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Each point: 1 Mark
Blood is a liquidwhich has cells of various kinds suspended in it. The major types of cells in the blood include - red blood cells, white blood cells and platelets.
Platelets help our body form clots to stop bleeding.
If one of the blood vessels gets damaged, it sends out signals that are picked up by platelets. The platelets then rush to the site of damage and form a plug, or clot, to repair the damage.

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Each point: 1 Mark
Veins are the vessels which carry carbon dioxide-rich blood from all the parts of the body back to the heart.
Veins have valves which stop the blood from flowing backward.This is because blood pressure inveinsis very low (compared to arteries).

Answer: Option B. -> atria 
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B
$\bullet$ Human heart consists of 4 chambers. The two upper chambers of the heart are called atria and the two lower chambers are called ventricles.
$\bullet$ Arteriesare the blood vessels that carry oxygenated blood from the heart to all parts of the body.
$\bullet$ Veins are the blood vessels that carry deoxygenated blood back to the heart from all parts of the body.

Answer: Option A. -> kidneys
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A
Kidneys area pair of organs present behind the abdominal cavity in either side of the backbone inhumans. It is the major excretory organ in the human body. Itsmain function is to filter waste and excess fluid from theblood and production ofurine.

Answer: Option B. -> Right ventricle 
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B
The heart has 4 chambers - two atria and two ventricles. The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle. The right ventricle pumps the oxygen deficient blood to the lungs for oxygenation.

Answer: Option D. -> uric acid 
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D
Nitrogenous wastes in birds is excreted as a semi-solid, white coloured substance composed of uric acid.
The excretory product in humans is urea. The excretory product in fishes is ammonia.

Answer: Option B. -> Pulmonary artery 
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B
Arteries transport oxygen rich blood to all parts of the body from the heart. Veins transport carbon dioxide rich blood to the heart from all parts of the body.
Pulmonary artery is the only artery that carries carbon dioxide rich blood to lungs for re-oxygenation. Since pulmonary artery carries blood away from the heart, it is called artery and not a vein.

Answer: Option C. -> Bladder
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C
Theurinary bladderis anorgan that collects and stores urine formed in thekidneys. Ureteristhe duct throughwhich urine passes from the kidney to the bladder. Urine is excretedthrough the urethra.

Answer: Option D. -> Left ventricle 
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D
Heart has four chambers- two upper atria and two lower ventricles. The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle. The right ventricle pumps this deoxygenated blood into the lungs. Left atrium receives the oxygenated blood from the lungs and pumps it to the left ventricle, from where it is circulated to all parts of the body, through aorta.

Answer: Option A. -> True 
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A
Absorption of food occurs in the small intestine.The inner lining ofsmall intestinehas a large number of finger-like projections called villi. These villi provide a large surface area forabsorptionoffood. The villi are richly supplied with blood vessels. The blood in the blood vessels absorbs the digested food from the small intestine and transports it other parts of the body.