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Q1
A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plants bearing white flowers. What will be the result in F₁ progeny?
Marks:1
Answer:

The result in F₁ progeny will be a violet flower because in this case, violet colour is the dominant character.

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Q2
Write the energy conversion that takes place in a hydropower plant.
Marks:1
Answer:

In hydropower plant, when the water stored at a certain height is released, its potential energy gets converted into kinetic energy. This kinetic energy is used to rotate the turbine.

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Q3
If the image formed by a spherical mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a labelled ray diagram to support your answer.
Marks:2
Answer:

A convex mirror always forms an erect and diminished imageirrespective of the position of the object placed in front of it.

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Q4
A compound 'X' on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound 'Y'. 'X' also reacts with sodium metal to evolve a colorless gas 'Z'. Identify 'X', 'Y' and 'Z'. Write the equation of the chemical reaction of formation of 'Y' and also write the role of sulphuric acid in the reaction.
Marks:2
Answer:

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Q5
(a) Name one gustatory receptor and one olfactory receptor present in human beings.

(b) Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.
Marks:2
Answer:

(a) Gustatory receptor: Tongue

Olfactory receptor: Nose
(b)

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Q6
Show how would you join three resistors, each of resistance 9Ω so that the equivalent resistance of the combination is
i. 13.5Ω
ii. 6Ω
Marks:3
Answer:

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Q7
(a) Write Joule's law of heating.

(b) Two lamps, one rated 100 W; 220 V, and the other 60 W; 220 V, are connected in parallel to electric mains supply. Find the current drawn by two bulbs from the line, if the supply voltage is 220 V.
Marks:3
Answer:

(a) Joule's law of heating: When a current (I) flows through aresistor of resistance (R) for time (t), then the amount of heatproduced (H) is given by

H = I²Rt

This is known as Joule’s law of heating.

(b) Given,

power of first bulb, P₁ = 100 W

voltage supply to first bulb, V₁= 220 V

power of first bulb, P₂ = 60 W

voltage supply to first bulb, V₂= 220 V

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Q8
State the laws of refraction of light. Explain the term 'absolute refractive index of a medium' and write an expression to relate it with the speed of light in vacuum.
Marks:3
Answer:

There are two laws of refraction of light:

(i) The incident ray, the refracted ray and the normal to theinterface of two media at the point of incidence – all three lie inthe same plane.

(ii) For the light of a givencolour and for given pair of media,the ratio of the sine of the angle of incidence to the sine ofthe angle of refraction is constant.The law is known as Snell’slaw.

Mathematically, it is given as,

Absolute refractive index of a medium:It is defined as the ratio of the velocity of light in vacuum or air to that of velocity of light in the medium.

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Q9
What is meant by power of a lens? Write its SI unit. A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens.
Marks:3
Answer:

Power of lens: Power of lens is defined as its ability to converge or diverge the rays of light falling on it. The SI unit of power is Dioptre (D).

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Q10

Name the hormones secreted by the following endocrine glands and specify one function of each:

(a) Thyroid (b) Pituitary (c) Pancreas

Marks:3

Answer:

Endocrine gland	Hormones	Function
Thyroid	Thyroxine	It regulates the metabolism of proteins, fats and carbohydrates in the body
Pituitary	Growth hormone	It regulates the growth and development of muscles and bones
	Prolactin hormone	It regulates the functions of mammary gland in females
	Vasopressin hormone	It maintains water and electrolyte balance in the body
	Oxytocin hormone	It is responsible for signaling contractions of the womb during labor and regulates milk ejection during lactation
Pancreas	Glucagon	It helps in increasing blood sugar level of the body
Pancreas	Insulin	It helps in maintaining blood sugar level.