Taxonomical aids are the collections of samples or preserved organisms which help in extensive research for the identification of various taxonomic hierarchy. Classifying organisms into various categories needs a lot of field and laboratory study. This is an essential process, because taxonomic categorization helps in identifying many organisms necessary in various fields like agriculture, industries, bio resources, etc.

The stomach has four parts :

(1) Cardiac stomach : It is proximal part. The opening of oesophagus into cardiac stomach is guarded by cardiac sphincter which prevents the regurgitation of food. 

Section of the stomach

(2) Fundus : It extends above cardiac aperture and is filled with air. The part of cardiac stomach which extends towards anterior end above level of cardiac aperture is called fundus.

(3) Body : It is the middle large part of the stomach.

(4) Pyloric stomach : It is the distal narrowest part of stomach which opens into duodenum. Its opening is guarded by pyloric sphincter which permits the passage of fine-food particles into duodenum.

• Vegetative characters
• Plants mostly, herbs, shrubs and small trees Stem: herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous, underground stem in potato
• Leaves: alternate, simple, rarely pinnately compound, exstipulate; venation reticulate

In two kingdom classification, there was no differentiation between the eukaryotes and prokaryotes, unicellular and multicellular and photosynthetic and non-photosynthetic organisms. In the two-kingdom classification the bacteria, blue-green algae, fungi, mosses all were included under the kingdom Plantae. It placed together groups which widely differed from each other. A large number of organisms did not fall into any category. Thus, the two-kingdom classification was insufficient and inadequate.

The five kingdom classification resolved the issues as it considered other factors like cell structure, mode of nutrition, thallus organisation, reproduction and phylogenetic relationships. This system of classification placed the organisms into five different categories. All the prokaryotes were placed under Kingdom Monera. The unicellular eukaryotes were placed under Kingdom Protista. The fungi occupied a separate kingdom. Thus, it proved to be adequate and much better than the two-Kingdom classification. 

Under suitable condition, slime moulds form plasmodium.

Binomial Nomenclature “Binomial nomenclature is the biological system of naming the organisms in which the name is composed of two terms, where, the first term indicates the genus and the second term indicates the species of the organism.”

Red, green, and brown algae have different types of pigments which give them their color. (Brown algae gets its color from the xanthophylls pigment fucoxanthin, red algae get their color from phycoerythrin, green is from chlorophyll.) These pigments have a certain chemical structure that allows them to absorb light. Phaeophyta (brown algae) A division of algae which includes no single-celled species; almost all are marine, growing mostly in the intertidal regions (but species of Bodenella and Heribaudiella occur in fresh water). They are the dominant seaweeds in the colder waters of the northern hemisphere.

Asexual reproduction in fungi:

1. fission of somatic cell
2. Budding of somatic cell
3. Fragmentation or disjoining of hyphae
4. Asexual spore formation

The cone bearing plants are called Conifers.

Features such as arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory or reproductive systems are the basis of animal classification.

Bryophytes are an informal group consisting of three divisions of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. They are characteristically limited in size and prefer moist habitats although they can survive in drier environments. The bryophytes consist of about 20,000 plant species. The aim is to give you a good understanding of bryophyte structure and of the similarities and differences between the three groups.

The seedless vascular plants include club mosses, which are the most primitive; whisk ferns, which lost leaves and roots by reductive evolution; and horsetails and ferns. Ferns are the most advanced group of seedless vascular plants. They are distinguished by large leaves called fronds and small sporangia-containing structures called sori, which are found on the underside of the fronds.

The pyrenoid, a dense structure inside or beside chloroplasts of certain algae, consists largely of ribulose biphosphate carboxylase, one of the enzymes necessary in photosynthesis for carbon fixation and thus sugar formation. Starch, a storage form of glucose, is often found around pyrenoids.

• Pachytene is the third stage of meiosis prophase-1 (a five-stage process). It is preceded by the zygotene stage, where synapsis, i.e. pairing of homologous chromosomes take place.
• In pachytene, exchange of genetic material between two homologous chromosomes known as crossing over takes place between non-sister chromatids of the homologous chromosomes.

• Recombination or crossing over takes place at this stage. In this process, there is an exchange of genetic material between non-sister chromatids of homologous chromosomes. There is rearrangement and reshuffling of the genetic material of two parental homologous chromosomes. It is an enzyme-mediated process. The enzyme involved in crossing over is known as recombinase.

  Recombination nodules appear and homologous chromosomes are linked to each other at the site of crossing over.

  Recombination is accompanied by the formation of chiasmata, which appear in the next stage called diplotene.

Object:

Demonstration of Relation between Transpiration and Absorption

Requirements:

A bottle with a side, tube, cork, a plant, oil, balance, etc.

Experiment:

Here, the apparatus must be completely filled up with water and air-tight. In the side marked tube of the apparatus some oil drops are being added so that the water may not evaporate. The cork is fitted in the wide mouth of the bottle in the way that the aerial part of a complete plant remains outside of it and the root system or the plant remains within the bottle.

Now the apparatus is weighed on a pan balance to note its weight and thereafter it is kept for few hours in such a place where sufficient transpiration from the aerial parts of the plant takes place. In the end the apparatus is weighed once again and the difference from that of the original weight may be calculated.

Observation:

This way the quantity of transpired water is known in grams. The oil drops present on the surface of water in the marked side tube travel somewhat downward and we know the actual quantity of absorbed water in ml by the roots. By comparison, it is noted that the quantity of absorbed water is always greater than the transpired water because some of the water is used in other metabolic activities.

• This tissue which has a free surface faces either a body fluid or the outside environment and thus provides a covering or a lining for some part of the body is called epithelial tissues.
• The cells are compactly packed with little intercellular matrix.
• There are two types of epithelial tissues
• simple epithelium
• compound epithelium.
• Simple epithelium is composed of a single layer of cells and functions as a lining for body cavities, ducts etc.
• Compound epithelium consists of two or more cell layers and has protective function as it does in our skin.

A cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components of the cardiac conduction system are the SA node, AV node, the bundle of His, bundle branches, and Purkinje fibers.

The sequence of electrical events during one full contraction of the heart muscle:

• An excitation signal (an action potential) is created by the sinoatrial (SA) node.
• The wave of excitation spreads across the atria, causing them to contract.
• Upon reaching the atrioventricular (AV) node, the signal is delayed.
• It is then conducted into the bundle of His, down the interventricular septum.
• The bundle of His and the Purkinje fibers spread the wave impulses along the ventricles, causing them to contract.

Components of the Cardiac Conduction System:

1. Sinoatrial Node: The sinoatrial (SA) node is a collection of specialized cells (pacemaker cells), and is located in the upper wall of the right atrium, at the junction where the superior vena cava enters. These pacemaker cells can spontaneously generate electrical impulses. The wave of excitation created by the SA node spreads via gap junctions across both atria, resulting in atrial contraction (atrial systole) – with blood moving from the atria into the ventricles.
2. Atrioventricular Node (AV Node) - The AV Node receives the signal from the SA Node with the help of Bachmann's Bundle. It takes a 0.1s delay for the signal to transmit from the AV node to the Bundle of His.
3. Atrioventricular Bundle:  The atrioventricular bundle (bundle of His) is a continuation of the specialized tissue of the AV node, and serves to transmit the electrical impulse from the AV node to the Purkinje fibers of the ventricles. It descends down the membranous part of the interventricular septum, before dividing into two main bundles: Right bundle branch – conducts the impulse to the Purkinje fibres of the right ventricle. Left bundle branch – conducts the impulse to the Purkinje fibers of the left ventricle.
4. The Purkinje fibers (sub-endocardial plexus of conduction cells) are a network of specialized cells. They are abundant with glycogen and have extensive gap junctions. These cells are located in the subendocardial surface of the ventricular walls and are able to rapidly transmit cardiac action potentials from the atrioventricular bundle to the myocardium of the ventricles. This rapid conduction allows coordinated ventricular contraction (ventricular systole) and blood is moved from the right and left ventricles to the pulmonary artery and aorta respectively.

The acid-soluble pool represents roughly the cytoplasmic composition whereas the macromolecules from cytoplasm and organelles become the acid-insoluble fraction. Together they represent the entire chemical composition of living tissues or organisms. Al! the compounds which are found in the add-soluble pool, have their molecular weights ranging from approx. 18 to around 800 daltons (Da). 

The acid-insoluble fraction, has only four types of organic compounds i.e., proteins, nucleic acids, polysaccharides and lipid.