Panthera leo  is the scienctific name of lion.

Negative feedback mechanism: 

Whenever there is a change in the normal state, the messages are sent to ‘increase’ secretions if there is a fall below normal or to ‘decrease’ secretions if there is a rise above normal to restore the normal body state. Such a mechanism is called a negative feedback mechanism.

Appendicular skeleton comprises of limb bones and girdles. Limb bones are again divided into bones of forelimbs and bones of hindlimbs. Girdles comprises of pectoral girdle and pelvic girdle

Limb Bones

• There are two pairs of limbs—a pair of forelimbs and a pair of hind limbs.
• Each fore limb is made of 30 bones.
• Bones of the forelimbs are

• Each hind limb is made of 30 bones.
• Bones of the hind limbs are

Pectoral Girdle

• The pectoral girdle is formed of two identical halves.
• Each half of the girdle consists of the following bones — scapula and clavicle.

• Scapula:
• The scapula is also called the shoulder bone.
• It is the flat, triangular bone located at the back of the thorax.
• It has a slightly elevated ridge called the spine.
• The spine projects as a flat, expanded process called the acromion.
• Below the acromion is a cup-shaped cavity called the glenoid cavity.
• The glenoid cavity articulates with the humerus of the forelimbs.
  • Clavicle:
  • It is also called collar bone.
  • It is a rod-shaped bone extending between the neck and the shoulder.

Pelvic Girdle

• It is made of two coxal bones.
• Each coxal bone comprises three bones—ilium, ischium and pubis.

• At the point where all the three bones fuse is a depression called the acetabulum. The head of the femur articulates with the acetabulum.

A line of fusion called the pubic symphysis is observed where the two halves meet

• The vascular system consists of complex tissues, the phloem and the xylem.
• The xylem and phloem together constitute vascular bundles.
• In dicotyledonous stems, cambium is present between phloem and xylem, such vascular bundles because of the presence of cambium possess the ability to form secondary xylem and phloem tissues, and hence are called open vascular bundles.
• In the monocotyledons, the vascular bundles have no cambium present in them, hence they do not form secondary tissues and they are referred to as closed vascular bundles.

Rh grouping

• The Rh antigen similar to one present in Rhesus monkeys is also observed on the surface of RBCs of majority of humans, hence the antigen is known as Rh antigen.
• The individuals having Rh antigen are called Rh positive (Rh+ve) and those in whom this antigen is absent are called Rh negative (Rh-ve).
• An Rh-ve person, if exposed to Rh+ve blood, will form specific antibodies against the Rh antigens, and hence Rh group should also be matched before transfusions.
• A special case of Rh incompatibility has been observed between the Rh-ve blood of a pregnant mother with Rh+ve blood of the foetus , which leads to a disease known as erythroblastosis foetalis.
• Rh antigens of the foetus do not get exposed to the Rh-ve blood of the mother in the first pregnancy as the two bloods are well separated by the placenta, during the delivery of the first child, maternal blood may get exposed to small amounts of the Rh+ve blood from the foetus and the mother starts preparing antibodies against Rh in her blood.
• In case of subsequent pregnancies, the Rh antibodies from the mother (Rh-ve) can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs, which cause severe anaemia and jaundice to the baby leading to a condition known erythroblastosis foetalis.
• Erythroblastosis foetalis can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child.

Pancreas is known as a mixed gland because it performs functions of both exocrine and endocrine glands.

It has both exocrine and endocrine cells. Exocrine cells secrete Pancreatic juice and endocrine cells secrete insulin and glucagon.

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Anura is the scientific name of frog and the most common species of Indian frog is Rana tigrina.

(i) It will be found in the meristems (meristems are the regions in plants, where cell divisions occur for plant growth).
(ii) The element is calcium.
(iii) It is also present in the middle lamellae of cells.

• Sliding filament theory explains the mechanism of muscle contraction, which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments.
• The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate.
• A neural signal, released by central nervous system, when reaches the junction releases a neurotransmitter (Acetyl choline) which generates an action potential in the sarcolemma, which spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm.

• Water potential is the difference between free energy of water molecules in a pure solvent and free energy of water molecules in a solution.
• Solute potential (Ψs) and pressure potential (Ψp) are the two main components that determine water potential.
• The greater the concentration of water in a system, the greater is its kinetic energy or ‘water potential’.
• Water potential is denoted by the Greek symbol Psi or Ψ and is expressed in pressure units such as pascals (Pa).
• The water potential of pure water at standard temperatures is taken to be zero.
• All solutions have a lower water potential than pure water; the magnitude of this lowering due to dissolution of a solute is called solute potential.
• For a solution at atmospheric pressure (water potential) Ψw = (solute potential) Ψs.
• The pressure exerted by the protoplasts due to entry of water against the rigid walls is called pressure potential (Ψp).
• When water enters a plant cell due to diffusion causing a pressure built up against the cell wall, it makes the cell turgid, which increases the pressure potential.
• Water potential of a cell is affected by both solute and pressure potential: Ψw = Ψs + Ψp

Matrix is the tissue in animal or plant cells in which specialized structures are fixed to a surrounding mass. For example, there are matrix such as mitochondrial matrix and Golgi apparatus matrix.

The gastric glands are located in different regions of the stomach. These are the fundic glands, the cardiac glands, and the pyloric glands. The glands and gastric pits are located in the stomach lining. The adrenal glands are small glands located on top of each kidney. They produce hormones that you can't live without, including *** hormones and cortisol. Cortisol helps you respond to stress and has many other important functions. With adrenal gland disorders, your glands make too much or not enough hormones.

Bundle of HIS is a collection of heart muscle cells specialized for electrical conduction. As part of the electrical conduction system of the heart, it transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the bundle branches. 

DISCOVERY OF ELECTRON:

The Electron was discovered by J.J Thomson by conducting a Cathode ray tube experiment.

For the experiment he used Crooke’s tube, which was 60cm long glass tube and had a small tube attached. To this small tube vacuum pump was attached, it also had two metal plates which were connected to battery by wires.

The tube contained gas at atmospheric pressure. when current at high voltage (10,000volts) was passed following observations were made:

1. When current was passed through a gas at 1 atmospheric pressure and at a very high voltage, nothing happened. That is no visible effect was seen inside the tube.
2. Then further the pressure of gas was reduced by pumping the air out, with the help of vacuum pump. The pressure was reduced to 10^-2atm, then on passing current it was seen that whole tube started glowing green.
3. Then further the pressure was reduced to 10^-4It was seen the whole glow vanished, but it was seen that at the end of the tube (anode side) there was a faint green glow observed.

To confirm the faint glow anode was made perforated, and a zinc sulphide screen (fluorescent material) was placed behind it.

When current was passed under same conditions it also started   glowing green. This confirmed that under those conditions some rays were emitted through cathode, and were travelling towards anode. Those rays were called as cathode rays and found to consist of negatively charged particles called electron.

The Process of Breathing :
Breathing involves the ribs, the intercoastal muscles, lungs and the diaphragm. Breathing process is carried out in two phases :
• Inhalation or Inspiration
• Exhalation or Expiration.
Inhalation : To make inhalation possible the intercoastal muscles contract and lift the ribs upward and outward. The diaphragm muscle also contracts and flattens. These movements increase the size of chest cavity; as a result the pressure inside the lungs decreases. As the pressure outside the lungs is greater and the air moves into the lungs.
Exhalation: When breathing out, the muscles relax, the ribs go back to their normal unexpanded position, and the diaphragm springs back into place. With the chest activity back to its normal size, the pressure inside the lungs increases and is greater than the atmospheric pressure. As a result the air moves out of the lungs through nose or mouth.

When the rate of evaporation is low, at night or in the early morning, excess water gets collected in the form of droplets at the special openings of veins of leaves of many herbaceous plants. Such water loss in its liquid phase is called guttation.