Plants Flashcards
What are plants?
Multi-celled, eukaryotic, photosynthetic autotrophs.
What are cell walls made of?
Cellulose
How is surplus carbohydrates stored?
It is stored as starch.
Describe the life cycle of plants.
It’s an alteration of generations.
Define alteration of generations.
One generation of the gametophyte generation is where all the cells of the plant are haploid. The alternate generation is the sporophyte generation where all the cells of the plant body are diploid.
Describe the evolution of plants.
Plants evolved from aquatic green algae about 500 million years ago. They colonized land during the Paleozoic era. Today most species live on land and have diversified into different species.
How do plants help the area around them?
Plants help stabilize the foils around them and provide a home for insects and other animals. They absorb carbon dioxide and release oxygen into the atmosphere.
Which plants do most of the world depend on for survival?
Rice, beans, soy, corn and wheat.
How are plants organized?
They are organized into two groups: bryophytes and tracheophytes.
What are bryophytes?
The plants with no transport vessels. Their sperm must swim through water to fertilize an egg. They’re restricted to moist habitats. They grow on rocks, soil and trees. They lack liginin fortified tissue.(Ex. mosses, liverworts, hornworms)
What are tracheophytes?
The plants with xylem and phloem for transport. They have lignified transport vessels. They have roots, leaves and a life cycle with a dominant sporophyte generation. They are divided into seed plants and seedless plants.
What purpose does lignin-fortified tissue serve?
It supports tall plants.
What purpose do the roots serve?
Roots absorbs water while also anchoring and supporting the plant.
What are characteristics of seedless tracheophytes?
They are primitive and reproduce by spores which are homosporous. They are still restricted to moist habitats even though they have transport tissue because their sperm is flagellated and can swim to fertilize the egg.
What does homosporous refer to?
It refers to seedless tracheophytes that produce only one type of spore which then develops into a bisexual gametophyte.
What are characteristics of seed tracheophytes?
They are split into gymnosperms and angiosperms.
What does heteroporous refer to?
It refers to seed tracheophytes that produce that produce megaspores and microspores. Megaspores develop into male gametophytes and microspores develop into female gametophytes. The sperm of seed plants have no flagella and do not need a a watery environment for fertilization.
What are characteristics of gymnosperms (conifers)?
These were the first seed plants to appear on Earth. Their seeds are not enclosed inside a fruit; they are better adapted for dry environments. Examples are pines, firs, redwoods, junipers and sequoia.
How are gymnosperm seeds better suited for a dry environment?
The seeds are on modified leaves that form cones. They include needle-shaped leaves, which have a thick, protective cuticle and a relatively small surface area. In addition, gymnosperms depend on wind for pollination.
What are characteristics of angiosperms (flowering plants)?
These are seed plants whose reproductive structures are flowers and fruits. They include 90 percent of all plants. There are two groups angiosperms: monocots and dicots.
What is the process of angiosperm seed dispersal?
The color and sent of a flower attracts animals that carry pollen. After pollination and fertilization the ovary becomes the fruit and the ovule becomes the seed. An animal eats and digests the fleshy (often sweet) part of the fruit while the tough seed passes through the digestive tract and is deposited with its feces in the fertilizer.
What are the benefits of angiosperms?
The fruit protects dormant seeds and aids in their dispersal. Maple trees have seeds with wings that enable them to be dispersed great distances by wind. Some plants have burrs on their fruit that cling to animals’ fur.
What are cotyledons?
They are seed leaves.
What are the differences between monocots and dicots?
Monocots have one cotyledon, scattered vascular bundles in the stem, parallel leaf venation, floral parts usually in 3s, and fibrous roots. Dicots have two cotyledons, vascular bundles in a rind in the stem, netlike leaf venation, floral parts in 4s and 5s, and a taproot system.
What modifications allowed plants to move to land?
- Cell walls due to lack of water support.
- Roots and roots hairs to absorb water/nutrients from the soil.
- Stomates that are open to exchange gasses and minimize water loss.
- Cutin which helps prevent excess water loss.
- Gametangia which precent drying out.
- Sporopollenin protects spores and pollen in harsh terrestrial environments.
- A reduced gametophyte generation.
- Xylem and phloem which allows the plants to grow tall.
- Lignin embedded in xylem and in plant cells that provides support.
- Seeds and pollen with a protective coat that prevents desiccation and disperse offspring.
What is cutin?
It is the waxy coating on the leaves.
What is gametangia?
Gametes and zygotes which from a protective jacket of cells in some plants.
What is sporollenin?
It’s a tough polymer that is resistant to almost all kind of environmental damage. It is found in the walls of spores and pollen.
What is the function of the meristem?
Plants contains this tissue that continually divides and generates new cells so which causes plants to grow as long as they live.
What is primary growth?
This is the elongation of the plant down to the soil and up into the air. The apical meristem is the source of primary growth. In herbaceous (non-woody) plants there is only primary growth.
What is the apical meristem?
This is located at the tips of the roots and in the buds of the shoots. It is the source of primary growth.
What is secondary growth?
This is an increase in girth by the lateral meristem. In woody plants secondary growth is responsible for the gradual thickening of the roots and shoots formed from primary growth.
What are the types of tissues in plants?
There are dermal, vascular and ground tissue.
What is dermal tissue and what is its purpose?
Dermal tissue covers and protects the plant. It includes epidermis and modifies cells like guard cells, root hairs and cells that produce a waxy coating.
What is vascular tissue and what is its purpose?
Vascular tissue consists of xylem and phloem. These transport water and nutrients around the plant.
What is ground tissue and what is its purpose?
This is most common tissue type which functions mainly in support, storage and photosynthesis. It consists of three cells: parenchymal, sclerenchmal, and collenchymal.
What is the xylem’s form? Describe the tracheids and the vessel elements.
The xylem tissue consists of two elongated cells: tracheids and vessel elements. Tracheids are long, thin cells that overlap and are tapered at the ends. Water passes from one cell to another through pits. Vessel elements are wider, shorter, thinner walled and less tapered than tracheids. The vessel elements are aligned end to end and the ends are perforated to allow free flow.
What is the xylem’s function?
It conducts water and minerals from roots to shoots. Tracheids support the plant as well. Xylem makes up wood.
What are pits (of the xylem’s tracheids)?
They are areas with no secondary cell wall. The secondary cell walls are hardened with lignin.
What types of plants have tracheids?
Only seedless vascular plants and gymnosperms have tracheids. Most angiosperms have both tracheids and vessel members.
What is the phloem’s form?
The vessels consists of chains of sieve tube members or elements whose end walls contain sieve plates. Connected to each sieve tube member is at least one companion cell that does contain a full complement of cell organelles and nurtures the sieve tube elements.
What is the phloem’s function?
It carries sugars from the photosynthetic leaves to the rest of the plant by active transport.
Describe the sieve plates (of the phloem’s sieve tube elements).
They facilitate the low of liquid from one cell to the next. They lack nuclei, ribosomes and vacuoles.
What are the characteristics of parenchymal cells?
These are classic plant cells. They have a primary cell walls that are thing and flexible and lack a secondary cell wall. They have one large vacuole and it carries out most metabolic functions.
What are the characteristics of collenchymal cells?
These have unevenly thickened primary cell walls but lack secondary cell walls. Mature collenchymal cells are alive and their function is to support the growing stem.
What are examples of parenchymal cells?
When turgid with water they give support and shape to the plant. Most parenchymal cells retain the ability to divide and differentiate into other cell types after a plant has been injured. In the mesophyll cells in the lead, these contain chloroplasts and carry out photosynthesis.
What are characteristics of sclerenchymal cells?
They have a very thick primary and secondary cell walls fortified with lignin. Their function is to support the plant and there are two forms: fibers and sclereids. Fibers are long, thin and fibrous like and they usually occur in bundles. Sclereids are short and irregular in shape. They make up tough seed coats and pits.
What is the function of the roots?
They absorb nutrients from the soil, anchor the plan and store food.
What is the structure of the roots?
The epidermis covers the entire surface of the root and is modified for absorption. Root hairs are located here. The cortex consists of parenchymal cells that contain many plastids for the storage of starch and other organic substances.
What are root hairs?
These are slender cytoplasmic projections from the epidermal cells. They extend out from the cell and increase the absorptive surface area.
