Plant Structure & Function

Main Plant Tissues Dermal Tissue - covers the outside of the plant & protects it –May produce a waxy coating to prevent water loss Ground Tissue - inside the dermal tissue; provides support, stores materials, & is the site of photosynthesis Vascular Tissue - transports water & nutrients throughout the plant –Xylem transports water –Phloem transports food

Plant Tissues See fig on pg. 642

Roots Roots anchor plants & absorb mineral nutrients & water from the soil Parts: –Vascular cylinder in center of root –Root hairs increase surface area to absorb water & nutrients –Root cap protects the growing part of the root –Meristem is where growth occurs

Root Structure See fig.21.7 on pg. 648

Stems Stems support plants, transport materials, & provide storage Primary growth takes place in apical meristems & makes stems grow taller Secondary growth takes place in lateral meristems & adds to the width of the stem

Stem Growth See pg.651

Leaves Leaves collect sunlight for photosynthesis The top of a leaf contains most of the chloroplasts & is where most photosynthesis takes place The underside of a leaf is the site of transpiration & gas exchange –Gases are exchanged through openings called stomata, which are opened & closed by surrounding cells called guard cells

Stomata & Guard Cells Fig on pg. 652Fig on pg. 652

Plant Reproduction

Angiosperms & Gymnosperms Angiosperms are flowering plants –Some flowers are strictly male OR female, some contain both male AND female reproductive structures –Fertilization produces seeds which are contained within a fruit Gymnosperms are cone-bearing plants –Male cones produce pollen, female cones contain ovules to be fertilized –Fertilization produces seeds which are contained in the scales of the cones

Angiosperms have Flowers Flowers contain sepals and petals, which are often brightly colored to attract pollinators The stamen is the male part –Filament supports the anther –Anther produces pollen grains The pistil is the female part –Stigma is at the top & collects pollen –Style is the tube leading from the stigma to the ovary –Ovary is where the egg cells are located

Parts of a Flower Fig on pg. 668

Copyright Pearson Prentice Hall Structure of Flowers Sepals enclose the bud before it opens and protect the flower while it is developing. Sepal

Copyright Pearson Prentice Hall Structure of Flowers Petals are often brightly colored and are found just inside the sepals. Petals attract insects and other pollinators to the flower. Petal

Copyright Pearson Prentice Hall Structure of Flowers – The male parts of a flower consist of an anther and a filament, which together make up the stamen. Filament Anther Stamen

Copyright Pearson Prentice Hall Structure of Flowers An anther is an oval sac where meiosis takes place, producing pollen grains. Anther

Copyright Pearson Prentice Hall Structure of Flowers The filament is a long, thin stalk that supports an anther. Filament

Copyright Pearson Prentice Hall Structure of Flowers The innermost floral parts are carpels, also called pistils, which produce the female gametophytes. Carpel Style Stigma Ovary

Copyright Pearson Prentice Hall Structure of Flowers Each carpel has a broad base forming an ovary. The ovary contains one or more ovules where female gametes are produced. Ovary Ovule

Copyright Pearson Prentice Hall Structure of Flowers The narrow stalk of the carpel is the style. Style

Copyright Pearson Prentice Hall Structure of Flowers At the top of the style is the stigma—a sticky portion where pollen grains frequently land. Stigma

Copyright Pearson Prentice Hall Structure of Flowers Ovary Ovule Carpel Style Stigma Ovary Filament Anther Stamen Parts of a Typical Flower Sepal Petal

Reproduction of Flowering Plants (Angiosperms) Flowers can either self-fertilize or pollen can be carried to another flower to fertilize When pollen fertilizes the egg cells, seeds form The ovary grows to become a fruit surrounding the seeds Fruit aids in the dispersal of seeds to new areas

Copyright Pearson Prentice Hall Fertilization in Angiosperms If a pollen grain lands on the stigma of a flower of the same species, it grows a pollen tube. Pollen grains (N) (male gametophyte) Pollen tubes Ovule

Copyright Pearson Prentice Hall The pollen tube grows into the style, reaches the ovary, and enters the ovule. Pollen grains (N) (male gametophyte) Pollen tubes Ovule

Copyright Pearson Prentice Hall One of the sperm nuclei fuses with the egg nucleus to produce a diploid zygote. The zygote will grow into the new plant embryo. Zygote (2N)

Copyright Pearson Prentice Hall The other sperm nucleus fuses with two polar nuclei in the embryo sac to form a triploid (3N) cell. This cell will grow into a food-rich tissue known as endosperm, which nourishes the seedling as it grows. Endosperm (3N) Zygote (2N)

Copyright Pearson Prentice Hall Fertilization in Angiosperms Because two fertilization events take place between the male and female gametophytes, this process is known as double fertilization.

Reproduction of Conifers (Gymnosperms) Male cones release pollen, which is carried by the wind to female cones Ovules within the scales of the female cones are fertilized and seeds develop Gymnosperm means “naked seed”

Copyright Pearson Prentice Hall Life Cycle of Gymnosperms –Pollen Cones and Seed Cones Pollen cones produce the male gametophytes, also called pollen grains. Pollen grain (N) (male gametophytes)

Copyright Pearson Prentice Hall Life Cycle of Gymnosperms Seed cones produce female gametophytes and are generally larger than pollen cones. Female gametophytes develop in two ovules located near the base of each scale.

Copyright Pearson Prentice Hall Life Cycle of Gymnosperms Within the ovules, meiosis produces haploid cells that grow and divide to produce female gametophytes. Each gametophyte contains egg cells.