PLANT DIVERSITY

Plants have an alternation of generations: the diploid spore-producing plant (sporophyte) alternates with the haploid gamete-producing plant (gametophyte).

ANGIOSPERMS (flowering plants) FLOWER SEED FLOWER AGAIN *Bright colored petals/attractive scent attract *Flower has many parts *Sepal, petals, stamen, stigma, ovary

Sepals sepal The sepals protect the flower before it opens.

Petals The petals attract pollinating insects with their bright colour and attractive scent.

Stamens The stamens are the male part of the flower. The plant makes pollen in the top part of the stamen, called the anther.

The Stigma The stigma is the top of the female part of the flower. The pollen from another flower collects on the stigma’s sticky surface.

The Ovary The ovary protects the ovules. Pollen travels to the ovules and fertilization takes place. Now the ovules will develop into seeds.

Pollination Insects visit flowers to search for nectar – their food. But the flowers use the insects for their own purposes!

Pollen gets stuck on the insect’s legs. As the insect probes for nectar, its body rubs against the stamens. Pollen gets stuck on the insect’s legs. You can often see bees with a heavy load of yellow pollen on their hind legs.

Pollination pollination. When the insect visits another flower of the same type, the pollen will stick to the stigma. This is called pollination.

Fertilization The pollen travels to the ovary, where it joins with an ovule. This is called fertilization.

Seeds The seeds develop inside the ovary, which grows to become the seed pod or fruit.

Seed Dispersal The seeds are dispersed; some by animals, some by the wind, some by explosion and some by water.

Angiosperms have 2 divisions

Angiosperm Life Cycle The sporophyte is the dominant generation, but multicellular male and female gametophytes are produced within the flowers of the sporophyte. Cells of the microsporangium within the anther undergo meiosis to produce microspores. Subsequent mitotic divisions are limited, but the end result is a multicellular pollen grain. The megasporangium is protected by two layers of integuments and the ovary wall. Within the megasporangium, meiosis yields four megaspores—three small and one large. Only the large megaspore survives to produce the embryo sac. Fertilization occurs when the pollen germinates and the pollen tube grows toward the embryo sac. The sporophyte generation may be maintained in a dormant state, protected by the seed coat

Gymnosperms Gymnosperms include gnetophytes, cycads, ginkgoes, and conifers Cone bearing plants

Bryophytes Bryophytes have life cycles that depend on water for reproduction. Lacking vascular tissue, these plants can draw up water by osmosis only a few centimeters above the ground they are low-growing plants that can be found in moist, shaded areas. mosses, liverworts, and hornworts

Bryophyte Life Cycle

Seedless Vascular Plants Ferns & Horsetails Like other vascular plants, ferns and their relatives have true roots, leaves, and stems. Roots are underground organs that absorb water and minerals

Seedless Vascular Plants Life Cycle

REVIEW

seed zygote sporophyte microspores megaspore microgametophyte Megagametophyte Ovary anther b. Sporophyte c. megaspores d. microspores

Epidermis Cortex Vascular bundle/xylem Pith Phloem Bark .

Epidermis Palisade mesophyll Leaf vein Spongy mesophyll Stomate Guard cell Leaf veins Cuticle Stomates A, B and C

Pressure Osmotic Higher turgid

Anther Filament Stamen Pollen Stigma Style Ovary Pistil Petal Sepal Ovule Pollen tube

Zone of cell division Zone of elongation Zone of maturation endodermis pericycle phloem xylem cortex epidermis Root hair Vascular cylinder Root cap

The sun causes water to evaporate at leaves Negative pressure Water molecules cling to one another (cohesion) and to sides of vessels (adhesion) Negative pressure potential Cohesion refers to water molecules clinging together and tension refers to negative pressure potential. Water flows upward along the length of the plant

Plant Adaptations to Life On Land Drying out: waterproof surfaces Gas exchange: stomata (above ground)/swim bladder Support: vacuole/cell walls Conduction: xylem and phloem/conducting cells Reproduction: moist surfaces/specialized delivery systems (pollen tubes)