Reproduction In Lower Forms Of Life

REPRODUCTION IN LOWER FORMS OF LIFE

• Reproduction may be asexual or sexual. • ASEXUAL REPRODUCTION- does not involve gametes or sex cells. • SEXUAL REPRODUCTION- involves sex cell. The sperm cell and egg cell unite to form zygote

ALGAE • Some algae reproduce only asexually by cell division or fission. • FISSION, it is a common form of vegetative reproduction among unicellular plants, is the process by which one cell divides in two.

• FRAGMENTATION it is a common vegetative reproduction among multicellular algae. It is a process whereby pieces of an organism may break off and regenerates into whole organisms. This process multiple the number of colonies not the number of cells

BREAD MOLD (AMAG) • Reproduces asexually through the SPORES encased inside a capsulelike container called SPORANGIUM. When condition becomes favorable, the spores germinate into new plants.

FERN • The brown structure underneath the leaflets are called SORI, they keep the sores intact. If the condition is favorable it will germinate into new plants.

ALTERNATION GENERATION • is the switching back and forth between the production of diploid (asexual) and haploid cells (sexual)

• The diploid stage is called SPOROPHYTE GENERATION, the diploid plant produces a spores. The sprorophytes undergoes meiosis to produce a haploid spores. Spores then develop to produce a haploid plant.

• In GAMETOPHYTE GENERATION, the haploid plants produces gametes(egg cells and sperm cell).the haploid plant develop a sperm producing ( ANTHERIDIA) and egg producing • (ARCHEGONIA) branches. These multi cellular haploid plants are called GAMETOPHYTES.

FUNGI • Mold can produce asexually through spore and sexually by CONJUGATION; it is a primitive form of sexual reproduction by which the contents of two cells unite to form a zygote.

VIRUSES • Cannot reproduce alone they need their host body to organize their own substances and produce another of their kind.

BACTERIA • They multiple by TRANVERSE BINARY FISSION and produce their daughter cells that will grow and mature. • This daughter cell may reproduce again in a period of only 20 minutes.

PROTOZOAN(paramecium, amoeba, euglena)

• Protozoans can reproduce by fission and conjugation.

REPRODUCTION IN FLOWERING PLANTS

• Flowering plants reproduce through sexual and asexual means

2 STAGES OF THEIR LIFE CYCLE

• VEGETATIVE STAGE this is the growth stage. • REPRODUCTIVE STAGE, flowers are produce and sexual reproduction occurs.

VEGETATIVE STAGE

2 KINDS OF VEGETATIVE REPRODUCTIVE PROCESSES

• Natural • Artificial

NATURAL VEGETATIVE REPRODUCTION

• RUNNERS (strawberry) grow along the ground from the parent plant. They form adventitious roots and shoots at the tip, giving rise to new plants.

• TIP LAYERING aerial stem arch downward so the tip touches the ground. The adventitious roots develop and new plant shoot would grow. • LEAF REPRODUCTION new plants develop along the margin of their leaves.

ARTIFICIAL PROPAGATION METHOD

• CUTTING a portion of the stems and roots are removed and transferred to loose , damp soil or sand. (gumamela, roses)

• GRAFTING is the splicing together of two stem, or the union of their cambium layersone of the STOCK(the rooted portion) and the other of the SCION ( the cut portion that is joined to the stock)

• BUDDING is similar to grafting except that a bud rather than a stem is used as the scion.

SEXUAL REPRODUCTION IN FLOWERING PLANTS

• FLOWERS are reproductive organ which have evolved from the leaves. • FLORAL PART • A typical flower has the following parts

• CALYX- collection of sepals, the several green, leaf like structure that covers and protect the rest of the flower in the bud stage. • COROLLA- refers collectively to the petals of the flower. Its attracts agents of pollination like insect and even man.

• STAMEN- the male reproductive part of a flower which produces pollen. It consists of the stalk or filament and an anther produces pollen. Pollen contains sperm nuclei which is essential for reproduction.

• PISTIL-the female reproductive part of a flower. It is composed of a head called stigma, a slender style, and an enlarged base called ovary which forms the egg. Ovary contains ovules which later become seed.

POLLINATION • In flowering plants, reproductive process that involves the transfer of pollen grains from the anther of the flower to the stigma of the same (self-pollination)or another flower (cross-pollination).

There are many agents of pollination that aids in the transport of pollen grains such as: • Insect that feed on the nectar of flowers. Bees are the best pollinators other are moths, butterflies. • Wind • Water • Man

FERTILIZATION • Is the union of the nuclei of male and female gametes during the process of sexual reproduction to form a zygote.

• Each gamete contain only half the number of chromosomes (haploid) of the species so that fertilization and consequently zygote formation result in a cell with a complete number of chromosomes (diploid), half of which derived from each parents

• In plants, fertilization also involves fusion of a sperm and egg to form zygote. In angiosperm, aside from the formation of the zygote, another sperm unites with the polar nuclei found in the ovule to form the endosperm. • Endosperm is the seed tissues which contain the food for the tiny plants.

KINDS OF FLOWERS • Flowers may vary in color, shapes and arrangement of its floral parts. • COMPLETE FLOWER has all the parts, petals, sepal, pistil and stamen • Ex. Rose, lily, gumamela

• INCOMPLETE FLOWER may lack sepals or petals • Ex .ilang -ilang, santan, bougainvillea and poinsettia

DEVELOPMENT OF FRUITS AND SEEDS FRUIT • A fully developed or ripened ovary SEED • A ripe or mature ovule. • Seed maybe dispersed through natural means or by dispersing media as animals, wind, water or even human.

Parts of the seed: • Embryo- stored food nourishes the young plant from the time it starts to grow until it matures. • Hilum- an oval scar on the inner curve of the seed where it was attached to the wall of the pod.

• Microphyle-it is tiny opening on the wall of the ovule through which the pollen tube enters just before fertilization. • Testa- is the outer seed coat; it is smooth and comes in different colors.

• Hypocotyl- is a finger like projection that fits into a protective pocket. at one end is the radicle (embryonic root) and the other is the epicotyls(two tiny leaves folded over each other)

SEED GERMINATION • When conditions are favorable for the growth of the particular seed, germination (sprouting) begins. • The ability of seed to germinate is called VIABILITY. • The conditions for germination include