Goal 4 - Plant Notes
Plant Kingdom - Pages 577-669
General Characteristics
Life Cycle of a plant
Consist of two distinct generations – alternation of generations
General Characteristics
- Multicellular, photosynthetic eukaryotes
- Cells usually contain chloroplasts and have cell walls made of cellulose.
- Sessile organisms (don’t move around from place to place).
- Cells are differentiated into tissues, organs, and organ systems.
Life Cycle of a plant
Consist of two distinct generations – alternation of generations
- Includes a sexual phase called gametophyte, and asexual phase called sporophyte
- The gameophyte generation is made up of haploid cells.
- Sporophytes contain spores that undergo meiosis and give rise to the gameophyte generation
4 Groups of Plants
There are four groups of plants
As plants moved onto land, they had to adapt. They had to deal with:
- Mosses
- Ferns
- Gymnosperms
- Angiosperms
As plants moved onto land, they had to adapt. They had to deal with:
- How to prevent water loss to environment
- How to support against gravity
- How to reproduce
Plant Parts
Vascular Tissue - Tube like elongated cells through which food and other materials are transported.Larger plants have special vascular tissues in their stems and leaves that transport materials
Roots - Organs that absorb water and minerals from soil and anchors plant in the ground. Roots absorb materials by diffusion.
Stems - Organs that provide support for growth and contain vascular tissue.
Leaves - Broad flat organ that traps light energy from sun for photosynthesis. Contain chlorophyll.
Vascular Tissue - Tube like elongated cells through which food and other materials are transported.Larger plants have special vascular tissues in their stems and leaves that transport materials
- Xylem = vascular plant tissue that transport water and minerals from roots to the rest of the plant.
- Phloem = vascular plant tissue transports sugar from leaves to all other parts of the plant
- Mosses do NOT have vascular tissue (non-vascular plants). Because of this, they must live in damp places. They have leaf-like, root-like and stem-like parts. Their cells are elongated to better absorb moisture and their leaves have a cuticle to help retain moisture. They depend of osmosis and diffusion to get water through their one cell thick leaves. They tend to be small plants due to the lack of roots and tissues that would support more extensive growth.
- Vascular plants like ferns, gymnosperms, angiosperms can live further from water and are not limited in size like the non-vascular plants.
Roots - Organs that absorb water and minerals from soil and anchors plant in the ground. Roots absorb materials by diffusion.
- Attached to the roots are root hairs, which increase the absorbing surface of the root.
- At the tip of the root is a root cap, which consist of thick-walled dead cells that protect the growing tip as it pushes through the soil.
- Some roots store materials such as starch-like potatoes.
Stems - Organs that provide support for growth and contain vascular tissue.
- In herbaceous plants (annuals) the stems are flexible.
- In woody plants, which live from season to season (perinnels), the stems are rigid and hard.
Leaves - Broad flat organ that traps light energy from sun for photosynthesis. Contain chlorophyll.
- Cuticle: Protective waxy waterproof coating covering the surface of the epidermis of most stems and leaves. Important adaptation in reducing g water loss.
- Stomata: Opening in leaf tissues that controls gas exchange.
- Vascular bundles: Tube-like, elongated cells through which water, food, and other materials are transported through the plant – includes phloem and xylem.
Reproduction
Plant Reproduction
All plants can reproduce through asexual reproduction, using single cell cultures, root, stem or leaf cutting, fragmentation (asexual reproduction where individual breaks into pieces and each piece grows into a new individual)
All plants can reproduce through asexual reproduction, using single cell cultures, root, stem or leaf cutting, fragmentation (asexual reproduction where individual breaks into pieces and each piece grows into a new individual)
- Mosses: Sexual with gametes that must have water
- Ferns: Seedless vascular plants like ferns produce spores. Must live in moist environments because they are aquatic organisms for part of their lives. Sexual with gametes that must have water, and asexual with spores type of haploid (n) reproduced cell with hard outer coat that forms new organism without the fusion of gametes. The stems of ferns are usually rhizomes, which grow underground. Roots grow from the rhizomes down into the soil. The leaves of the fern (fronds) grow up from the rhizome and have a cuticle to help retain moisture. Since ferns are vascular not limited in height.
- Gymnosperms: Non-flowering plants. Produce seeds located outside of the plant within a structure called a cone. They are covered in a seed coat, but not covered in a fruit. Conifers have both male and female cones. Male cones are smaller and produce pollen. Female cones contain the ovule and are much larger. Pollen is transported by wind to the female cones where fertilization takes place. The sporophyte stage is dominant. Conifers have needle like leaves and are evergreen (which means that they do not shed their leaves in the winter). Pines, Hemlocks, Fir, Spruce, etc.
- Angiosperms: Produce seeds within reproductive structures, flowers. Fertilization of the female part of the flower creates a seed (zygote) and a fruit. Can be divided into monocots and dicots – based upon the number of cotyledons the seed posses. A cotyledon is a seed leave that provides nutrition to the developing seed or is the first leaf of the plant able to perform photosynthesis.
- Monocots have one cotyledon, parallel leaf veins, a fibrous root system, and floral parts arranges in threes or fives (grasses, palms, lilies, orchids).
- Dicots have two cotyledons, net veined leaves, a taproot system (large central root), floral parts arranged in fours or fives, and their vascular tissues is arranged in a circle around the outside of the stem (fruit trees, roses, melons, and beans).
Flowering Plants - Angiosperms
Flowers
Petals =Leaf-like colorful structures that surround flower attracts pollinators to fertilize ovary.
Sepals = Leaf-like usually green and surround the flower.
Flowers contain both male and female parts.
Petals =Leaf-like colorful structures that surround flower attracts pollinators to fertilize ovary.
Sepals = Leaf-like usually green and surround the flower.
Flowers contain both male and female parts.
- Stamen= Male reproductive structures – anthers produce pollen. The filament supports the anther.
- Pistil = Female structure of flower includes the stigma, style, and the ovary. The bottom part contains ovary which contains ovules (eggs found here).
Seeds
Plant reproduction has double fertilization. One sperm fertilizes and egg to form a zygote (seed). One sperm fertilizes a special cell producing endosperm = food storage tissue that supports development of the seed. Some plants use insects to transfer pollen from one flower to another (pollination). Pollen grains from the anthers must get onto the stigma or usually another flower. When the pollen lands on the stigma of a flower of the same kind it will travel down the style, into the ovary and fertilize the ovule inside. This will then grow to form another seed.
In angiospems, the fruits contain the seeds. They are produced from the ovary of the flower. Fruits may be obvious and fleshy (apple, tomatoes, squash) or fairly inconspicuous (peanuts, walnuts)
Seeds
In angiospems, the fruits contain the seeds. They are produced from the ovary of the flower. Fruits may be obvious and fleshy (apple, tomatoes, squash) or fairly inconspicuous (peanuts, walnuts)
Seeds
- Flowering plants grow from seeds.
- Seeds are “ plant babies”
- Seeds contain a tiny, dormanat baby = a embryo plant
- Endosperm = food supply (placenta) also fund in the seed
- Seed Coat = surround the seed for protection from harsh environment. Usually a dark brown color, which provides camouflage
Germination
Germination - beginning of development of embryo of new plant. When a seed arrives at just the right habitat, with the right amount of water and sunlight, it will start to grow (germinate). When the seed germinates, the food reserves inside it are turned into a form the plant embryo can use for energy to grow. First, the root comes out of the seed coat, followed by the shoot. The root always grows downward into the soil, while the shoot always grows upward toward the light. The maturing shoot continues to grow toward the light and becomes the stem, the leaves unfold to take in more light and branches begin to appear.
Seed dispersal
Dispersal of the seed is important. It needs to move away from the parent to limit competition for sunlight, soil and water.
How?
How?
- The seed needs to move away from parent to limit competition.
- Seeds are moved by wind, water, and animals
- Animals may eat seeds (and poo out later) or the seeds may attach to the animals and be transported to a new location.