Q27 of 30 Page 1

(a) Write the correct sequence of steps followed during journey of oxygen rich blood from lungs to various organs of human body.

(b) What happens when the system of blood vessels develops a leak?


(a) The sequence of oxygen rich blood flow from the lungs is as follows

•oxygen rich blood leaves lungs via pulmonary vein


•left Atrium receives pulmonary aorta


•blood flows from the left atrium to the left ventricle


•from left ventricle blood gets pumped to the aorta which branches to different major organs


(b) When a system of blood vessels develops a leak


•the damaged cells attract platelets and phagocytes to the region


•phagocytes start to leak out looking for possible pathogens and digesting them


•platelets start to clump the leak and close the blood vessels to prevent blood leakage


•fibrin fibres form the clot which adds to closure of the leak


•tissue repair starts


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25

Write balanced chemical equations to explain what happens, when

(i) Mercuric oxide is heated.


(ii) Mixture of cuprous oxide and cuprous sulphide is heated.


(iii) Aluminium is reacted with manganese dioxide.


(iv) Ferric oxide is reduced with aluminium.


(v) Zinc carbonate undergoes calcination.


OR


(i) By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound.


(ii) Ionic compounds are solids. Give reasons.


(iii) With the help of a labelled diagram show the experimental set up of action of steam on a metal.


 26

(a) Compare soaps and detergents on the basis of their composition and cleansing action in hard water.

(b) What happens when ethanol is treated with sodium metal? State about the behaviour of ethanol in this reaction.


(c) Draw the structure of cyclohexane.


(d) Name the following compound



28

(a) Draw a diagram showing germination of pollen on stigma of a flower and mark on it the following organs/parts:

(i) Pollen Grain


(ii) Pollen tube


(iii) Stigma


(iv) Female germ cell


(b) State the significance of pollen tube.


(c) Name the parts of flower that develop after fertilization into


(i) Seed


(ii) Fruit


OR


(a) Use of a condom is beneficial for both the sexes involved in a sexual act." Justify this statement giving two reasons.


(b) How do oral contraceptive help in avoiding pregnancies?


(c) What is sex selective abortion? How does it affect a healthy society? (State any one consequence)


 29

(a) For the combination of resistors shown in the following figure, find the equivalent resistance between M & N.


(b) State Joule's law of heating.


(c) Why we need a 5 A fuse for an electric iron which consumes 1 kW power at 220 V?


(d) Why is it impracticable to connect an electric bulb and an electric heater in series?