Biology Exam 3: Ch 28
Plant Organs: Roots
Below ground
Which of the following are the parts of a typical leaf?
Blade and petiole
Meristems
Areas of dividing cells that allows growth in all plants -Undifferentiated (unspecialized) cells that divide frequently, generating new cells and tissues. -Apical Meristems: Occur at the tips of roots and shoots & enable primary growth, growth in length
Vascular Cambium
Ring of dividing cells -Between the primary xylem and primary phloem -Uneven activity of the vascular cambium causes a visible ring each year
Where would you find the mesophyll?
In the leaf
What is the movement in the xylem?
One way
Stomata Regulate Transpiration
Open during the day, which allows CO2 to enter the leaf from the atmosphere for photosynthesis when light is available -At night, there is no light for photosynthesis, therefore no need for CO2, and the stomata are closed
What cell type is responsible for the bulk of photosynthesis in a typical leaf?
Parenchyma
How do cells in a meristem differ from other cells in a plant?
They are undifferentiated and continue to divide and generate new cells and tissues
Collenchyma Cells
Unevenly thickened primary walls; support for actively growing parts
Angiosperms
"The flowering plants" -90% of the plant kingdom -Organs are composed of different tissues (roots, shoots=stems, leaves, flowers) -Tissues composed of cells of different types
Functions of a Plant's Roots
1. Anchor the plant in the soil 2. Store food in the form of carbohydrates such as starch 3. Absorb and transport minerals and water 4. Root hairs increase the surface area of the root
Primary growth in a root is achieved by:
1. Cell division 2. Cell elongation (mainly by taking up water)
Process of Secondary Growth
1. The epidermis is sloughed off 2. It is replaced with a new outer called cork (produced by cork cambium) 3. Mature cork cells are dead (thick waxy walls to protect underlying tissues) 4. Bark consists of everything external to the vascular cambium -Secondary phloem, cork cambium, cork
Plant Organs: Shoots
Above ground -Stems, leaves, flowers
Food-conducting Cells
Arranged end to end, forming tubes. -Remain alive at maturity -Phloem sap moves in various directions: from a sugar source (where sugar is produced) to a sugar sink (where sugar is stored or consumed)
Vascular Bundles
Arranged vascular tissue systems in the stem -The center of the stem is often important in food storage
What is meant by the term "indeterminate growth?"
Continued growth of an organism as long as it lives
The primary function of guard cells is to __________.
Control the rate at which a plant loses water and takes in CO2
Dermal Tissue
Covers and protects leaves, stems, and roots -Helps prevent water loss with the cuticle (a waxy coating)produced by epidermal cells
What are the 3 types of plant tissues?
Dermal, Vascular, & Ground
What is not a function of the root system?
Food production
Ground Tissue
Functions in photosynthesis, storage, support
Stems
Generally grow above ground -Support the leaves and flowers -Have nodes, the points at which leaves are attached, and attached, the portions of the stem between nodes internodes bud, at the apex (tip) of the stem -Terminal buds, at angles formed by a leaf and the stem phenomenon of apical dominance
Plant Tissues
Group of cells that form organs of plants -3 types (dermal, vascular, ground)
Determinate Growth
Growth ends after reaching a certain size (animals)
A major role of root hairs is to __________.
Increase the root surface area for absorption
Primary growth produces ____ whereas secondary growth produces ____?
Increased length; increased thickness
How does transpiration play a role in the functioning of plant organs?
It creates tension that pulls water up through the xylem
Parenchyma Cells
Most abundant cell type; variety of functions -Located inside Sclerenchyma (aka ground tissue)
Which of the following is correct when considering the function of primary and secondary growth?
Primary growth adds height, and secondary growth adds girth.
Secondary Growth
Process which the stems and roots of many plant species thicken over time (annual growth rings) -Woody vs. Nonwoody (herbaceous) plants -Adds cells on either side
Lateral Meristems
Produce secondary growth
Importance of Plants
Provide shelter, food, and breeding areas for other organisms -Humans depend on plants for food, fuel, and clothing
Vascular Tissue
Provides support and long-distance transport -Phloem: transports sugars from leaves or storage tissues to other parts of the plant. -Xylem: conveys water and dissolved minerals upward from the roots to the stems and leaves.
Sclerenchyma Cells
Secondary strengthened with light in, main chemical in wood; support -Located inside the epidermis
Which of the following is the main component of wood?
Secondary xylem
What is not a plant tissue?
Stoma
Which of the following best describes the daily cycle of stomata in most plants?
Stomata are open during the day and closed at night.
Indeterminate Growth
The ability for plants to grow throughout life -The life span of plants varies greatly
Cells that contain the most chloroplasts are found in what region of a typical leaf?
The mesophyll
Which of the following best describes the region on a plant stem where one typically finds leaves?
The node
Leaves
The primary sites of photosynthesis; consist of: 1. A flattened blade 2. A stalk, or petiole, which joins the leaf to the stem -Leaves are highly varied in their arrangements & shapes -Epidermis contains stomata (tiny pores between two specialized guard cells that regulate the size of the stomata) -Ground tissue = mesophyll, the main site of photosynthesis. -Vascular tissue system is made up of a network of veins
Plant's Roots
The root is pushed through the soil by primary growth -The root cap protects the actively dividing cells
Where would you find a node?
The stem
Angiosperms: 2 Types of Water-conducting Cells
Tracheids & vessel elements -They are dead with only their cell walls remaining; arranged in chains of hallow tubes with overlapping ends
Which one of the following describes the loss of water through the stomata in a plant's leaves?
Transpiration
Thinking about our circulatory system, which tissue system in a plant would be most analogous?
Vascular tissue
Cross Section of a Root
Vascular tissue system: forms a cylinder in the center Ground tissue system: forms the cortex where cells store food -Innermost layer is endodermis, selective barrier that regulates the passage of substances between the cortex and the vascular tissue.
Xylem Transport
Water, dissolved ions from the roots to the tips of the leaves through vertical Xylem tubes. -Transpiration: loss of water by evaporation, occurs through pores in the leaves called stomata; pulls water up the plant against gravity