Unit 3 Biology Test

Plant Organs

The three principal organs of seed plants are roots,stems, and leaves. These organs perform functions such as the transport of nutrients, protection, and coordination of plant activities.

Roots Function

Absorb water and dissolved nutrients

Anchor plants in the ground

Protect the plant from harmful soil bacteria and fungi

Stem Function

A support system for the plant body

A transport system that carries nutrients 

A defense system that protects the plant against predators and disease

Leaf Function

Are a plant’s main photosynthetic systems

Increase the amount of sunlight plants absorb

Adjustable pores conserve water and let oxygen and carbon dioxide enter and exit the leaf

Plant Tissues

Dermal Tissue

The outer covering of a plant consists of epidermal cells.

Epidermal cells make up dermal tissue.

The outer surfaces of epidermal cells are covered with a thick waxy layer, known as cuticle.

The cuticle protects the plant against water loss and injury. (Will get thicker with drought)

Projections called trichomes that help protect the leaf and also give it a fuzzy appearance 

In roots, dermal tissue includes root hair cells that provide a large amount of surface area and aid in water absorption.

On the underside of leaves, dermal tissue contains guard cells, which regulate water loss and gas exchange.

Vascular Tissue

Vascular tissue forms a transport system that moves water and nutrients throughout the plant.

Vascular tissue is made up of Xylem, a water-conducting tissue, and phloem, a food-conducting tissue. 

Xylem- all seed plants have tracheids 

Tracheids are long, narrow cells that are impermeable to water. They are pierced by openings that connect neighboring cells to one another.

Angiosperms also have vessel elements. 

Vessel elements form a continuous tube through which water can move

Slowing increasing H20 and adhesion

Capillary action 

Phloem contains sieve tube elements and companion cells

Sieve tube elements are phloem cells joined end-to-end to from sleeve tubes

The end walls of sieve tube elements have many small holes

Sugars and other food can move through these holes from one adjacent cell to another

Companion cells are phloem cells that surround sieve tube elements

Companion cells support the phloem cells and aid  in the movement of substances in and out of the phloem

Ground Tissue

Cells that lie between dermal and vascular tissues make up the ground tissues

Ground tissue produces and stores sugar, and contributes to physical support of the plant

The three kinds of ground tissues are:

Parenchyma

a type of simple permanent tissue that makes a major part of ground tissues in plants, where other tissues like vascular tissues are embedded. They are non-vascular and composed of simple, living and undifferentiated cells, which are modified to perform various functions.

Collenchyma

a cellular tissue that, along with parenchyma, composes the bulk of plant tissues. Like parenchyma, collenchyma cells are living cells. They have cellulose cell walls and are filled with water – which helps the plants to keep their shape.

Sclerenchyma

support tissue composed of any of various kinds of hard woody cells. The sclerenchymatous cells are long and narrow in shape. The cell walls of the sclerenchyma are evenly thick at the corners and contain lignin (water transport). Typically contains dead cells.

Plant Tissues Meristematic

New cells are produced at the tips of the roots and stems

Produced in meristems

A meristematic is a cluster of tissues that is responsible for continuing growth throughout a plant's lifetime.

The new cells produced in meristematic tissues are undifferentiated

As the cells develop into mature cells,they differentiate 

Differentiation is the process in which cells become specialized in structure

As the cells differentiate, they produce dermal,ground, and vascular tissue (whatever the plants need)

Near the tip of each growing stem and root is an apical meristem

An apical meristem is a group of undifferentiated cells that divide to produce increased length of stems and roots

Taproots-

Found mainly in dicots 

Primary root grows long and thick.

A carrot is an example of a taproot

Dermal

Fibrous-

Found mainly in monocots 

Branch to such an extent that no single root grows larger than the rest

Found in grasses

Roots Structure-

Covered with cellular projections called root hairs

Root hairs provide a large surface area through which water can enter the plant

The epidermis protects the root and absorbs water

Inside the epidermis is a layer of ground tissue called the cortex

The cortex extends to another layer of cells, the endodermis

The endodermis completely encloses the vascular cylinder

Things that stay trapped in their are because of the endodermis 

The vascular cylinder is the central region of a root that include the xylem (carries water) and phloem (carries food)

Roots grow in length as their apical meristem produces new cells near the root tip.

New cells covered by the root cap that protects the root as it forces its way through the soil

Root Function-

Roots anchor the plant

Roots absorb nutrients and water from the soil

Root Absorption-

Transport proteins use ATP to pump mineral ions from the soil into the plant

Active transport

low  →high

Pull things in

Water moves into the vascular cylinder by osmosis.

The endodermis traps water and minerals, allowing a one-way passage of materials into the vascular cylinder.

Transport proteins use ATP to actively pump minerals from the soil into the plant.

High concentrations of minerals cause water to move into the plant by hypertonic conditions and hydrostatic pressure (root pressure).

Root Pressure-

 As minerals are pumped into the vascular cylinder, more and more water follows by osmosis, producing a strong pressure.

This root pressure forces water through the vascular cylinder and into the xylem.

Root pressure is the starting point for the movement of water through the vascular system of the entire plant.

Taproots

the presence of a large single root growing downward from the base of the plant. Taproots often have smaller hair-like roots that emerge from the central root. Some examples of plants with taproots include dandelions, carrots, parsnips, and beets.

Fibrous roots

 Thin, branched roots that arise from the base of the stem are known as fibrous roots. Grasses and monocotyledons are characterised by the presence of fibrous roots. The roots are moderately branched, but once a tree fully matures it gives a mat-like appearance.

Endodermis

 an inner layer of cells in the cortex of a root and of some stems, surrounding a vascular bundle.

Casparian strip

form a barrier to the apoplastic flux, forcing ions to pass through the selectively permeable plasma membrane into the cytoplasm, rather than move along the cell wall.

Ions through Active transport

the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient.

Water through osmosis to balance ions

ensures that optimal concentrations of electrolytes and non-electrolytes are maintained in cells, body tissues, and in interstitial fluid. Solutes or water move across a semipermeable membrane, causing solutions on either side of it to equalize in concentration.

Root pressure

force that helps to drive fluids upward into the water-conducting vessels (xylem). It is primarily generated by osmotic pressure in the cells of the roots and can be demonstrated by exudation of fluid when the stem is cut off just above ground.

Nodes

the points on a stem where the buds, leaves, and branching twigs originate. They are crucial spots on the plant where important healing, structural support, and biological processes take place.

Internodes

The portion of a stem between the level of insertion of two successive leaves or leaf pairs (or branches of an inflorescence). A segment of a stem between two nodes. The portion of stem found between lateral meristems in plants.

Buds

If a bud occurs on the tip of a stem, then it is called a terminal or apical bud. Lateral buds are those which occur on the side of stems. Those lateral buds that occur at the leaf axil where the leaf attaches to the stem are called axillary buds.

Simple leaf

 The blade is completely undivided; leaves may also be formed of lobes where the gaps between lobes do not reach to the main vein.

Compound leaf leaflet

 The leaf blade is divided, forming leaflets that are attached to the middle vein, but have their own stalks. The leaflets of palmately-compound leaves radiate outwards from the end of the petiole.

Petiole

the stalk that attaches the leaf blade to the stem. It is able to twist the leaf to face the sun, producing a characteristic foliage arrangement (spacing of blades), and also optimizing its exposure to sunlight.

Blade

the leaf of a plant, especially grass; the flat or expanded portion of a leaf; lamina.

Palisade Mesophyll

 one or more layers of cells located directly under the epidermal cells of the adaxial leaf blade surface. The palisade mesophyll is oriented vertically and is longer than broad. Photosynthesis takes place in both palisade and spongy mesophyll.

Spongy Mesophyll

In a leaf, mesophyll tissue comprising cells of irregular shape, some of them lobed, separated by large spaces in which the atmosphere is humid. Spongy mesophyll is the site of gaseous exchange for photosynthesis and respiration

Stomata

 the tiny openings present on the epidermis of leaves. Stomata play an important role in gaseous exchange and photosynthesis.

Guard Cells

cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. Light is the main trigger for the opening or closing. Each guard cell has a relatively thick and thinner cuticle on the pore-side and a thin one opposite it.

Epidermis

The protective outer layer of the skin. In invertebrate animals, the epidermis is made up of a single layer of cells.

Cuticle

 the various forms of the outermost covering of organisms. In some animals, such as the invertebrates, the cuticle is the superficial layer that covers the epidermis.

Trichomes

 unicellular or multicellular appendages, which are an extension of the above-ground epidermal cells in plants. These appendages play a key role in the development of plants and occur in a wide variety of species.

Root Hairs

tiny extensions or projections from the outer surface of plant roots.

Guard Cells

specialized cells within the plant epidermis that form the stomatal pores that are responsible for the exchange of gasses into and out of leaves and thus, plants as a whole.

Root Cap

 a type of tissue at the tip of a plant root. It is also called calyptra. Root caps contain osteocytes which are involved in gravity perception in plants. If the cap is carefully removed the root will grow randomly. The root cap protects the growing tip in plants.

Vascular Tissue

The tissue in vascular plants that circulates fluid and nutrients. There are two kinds of vascular tissue: xylem , which conducts water and nutrients up from the roots, and phloem , which distributes food from the leaves to other parts of the plant.

Xylem

a vascular tissue that transports water throughout a plant's body. The complex processes and various cell types constitute xylem transfer water and dissolved nutrients to maintain and nourish plants.

Tracheid

a long and tapered lignified cell in the xylem of vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms use another type of conductive cell, called vessel elements, to transport water through the xylem.

Vessel Element Phloem

a long and tapered lignified cell in the xylem of vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms use another type of conductive cell, called vessel elements, to transport water through the xylem.

Sieve Tube Element

An elongated, food-conducting cell in phloem in angiosperms.Sieve elements have living protoplasts when mature, but they lack a nucleus and are dependent upon companion cells for certain functions.

Companion Cells

A type of cell found within the phloem of flowering plants. Each companion cell is usually closely associated with a sieve element. Its function is uncertain, though it appears to regulate the activity of the adjacent sieve element and to take part in loading and unloading sugar into the sieve element.

Spongy Cortex (Root)

thick external layer

Cortex (Stem)

 an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation.

Pith (Stem)

a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In dicotyledons, pith is located in the center of the stem.

Mesophyll (leaf)

the internal ground tissue located between the two epidermal cell layers of the leaf; and is composed of two kinds of tissues: the palisade parenchyma, an upper layer of elongated chlorenchyma cells containing large amounts of chloroplasts; and the spongy parenchyma, a lower layer of spherical or ovoid.

Undifferentiated

a plant body where the vascular tissue has not developed, as in the thallophytes.

Differentiated

a process through which meristematic tissues undergo permanent change to form specialized cells in the plant body. Differentiation leads to the formation of permanent tissues which have specialized structures for specific functions.

Apical

relating to, located or situated at, or constituting, an apex. A 'base' is defined as the 'lowest or bottom part of an object on which it stands' or the 'main part to which other parts are added'.

Primary Growth

the rapid dividing of cells, primarily in the apical meristems of plants, located at the tips of roots and stems. Primary growth in plants results in the elongation of these organs, both upward in stems, and outward in roots.

Secondary Growth

a type of growth characterized by an increase in the thickness of the stem and the root, and it results from the formation of secondary vascular tissue by the vascular cambium.

Angiosperms

plants that produce flowers and bear their seeds in fruits.

Root Pressure

force that helps to drive fluids upward into the water-conducting vessels (xylem). It is primarily generated by osmotic pressure in the cells of the roots and can be demonstrated by exudation of fluid when the stem is cut off just above ground.

Capillary Action

 the movement of a liquid through or along another material against an opposing force, such as gravity. Capillary action depends on cohesion, the attraction between particles of the same substance, and adhesion, the attraction between particles of different substances.

Transpiration Pull

a biological process in which the force of pulling is produced inside the xylem tissue. This force helps in the upward movement of water into the xylem vessels.

Source

primarily occurs in the small intestine, where most digestion and absorption of nutrients take place. There are two main types of transport mechanisms: passive transport (which does not require energy) and active transport (which requires energy to move substances against a concentration gradient).

Sink (Nutrient transport)

any location where sugar is delivered for use in a growing tissue or storage for later use. Growing tissues might include apical and lateral meristems or developing leaves, flowers, seeds, and fruits; storage locations might include roots, tubers, and bulbs.

Source (Hormones)

Endocrine glands, which are special groups of cells, make hormones. The major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal glands, and pancreas.

Target Cell

A target cell responds to a hormone because it bears receptors for the hormone. In other words, a particular cell is a target cell for a hormone if it contains functional receptors for that hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone.

Auxins

A family of plant hormones. They are mostly made in the tips of the growing stems and roots, which are known as apical meristems, and can diffuse close diffusionThe movement of molecules from an area of higher concentration to an area of lower concentration. to other parts of the stems or roots.

Apical Dominance

most likely adaptive. Typically, the end of a shoot contains an apical bud, which is the location where shoot growth occurs. The apical bud produces a plant hormone, auxin (IAA), that inhibits growth of the lateral buds further down on the stem towards the axillary bud.

Gibberellins

phytohormones that are essential for many processes of plant development, such as seed germination, stem elongation, leaf expansion, flowering, and seed development.

Abscisic Acid

 is a hormone involved in pivotal physiological functions in higher plants, such as response to abiotic stress and control of seed dormancy and germination.

Ethylene

regarded as a multifunctional phytohormone that regulates both growth, and senescence. It promotes or inhibits growth and senescence processes depending on its concentration, timing of application, and the plant species.

Phototropism

 the ability of the plant to reorient the shoot growth towards a direction of light source. Phototropism is important to plants as it enhances the ability of plants to optimize their photosynthetic capacity.

Gravitropism

the movement or growth of a plant in response to gravity. Roots demonstrate positive gravitropism because they grow in the direction of gravity. Plant shoots demonstrate negative gravitropism since they grow in the opposite direction of gravity.

Thigmotropism

directional growth movement which occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however plant biologists have also found thigmotropic responses in flowering plants and fungi.

Rapid Response

the process of reacting to the detection once the organism has been authoritatively identified and response options have been.

Storing Energy

One of the most important compounds is adenosine triphosphate

Adenosine diphosphate is a compound that looks almost like ATP, except that it has two phosphate groups instead of three. The difference is the key to the way in which living things store energy. When a cell has energy available, it can store small amounts of it by adding phosphate to ADP to produce ATP. 

Releasing Energy

Cells can release the energy stored in ATP by the controlled breaking of the chemical bonds between atoms in the second and third phosphate groups. Because energy is released when a phosphate group on ATP is split off and released, ATP serves the cell as a way of storing and releasing energy as needed.

How cells use ATP

ATP provides the energy that keeps this pump working, maintaining a carefully regulated balance of ions on both sides of the cell membrane. In addition, ATP enables cells to move, powers the process of protein synthesis and fuels the response to chemical signals at the cell surface to name a few.

Small amount of ATP-enough to last for only a few seconds

Heterotrophs

Organisms that obtain food by consuming other living things

Autotrophs

Organisms that make their own food 

Plants, Algae, and some bacteria

Chlorophyll

Chlorophyll is a pigment found in the chloroplasts of cells. During photosynthesis, chlorophyll absorbs light from the sun and turns it into chemical energy the plant can use as food. Chlorophyll has also been used in alternative medicine and has shown to have medicinal benefits.

Chlorophyll absorbs light very efficiently,transferring light energy to its own electrons. These high-energy electrons are then available to do chemical wor, such as the building of sugar molecules from low-energy compounds like carbon and water. 

Chloroplast

Chloroplasts are surrounded by two envelope membranes, and they are  filled with saclike chlorophyll-containing membranes called thylakoids. These thylakoids are interconnected and arranged 

in stacks known as grana. The fluid portion of the chloroplast, outside the thylakoids is known as the stroma.

High-Energy Electrons

An electron carrier is a compound that can accept a pair of high-energy electrons and transfer them, along with most of their energy, to another molecule.

One of these carrier molecules is a compound known as NADP+ accepts and holds two high-energy electrons, along with a hydrogen ion (H+). This converts NADP+ into NADPH. THe conversion of NADP+ into NADPH is one way in which some of the energy sunlight can be trapped in chemical form.

Photosynthesis: An overview

Photosynthesis uses the energy of sunlight to convert water and carbon dioxide (low-energy reactants) into high-energy sugars and oxygen (products).

Light Dependent Reactions

Take place in the thylakoid membranes and use energy from sunlight to add a third phosphate to ADP to make ATP.

Take low-energy electrons from water molecules, and use solar energy to raise them to a much higher lever. These high-energy electrons are then transferred to the electron carrier, NADP+, which is converted to NADPH.

Light Independent Reactions

The ATP and NADPH molecules produced in the light-independent reactions are used to build high-energy sugars. No light is required to power the light-independent reactions. These reactions take place outside the thylakoids, in the stroma on the chloroplasts. 

The Process Of Photosynthesis

The light dependent reactions use energy from sunlight to convert ADP and NADP+ into energy and electrons carry ATP and NADPH. These reactions also produce oxygen (O2) as a by-product.

During the light-independent (calvin cycle) reactions, ATP and NADPH from the light-dependent reactions are used to synthesize high energy sugars.

The two sets of photosynthesis reactions work together-the light dependent reactions trap the energy of sunlight in chemical form, and the light-independent(calvin cycle) reactions use that chemical energy to synthesize stable high energy sugars from carbon dioxide and water.

Stem Structures

Leaves attach to the stem at structures called nodes

The regions of stem between the nodes are internodes

Small buds are found where leaves attach to nodes

Buds contain undeveloped tissues (meristematic) that can produce new stems and leaves

Monocot Stems

Vascular bundles are scattered throughout the ground tissue

Ground tissue consists mainly of parenchyma cells

Dicot Stems

Dicot stems have vascular bundles arranged in a ringlike pattern

The parenchyma cells inside the vascular tissue are known as pith

The parenchyma cells outside of the vascular tissue form the cortex of the stem

Primary Growth

stems is the result in vertical growth

Secondary Growth

results in lateral growth

Moncot vs Dicot stems