Plant Biology: Auxins and Their Functions

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Questions and Answers

What are Auxins and their purpose?

Auxins control growth direction and light consumption

What are Gibberellins and their purpose?

Give the plant a growth boost, seed fermentation and elongation.

What are Cytokinins and their purpose?

They control the cell division in the plant.

What are Ethylenes and their purpose?

Aids in ripening and protecting the plant from stress Signup and view all the answers

What are Abscisic Acid and their purpose?

Keeps buds dormant until the right light and temperature levels. Signup and view all the answers

What is Succession?

Succession is a gradual change of the species to form a community over time. Signup and view all the answers

What are the types of Succession?

Primary succession progression in an area that has no plants, animals or soil. Secondary succession progression in an area that has been affected by a natural disaster or human interaction Signup and view all the answers

How does the water in a plant move up the stem? What are the three types?

Root Pressure Using Hydrogen bonds, strong forces of attraction. Kind of like a magnet force between the water molecules. Capillary action - water molecules like to stick together from adhesion cohesion and surface tension, they ride the cellulose walls up the plant till they get evaporated in the leaves. Transpiration, as a water molecule evaporates it pulls the next molecule Signup and view all the answers

What Happens when Stomata is Open vs Close?

When it's open there is a transfer of gases, through diffusion. Taking in the CO2 and releasing O2. It closes generally when the concentration in the guard cell drops, signaling it too close to preserve its water supply usually happening around night time. Signup and view all the answers

What is Stomata? Where is it Located and What's its Function?

Many are located near the bottom of the epidermis. Found in pairs. They are protected by a guard cell that keeps the plant regulated. Guards cells have chloroplast which are the cells that are used to do photosynthesis which is the starting point for producing more organic matter. Signup and view all the answers

What are the parts of Leaves?

Blade; Thin flattened section, positioned along where the leaf begins to grow [nodes] Petisolte; Stalk that attaches the stem to the blade. Makes waterproof barrier of connection. Signup and view all the answers

What is the function of Leaves?

Maintain Photosynthesis systems Collect and sight oxygen and carbon Signup and view all the answers

What are the types of Stems?

Herbaceous; Flesh soft green stem, contains little to no wood. Woody; Increased diameter each year, found in perennial plants. Perennials last many years but annuals last only one season. Signup and view all the answers

What are the Three types of Stem Tissues, and their functions?

Dermal Tissue; Outer surface of the stem Ground Tissue; The [parenchyma] cells around vascular tissue. Store starch, photosynthesis and support the plant Vascular Tissue; Transport and Structural support. Signup and view all the answers

What is the Function of a Stem?

Used as a defence system Store water and carbohydrates Transport Nutrients across the plant Stabilize and support the plant body. Signup and view all the answers

What does the root structure consist of?

Meristems; fastest actively growing part. Most Mitosis Root Cap; The part that protects the Meristems from damage. Epidermis; Outer part, has root hairs which are fine extensions to aid in nutrient absorption. Kinda like the fuzzy part of the root when you touch one. Signup and view all the answers

What are the types of Root?

Taproots; Found in Dicots, Long and thick and usually grow more downward. Fibrous Roots; Found in Monocots, No main root, many thin roots. Signup and view all the answers

What are the two parts of a Root?

Primary: Originates from the seed Secondary: Originated from the Primary (Smaller than main root) Signup and view all the answers

What Is the Function of Roots?

Absorption of nutrients Stability & Grounding Produce compounds eg. Hormones Signup and view all the answers

What are the three types of tissues in plants?

Roots, Steams, Leaves (Conduction Tissue- Xylem, Water {It can only go one way}) and Phloem [Food] are tissues that transport important nutrients from the leaves to the roots of the plants. Cambium produces more Xylem cells and Phloem cells. Signup and view all the answers

What are Monocots?

Monocots usually have pedals in a multiple of three 3. Long slender leaves with veins usually. Vascular tissues spread out randomly throughout the stem. Signup and view all the answers

What are Dicots

Dicots usually come in 4-5 pedals or multiples of them. Leaves are usually wide with the veins branching off a lot. Vascular tissue is arranged in the form of a circle. Usually has two Cotyledon which is another term for seed leave Cotyledon is the thing that supplies nutrients to the embryo An embryo is basically the initial stage of development of multicellular organisms. Signup and view all the answers

What are the Two Divisions Of Plants?:

Non Vascular Plants, also known as Bryophyta. They normally are limited to moist environments and transport a lot of nutrients through diffusion. Vascular Plants; Also known as Tracheophytes Have / Use a lot of Vascular tissue which are like tubes in their body responsible for transporting food and water and minerals throughout the body. Can obtain separate resources such as roots, stems, leaves. Signup and view all the answers

What are the Three Classifications of Reproductive Plants?:

Bryophyta; Amphibious Plants [eg. Moss] Gymnosperm; Naked seeds “All Conifers” [eg. Pine] Angiosperm; Seeds closed inside Ovary [eg. Flowering plants] Signup and view all the answers

Study Notes

Auxins

Promote cell elongation and growth, especially in shoots and roots.
Influence root formation, apical dominance (suppressing lateral bud growth), and fruit development.

Gibberellins

Stimulate stem elongation and cell division.
Promote seed germination, flowering, and fruit development.

Cytokinins

Promote cell division and differentiation.
Delay leaf senescence (aging), and influence lateral bud growth.

Ethylenes

A gaseous plant hormone that regulates fruit ripening, leaf abscission (shedding), and senescence.
Promotes the breakdown of cell walls, leading to softening of fruits.

Abscisic Acid

Acts as a growth inhibitor, promoting dormancy in seeds and buds.
Plays a role in closing stomata during water stress to conserve water.

Succession

The gradual process of change in an ecosystem over time, involving the replacement of one community by another.

Types of Succession

Primary Succession: Occurs in areas devoid of soil, like newly formed volcanic islands.
Secondary Succession: Occurs in areas where existing vegetation has been disturbed, like after a fire.

Water Movement in Plants

The movement of water up the stem is facilitated by transpiration, the loss of water through the leaves.
Cohesion-tension theory: Water molecules stick together (cohesion) and to the walls of the xylem vessels (adhesion), creating a continuous column of water.
Capillary action: Water moves up the narrow xylem vessels due to surface tension and adhesion.
Root pressure: Roots actively pump water into the xylem.

Stomata

Pores or openings on the surface of leaves that allow for gas exchange (oxygen in, carbon dioxide out) and transpiration.
Located mainly on the underside of leaves to minimize water loss.

Stomata Opening and Closing

Open: Allows for gas exchange and transpiration, enhancing photosynthesis.
Closed: Reduces water loss during drought conditions or hot weather.

Leaf Parts

Blade: The flattened portion of the leaf where photosynthesis occurs.
Petiole: The stalk that attaches the blade to the stem.
Veins: Transport water and nutrients through the leaf.

Leaf Function

Photosynthesis: Production of food (sugars) using sunlight, carbon dioxide, and water.

Stem Types

Herbaceous: Soft, green stems, often found in annual plants.
Woody: Hard, lignified stems, typically found in trees and shrubs.
Underground stems: Modified stems that grow below the ground, like rhizomes, tubers, bulbs.

Stem Tissues

Xylem: Transports water and dissolved minerals from roots to other parts of the plant.
Phloem: Transports sugars (food) produced by photosynthesis from leaves to other parts of the plant.
Cambium: Lateral meristem, responsible for secondary growth (wood and bark formation) in woody plants.

Stem Function

Support: Provides structural support for the plant.
Transport: Conducts water and nutrients throughout the plant.
Photosynthesis: Some stems, especially herbaceous stems, can perform photosynthesis.

Root Structure

Tap root: A main, central root with smaller lateral roots branching off.
Fibrous root: A system of thin, branching roots that are about the same size.
Adventitious root: Roots that grow from stems or leaves instead of the root system.

Root Parts

Root cap: Protective layer covering the root tip.
Root hair: Tiny extensions of root cells that increase surface area for absorption of water and nutrients.

Root Function

Anchorage: Provides stability and support for the plant in the soil.
Absorption: Takes in water and dissolved nutrients from the soil.
Storage: Some roots, like carrots and beets, store food reserves.

Plant Tissues

Dermal tissue: The outer protective layer of the plant, including the epidermis and cuticle.
Vascular tissue: Includes xylem and phloem, responsible for transport.
Ground tissue: The bulk of the plant body, involved in photosynthesis, storage, and support.

Monocots

Have one cotyledon (seed leaf) in their embryo.
Parallel leaf venation.
Fibrous root systems.
Flowers with petals in groups of three.

Dicots

Have two cotyledons in their embryo.
Net-like leaf venation.
Tap root systems.
Flowers with petals in groups of four or five.

Plant Divisions

Bryophytes: Nonvascular plants, like mosses and liverworts.
Pteridophytes: Vascular plants without seeds, like ferns.
Spermatophytes: Vascular plants with seeds; they are further divided into:
- Gymnosperms: Seed plants that bear their seeds in cones, like conifers.
- Angiosperms: Flowering plants that bear their seeds in fruits.

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Explore the role of auxins in plant growth and development. This quiz will test your knowledge on the various types of auxins and their specific functions within the plant system. Understand how these hormones influence processes such as cell elongation and fruit development.