LESSON OBJECTIVES
After going through these lessons, you are
expected to:
1. Compare and contrast the following processes
in plants and animals: reproduction and
development. (STEM_BIO11/12-IVa-h-1)
2. Identify methods of reproduction in both plants
and animals
3. Describe the key processes of development.
4. Appreciate reproduction and development in
species survival.
Module 1 – REPRODUCTION
& DEVELOPMENT
GENERAL BIOLOGY 2
REPRODUCTION
• the biological process by which new
“offspring” (individual organisms) are
produced from their “parents. ”
• necessary for the survival of a species.
• methods of reproduction are broadly
grouped into two main types: sexual
and asexual.
ANIMAL REPRODUCTION
Methods of Reproduction - Asexual and Sexual
Reproduction
ASEXUAL REPRODUCTION
•an individual can reproduce without
involvement with another individual of
that species.
•This type of reproduction produces
genetically-identical organisms (clones).
Types of Asexual
Reproduction
in Animals
1. Fission, also called binary fission
• occurs in prokaryotic microorganisms
and in some invertebrate.
• After a period of growth, an organism
splits into two separate organisms.
Some unicellular eukaryotic organisms
undergo binary fission by mitosis. In
other organisms, part of the individual
separates, forming a second individual.
• Examples: amoeba, trypanosome,
flagellate & paramecium.
2. Budding
• results from the outgrowth of a part of a cell or
body region leading to a separation from the
original organism into two individuals.
• occurs commonly in some invertebrate animals
such as corals and hydras.
3. Fragmentation
• is the breaking of the body into two
parts with subsequent regeneration. If
the animal is capable of fragmentation,
and the part is big enough, a separate
individual will regrow.
• Examples: sea star, annelid worms,
turbellarians, and poriferans.
*Note that there is generally a noticeable
difference in the size of the individuals,
whereas in fission, two individuals of
approximately the same size are formed.
4. Parthenogenesis
• an egg develops into a complete
individual without being fertilized. The
resulting offspring can be either haploid
or diploid, depending on the process
and the species.
• Examples: water fleas, rotifers, aphids,
stick insects, some ants, wasps, and
bees.
SEXUAL REPRODUCTION
• the combination of (usually haploid) reproductive
cells from two individuals to form a third (usually
diploid) unique offspring.
• produces offspring with novel combinations of
genes. This can be an adaptive advantage in
unstable or unpredictable environments.
Hermaphroditism
• occurs in animals where one
individual has both male and
female reproductive parts.
• Examples: earthworms, slugs,
tapeworms and snails
• Hermaphrodites may self-fertilize or
may mate with another of their
species, fertilizing each other and
both producing offspring.
PLANT
REPRODUCTION
PLANT REPRODUCTION
Methods of Reproduction - Asexual and Sexual
Reproduction
ASEXUAL REPRODUCTION
• does not require the investment required to
produce a flower, attract pollinators, or find a
means of seed dispersal
• produces plants that are genetically identical
to the parent plant because no mixing of
male and female gametes takes place.
Types of Asexual
Reproduction
in Plants
1. Vegetative reproduction
• results in new plant individuals without the
production of seeds or spores. Many different types
of roots exhibit vegetative reproduction. The corm
is used by gladiolus and garlic. Bulbs, such as a
scaly bulb in lilies and a tunicate bulb in daffodils,
are other common examples of this type of
reproduction. A potato is a stem tuber, while
parsnip propagates from a taproot. Ginger and iris
produce rhizomes, while ivy uses an adventitious
root (a root arising from a plant part other than the
main or primary root), and the strawberry plant has
a stolon, which is also called a runner.
2. Apomixis
• Some plants can produce seeds without
fertilization.
• Either the ovule or part of the ovary, which is
diploid in nature, gives rise to a new seed.
• Examples of apomixis can be found in hawthorns,
shadbush, rowans and whitebeams, brambles or
blackberries, meadow grasses, matgrass,
hawkweeds and dandelions.
SEXUAL REPRODUCTION
Pollination
• In angiosperms, pollination is defined as the placement
or transfer of pollen from the anther to the stigma of
the same flower or another flower.
• In gymnosperms, pollination involves pollen transfer
from the male cone to the female cone. Upon transfer,
the pollen germinates to form the pollen tube and the
sperm for fertilizing the egg.
• Pollination takes two forms: self-pollination and crosspollination.
Self-Pollination vs. Cross-Pollination
DEVELOPMENT
• the process by
which a
multicellular
organism,
beginning with
a single cell,
goes through a
series of
changes, taking
on the
successive
forms that
characterize its
life cycle.
Development
FOUR KEY PROCESSES
UNDERLIE DEVELOPMENT
The developmental changes an organism undergoes
as it progresses from an embryo to mature adulthood
involve four processes:
D–D–M–G
1. Determination
• sets the developmental fate of a cell—what type
of cell it will become—even before any
characteristics of that cell type are observable.
• example, in a developing mammalian embryo,
as well as in some adult organs, there are
mesenchymal stem cells that look unspecialized.
But their fate to become muscle, fat, tendon, or
other connective tissue cells has already been
determined.
2. Differentiation
• the process by which different types of cells arise
from less specialized cells, leading to cells with
specific structures and functions.
• example, mesenchymal stem cells differentiate
to become muscle, fat, tendon, or other
connective tissue cells
3. Morphogenesis
• (Greek for “origin of form”) is the organization
and spatial distribution of differentiated cells into
the multicellular body and its organs.
• can occur by cell division, cell expansion
(especially in plants), cell movements, and
apoptosis (programmed cell death).
4. Growth
• is the increase in size of the body and its organs
by cell division and cell expansion.
• occur by an increase in the number of cells or by
the enlargement of existing cells.
• continues throughout the individual’s life in some
organisms, but reaches a more or less stable end
point in others.
REVIEW/GENERALIZATION
ASEXUAL
SEXUAL
DETERMINATION
FISSION
VEGETATIVE
POLLINATION
DIFFERENTIATION
BUDDING
APOMIXIS
HERMAPHRODITISM
SELF-POLLINATION
MORPHOGENESIS
FRAGMENTATION
CROSS-POLLINATION
PARTHENOGENESIS
GROWTH