Q18 of 27 Page 1

(a) Mention any two components of blood.

(b) Trace the movement of oxygenated blood in the body.


(c) Write the function of valves present in between atria and ventricles.


(d) Write one structural difference between the composition of artery and veins.


OR


(a) Define excretion.


(b) Name the basic filtration unit present in the kidney.


(c) and label the following organs of


excretory system which perform following functions :


(i) form urine.


(ii) is a long tube which collects urine from kidney.


(iii) store urine until it is passed out.


(a) The two components of blood are:

•Plasma


•Red blood cells


(b) The movement of oxygenated blood in the body can be depicted by the following flow chart:


Lungs → Left part of the heart → aorta → various organs


•The deoxygenated blood enters the heart through veins. The deoxygenated blood reached the lungs where it gets oxygenated.


•The oxygenated blood leaves the lungs via the pulmonary vein and returns to the left side of the heart.


•The blood then enters the left atrium, gets pumps through the mitral valve and then into the left ventricle.


•The left ventricle pumps the oxygenated blood to the different organs and body parts.


(c) The valves present between the atria and ventricles of the heart prevent the blood from flowing back when a contraction takes place.


(d) Arteries have thick elastic walls while veins are thin walled.


OR


(a) Excretion is the biological process of removal of toxic waste generated by the body. The waste produced is in form of excess water, salts, urea, uric acid etc.


(b) Nephrons are the basis filtration unit of the kidney. Each nephron includes a filter, called the glomerulus, and a tubule.


(c) (i) urine is formed by kidneys.


(ii) urine collection tube: Ureter


(iii) Stores urine: Urinary bladder


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More from this chapter

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16

(a) Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.

(b) How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper.


 17

(a) The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

(b) Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.


(c) State Modern periodic law.


 19

(a) Write the function of following parts in human female reproductive system :

(i) Ovary (ii) Oviduct (iii) Uterus


(b) Describe in brief the structure and function of placenta.


 20

(a) A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

(b) Why do stars twinkle? Explain.


OR


(a) Write the function of each of the following parts of human eye:


(i) Cornea (ii) Iris (iii) Crystalline lens (iv) Ciliary muscles


(b) Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an astronaut on the Moon? Give reason to justify your answer.