a nucleolus is a small spherical structure found in the nucleus of a cell, it takes up about 25% the space in rhe nucleus and synthesises ribosome
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From the time of origin of life on earth has chaged many ways. The earth has also changed from the time of its origin. Both lives on earth itself are dynamic.
Different geolgical phenomena such as volcanic erruptions, tectonic movement etc., have changed the configurations of continents. These changed environment of the continents have affected the lives on the earth.
The Earth is 4.8 billion years old, while the origin of life on the earth is 3.5 billion years old. Gradually these changes have given the chaces of variations, from which the suitable organisms are selected on the earth.
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Within the fields of molecular biology and pharmacology, a small molecule is a low molecular weight organic compound that may regulate a biological process, with a size on the order of 1 nm. Many drugs are small molecules.
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<span>The blood is the circulating fluid connective tissue. It is the system of blood, heart and blood vessels. The main function of this system is to distribute the digested food and oxygen to the different parts of the body, in order to release energy to carry out life activities.
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1. Heart · Heart is triangular muscular pumping organs. · Heart of frog is situated ventrally to the liver in the pericardial cavity. · Heart is three –chambered. · Upper two chambers are called auricle sand lower one chamber is called ventricle. · Its anterior end is broader then posterior end. · The broader part anterior is known as auricle. · The posterior part is known as ventricle. · The ventricle is thick walled than auricles .right auricle is larger than left auricle.
Arterial system of frog
Blood vessels, which carry oxygenated blood away from heart to different part of the body, are called arteries. They constitute a system called arterial system. Truncus arterious gives two branches right aortic trunk and left aortic trunk. Each aortic trunk again divides into three branches- a) Carotid arch: it divides into – Lingual artery – it supplies blood to tongue and hyoid. Common carotid – it supplies blood to buccal cavity and brain. it consists swelling at the base called carotid labyrinth.
b) Systemic arch – two systemic arches move upward and then curve backward to join each other behind the heart to form dorsal aorta before meeting each other each systemic arch gives- Oesophageal artery – it supplies blood to osephagus. Occipito vertebral artery – it supplies blood to head and vertebral column. Subclavian – it supplied blood to shoulder and forelimb. From the junction of two systemic arches coeliaco – mesenteric artery arise which gives following branches. Coeliac artery arises and gives two branches – Hepatic artery artery – it supplies blood to liver. Duodenal artery –it supplies blood to duodenum. Intestinal artery – it supplies blood to small intestine (ileum). Spleenic artery – it supplies blood to spleen (meeting place of ileum and rectum). Posterior mesenteric artery- It is Long Branch and supplies blood to the rectum. The dorsal aorta runs backward and gives following branches- Gonadial artery – it supplies blood to testes and ovary. Renal artery- it supplies blood to kidney. At the end, the dorsal aorta runs posterior and bifurcates into right and left common iliac arteries. Each of iliac arteries gives Femoral artery – it supplies blood to hip and thigh. Sciatic artery – it supplies blood to lower region of hind legs. Epigastric artery- it supplies blood to urinary bladder.
c) Pulmo-cutanous arch- it divides into Pulmonary artery – it receives deoxygenated blood from different parts of the body and open into lungs. Cutanous artery- it supplies oxygenated blood to skin.
Venous System of frog
Blood vessels, which carry the deoxygenated blood from different parts of the body to the heart, are called veins. They constitute a system called venous system. Venous system of frog can be studied under too heading
A) Systemic Venous System This system includes the three large veins, which receives the deoxygenated blood from all the parts of the body and collect to the sinus venous. The three veins are- Right Precaval, Left precaval and Post cavals
1. Right and Left Precaval Vein: Each precaval is formed by the union of 3 veins External jugular vein - it is formed by the two veins. a. lingual vein – it receives deoxygenated blood from mouth and tounge. b. mandibular vein – it receives deoxygenated blood from lower jaw. innominate vein – it is formed by two veins. a. internal jugular vein- it receives deoxygenated blood from eye brain and skull. b. subscapular vein- it receives deoxygenated blood from shoulder and arm.subclavian vein- it is formed by two veins- a. brachial veins- it receives deoxygenated blood from fore limb. b. muscub cutanous vein – it receives deoxygenated blood from muscles and skin.
2. Post Caval Vein: It receives deoxygenated blood from following 3 veins. Hepatic vein- it receives deoxygenated blood from liver. Gonodial vein- it receives deoxygenated blood from gonads. Renal vein – it receives deoxygenated blood from kidney.
B) Pulmonary Venous System The pulmonary vein receives pure blood from lungs into left auricle of heart
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You take off a zero every step up you go. 1000 - Producer ; 100 - Grasshopper ; 10 - Lizard ; 1 Crow.
