Chapter 13 : TRANSPORTATION, CIRCULATION, EXCRETION

1. Answer in brief:
   1. Mention the colour of blood and lymph.
   2. Define Transpiration.
   3. What is transported through phloem?
   4. Define Ultrafiltration.
   5. Name the organs of excretory system in human being.
   6. Name the components of human circulatory system.
   7. Why is the wall of artery thick and elastic?
   8. What is the advantage of four-chambered heart?
   9. Define Excretion.
   10. Mention two components of xylem.
   11. Define Human circulatory system.
   12. What is lymph?
   
   ANS
   1. The colour of blood is red and lymph is colourless.
   2. The loss of water in the form of vapour from the aerial parts of the plant is called transpiration.
   3. Carbohydrates produced in leaves, amino acids and plant hormones synthesized at the shoot and root tips are transported through phloem.
   4. The filtration of blood carrying waste materials under pressure in glomerulus (Bowman's capsule) is called ultrafiltration.
   5. A pair of reddish brown bean-shaped kidneys, a pair of ureters (onr from each kidney), a urinary bladder, a muscular tube called urethra and urinary opening are organs of human excretory system.
   6. • Heart, blood vessels (arteries, veins, capillaries) and blood are components of blood circulatory system.
      • Lymph, lymph vessels, lymphatic capillaries and lymphatic nodes are components of lymph circulatory system.
   7. The wall of artery is thick and elastic because artery receives blood pumped by heart under high pressure.
   8. The advantage of four-chambered heart is that mixing of oxygen-rich blood with blood containing carbon dioxide is prevented.
   9. The process of removal of biochemical wastes generated within the body in liquid form is called excretion.
   10. Tracheids and Tracheae (vessels) are main components of xylem.
   11. The system associated with the transport of various substances like nutrients, hormones, enzymes, respiratory gases, excretory products, etc. is called circulatory system.
   12. The transparent (colourless) fluid which oozes out in the surrounding intercellular space from the blood flowing in the capillaries is called lymph.
   
   
2. Write a note on Lymphatic system.
   ANS
   Lymphatic system consists of lymph, lymph vessels, lymph capillaries and lymphatic nodes.
   • Lymph is colourless fluid involved in transportation.
   • Lymph is formed by plasma, some proteins and blood cells that escape from the walls of capillaries into the intercellular space.
   • From intercellular space lymph drains into lymphatic capillaries.
   • Lymphatic capillaries join to form lymph vessels.
   • Lymph vessels open into large veins.
   • FUNCTIONS OF LYMPHATIC SYSTEM
     • It collects intercellular fluid through lymph vessels and returns it to blood circulation.
     • Lymph vessels in the villi of small intestine absorb lipids and carry them to blood circulation.
     • It protects against diseases.
   
   
3. Distinguish between artery and vein.
   ANS
   
   
   
   
4. Describe excretory system in human being.
   ANS
   
   
   • Human excretory system consists of a pair of kidneys, a pair of ureters (one from each kidney), a urinary bladder, a muscular tube called urethra and urinary opening. The kidneys are reddish brown, bean-shaped and are located on dorsal side in abdomen.
   • From each kidney opens an excretory tube called ureter.
   • Ureter opens into urinary bladder and urinary bladder passes into a muscular tube called urethra.
   • Urethra opens out as small opening called urinary opening.
   • Each kidney is divided into cortex and medulla.
   • Each kidney has minute convoluted structures called uriniferous tubules (nephron).
   • Each kidney has about one million such tubules.
   
   
   
   
5. Explain structure and working of human heart.
   ANS
   
   
   • STRUCTURE
     • Human heart is located slightly on the left side in the space between two lungs.
     • It is conical and of the size of a closed fist.
     • It has four chambers. Two upper chambers are called atrium and the lower chambers are called ventricle.
     • Left atrium, right atrium, left ventricle and right ventricle are the four chambers based on their location in heart.
     • The walls of the atria are thin whereas the walls of ventricles are thick.
     • All four chambers are separated from one another by partition called septa.
     • There is a bicuspid valve between left atrium and left ventricle whereas there is a tricuspid valve between right atrium and right ventricle.
     • These valves allow blood to flow from atrium to ventricle but do not allow it to flow from ventricle to atrium.
     • Heart is made of cardiac muscles.
   • WORKING
     • When all four chambers of heart are in relaxed state (diastolic stage), deoxygenated blood from the organs enters the right atrium through superior and inferior vena cava.
     • At the same time oxygenated blood from lungs enters the left atrium through the pulmonary vein.
     • When both atria are filled with blood, they contract and deoxygenated blood from right atrium is poured into right ventricle through tricuspid valve. Similarly, the oxygenated blood from the left atrium is poured into left ventricle through bicuspid valve.
     • When both ventricles are filled with blood, they contract (systolic stage) and deoxygenated blood from right ventricle goes to lungs through pulmonary artery and oxygenated blood from left ventricle is distributed to all the parts of the body through aorta.
     • Since blood flows twice through the heart it is called double circulation.
   
   
6. Describe the structure of nephron and explain the process of formation of urine.
   ANS
   
   
   
   • STRUCTURE
     • A kidney has very minute tubular and convoluted structures known as uriniferous tubules(nephron).
     • A kidney has about one million (ten lac) such units.
     • Each nephron has a double-walled cup-shaped structure called Bowman's capsule at its beginning.
     • Bowman's capsule encloses a small group of capillaries called glomerulus.
     • The short region after Bowman's capsule is called the neck.
     • The tubule after the neck is narrow and coiled.
     • It consists of proximal convolution, Henle's loop and distal convolution.
     • The distal convolutions of many nephrons join to a common collecting duct which leads to the renal pelvis.
     • Renal pelvis opens into the ureter.
   • PROCESS OF FORMATION OF URINE
     • Renal arteries bring blood containing the waste material to the kidney.
     • By ultrafiltration the blood is filtered out from blood capillaries into Bowman's capsule under pressure.
     • During the passage of this filtrate through tubular parts of nephron, useful materials such as water, amino acids, minerals, ions, etc are re-absorbed by blood capillaries surrounding the nephron.
     • The remaining fluid contains excretory substance called urine which passes into urinary bladder through ureter. When the bladder is filled with urine, it contracts and urine passes out of the body.
   
   
7. 
   ANS