• Tissue has a free surface, which faces either a body fluid or the outside environment and thus provides a covering or a lining for some part of the body. The cells are compactly packed with little intercellular matrix.

• There are two types of epithelial tissues namely simple epithelium and compound epithelium, Simple epithelium is composed of a single layer of cells and functions as a lining for body cavities, ducts, and tubes. The compound epithelium consists of two or more cell layers and has protective function as it does in our skin.

• On the basis of structural modification of the cells, simple epithelium is further divided into three types. These are

(i) Squamous, (ii) Cuboidal, (iii) Columnar. 

• The squamous epithelium is made of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in a functions like forming a diffusion boundary.

• The cuboidal epithelium is composed of a single layer of cube-like cells. This is commonly found in ducts of glands and tubular parts of nephrons in kidneys and its main functions are secretion and absorption. The epithelium of proximal convoluted tubule (PCT) of nephron in the kidney has microvilli.

• The columnar epithelium is composed of a single layer of tall and slender cells. Their nuclei are located at the base. Free surface may have microvilli. They are found in the lining of stomach and intestine and help in secretion and absorption. If the columnar or cuboidal cells bear cilia on their free surface they are called ciliated epithelium. Their function is to move particles or mucus in a specific direction over the epithelium. They are mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes.

• Some of the columnar or cuboidal cells get specialised for secretion and are called glandular' epithelium. They are mainly of two types: unicellular, consisting of isolated glandular cells (goblet cells of the alimentary canal), and multicellular, consisting of cluster of cells (salivary gland).

• Compound epithelium is made of more than one layer (multi-layered) of cells and thus has a limited role in secretion and absorption. Their main function is to provide protection against chemical and mechanical stresses. They cover the dry surface of the skin, the moist surface of buccal cavity, pharynx, inner lining of ducts of salivary glands and of pancreatic ducts.

Markings of the Axis Bone:

1. Body or centrum (Corpus vertebrae) is a cylindrical mass on anterior side of the vertebra. It articulates with body of the vertebra below (C3).
2. Odontoid process or dens (Dens axis) is a prominent rounded superior projection from the body.
   This tooth-like elevation serves a stable point around which the atlas bone rotates (Gr., odous, tooth).
3. Superior articular facet (Facies articularis superior) is a smooth, sightly convex surface that articulates with the inferior articular facet on the altas bone above (C1)

The atlas is the first cervical vertebra and articulates with the occiput of the head and the axis (C2). It differs from the other cervical vertebrae in that it has no vertebral body and no spinous process. Instead, the atlas has lateral masses which are connected by an anterior and posterior arch.

Anaerobic respiration generates less energy because only glycolysis occurs which forms 2ATP molecules.
However in aerobic repiration there is krebs cycle taking place which is responsible for making around 30 ATP molecules. In total, aerobic respiration generates 36-38 ATP molecules.

Cytoplasmic streaming also called protoplasmic streaming or cyclosis refers to the streaming of cytoplasm inside a living cell. This motion enables materials to reach all parts of a cell including oxygen and nutrients.

The absence of any element necessary for the nourishment of that particular plant will lead to the morphological changes. And this change is an indication of a deficiency.

Of course, if the deficient element is provided to the plant in good time, the symptoms of deficiency disappear. However, if the process is delayed, eventually the plant will die.

Root nodules are found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria known as rhizobia. Nodules are formed as a result of infection of the roots by soil bacteria. ... The complex process by which plant roots are infected by rhizobia is known as infection. The complex process in which nodules are formed is known as nodulation.

Glycolysis produces 2 ATP, 2 NADH, and 2 pyruvate molecules: Glycolysis, or the aerobic catabolic breakdown of glucose, produces energy in the form of ATP, NADH, and pyruvate, which itself enters the citric acid cycle to produce more energy. Cellular respiration has a potential to produce between 36 and 38 moles of ATP per mole of glucose (C6H12O6). ... Each NADH [from glycolysis] produces a net 1.5 ATP (instead of usual 2.5) due to NADH transport over the mitochondrial membrane. Glycolysis has mainly two parts: First part converts glucose to Fructose, consuming 2 ATP. Second part converts the fructose into pyruvate, producing 2 ATP (the process occurs twice, so it producing a total of 4 ATP)

Nicotinamide adenine dinucleotide phosphate, or NADP+, is a similar molecule with a similar function, differing from NAD+ in that it contains an additional phosphate group. The oxidized form is NADP+, while the reduced form is NADPH. The function of NAD+ that is similar to that of NADP+ is that each NAD+ accepts a pair of high-energy electrons. Describe glycolsis in terms of energy input, energy output, and net gain of ATP. In glycolysis, glucose is converted to molecules of pyruvic acid. ... NAD becomes NADH. The main role of NAD+ in metabolism is the transfer of electrons from one molecule to another. Reactions of this type are catalyzed by a large group of enzymes called oxidoreductases.

Hyoid bone, U-shaped bone situated at the root of the tongue in the front of the neck and between the lower jaw and the largest cartilage of the larynx, or voice box. The primary function of the hyoid bone is to serve as an anchoring structure for the tongue. It has no articulation with other bones.

XYY syndrome is a genetic condition that occurs when a male has an extra copy of the Y chromosome in each of their cells (XYY). Sometimes, this mutation is only present in some cells. Males with XYY syndrome have 47 chromosomes because of the extra Y chromosome. Most cases of 47,XYY syndrome are not inherited. The chromosomal change usually occurs as a random event during the formation of sperm cells. An error in cell division called nondisjunction can result in sperm cells with an extra copy of the Y chromosome.

Boys with XYY syndrome may have some or all of these physical symptoms to some degree:

• taller than average height.
• low muscle tone, or muscle weakness (called hypotonia)
• very curved pinky finger (called clinodactyly)
• widely spaced eyes (called hypertelorism)
• cystic acne during adolescence.

Selective reabsorption is the process whereby certain molecules (e.g. ions, glucose and amino acids), after being filtered out of the capillaries along with nitrogenous waste products (i.e. urea) and water in the glomerulus, are reabsorbed from the filtrate as they pass through the nephron.  Feedback mechanism refera to a syatem in which hormones are regulated according to demand. Example-when blood sugar level is high in body,message is sent to Feeback mechanism to regulate more Insulin and when required level is reached secretion becomes normal.

Parenchyma are thin-walled round or oval shaped cells having spaces between them.

It is present in stem, leaves, flowers, fruits and seeds.
Most of them contain leucoplast and store food.
Chloroplast containing parenchyma is called chlorenchyma  and deal with photosynthesis.

Heterodont : It is the condition of having different types of teeth. For example humans have four different types of teeth namely incisors, canines, molars and premolars.

Diphyodont : The type of dentition characterised by two sets of teeth. First set is of temporary and second is of permanent.