XI Biology Practicals PDF

BIOLOGY PRACTICALS TERM- I SECTION- A EXPERIMENT NO. 1 STUDY AND DESCRIPTION OF THE FLOWERING PLANT Family – Solanaceae Solanum melongena (Brinjal) Vegetative Characters Plants mostly herbs, shrubs and rare...

BIOLOGY PRACTICALS TERM- I SECTION- A EXPERIMENT NO. 1 STUDY AND DESCRIPTION OF THE FLOWERING PLANT Family – Solanaceae Solanum melongena (Brinjal) Vegetative Characters Plants mostly herbs, shrubs and rarely small trees. Stem: herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous. Leaves: alternate, simple, rarely pinnately compound, exstipulate; venation reticulate. Floral Characters Inflorescence : Solitary, axillary or cymose as in Solanum. Flower: bisexual, actinomorphic. Calyx: sepals five, united, persistent, valvate aestivation. Corolla: petals five, united; valvate aestivation. Androecium: stamens five, epipetalous. Gynoecium: bicarpellary obligately placed, syncarpous; ovary superior, bilocular, placenta swollen with many ovules, axile placentation. Fruits: berry or capsule. Seeds: many, endospermous. Floral Formula: Floral structure & floral diagram of a typical plant (Solanum melongena) of family Solanaceae EXPERIMENT NO. 2 STUDY OF OSMOSIS BY POTATO OSMOMETER AIM To demonstrate osmosis by potato osmometer. REQUIREMENTS A large potato, knife, 10-20% sugar solution,petridish, beaker, water, pins etc. PROCEDURE 1. Peel off the outer skin of potato. Cut one end flat and make a cavity in the centre of the potato opposite to the flat side almost upto the bottom. 2. Now place the potato on its flat cut end in a petridish half full of water. 3. Fill half of the cavity of the potato with 10-20% sugar solution, and mark the level of sugar solution in the cavity with the help of a pin. It functions as an osmometer. 4. Leave the osmometer undisturbed for about one hour and then mark the rise in the level of sugar solution in the cavity with another pin. Fig: Demonstration of osmosis by potato osmometer  OBSERVATION AND RESULT The level of sugar solution in the potato cavity rises after someti me due to the entry of water into the sugar solution through selectively permeable mem brane of the cells of potato osmosis. CONCLUSION The movement of water from the petridish occurs because of the difference in the concentration of solvent (water) molecules in the two regions. i.e., in the sugar solution in the cavity and water in the petridish. The cell membranes enclosing the cells of potato act as selectively permeable membrane for the movement of water. PRECAUTIONS 1. The cavity should be deep enough to keep only a thin layer of tissues at the base. 2. The lower end of the potato should be flat so as to keep the potato stable in the petridish. 3. The sugar solution should be of sufficiently high osmotic concentration compared to the cell sap of potato cells.  SECTION- B SPOTTING B1- STUDY OF THE PARTS OF A COMPOUND MICROSCOPE Fig: Compound microscope PARTS OF COMPOUND MICROSCOPE The parts of the compound microscope can be categorized into:  Mechanical parts  Optical parts (A) Mechanical Parts of a Compound Microscope 1. Foot or base It is a U-shaped structure and supports the entire weight of the compound microscope. 2. Arm The entire microscope is handled by a strong and curved structure known as the arm. 3. Stage The flat and rectangular plate that is connected to the arm’s lower end is called the stage. The specimen is placed on the stage for studying and examining the various features. The centre of the stage has a hole through which light can pass. 4. Clips The upper part of the stage is connected to two clips. The slide can be held in its position with the help of the clips. 5. Diaphragm The diaphragm is fastened below the stage. It controls and adjusts the intensity of light that passes into the microscope. 6. Nose piece The nose piece is circular and a rotating metal part that is connected to the body tube’s lower end. The nose piece has two holes wherein the objective lenses are embedded. 7. Body tube The upper part of the arm of the microscope comprises a hollow and tubular structure known as the body tube. The body tube can be shifted down and up using the adjustment knobs. 8. Fine adjustment knob It is the smaller knob, which is used for sharp and fine focusing of the object. For accurate and sharp focusing, this knob can be used. 9. Coarse adjustment knob It is a large knob that is used for moving the body tube down and up for bringing the object to be examined under exact focus. (B) Optical Parts of Compound Microscope 1. Eyepiece lens or Ocular At the top of the body tube, a lens is planted which is known as the eyepiece. The object’s magnified image can be observed with the help of an eyepiece. 2. Mirror A mirror is found attached wither to the pillar or the lower end of the arm. It consists of a concave mirror on one side and a plain mirror on the other side. It can be used for reflection of light rays into the microscope. 3. Objective lenses At the bottom of the body tube, there are two objective lenses (High power objective – 45X & Low power objective – 10X), which are connected to the revolving nose piece.  B2- IDENTIFICATION OF THE GIVEN SPECIMENS/ SLIDES i) SPIROGYRA CORRECT IDENTIFICATION- The given specimen is spirogyra. POINTS OF IDENTIFICATION 1. It is a single cell thick, cylindrical filament, slimy to touch green coloured algae. 2. The filament has cells joined end to end. 3. It has spiral shaped ribbon like chloroplast hence it is named Spirogyra. 4. Each cell is rectangular with nucleus in the centre. 5. Cell wall is clearly seen. 6. Chlorophyll is present in chloroplast and helps in photosynthesis. ii) AGARICUS CORRECT IDENTIFICATION-The given specimen is Agaricus (Mushroom). POINTS OF IDENTIFICATION 1. Agaricus is commonly called mushroom. 2. It is a saprophytic fungus. 3. Septate mycelium produces basidiocarp. 4. Basidiocarp is umbrella shaped and consist of a stalk like stipe and cap like pileus. 5. The basidiospores are placed on the basidia. iii) FERN (Dryopteris) CORRECT IDENTIFICATION- The given specimen is Dryopteris (Fern). POINTS OF IDENTIFICATION 1. Commonly called ferns. 2. It is a pteridophyte found growing in cool damp places. 3. Main plant body is diploid sporophyte. 4. Plant body is differentiated into roots, stem and leaves. 5. The gametophyte bears male and female sex organs. iv) MOSS (Funaria) CORRECT IDENTIFICATION- The given specimen is Funaria (Moss). POINTS OF IDENTIFICATION 1. Moss plant grows in dense patches in moist shady and cool places. 2. Main plant body is haploid gametophyte. 3. Gametophyte bears male and female sex organs. 4. The sporophyte is dependent on gametophyte for nourishment. 5. They show alternation of generation i.e. the gaemetophytic stage alternates with the sporophytic stage. v) MONOCOTYLEDONOUS PLANT Oryza sativa (Rice plant) CORRECT IDENTIFICATION- The given specimen is Oryza sativa, a monocotyledonous plant. POINTS OF IDENTIFICATION 1. It has fibrous root system. 2. The leaves with parallel venation. 3. Flowers trimerous. 4. The seeds are enclosed within the fruit. 5. Embryo with one cotyledon. vi) DICOTYLEDONOUS PLANT Coffea arabica (Coffee plant) CORRECT IDENTIFICATION- The given specimen is Coffea arabica , a dicotyledonous plant. POINTS OF IDENTIFICATION 1. It has tap root system. 2. The leaves with reticulate venation. 3. Flowers tetramerous or pentamerous. 4. The seeds are enclosed within the fruit. 5. Embryo with two cotyledons. B3- IDENTIFICATION OF THE GIVEN SPECIMENS i) HYDRA CORRECT IDENTIFICATION-The given specimen is Hydra. POINTS OF IDENTIFICATION  The body resembles a cylindrical and an elongated tube.  The posterior end is attached to the substratum by a basal disc and the anterior end is free.  The mouth is girdled with structures known as tentacles.  The tentacles help in capturing prey as these structures contain cnidoblasts.  The gastrovascular cavity is present which opens to the mouth. ii) ROUNDWORM (Ascaris lumbricoides) CORRECT IDENTIFICATION-The given specimen is Ascaris. POINTS OF IDENTIFICATION  It is an endoparasite found in the intestine of man.  The body is long, cylindrical and unsegmented with pointed edges.  The anterior end of the body possesses a mouth.  On the ventral surface, the excretory pore is located just a little behind the mouth.  They exhibit sexual dimorphism. iii) EARTHWORM (Pheretima posthuma) CORRECT IDENTIFICATION-The given specimen is an earthworm. POINTS OF IDENTIFICATION  Commonly found in moist soil.  The body is long, triploblastic, cylindrical, coelomate and metamerically segmented.  The mouth is at the anterior end and anus at the posterior end.  The clitellum (a circular band of glandular tissue) is located at the 14th, 15th, and 16th segments  Earthworms are hermaphrodites.  Setae are the locomotory structures. iv) STARFISH (Asterias) CORRECT IDENTIFICATION-The given specimen is starfish. POINTS OF IDENTIFICATION  It is a marine form found in the rocky and sandy parts of the sea.  A star-shaped body consisting of a central disc with 5 radiating arms.  Mouth on the lower (ventral) side and anus on the upper (dorsal) side.  Water vascular system is present.  They carry out movements with the help of tube feet that are part of the water vascular system.