: Sea Stars
• Sea urchins, sea cucumber, sponges, and
• Producing new body parts: Gecko
• Newts, tadpoles, crabs, hydra, and zebra fish
• Fragmentation is another mode of asexual reproduction
exhibited by organisms such as spirogyra, planaria etc. The
parent body divides into several fragments and each
fragment develops into a new organism.
17. VEGETATIVE REPRODUCTION
• Vegetative Propagation: Asexual reproduction in plants occurs
through their vegetative parts such as leaves, roots, stems, and
buds. This is called vegetative propagation. For example, potato
tubers, runners/stolon, onion bulbs, corms, suckers (root sprouts),
and plantlets.etc., all reproduce through vegetative propagation.
• As for artificial means, examples are those that arise from
cutting, grafting, layering, tissue culture, and offset.
29. 1) cutting :- a
cutting is separated
portion of root stem
or leaf it is very
common method of
citrus plant, grapes,
30. 2) grafting :grafting
between two plants
of closely related
variety, the plant of
which the root
system is to be
taken is called stock
and the other of
which shoot system
is to be used is
known as scion.
32. 3) budding :- in budding process a bud with small portion of
surrounding bark is taken from stem of Desire plant. Then it
is inserted into a small slit made in bark of stock both are
tied together and not allowed to dry. This method is widely
practices in rose
4) layering :- in this layering method stem branch chosen for
propagation remain attached to parents till it has produce
ground layering :- in ground layering system is capable of bending
and the selected branch is bent down to the soil. Portion of stem
which touch the soil is cleared of leaves
• Parent plants sends out runners
• Where the runner touches the ground, roots can grow
• A new plant is produced even if the runner is broken
• Each new plant is uniform and identical to the parent.
• Examples: strawberries, potatoes, ivy, crabgrass
37. Advantages: Asexual Reproduction
• Enables organisms to reproduce without a
• No wasted time and energy
• Enables some organisms to rapidly
reproduce a large number of uniform
38. Disadvantages: Asexual Reproduction
Because their offspring are identical, there is no
genetic variation that can give an organism a better
chance for survival
Example: If a weed killer can kill the parent, it will
also kill the offspring
A whole species can be wiped out from a disease
Dangerous mutations in DNA – if the parent has
the mutation in their DNA, the offspring will have it
40. Advantages of Asexual Reproduction
• Following are the advantages of asexual reproduction:
• Mates are not required.
• The process of reproduction is rapid.
• An enormous number of organisms can be produced in very less time.
• Positive genetic influences pass on to successive generations.
• It occurs in various environments
41. Disadvantages of Asexual Reproduction
• The major disadvantages of asexual reproduction are:
• Lack of diversity. Since the offsprings are genetically identical to the
parent they are more susceptible to the same diseases and nutrient
deficiencies as the parent. All the negative mutations persist for
• Since only one organism is involved, the diversity among the
organisms is limited.
• They are unable to adapt to the changing environment.
• A single change in the environment would eliminate the entire
43. Sexual reproduction brings variations in the population. When
gametes (reproductive cells) from two individuals meet, genes from
two individuals are coming together. So the offspring will be
different from both parents. That is how more variety can be seen in
the offspring in sexual reproduction.
Variety is important for the population to adapt to any change in
Asexual reproduction produces carbon copies of individuals. Variety
is not seen in populations. So they cant adapt well if changes occur
in a population.
44. Binary fission A cell divides to produce two identical cells. Each cell has the
potential to grow to the size of the original cell.
Many bacteria, protists, unicellular
Budding The formation of an outgrowth (or bud) from an organism
capable of developing into a new individual. The outgrowth is
genetically the same as the parent but relatively smaller.
Yeasts, hydra, certain bacteria
and Stella spp.)
A new plant emerges from vegetative parts, such as
specialized stems, leaves, and roots, and then they take root
Various plants, e.g. those naturally
emerging from stolons, bulbs, tubers,
corms, suckers (root sprouts), and
plantlets, and those artificially grown by
cutting, grafting, layering, tissue culture,
Spore formation An asexual reproduction wherein spores are produced to
germinate into new individuals
Fungi, slime molds, and vascular plants
Fragmentation The parent organism breaks into fragments. Each fragment is
capable of developing into a new organism.
Certain fungi (e.g. yeasts, and lichens),
molds, vascular and nonvascular plants,
cyanobacteria, and certain animals (e.g.
sponges, sea stars, planarians, and many
45. Advantages of asexual reproduction:
1.Asexual reproduction is a less-energy requiring process.
2.It takes place in different environments.
3.It allows species to survive in their surroundings.
4.A single organism is capable of developing a colony.
5.All the positive characteristics of an organism are transferred to the
6.The organisms formed mature rapidly.
Disadvantages of asexual reproduction:
1.The offspring produced in asexual reproduction is a clone, and any
harmful mutation will also pass on to the offspring.
2.The organisms produced have shorter lifespans.
3.It is hard to control the increasing population.
4.There is only limited diversity within the life forms.
5.Offsprings will not be able to adapt to their surroundings.
• Create a creature that reproduces asexually.
• Draw the creature
• Describe how the creature reproduces asexually
• Describe 1 advantage of reproducing this way
• Describe 1 disadvantage of reproducing this way
• Name your creature
• How the uniform offspring of your creature
When pollen grains reach a receptive stigma of the same species (Pollination),
in principle each vegetative cell of the pollen grain can develop a tube. The
much smaller generative cell, or her mitotic products, the two -haploid- sperm
cells, are enclosed inside the vegetative compartment and migrate forward
along with the growing tube tip. The pollen tube penetrates the stigma and
continues to grow through the style to an ovule inside the ovarium. Each ovule
contains one embryo sac (ES),in fact a small female gametophyte, bearing a.o.
one egg cell and one central cell. When the pollen tube reaches the embryo
sac it bursts open and releases the two sperm cells, the actual sex cells. Then
double fertilization occurs. One sperm cell fertilizes the egg cell so that a
diploid zygote arises, from which an embryo develops. The other sperm cell
fertilizes the large central cell in the middle of the embryo sac and give rises
through series of divisions to the endosperm, which function as a storage
organ of nutrient for the seed. (Sometimes the storage food is transfered from
the endosperm to the cotyledons). The ripe dry ovule with the mature embryo
and the endosperm is the seed. Fruits are the ripened ovary with inside one
(e.g. wheat) or several (e.g. tomato) seed(s).