FINALS BOTLAB PDF

10. Consider a professional service MODULE 1: THE MICROSCOPE The company where the microscope was bought can be Proper care and maintenance of a microscope is paramount contacted for a range of products to h...

10. Consider a professional service MODULE 1: THE MICROSCOPE The company where the microscope was bought can be Proper care and maintenance of a microscope is paramount contacted for a range of products to help keep your laboratory and can help extend its life. microscopy equipment in tip-top condition. 1. Handle with care PARTS OF THE MICROSCOPE AND ITS USES Improper handling is a common cause of many problems The origin of the word microscope according to the Online that occur with microscopes. When carrying a microscope, hold it Etymology Dictionary is as follows: 1656, from Mod.L. by the base and the metal support arm. The stage on a microscopium, lit. "an instrument for viewing what is small," from ] microscope is the flat plate where the slides are placed for mikros (small.) + -skopion. "means of viewing," from skopein observation. Avoid picking your microscope up by the stage or the "look at." Microscopic "of minute size" is attested from the 1760s. eyepiece holder, as this can cause misalignment. The following are elemental parts of a typical microscope 2. Look after lenses used in the laboratory classes: When using your microscope, the objective lens is 1. The Eyepiece Lens lowered to adjust the focus. However, be careful not to let the lens touch the slide you’re looking at, as this can damage the lens. The eyepiece contains the ocular lens which you will be Furthermore, dirty lenses are notoriously difficult to clean. looking through to see the magnified specimens withmagnification ranging from 5X to 30X, but 10X or 15X is the Avoid touching the lenses of the microscope. most common in use. The ocular lens provides a re-magnified image to see when light enters through the objective lens. 3. Keep covered 2. The Eyepiece tube Microscopes should always be sold with dust covers. Whether transporting or storing your instrument, make the most of It connects the eyepiece and ocular lens to the objective the microscope bag, and remember to keep your microscope lenses. covered when not in use. The microscope’s eye tubes also need to be kept dust-free. If the eyepieces need to be removed, cover the 3. The Microscope Arm tubes with caps and store them with the microscope. It connects the eyepiece tube to the base which you 4. Store safely should hold when carrying the microscope. Ensure you store your microscope in a clean, dry space 4. The Microscope Base with good ventilation. Salt air or damp, for example, can cause damage to equipment over time. Expensive, precision equipment It provides stability and support for the microscope in its should not be stored next to solutions that may leak. Similarly, upright position. Typically, it holds the source of light or illuminator. keep your microscope away from areas with potentially corrosive chemical fumes. Such fumes can destroy lenses or corrode metal 5. The Microscope Illuminator parts. It is a light source that can come in the form of a built-in, 5. Keep clean low-voltage illuminator light, or a mirror that reflects an external light source like sunlight. Oil immersion is a technique used to increase the resolving power of a microscope. Both the objective lens and 6. The Stage and Stage Clips sample are immersed in a transparent oil of high refractive index so that high magnifications can be achieved while still maintaining It serves as the platform for slides that hold the specimen good resolution. It is essential to ensure careful cleaning takes in place through a staged clip on either side. Some have place immediately after using immersion oil and do not use mechanical stages with adjustment knobs that allow the damaging solvents. movement of slides to achieve more precise positioning. 6. Take care of bulbs COARSE ADJUSTMENT KNOB — A rapid control that allows for quick focusing by moving the objective lens or stage up and down. After using your microscope, turn off the illuminator It is used for initial focusing. and wait for it to cool down before putting it away. Allowing the bulb to cool will extend its life and avoid the unnecessary cost of FINE ADJUSTMENT KNOB — A slow but precise control used to expensive replacements. Similarly, if used constantly on full power, fine focus the image when viewing at the higher magnifications. the bulb will overheat and blow. Remember too, to turn the illuminator off when not in use. 7. The Microscope Nosepiece It contains objective lenses. You can rotate this part by 7. Clean carefully switching objective lenses and adjusting the magnification power. Microscope lenses are delicate. Treat them carefully to avoid any scratches. Use an aspirator to remove dust. Moisten 8. The Objective Lenses special lens paper with distilled water or appropriate cleaning Generally, microscopes feature three or four objective lenses, solution. Rubbing gently in a circular motion will remove any sticky with magnification levels ranging from 4X to 100X. Objective residue. Never use anything abrasive on microscope lenses. lenses are combined with the eyepiece lens to increase magnification levels. Objective lenses are the lenses that protrude Rotate the nosepiece of the microscope all the way down to its lowest level when you have finished using the downward over the specimen. microscope. a. scanning lens – 4X 8. Refer to the user’s manual b. LPO – 10X Your microscope should be sold with a user’s manual and c. HPO – 40X specialist spanners as required. Always refer to the manual when making any adjustments to the microscope and use the supplied d. OIO – 100X spanners. Never use force, inappropriate tools or over-tighten when making adjustments to your microscope, as this will only 9. The Rack Stop result in equipment damage. It prevents users from moving the objectives too close to 9. Maintain your microscope the slide. An annual maintenance check of microscopes is always a 10. Control Focus Knobs good idea. Moving parts should be cleaned and lubricated. Similarly, inspect the power cords and plugs for safety. Turning the knobs adjusts the distance between the stage and the lens. The coarse adjustment knob is used to bring the specimen into initial focus -- visible but not sharp. The fine readjust the sample into focus and/or readjust the condenser and adjustment knob is then turned to bring the specimen into sharp light intensity). focus. Do not let the objective lens touch the slide! 11. The Condenser Lens and Diaphragm Both eyes should be open when viewing through the These parts are located under the microscopic stage. The microscope. condenser concentrates the light on the specimen whereas the diaphragm with a small movable lever is adjusted to regulate the 10. Complete your drawings (image seen under LPO, HPO). entry of light. 11. When finished, lower the stage, click the low-power lens into MOUNTING OF SPECIMEN ON MICROSCOPIC SLIDE position, and remove the slide. Mounting of specimens on slides can be done in three different 12. Wash and dry the slides and keep it on your storage rack or ways as discussed below in simple ways. tray. Dry mount slide MODULE 2: MAGNIFICATION AND RESOLVING POWER 1. Place a sample seed of sesame on a clean glass slide at the center and cover it. FIELD OF VIEW Wet mount slide Power of resolution – is the measure for the ability to tell two points apart. It describes whether two adjoining points can still be 1. Place a drop of water at the center of the slide. perceived as separate. 2. Using a tweezer, place the pollen of the gumamela flower or any Magnification of a microscope – is the product of Vobjective X flower with pollen in the middle of the drop. Vocular 3. While holding the cover slip upright and by the edges, carefully Numerical aperture – is the sine of half the angle of the cone of place one edge of the coverslip next to the water. light from each point of the object that can be accepted by the objective multiplied by the index of refraction of the medium in 4. Set one edge against the slide and lower it until it contacts the which the object is immersed. The N.A. represents a performance liquid. Slowly lower the upper edge of the cover and slip onto the number that can be compared to the relative aperture (f-number) water. of a camera lens. The N.A. values can be used for directly comparing the resolving powers of all types of objectives. The 5. An absorbent towel can be placed at the edge of the coverslip to larger the N.A., the higher the resolving power is. draw out some of the water, further flattening the wet mount slide. Working distance – refers to the distance from the cover glass to Staining a Slide the nearest point of the objective. The starch slurry will be mounted on a slide. Focal depth - refers to the distance between the upper and lower 1. Place one drop of methylene blue stain or iodine solution on limits of sharpness in the image formed by an optical system. As one edge of the coverslip and the flat edge of a piece of paper you stop down the aperture iris diaphragm, the focal depth becomes larger. The larger the N.A. of an objective the shallower towel on the other edge of the coverslip. (The paper towel will draw the water out from under the coverslip and the cohesion of water the focal depth is. will draw the stain under the coverslip.) Field number – This is a number that represents the diameter in 2. If the stain has covered the area containing the specimen, you mm of the image of the field diaphragm that is formed by the lens are done. (The stain does not need to be under the entire coverslip. in front of it. If the stain does not cover the area needed, get a new piece of paper towel and add more stain until it covers.) Field of view diameter -The actual size of the field of view in mm on the object surface. a better focus should reflect a circular one. 3. Wipe off the excess stain with a paper towel so it will not mess up with objective lenses. 4. The slide can now be placed on the microscopic stage. HOW TO FOCUS IMAGE UNDER THE MICROSCOPE 1. Place the microscope on a flat, level, firm table free from vibration seeing to it that the arm is towards you while the stage is going away from you. Do not place it in front of a brightly lit window. 2. Turn on the light source and adjust the optimum light setting to ensure the correct level of brightness by turning or sliding the brightness adjustment knob at the base. To calculate the dFOV illustrated on the slide above, you will need 3. Turn the revolving nosepiece (turret) so that the lowest power to place a plastic transparent ruler on the stage, focus the ruler objective lens is clicked into position. until you see the field of view, and then measure the diameter of the field of view in millimeters. 4. Place the slide (dry mount, wet mount, prepared mount) on the mechanical stage secured with clips. Enlargement or magnification of a specimen is the function of a two-lens system; the ocular lens is found in the eyepiece, and 5. Look through the eyepiece and move the focus knob until the the objective lens is situated in a revolving nose-piece. These image comes into focus. lenses are separated by the body tube. The objective lens is nearer the specimen and magnifies it, producing the real image that is 6. Adjust the condenser and light intensity for the greatest amount projected up into the focal plane and then magnified by the ocular of light. lens to produce the final image. 7. Move the microscope slide around until the sample is in the The most commonly used microscopes are equipped with a center of the field of view. revolving nosepiece containing four objective lenses possessing 8. Manipulate the focus knob and readjust the condenser and light different degrees of magnification. When these are combined with intensity to obtain the clearest image possible. the magnification of the ocular lens, the total or overall linear magnification of the specimen is obtained. 9. Once the image is sharp with LPO, move to HPO and do minor adjustments using the fine adjustment knob. (You might need to Magnification does not describe the quality of the image. Magnifying an object without good resolution is called empty magnification, as the image appears larger but no greater detail Let's say, for example, using medium power (10X objective), the can be seen. diameter of the field of view is measured as 2 mm. Looking across the diameter are cells aligned? Counting it gives you 8 cells. The microscope magnification depends on both ocular lens Therefore there are 8 cells visible across the dFOV of 2 mm. You and objective lens magnifications. are determining the approximate size of each cell, dividing the Microscope magnification = Vobjective X Vocular dFOV by a number of cells (2 mm / 8 ) will give you 0.25 mm. The size of each cell is therefore 0.25 mm or 250 µm. For example, the magnification of the ocular lens is 10X with a magnification of lenses of objectives as follows: 4X, 10X, 40X, DRAWING MAGNIFICATION and 100X. So what will be the magnifications at low, medium, high power, and oil immersion? For some time you need to draw the image you've seen under a microscope or attached camera to take photos of the image. The magnification at low power = 10 x 4 = 40 times question is how many times your drawing has been enlarged relative to the true size of the object? I am referring to drawing magnification at medium power = 10 x 10 = 100 times magnification. Below is the equation for calculating the drawing magnification. magnification at high power = 10 x 40 = 400 times Magnification of drawing = size of the drawn object in μm magnification at oil immersion type of power = 10 x 100 = /object’s actual size in μm 1,000 times Let us say the drawing is roughly 7 cm long. This equates to How do you now calculate the field of view in your 70 mm or 70,000µm. The actual size of the specimen is about 500 microscope: µm. What is the drawing magnification? 1. If using an eyepiece only? Drawing magnification = drawing size / actual size. Please check the specifications of the eyepiece, let's say you have 70,000 µm / 500 µm = 140 X WF 10X/20. The magnification of the eyepiece is 10X with a field number of 20. Therefore the FOV here is 10 divided by 20 is 0.5 or Drawing Magnification = 140 X an FOV diameter of 0.5 millimeters. Let us say the corpse flower (Rafflesia arnoldi) below 2. If eyepiece and objective lens are used? measures around 1 meter in diameter. You are instructed to draw on a paper such that the diameter will measure only 10 Let us use the specification of the eyepiece in the example above, centimeters. Applying the formula above will give you 0.1 X. So WF 10X/20 and you set the objective lens at 40. Multiple 10 what does this mean? (Vocular ) by 40 (Vobjective ) to get 400. An FOV diameter of 0.05 mm will be obtained in dividing 20 by 400. Scale bars are a useful way to indicate the size of a cell or object of study If you know the dFOV for low power lens, the FOV of higher power lenses can be calculated using the ratio as follows and vice versa: A. use a ruler to measure the length of the scale bar in mm. Low Power Magnification × Low Power Field of View = Higher B. convert into the same units as the scale bar. Power Magnification × Higher Power Field of View C. divide the IMAGE scale bar length by the ACTUAL object scale bar length. Example: The Vocular of 10× with the Vobjective of 10× produced the field of view of 800 µm. Compute the field of view when the Please see the example below. Vocular is 40× and the Vobjective is 100×. Solution: The magnification at lower power is 10 × 10 = 100 The magnification at higher power is 40 × 100 = 4000 Field of view = 100 × 800 / 4000 = 20 µm OBJECT (ACTUAL) SIZE SCIENTIFIC NAMES: Gumamela - Hibiscus rosa-sinensis Sesame Seeds - Sesamum indicum Indian Rubber Tree - Ficus elastica Onion Bulb - Allium cepa Digman leaf/ Hydrilla - Hydrilla verticillata Bangka-bangkaan - Tradescantia Spathacea Patatoes - solanum tuberosum Sabila leaf - Aloe vera MODULE 3 Lesson 1: PLANT CELLS AND TISSUES Robert Whittaker ⬧ During the late twentieth century, Robert Whittaker's ⬧ a rigid layer that is composed of polysaccharides cellulose, five-kingdom system was a standard feature of biology pectin, proteins and hemicellulose. textbooks, serving as an important organizing scheme for ⬧ it is located outside the cell membrane discussing biodiversity. ⬧ to protect and provide structural support to the cell. 5 Kingdom of Classifications PLASMA MEMBRANE Monera Protista ⬧ involved in the production and assembly of cellulose for cell Fungi walls. Animalia NUCLEUS Plantae (Botany) CELLS ⬧ a membrane-bound structure that is present only in eukaryotic cells. ⬧ vital function of a nucleus is to store DNA or hereditary Cell, in biology, is the basic membrane-bound unit that contains information required for cell division, metabolism, and the fundamental molecules of life and of which all living things growth. are composed. 1. Nucleolus: it manufactures cells' protein-producing A single cell is often a complete organism in itself, such as a structures and ribosomes. bacterium or yeast. 2. Nucleopore: allow proteins and nucleic acids to pass through. Other cells acquire specialized functions as they mature. ⬧ Nuclear Envelope ⬧ Nucleoplasm PROKARYOTIC CELL PRO- before ENDOPLASMIC RETICULUM KARYON – nucleus ⬧ it facilitates the transport of materials within the cell. EUKARYOTIC CELL ⬧ many important activities, such as the synthesis of EU – well or good membranes for other organelles and modification of proteins from components assembled from elsewhere within the cell, occur either on the surface of the endoplasmic reticulum or within its compartments. RIBOSOMES ⬧ these are dense granules present in the cytoplasm involved in protein synthesis. ⬧ each ribosome is composed of two sub-units that are composed of RNA and proteins ⬧ functions as a micro-machine for making proteins. ⬧ they are the smallest membrane-bound organelles that comprise RNA and protein. ANIMAL CELL VS. PLANT CELL DICTYOSOMES – Golgi Bodies Plant Cell Animal Cell ⬧ post office of the cell ⬧ stacks of flattened discs or vesicles known as dictyosomes Plant cell is large and has a Animal cell is small and fixed rectangular shape. irregular or round in shape. may be scattered throughout the cytoplasm of a cell. ⬧ These bodies play an important role in the secretory activities of the cell and serve as packaging areas for secretion. Cell wall is present Cell wall is absent PLASTIDS The nucleus lies on one side of The nucleus lies in the center the cell. ⬧ they are membrane-bound organelles that have their own Mitochondria are present in Mitochondria are present in DNA. fewer numbers. large numbers ⬧ necessary to store starch and to carry out the process of photosynthesis Plastids are present Plastids are absent Centrosomes are absent Centrosomes are present 1. CHROMOPLASTS: are heterogeneous, colored plastid which is responsible for pigment synthesis and for storage in One large central vacuole is Many small vacuoles are photosynthetic eukaryotic organisms present present Chromoplasts have red, orange, and yellow colored pigments WHAT IS A PLANT CELLS? which provide color to all ripe fruits and flowers. Plant cells are eukaryotic cells that vary in several fundamental 2. CHLOROPLASTS: elongated organelle enclosed by factors from other eukaryotic organisms. phospholipid membrane Both plant and animal cells contain a nucleus along with similar The chloroplast is shaped like a disc and the stroma is the fluid organelles. within the chloroplast that comprises circular DNA One of the distinctive aspects of a plant cell is the presence of a The chlorophyll absorbs light energy from the sun and uses it to cell wall outside the cell membrane. transform carbon dioxide and water into glucose. PLANT CELL STRUCTURE Corkscrew-like ribbons shaped; cells of the green algae Spirogyra. Bracelet-shaped chloroplasts: other green algae, such as Ulothrix. CELL WALL Within the chloroplast are numerous GRANA (singular: granum), usually found in all plant roots and are mainly involved in which are formed from membranes and have the appearance of providing support to plants stacks of coins with double membranes Xylem Cells There are usually about 40 to 60 grana linked together by arms in each chloroplast, and each granum may contain from two or the transport cells in vascular plants. three to more than 100 stacked THYLAKOIDS they help in the transport of water and minerals from the The liquid portion of the chloroplast is a colorless fluid matrix roots to the leaves and other parts of the plants. called STROMA Phloem Cells 3. LEUCOPLAST: they are found in the non-photosynthetic tissue of plants. Phloem cells are other transport cells in vascular plants. They transport food prepared by the leaves to different Amyloplasts parts of the plants. Elaioplasts Plant Cell Functions If exposed to light, some leucoplasts will develop into chloroplasts, and vice versa. They are used for the storage of protein, lipids, and starch. PHOTOSYNTHESIS Chloroplast - Contain chlorophyll (green pigment) that absorbs sunlight in photosynthesis ⬧ the process in which light energy is converted to chemical - Produce and store glucose energy in the form of sugars. Chromoplast - Contain carotenoids (red, orange, and yellow ⬧ The Light-dependent reaction which stores energy from the pigments) sun through the form of ATP (adenosine triphosphate) and - Found in flowers and fruit NADPH (nicotinamide adenine dinucleotide phosphate). Leucoplast - Contain no pigment ⬧ The Calvin cycle reactions can be organized into three basic - Used to store starch stages fixation, reduction, and regeneration. CENTRAL VACUOLE Lesson 2: PLANT TISSUE ⬧ Tonoplast is a membrane that surrounds the central vacuole. ⬧ The vital function of the central vacuole, for storage and to Permanent: THREE BASIC TYPES OF PLANT TISSUES sustain turgor pressure against the cell wall. ⬧ The central vacuole consists of cell sap. a. Parenchyma Tissue b. Collenchyma Tissue c. Sclerenchyma Tissue Crystals occurs in various shapes and size. They are differentiated Types of Parenchyma Tissue based on their composition and shape. ⬧ Normal Parenchyma Cells Calcium oxalate crystals in the stem and leaf of Cynanchum ⬧ Rounded acutum (Stranglewort) ⬧ Angular ⬧ Prosenchyma (A-C) Druse crystals in the cortex of the stem at different ⬧ Xylem Parenchyma magnifications. (D) Druse crystals in the leaf mesophyll. (E) Druse ⬧ Epidermal Cells crystals around the major vein. (F) Druse and prismatic crystals ⬧ Mesophyll along the vascular bundle. ⬧ Aerenchyma Calcium oxalate (CaC204): Types of Sclereids: RAPHIDE: fine, needle-like crystals occurring singly or in clusters, ⬧ Stone cell branchysclereid, with pit canals scattered or enclosed in a sac as in gabi or other succulent plants ⬧ Macrosclereid ⬧ Osteosclereid PRISMATIC: prism-like or diamond-like crystals found in leaves of ⬧ Astrosclereid begonia or Bangka-bangkaan ⬧ Fillform sclereid ROSETTE: flowerlike appearance in santan and stem of kutsarita Plant Tissues plant STYLOID: knife-like, tapering at both ends Types: Meristematic tissue Calcium carbonate (CaCO3): Permanent (or non-meristematic) tissue. CYSTOLITH: grapelike as seen in the hypodermal cell of the leaf of Meristematic VS Permanent Tissue an Indian rubber tree or ampalaya-like plant. Meristematic tissue is analogous to stem cells in animals. meristematic cells are undifferentiated and continue to divide Specialized Plant Cell Types and contribute to the growth of the plant (cell division). In contrast, permanent tissue consists of plant cells that are no longer actively dividing. Collenchyma Cells PLANT TISSUES Meristems produce cells that quickly differentiate, or specialize, they are hard or rigid cells, which play a primary role in and become permanent tissue. providing support to the plants when there is restraining growth in a plant due to a lack of hardening agent in Such cells take on specific roles and lose their ability to divide primary walls. further. Sclerenchyma Cells They differentiate into three main tissue types: dermal, vascular, and ground tissue. more rigid compared to collenchyma cells and this is Each plant organ (roots, stems, leaves) contains all three tissue because of the presence of a hardening agent. These cells are types.  Tracheids have hardened secondary cell wall. and function in water conduction. Vessel Elements resemble open-ended tubes that are arranged end to end allowing water to flow within the tubes. 2. Vascular plants also have another type of conducting tissue called phloem. Sieve tube elements are the conducting cells of the phloem. They transport organic nutrients, such as glucose, throughout the plant. The cells of sieve tube elements have few organelles allowing for easier passage of nutrients. Since sieve tube elements lack organelles, such as ribosomes and vacuoles, specialized parenchyma cells, called companion cells, must carry out metabolic functions for sieve tube elements. Simple Permanent Tissue DIFFUSION 1. Epidermis is the outermost layer of any plant organ with primary growth. All molecules in liquids and gases characteristically tend to move Specialized cells present in the epidermis are the guard or diffuse in all directions until they are distributed evenly cells of the stomata. The outward growth of epidermal throughout the available space. cells is known as epidermal hair or trichome. Diffusion is the movement of molecules from a region of high The epidermis produces a waxy material called cuticle. concentration to a region of low concentration. Epidermis on stems and leaves prevent water loss by In a closed environment, the molecules will disperse themselves transpiration. until the concentration is equal throughout – which is referred to 2. Parenchyma is the least specialized permanent tissue as equilibrium. composed of living thin-walled cells. These cells help to synthesize and store organic products in the plant. The middle tissue laver of leaves (mesophyll) is composed of parenchyma cells, and it is this layer that contains plant chloroplasts, Chlorenchyma are elongated cylindrical cells with long axis at the right angle to the surface of the organ. Aerenchyma are specialized for gas exchange. The rate of diffusion is influenced by the: I. the temperature of the environment, 3. Collenchyma cells have a support function in plants, II. the density of the diffusing molecule, particularly in young plants. III. medium of diffusion, and These cells help to support plants, while not restraining IV. concentration gradient growth. Collenchyma cells are elongated in shape and have thick primary cell walls composed of the carbohydrate ⬧ Increase in temperature increases the average kinetic polymers cellulose and pectin. energy of the particles, thus increasing their velocity. able to stretch along with a plant as it grows. ⬧ At a certain temperature, lighter atoms, such as hydrogen, Collenchyma cells are found in the cortex (layer between carbon, oxygen, and nitrogen travel faster and are more the epidermis and vascular tissue) of stems and along mobile than larger atoms such as copper or iron. Thus, leaf veins. materials made of these lighter atoms diffuse faster than 4. Sclerenchyma cells also have a support function in plants, heavier materials. but unlike collenchyma cells, they have a hardening agent in ⬧ The diffusion rate also depends on the medium where the their cell walls and are much more rigid. movement of molecules takes place. The particles present in Sclereids have varied sizes and shapes, and most of the the medium act as the barrier to diffusion, e.g. adding sugar volume of these cells is taken up by the cell wall. into water increases its viscosity. The particles present in the medium may collide with the diffusing molecules thus Fibers are elongated, slender cells that are strand-like in reducing diffusion rate. appearance. Fibers are strong and flexible and are found ⬧ The concentration gradient pertains to the difference in in stems, roots, fruit walls, and leaf vascular bundles. concentration either side of the membrane. Molecules tend to move down the concentration gradient, toward areas of lesser 5. Cork is the outer impermeable protective layer of a concentration. secondary plant body. ⬧ The greater the concentration gradient the greater the rate of It is composed of compactly arranged dead lignified diffusion. and suberized cells without intercellular spaces. DIFFUSION (IN CELL MEMBRANE) The rate of diffusion also depends on the thickness of the Complex Permanent Tissue membrane and the surface area. For molecules (e.g., drug molecules) to diffuse into the cell, they 1. Water-conducting cells of the xylem have a support function need to traverse the cell membrane. in plants. The cell membrane is so thin that most molecules diffuse through it  he xylem has a hardening agent in the tissue that makes it rigid T at a faster rate. and capable of functioning in structural support and The larger the area over which diffusion can occur, the greater the transportation. rate of diffusion. The main function of the xylem is to transport water throughout Cell membranes allow some molecules to pass through such as the plant. water and oxygen by diffusion, however, other molecules do not Two types of narrow, elongated cells compos xylem: tracheids and freely move across the membrane. vessel elements The selective permeability of the cell membrane is an important duplicates itself to form two daughter centrosomes that migrate to consideration in understanding the mechanism of diffusion. opposite ends of the cell. The centrosomes organize the production of microtubules that form the spindle fibers that constitute the OSMOSIS mitotic spindle. The chromosomes condense into compact structures. Each replicated chromosome can now be seen to consist of two identical chromatids (or sister chromatids) held Osmosis is a diffusion process where water molecules move together by a structure known as the centromere. across the semipermeable membrane Prometaphase Water molecules will move in the direction where there is a high concentration of solute and a low concentration of water. The chromosomes, led by their centromeres, migrate to the Hence, concentrations on both sides of the membrane are equatorial plane in the midline of the cell - at right angles to the equalized axis formed by the centrosomes. This region of the mitotic spindle is known as the metaphase plate. The spindle fibers bind to a In most situations, water molecules move from the structure associated with the centromere of each chromosome less-concentrated (hypotonic) to the more-concentrated called a kinetochore. Individual spindle fibers bind to a (hypertonic) solution. This tends to reduce the difference in kinetochore structure on each side of the centromere. The concentration, thus achieving equilibrium. chromosomes continue to condense. Metaphase The chromosomes align themselves along the metaphase plate of the spindle apparatus. Anaphase This is the shortest stage of mitosis. The centromeres divide, and the sister chromatids of each chromosome are pulled apart - or 'disjoin' - and move to the opposite ends of the cell, pulled by spindle fibers attached to the kinetochore regions. The separated sister chromatids are now referred to as daughter chromosomes. Solvents are liquids in which substances dissolve (It is the alignment and separation in metaphase and anaphase that is important in ensuring that each daughter cell receives a Membranes through which different substances diffuse at different copy of every chromosome.) rates are described as SEMI-PERMEABLE. All plant cell membranes appear to be semi-permeable. Telophase In plant cells, osmosis is essentially the diffusion of water through a semipermeable membrane from a region where the water is The final stage of mitosis and a reversal of many of the processes more concentrated to a region where it is less concentrated. observed during prophase. The nuclear membrane reforms around the chromosomes grouped at either pole of the cell, the chromosomes uncoil and become diffuse, and the spindle fibers OSMOTIC POTENTIAL disappear. The OSMOTIC POTENTIAL (represented by us) of a solution is a measure of the potential of water to move from one cell to Cytokinesis another as influenced by solute concentration. This is the final cellular division to form two new cells. In plants a Water enters a cell by osmosis until the osmotic potential is cell plate forms along the line of the metaphase plate; in balanced by the resistance to the expansion of the cell wall animals, there is a constriction of the cytoplasm. The cell then enters interphase - the interval between mitotic divisions. MITOSIS It ensures that the two new cells (daughter cells) resulting from a cell undergoing mitosis each have precisely equal amounts of DNA The daughter cells that result from mitosis each have the same Plant Cell Division number of chromosomes and distribution of DNA as the parent cell. G1 phase. Metabolic changes prepare the cell for division. At a certain point - the restriction point - the cell is committed to Mitosis is initiated with the appearance of a ringlike preprophase band of microtubules just beneath the plasma membrane and is division and moves into the S phase. usually divided into four arbitrary phases, primarily for S phase. DNA synthesis replicates the genetic material. Each convenience. chromosome now consists of two sister chromatids. PROPHASE G2 phase. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and cytokinesis. the chromosomes become shorter and thicker, and their two-stranded nature becomes apparent M phase. A nuclear division (mitosis) is followed by a cell the nuclear envelope dissociates, and the nucleolus disintegrates. division (cytokinesis). The period between mitotic divisions - that is, G1, S, and G2 - is known as interphase. Mitosis, although a continuous process, is conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. The beginning of the prophase is marked by the appearance of the Prophase chromosomes as faint threads in the nucleus. Prophase occupies over half of the mitosis. The nuclear These chromosomes gradually coil or fold into thicker and shorter membrane breaks down to form a number of small vesicles and structures, and soon, two strands, or CHROMATIDS, can be the nucleolus disintegrates. A structure known as the centrosome distinguished for each chromosome.  The coils appear to tighten and condense until the chromosomes 1. Root cap - thimble-shaped cell mass that protects the growing have become relatively short, thick, and rodlike, with areas called root tip by covering the apex of the root. CENTROMERES holding each pair of chromatids together. 2. Meristematic region - the location of cell division. As the prophase progresses, the nucleolus gradually becomes less 3. Region of elongation - area of root lengthening. The cell produced distinct and eventually disintegrates. from the meristematic region grow in the elongation region. By the end of prophase, spindle fibers consisting of microtubules 4. Region of maturation - this is where the cells that grew in the have developed elongation region fully develop and become adult cells. these spindle fibers extend in arcs between two invisible poles located toward the ends of the cell. EXTERNAL STRUCTURE OF ROOT: METAPHASE 1. Primary root - first root of a plant, originating in the embryo. The main feature of metaphase is the alignment of the 2. Secondary roots - produced on the primary root chromosomes in a circle midway between the two poles around 3. Tertiary roots - grow in various directions and help in fixing the the circumference of the spindle and in the same plane as that plant firmly into the soil. previously occupied by the preprophase band. INTERNAL STRUCTURE OF ROOT: 1. Epidermis is the outermost layer that absorbs water and dissolved material from the soil and protects the inner tissue of the root. 2. Cortex is found inside the epidermis, which is composed of parenchyma cells with large intercellular spaces, secretory cells, resin ducts, and endodermis. 3. Endodermis is the innermost cell layer that regulates ion ANAPHASE movement into the xylem. The Casparian strip embedded in the cell Anaphase—the briefest of the phases—involves the sister wall inhibits mineral movement through the wall. chromatids of each chromosome separating and moving to 4. Vascular cylinder - is the innermost layer with the xylem and opposite poles. phloem cells for the conduction of materials, parenchyma cells for food storage and support of the other tissues TYPES OF MODIFIED ROOTS: 1. Adventitious roots - arise along stem or locations other than base of plant. 2. Aerial roots - roots that extend out into the air, unconnected to the ground. 3. Prop roots - located on lower part of stem of some monocots like TELOPHASE corn, grow down into ground, anchor against wind The five main features of telophase are these: 4. Pneumatophores - spongy outgrowths from underwater roots, may extend above water, increase oxygen supply to roots. i. each group of daughter chromosomes becomes surrounded by a reformed nuclear envelope 5. Parasitic roots - penetrate host plants to parasitize them ii. daughter chromosomes become longer and thinner and finally become indistinguishable 6. Storage roots - branch roots of plants like sweet potatoes produce iii. nucleoli reappear extra parenchyma cells for carbohydrate storage iv. many of the spindle fibers disintegrate; and 7. Buttress roots - produced by certain varieties of fig and tropical v. a cell plate forms. trees for support. Corn - Zea mays Calamansi - Citrus mitis Mango - Mangifera indica Carrot - Daucus carota Camote - Ipomoea batatas Mongo - Phaseolus vulgaris Mayana - Coleus blumei Exercise No. 8 Santan – Ixora coccinea THE ROOTS The plant root system performs various functions which are essential to Exercise No. 9 the growth and development of the plant. THE STEM The functions of the plant root system includes; Stem is the aerial part of the plant where leaves and reproductive shoots a. anchorage of the plant in the soil, are attached. b. conduction of water and minerals upward to the stem, c. reproduction in the form of plant propagation, Functions of stem: d. absorption of water. a. provides mechanical support to the plant b. exposes the leaves for photosynthesis TWO MAIN TYPES OF ROOT SYSTEMS: c. positions the reproductive shoots for optimal access to pollinators d. conducts water and minerals from roots to the leaves. 1. Fibrous root system (monocot plants) 2. Tap root system (dicot plants). TYPES OF STEM: FOUR REGIONS OF A TYPICAL ROOT TIP: 1. Herbaceous stems - thin, soft and green in colour except those 4. Oblanceolate - reverse of lanceolate, broadest above middle and that grow underground. Plants with herbaceous stems are also tapering downward known as herbs. 5. Cuneate - wedge-shaped, broad at the tip and tapering by nearly straight lines to 2. Woody stems - taller, thicker, and harder than herbaceous stems. 6. Spatulate - broadly rounded above and long and narrow below 7. Ovate - broadest part below the middle; more or less narrow, EXTERNAL PARTS OF STEM narrowed towaro the tip; egg-shaped 8. Obovate - broader part above the middle; the reverse of ovate 1. Bud - growing point of the stem 9. Elliptical - broadest at the middle tapering more or less equally to the base and арех 2. Terminal bud - single bud located at the apex of the stem 10. Rhomboid - diamond-shaped, with equal sides but unequal angles 3. Bud scales - protects and covers the bud 11. Deltoid - triangular 12. Orbicular - more or less circular in outline; flat 4. Terminal bud scale scars - marks leaves on the stem from the 13. Reniform - kidney-shaped previous years which serve as external measure of annual growth. 14. Cordate - heart-shaped 5. Lateral buds/Axillary buds - occur in the leaf axils on the side of a stem. 6. Leaf scar - mark that leaves on the stem after the leaf falls down 7. Lenticel - pores that facilitate gas exchange 8. Node - segment of stem where leaves and lateral buds are attached. 9. Internode - section of a stem between two nodes. 10. Bundle scar - used in the identification of the woody plants and it is a mark left in the leaf scar from the vascular tissue attachment. INTERNAL STRUCTURE OF STEM: 1. Epidermis - outermost layer of the stem and usually functions to waterproof, protect and control gas exchange. LEAF MARGINS 2. Cortex - lies below the epidermis, it consists of hypodermis, parenchyma cell, and endodermis. 1. Entire - even line, without teeth, notches, or lobes 2. Serrate - cut into sharp, saw-like teeth pointing forward 3. Vascular bundles - comprises of phloem and xylem. 3. Undulate - margin of the leaf forms a wavy line, bending slightly Exercise 10 inward and outward in succession 4. Sinuate - like undulate, margin is very wavy (sinuous) THE LEAF 5. Crenate - teeth are short and rounded; also called scalloped 6. Crenulate - very finely notched with rounded projections Leaf is a flattened or expanded lateral projection on a stem at a node 7. Dentate - teeth point outward and subtending a bud. The leaves and stem together form the shoot. 8. Denticulate - leaf having a finely toothed margin Essential functions of leaves: 9. Doubly crenate - coarsely crenate, the teeth margins again a. photosynthesis, crenated b. transpiration, 10. Doubly serrate - coarsely serrate, the teeth margins again serrated c. guttation, 11. Doubly dentate - coarsely dentate, the teeth margins again d. storage, dentated e. defense 12. Lobed - incisions do not extend deeper than halfway between the margin and the center of the blade and are rounded EXTERNAL STRUCTURE OF A LEAF Leaves have two main parts: the blade and the petiole. The blade or also known as lamina, it is the broad portion of the leaf conisted of apex, margin, vein, midrib, and base. Petiole is a thin stalk that attaches the leaf to a stem. Some plants also have a third part, called the stipules. It is the leaf-like structures at the leaf base. TYPES OF LEAVES 1. Simple leaves consist of a single blade 2. Compound leaves have a blade that is separated into two or more parts on a common petiole a) Palmately compound - leaflets are attached directly to the end of the petiole LEAF BASES b) Pinnately compound - leaflets are arranged on the sides of the main leaf stalk 1. Cuneate - wedge-shaped, tapering evenly to a narrow point 2. Cordate - heart-shaped LEAF SHAPES 3. Oblique - slanting, unequal-sided 4. Acuminate - prolonged apex tapering to a long, narrow point 1. Linear - narrow and long with approximately parallel sides 5. Acute - forming an acute angle of less than 90 degrees 2. Oblong - longer than broad with nearly parallel sides and with a 6. Obtuse - blunt; the sides forming an angle of more than 90 degrees rounded base and apex 7. Rounded - forming an arc 3. Lanceolate - widest below and tapers toward both ends 8. Truncate - abruptly cut off transversely at the base 9. Sagittate - arrow-shaped, the auricles turned inwards. Palay, Oryza sativa 10. Hastate - halberd-shaped; lobes at base pointed and narrow and nearly at right angles to petiole Pandan, Pandanus odoratissimus 11. Auriculate - small pair of projections, or ears, usually at the base Anahaw, Livistona rotundifolia Buntot-tigre, Sansevieria zeylanica Tanglad, Andropogon citratus Camia, Hedychium coronarium Corazon de maria, Caldium bicolor DICOT LEAVES Papaya, Carica papaya Tamarind, Tamarindus indica Guava, Psidium guajava LEAF APEX Malunggay, Moringa oleifera 1. Mucronate - abruptly tipped with a small, short point; like a mere Santan, Ixora coccinea projection of the midrib 2. Cuspidate - tipped with an elongated sharp or rigid point Calamansi, Citrus mitis 3. Retuse - with a rounded sinus at the tip 4. Emarginate - indented or notched Ipil-ipil, Leucaena leucocenphala 5. Truncate - square end that looks cut off 6. Acuminate - prolonged into a narrowed or tapering point Gumamela, Hibiscus rosasinensis 7. Acute - ending in an acute angle, but not a prolonged point 8. Obtuse - blunt or rounded apex Calachuchi, Plumeria acutifolia 9. Rounded - broad and semi-circular in outline Camias, Averrhoa bilimbi Lettuce, Lactuca sativa Saluyot, Corchorus olitorius Exercise 11 THE FLOWER Flower is the reproductive part of a plant. The functions of flower is to produce seeds through the union of male sperm with female ovum. LEAF VENATION The process begins with pollination followed by fertilization. Pollination is a process when pollen grains from the flower anther is Venation is the pattern of veins in the blade of a leaf. The venation transferred to the stigma, while fertilization is a process of fusion of pattern of a leaf has three main types: the pollen grains with the ovum to form the zygote. 1. PARALLEL OR CLOSED - characteristic of the monocotyledons. Parts of a flower can be grouped into two categories: accessory and Veins running nearly parallel to each other from base to apex and essential parts. are connected by transverse veinlets. Accessory parts are also called as vegetative whorls, these are 2. NETTED OR OPEN - characteristic of the dicotyledons. Veins structures that are not involved in the reproductive process such as anastomosing some of which are running out and end blindly in the receptacle, sepals and petals. leaf tissue. a) Palmately veined- when three or more secondary veins Essential parts are also called as reproductive whorls which includes branch radially from the base of the leaf. stamens and pistil. b) Pinnately veined - when the secondary veins branch off at Stamen is the male reproductive parts of the flower that is made up intervals from a prominent midrib. of filament and an anther, which produces pollen. c) Arcuate type - when the secondary veins curve and run almost parallel to the leaf margin for some distance Pistil is the female reproductive part of a flower that is made up of ovary, style, and stigma. ARRANGEMENT OF LEAVES The ovary produces ovules which are the female reproductive egg cells. Phyllotaxy is the mode of arrangement of leaves on the stem. It can Style is a tube on top of the ovary, it allows pollen grain to travel from be classified either alternate, spiral, opposite, or whorled. stigma to ovule. 1. Alternate - only one leaf per node, it is placed alternate on each Stigma receives the male pollen grains during fertilization. side of the stem in a flat plane 2. Opposite - two leaves arise at the same point, with the leaves connecting opposite each other along the branch CLASSIFICATION OF FLOWERS 3. Spiral - one leaf per node, but it is arranged in a spiral along the stem A. Based on the presence of accessory parts 4. Whorled - three or more leaves connected at a node 1. Complete - possess all the four whorls 2. Incomplete - do not possess any one or more of the four MONOCOT LEAVES whorls Banana, Musa paradisiaca B. Based on the presence of essential parts 1. Perfect - with both male and female reproductive organs. Corn, Zea mays 2. Imperfect - with only one reproductive organ, either male or Coconut, Cocos nucifera female. - Pistillate - only the pistil is present Onion, Allium cepa - Staminate - only the stamen is present 3. Monoecious -with male and female flowers in separate Cogon, Imperata cylindrical structure on the same plant. 4. Dioecious - with male and female flowers on different plants.  5. Polygamous - with male and female in the same flower on the same plant. C. Based on the location of the ovary 1. Hypogynous - with superior ovary 2. Perigynous - with a half-inferior ovary 3. Epigynous - with an inferior ovary D. Based on the symmetry 1. Regular - wheel-like form or radially symmetric flower 2. Irregular - form which can be divided into two equal halves. E. Based on the inflorescence 1. Catkin - spike with only pistillate or staminate flowers 2. Composite or Head - daisy-type flower composed of ray flowers around the edge and disc flowers that develop into seed in center of the flat head. 3. Corymb - stemlets arranged along main stem. Outer florets have longer pedicals than inner florets giving the display a flat top. 4. Cyme - determinate, flat or convex flower, with inner floret opening first. 5. Panicle - indeterminate flower with repeated branching. It can be made up of racemes, spikes, corymbs, or umbels. 6. Raceme - modification of a spike with flowers attached to a main stem by stemlets. 7. Solitary (or single) - one flower per stem 8. Spadix - showy part is a bract or spathe, partially surrounding the male and female flowers inside. 9. Spike - flowers attached to main stem, without stemlets, bottom florets open first. 10. Umbel - forets with stemlets attached to main stem at one central point, forming a flat or rounded top.