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Explore the characteristics and life cycle of plants in the Kingdom Plantae, including algae, bryophytes, pteridophytes, and angiosperms. Learn about the importance of seeds and vascular tissue, as well as the different plant organs and tissues. Discover the classification of plants and the three categories of plant life spans.
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Why are Plants needed? What are some characteristics of the kingdom Plantae?
Describe a plant’s life cycle. What do plants need in order to survive?
Algae • 50-90% of all photosynthesis • Most live in water • Unicellular, colonial, or multicellular • Green algae are in the phylum Chlorophyta • Ancestor of green plants • Ex. Chlmydomonas
Gametophyte is the dominant generation • Single celled Chlorophyta are considered protists. • Multicellular Chlorophyta are plants. Ex. Ulva and spirogyra
Phylum Bryophyta • Nonvascular plants • Mosses, liverworts, and hornworts. • First land plants • Tied to water for reproduction • Gametophyte is dominant. Sporophyte grows from the top of the gametophyte. • Male reproductive structure-antheridia • Female- archegonium
Phylum Pteridophyta Ferns Dominant generation is the sporophyte They lack seeds Reproduction occurs by spores spreading
The Origin of Vascular Plants- Requirements • Seeds for reproduction- protect the developing embryo. • Vascular tissue- xylem carries water and phloem carries products of photosynthesis • Phylum Tracheophyta- gymnosperms and angiosperms
Ferns • Leaves are called fronds • Spores are under the frond in the sorus • Attached to ground by the rhizome and rhizoids, which are root like structures • Dominant generation is the sporophyte
Tracheophytes are divided into gymnosperms and angiosperms • The seeds of gymnosperms(conifers, cycads, and ginkos), are called naked seeds. Seeds are on the cones of conifers. Male cones are smaller than female cones and usually occur on the same tree. Males have microsporangia and females have megasporangia.
Angiosperms are flowering plants • Gametocyte is found in the flower. • The flower is made of layers. • Outermost whorl of a flower is called the sepal. It encloses and protects a developing flower. • Second whorl forms the flower petals. • 3rd whorl forms the male gamete.
The male gamete is made of a filament and an anther containing pollen. It is called the stamen. 4) The 4th whorl is the female gamete. It is called the pistil or carpel. The pistil has a sticky top called a stigma, and tube for the pollen to travel through called the style, and the ovule in the ovary. When pollination occurs, the seeds are covered with a seed coat for protection.
The ovary develops into a fruit to nourish the embyro. It also aids in seed dispersal. • Seed dispersal occurs through wind, water, or animals(vector). The ripe fruit eaten by animals, helps seeds become dispersed.
Monocots Veins in leaves are parallel Flower parts of 3s Vascular bundles scattered in stem Vascular bundles alternate in circle in root Stems don’t get thicker from year to year Dicots Branching veins in leaves Petals in 4s or 5s Vascular bundles in rings in stems Vascular bundles arranged in X in roots Stems thicken from year to year Major divisions of angiosperms
3 categories of plant life spans • Annuals- have to be planted every year. Ex. Corn, petunias • Biennials- 2 year cycles. Ex. Carrots. The carrot will grow in one year. It takes 2 years for seeds to form. • Perennials-grow for many years. Ex. Holly
Fertilization in angiosperms Double fertilization 1 sperm fertilizes the egg to form a zygote The other fertilizes 2 polar bodies in the embryo sac to form an endosperm. The endosperm is rich in food to nourish the embryo.
Plant organs Dermal tissue- outer covering with a waxy cuticle Vascular tissue- conducts Ground tissue- anything that isn’t dermal or vascular. Surrounding vascular=cortex Inside vascular=pith
Plant tissues • Roots, stems, and leaves needed to live on land. • Vascular tissue is xylem and phloem • Veins are arranged into vascular bundles. • Meristematic tissue is the only plant tissue that divides by mitosis.
Plant cells Parenchyma cells- most abundant; metabolism Collenchyma- support growing parts of plants Schlerenchyma- dead; support Xylem and phloem
Vascular Tissue • Xylem- made of vessel elements, which are wide and must die before they conduct water, and tracheids, which are long and narrow and also must die to work. • Phloem- made of sieve tube elements with many holes in them and companion cells, which surround and control sieve tube elements. Sugars move from the sugar source to the sugar sink by diffusion.
Types of Meristematic Tissue • Apical meristem-allows trees to grow taller • Cork cambian- allows stems to thicken • Vascular cambian- allows new vascular tissue to form. • Pericycle- allows roots to grow.
Phloem cells Xylem cells
Plant Classification • Bryophyta- mosses, liverworts, and hornworts. • Pteridophyta- ferns and horsetails. • Coniferophyta- conifers. Cycadophyta- cycads. Ginkophyta- ginkos • Angiospermophyta, class Monocotyledoneae (irises, lillies, corn, wheat, bananas, etc) and class Dicotyledoneae (trees, shrubs, and most fruit trees)
Roots • Taproots- long, thick primary root with tiny roots hairs. Found in oak and hickory trees, carrots, dandelion, beets, and radishes. • Fibrous roots- Found in grasses and many trees. • Roots have 3 tissue layers- 1) Epidermis- outermost. 2) Cortex- transports water and nutrients inward. 3) vascular cylinder- contains xylem and phloem.
4 root tip sections • Root cap- protects the root and secretes CO2, which forms carbonic acid. This acid dissolves soil and allows the root to push through the soil • Meristematic region- growth/mitosis • Region of elongation- meristematic cells form this region, where root cells increase in length, new protoplasm forms, and vacuoles get larger.
4) Zone of maturation- differentiation occurs, forming the mature tissues, xylem, phloem, and the root hairs.
Leaves • Cuticle- waxy layer. Keeps water from evaporating. • Epidermis- thin layer that light passes through • Palisade mesophyll- columnar cells with chloroplasts for photosythesis. • Spongy mesophyll- loose layer of cells that photosynthesis occurs in. CO2 can move through this layer.
More of the leaf • Xylem and phloem take water and minerals into the leaf and nutrients out. • Stoma (stomata) open and close to let CO2 in and O2 out of the leaf. It has to balance the need for CO2 with the cost of water loss. Guard cells control the opening and closing of stomata.
Water moves in through the root hairs, through the epidermis and cortex. A Casparian strip divides the cortex and vas. Cylinder. Once water moves through the Cas. Strip, it can’t move back out. This is called root pressure and is one way that water moves through a plant.
Water movement in plants • Root pressure- moves water a short distance. • Capillary action- combination of adhesion and cohesion. Short distances only. • Transpirational pull- as water evaporates through the leaves, more water moves into those cells by osmosis. This can pull water up a tall tree.
Stems • Stems hold leaves up to the sun and conduct substances between roots and leaves.
Plant Hormones • Auxins- produced in the apical meristem and move downward. They stimulate cell elongation. They are also responsible for response to gravity. Roots grow downward, stems grow upwards. Auxins inhibit growth of lateral buds. • Cytokinins- stimulate cell division and the growth of lateral buds, and cause dormant seeds to sprout. Root growth.
Gibberellins- produce dramatic increases in size, particularly in stems and fruits. Seed germination, fruit development, and leaf growth. • Ethylene- in response to auxins, fruit tissues release small amounts of this gas. This in turn stimulates the fruit to ripen. • Absisic acid- inhibits growth and promotes dormancy.
Photoperiodism • It is responsible for the timing of seasonal activities such as flowering and growth. • Some plants are short-day plants, some are long-day plants. Some flowers open in the day, others only at night.
Plant responses • Tropisms- response to external stimuli. There are several types. • Gravitropism- roots grow down(positive gravitropism) and shoots grow up(negative). • Phototropism- plants grow towards light. • Thigmotropism-response to touch. Some will have their growth stunted, some will twist to avoid touch, others will grow tendrils into an object.
SOIL • A mixture of sand, silt, clay, and bits of decaying animal and plant tissue. • Humus- dead plants and animals • Topsoil- made of humus, sand, clay, and minerals. Lots of air spaces. • Subsoil- mixture of rocks and inorganic soil particles. There is little air here. • Bedrock- solid, can’t be penetrated by plant roots.
EssentialNutrients • Plants need carbon dioxide, water, and inorganic nutrients to grow. • The most important inorganic nutrients are nitrogen, phosphorus, calcium, magnesium, and other trace elements. • For example: nitrogen is needed for leaf growth and color. Phosphorus is needed for making DNA, roots, stems, flowers, and seeds.
