Karnataka SSLC Science Model Question Paper 1 with Answers

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Karnataka State Syllabus SSLC Science Model Question Paper 1 with Answers

Time: 3 Hours
Max Marks: 80

I. Four alternatives are provided for each of the following questions or incomplete statements. Choose the most appropriate alternative and write with its alphabet. ( 8 × 1 = 8 )

Question 1.
Which of the following is the correct sequence of events of sexual reproduction in a flower?
A) Pollination, fertilisation, seedling, embryo
B) Seedling, embryo, fertilisation, pollination
C) Pollination. Fertilisation, embryo, seeding
D) Embryo, seedling, pollination, Fertilisation
Answer:
C) Pollination. Fertilisation, embryo, seeding

Question 2.
How many times does an alternating current (AC) with frequency 50 Hz change its direction?
A) 25
B) 50
C) 100
D) 200
Answer:
C) 100

Question 3.
Which among the following are unsaturated hydrocarbons
A) H₃C – CH₂ – CH₂ – CH₃
B) H₃C – C ≡ C – CH₃
C)

D) CH₃ – CH₂ – CH₃
Answer:
B) H₃C – C ≡ C – CH₃

Question 4.
Fresh water problem arises due to
A) Global availability of stocks are insufficient
B) Uneven distribution on earth
C) No regeneration of required quantity through natural hydrological cycle.
D) Any one of above
Answer:
B) Uneven distribution on earth

Question 5.
Copper chloride is a light brown solid, which slowly absorbs mositure to form a
A) Orange dihydrate
B) Red dihydrate
C) Blue – green dihydrate
D) Blue dihydrate
Answer:
C) Blue – green dihydrate

Question 6.
Two pink colored flowers on crossing results in 1 red, 2 pink and 1 white flower progeny. The nature of the cross is
A) Cross fertilisation
B) Self pollination
C) Double fertilisation
D) No fertilisation
Answer:
A) Cross fertilisation

Question 7.
The sulphide ore among the following is
A) Haematite
B) Bauxite
C) Argentite
D) Zinc blende
Answer:
D) Zinc blende

Question 8.
Artifical ripening of fruit is carried out by
A) Auxine
B) Ethylene
C) Abscisic acid
D) Gibberlline
Answer:
B) Ethylene

II. Answer the following questions ( 8 × 1 = 8 )

Question 9.
Why is photosynthesis considered an endothermic reaction?
Answer:
As sunlight energy is absorbed during the process of photosynthesis, it is considered as endothermic process.

Question 10.
What is the role of diaphragm during inhalation and exhalation.
Answer:
Diaphragm changes its shape during inhalation and exhalation, increases and decreases volume of thoracic cavity respectively. This causes entry and expulsion of air from lungs.

Question 11.
Define resistance. What is the SI unit of reistance.
Answer:
Resistance is a property that resists the flow of electrons in a conductor. It controls the magnitude of the current. The SI unit of resistance is ohm (Ω).

Question 12.
Why is LPG considered as a better fuel than coal?
Answer:
Burning of coal leaves residues which are harmful and cause air pollution, where as LPG does not produce smoke or ash.

Question 13.
Which process taking place in the nucleus of a cell leads to variation in the offspring during reproduction?
Answer:
DNA copying.

Question 14.
Find the focal length of lens of power -2.0 D. What type of lens is this?
Answer:
Power of lens P = \(\frac{1}{f}\)
P = 2D
f = \(-\frac{1}{f}\) = -0.5cm
A concave lens has a negative focal length. Hence it is a concave lens.

Question 15.
Why is a normal eye not able to see clearly the object placed closer than 25 cm?
Answer:
A normal eye is unable to clearly see the object placed closer than 25 cm because the ciliary muscles of eyes are unable to contract beyond a certain limit.

Question 16.
What are the functions performed by the testis in human beings.
Answer:
In human beings, testis performs dual function:

Production of sperms
Secretion of male hormone testosterone

III. Answer the following questions ( 8 × 2 = 16 )

Question 17.
What is the role of glomerulus in kidney.
Answer:
Glomerulus is a group of capillaries present in the cup like Bowman’s capsule. It receives blood from renal artery which brings excretory wastes from body to the kidney. It filters water, salts, glucose, urea, the nitrogen containing end products of proteins and yellow bile compounds from the liver.

What is the advantages of four chambered heart.
Answer:
The right and left part are separated by a septum to prevent oxygenated and deoxygenated blood from mixing. This fulfills the constant use of energy to maintain their body temperature. The energy high which is fulfilled efficiently because of non – mixing of oxygenated and deoxygenated blood.

Question 18.
Draw the diagram of an electric circuit for studying ohm’s law?
Answer:

Question 19.
How do Mendel’s experiments show that traits are inherited independently?
Answer:
Mendel crossed pure breeding tall plants having round seeds with pure breeding short plant with wrinkled seeds to prevent speciation in this case, plants having wrinkled seeds. The plants of F₁ yielded plants with characters of tall round seeded, 3 tall wrinkled seeded, 3 short round seeded and one short winkled seeded. Tall wrinkled seeded and combination which can ‘ develop only when the trait are inherited .independently.

Question 20.
Draw the diagram of the arrangement of apparatus that add solution in water conducts electricity and label the parts.
Answer:

Question 21.
Explain the process of translocation of food materials in plants.
Answer:

The transport of soluble products of photosynthesis is called translocation.
It occurs in the phloem.
The products of photosynthesis are transported from leaves to all parts of the plant body.
Translocation takes places in the sieve tubes with the help of companion cells.

Question 22.
Draw the structure of a neuron and label and following parts.
Answer:

Question 23.
Explain the role of fuse in series with any electrical appliance in an electric circuit why should fuse with defined rating for an electric circuit not be replaced by one with a larger rating?
Answer:
Fuse is a safety device connected in series with a live wire or with any electrical appliance in an electric circuit. It stops the flows of unduly high electric current in the circuit by getting melted due to rise in temperature as per Joule’s law of heating. High rating fuse wire has the larger capacity. So it will not stop the flow of any relatively high current. Therefore, electrical devices cannot be protected from the possible damage.

Name two safety measures commonly used in electric and appliances.
Answer:
Two safety measures commonly used in electric circuit and appliances are :

Electric fuse : An electric fuse is connected in series it protects the circuit from overloading and prevents it from short circuiting.
Proper earthing of all electric circuit in which any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.

Question 24.
Compare and contrast nervous and hormonal mechanisms for control and co-ordination in animals.
Nervous mechanism:

Components : Neurons, nerves and Nervous system
Action : It can be voluntary or involuntary
Effects : Only for short period.
Growth and developments : Plays very little role.
Response : Quick and limited to those cells that are inervated.

Hormonal mechanism:

Endocrine glands and their secretions.
It is involuntary.
Lasts for longer period.
This system control growth and development.
Response is slow and produced by all the cells of the target tissues.

IV. Answer the following questions ( 9 × 3 = 27 )

Question 25.
Explain the structure of a bio-gas plant and the process of production of fuel in bio-gas plant.
Answer:
The Biogas plant has a dome – like structure built with bricks. A slurry of cow dung and water is made in the mixing tank from where it is fed into the digester. The digester is a sealed chamber in which there is no oxygen. Anerobic micro – organisms that do not require oxygen decompose or breakdown complex compounds of the cowdung slurry.

It takes a few days for the decomposition process to complete and generate gases like methane, carbondioxide, hydrogen and hydrogen sulphide. The biogas is stored in the gas tank above the digester from which they are drawn through pipes for use.

“We cannot establish nuclear power reactors everywhere though large amount of electricity is produced by nuclear energy” Why? Explain.
Answer:
A small quantity of nuclear fuel produces a large amount of useful energy. Nuclear fuel can run a nuclear power plant over a long period of time, such nuclear fuel can be part of a self sustaining fission chain reaction that releases energy at a controlled rate. The released energy can be used to produce steam and generate electricity. But in nuclear reactor the fuel (uranium) which is used have limited availability.

Further there is a risk of accidental leakage of nuclear radiation and the investment for the construction of nuclear plant is very high and must be recovered as soon as possible, so it raises the cost of electricity generated. In other words, the generated electricity is cheap compared to the cost of fuel, but the recovery of its construction is much more expensive and also it have a limited life.

At the same time nuclear waste contains radioactive substance which emit harmful nuclear radiations. The emitted radiation from the nuclear waste penetrate deep inside the human or animal body where they can damage, biological cells thereby initiate cancer or causes genetic diseases. Increased mortality of plants soil invertebrates and mammals and reproductive losses in plants animals have also been observed.

Question 26.
Draw the ray diagram showing the image formation by concave lens, when the object is at infinity with the help of the diagram mention, the nature of the image formed.
Answer:

The nature of the image is virtual and erect

Question 27.
a) What is meant by analogous organs? Taking a suitable example. Explain how they support the theory of organic evolution.
Answer:
Analogous organs are those organs which have different basic structural design and developmental origin but have similar appearance and perform similar functions.

Ex : The wings of birds and bats look similar but have different design in their structure. They have a common function of flying and their origins are not common. So, birds and bat are not closely related.

b) Define variation in relation to a species.
Answer:
Variation refers to the differences in the characters or traits among the individual of a species.

a) Why are small number of surviving tiger a cause of worry from the point of view of genetics.
Answer:
A small number of surviving tigers are a cause of worry from the point of genetics because these tigers carry genes which have made them adopt do the particular environment during the long process of evolution. If these tigers become extinct then the genes responsible for survival would also become extinct and would not be able to contribute in the survival of future generations.

b) How do Mendel’s experiment show that trait may be dominant or recessive.
Answer:
The trait which appear in all the member of F₁ generation arid also in 75% members of F₂ generation obtained by self fertilisation of F₁ generation is dominant character. The trait after self fertilisation of F₁ generation, reappear in 25% of F₂ generation is known as recessive.

Question 28.
Draw a diagram of an schematic section view of the human heart and label the following parts.
a) Aorta
b) Chamber of the heart the recives dioxygenated blood.
Answer:

Question 29.
List three safe methods of disposal of non-biodegradable wastes.
Answer:
Non – biodegradable wastes can be disposed by any of the following methods:

Recycling : Plastic, metals and glass materials present in the wastes can be recycled and fresh articles produced out of them can be used.
Incineration : Medical and toxic wastes are burnt at high temperature in incinerators. Incinerators transform the waste into ashes.
Land filling : Oldest method of disposal of solid wastes such as gravel, rubber or other loose materials in low lying areas in between the layers of soil which help in reclamation of land.

Question 30.
Name the three common defects of vision. What are the cause? Name the type of lens used to correct each of them.
Answer:
i) Myopia :
Cause: Elongation of eyeball
Type of lens used for correction: concave lens of suitable power.

ii) Hypermetropia :
Cause: shrinking of eye ball.
Type of lens used for correction: convex of suitable power.

iii) Presbyopia:
Cause: Weakening of ciliary muscles.
Type of lens used for correction: Bifocal lens.

a) What is Tyndall effect?
Answer:
The phenomenon of scattering of light by the colloidal particles is called Tyndall effect.

b) The far point of a myopic person in 150 cm in front of the eye, calculate the focal length and the power of lens to enable see distant object clearly.
Answer:
Far point (v) = 150 cm

Question 31.
a) Explain the following terms with one example each
i) Corrosion
ii) Rancidity.
Answer:
i) Corrosion : Corrosion is defined as a process where materials, usually metals deteriorate as a result of a chemical reaction with air moisture, chemicals etc. Ex: Iron in the presence of moisture reacts with oxygen to form hydrated iron oxide.

ii) Rancidity : Rancidity is the process of oxidation of fats and oils that can be easily noticed by the change in taste and smell. Ex : The taste and smell of butter changes when kept for long.

b) Classify the following reaction as combination, decomposition, displacement and double displacement
i) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
ii) ZnCO₃ → ZnO + CO₂
Answer:
i) Double displacement
ii) Decomposition

Question 32.
a) What is an armature? What are its advantages.
Answer:
The soft iron core on which the coil is wound plus the coil is called an armature. It is used in electric motors to act as an electromagnet. The armature enhances the power of the motor

b) What are the advantage of electromagnet over permanent magnet.
Answer:
The advantages are:

You can turn the electromagnet by switching ON or OFF the current.
You can reverse the poles of the electromagnet by reversing the direction electric current flow in the coil.
The magnetic field strength can be changed by changing the amount of current in the coil.
An electromagnet can easily be made more powerful than a permanent magnet.

Question 33.
a) What is rusting?
Answer:
The process of slow heating of the surface of metal iron when exposed to air for a longer period of time is called rusting.

b) Differentiate between roasting and calcination. Explain the two with the help of suitable chemical equations.
Answer:
Roasting: It is a process in which sulphide ore is heated in the presence of oxygen to convert into oxide.
2ZnS + 3O₂ → 2ZnO + 2SO₂
Calcination : It is a process in which carbonate ore is heated in the absence of air to form oxides.

a) Show the formation of Na₂O by transfer of electrons.
Answer:
Sodium has one electron in the outermost shell while oxygen has six. To complete its octet. Oxygen needs two more electrons. But to complete the octet, sodium loses one electron. In order to equalise the number of electrons lost and gained, two atoms of sodium combine with one atom of oxygen. The formation of Na₂O is shown below

b) Why do you apply paint on iron articles.
Answer:
We apply paint on iron articles because it forms a protective coating on the surface of iron and we can protect it against rusting.

V. Answer the following questions. ( 4 × 4 = 16 )

Question 34.
a) Why do we classify elements?
Answer:
Classification of elements helps in :

Systematic study , of the properties of elements.
Easy to understand and remember the properties of elements.

b) What were the two criteria used by Mendeleev in creating his periodic table?
Answer:
The two criteria used by Mendeleev are

Increasing order of atomic mass.
Similarity in the properties of elements

c) In Mendeleev’s periodic table, why was there no mention of Nobel gases like Helium, Neon and Argon?
Answer:
There was no mention of noble gases like
helium, neon and argon as they were not known at that time and there were discovered much later.

d) Would you place two isotopes of chlorine, Cl – 35 and Cl – 37 in different slots because of the different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
Answer:
According to Mendleev’s periodic table Cl – 35 and Cl 37 should be placed at different positions on the basis of classification in the increasing oder of atomic mass. But since their chemical properties are same, they should be
placed in the same position in the periodic table. Mendeleev’s classification does not explain the position of isotopes.

An element X (Z = 17) reacts with an element Y (Z = 20) to form a divalent halide.
a) What were the placed in periodic table.
Answer:
Atomic number of ‘X’ is 17 and its electronic configuration in 2, 8, 7. Since it has 7 valence electrons, it lies in group 17 = (10 + 7). As three shells are prevent, it is in 3rd period. Atomic number of Y is 20 and so its electronic configuration is 2,8,8,2. Since if has 2 valence electrons, it lies in 2nd group and as it has four shells, place in 4th period.

b) Classify them based on their properties.
Answer:
Since element ‘X’ has seven electrons in the valance shell and needs one more electron complete its octet, it is a non – metal. As ‘Y’ has two electrons in the valence shell which it can easily lose to achieve the stable electronic configuration it is a metal.

c) What will the nature of oxide of Y?
Answer:
Since element ‘Y’ is a metal, its oxide must be basic in nature.

d) Identify the nature of bonding in the above compound and in the divalent halide formed by ‘X’ and ‘Y’.
Answer:
Both YO and YX₂ are ionic compounds as metals lose electrons and non – metals gain electrons during chemical reactions.

Question 35.
a) What are marginal rays?
b) Name the type of mirror used in the following situations.
i) Headlights of a car
ii) Side / rear view mirror of a vehicle.
c) Solar furnace
Support your answer with reason.
Answer:
a) The rays which strike the mirror surface near the periphery are called marginal rays.
b) i) Concave mirror : This is because concave mirror can produce powerful parallel beam of light when the light source is placed at their principal focus.
ii) Convex mirror : This is because of its largest field of view.
iii) Concave mirror : This is because it concentrates the parallel rays of light at principal focus.

Question 36.
a) Write the balanced chemical equations for the following chemical reactions.
i) Potassium bromide reacts with Barium iodide.
ii) Zinc carbonate is heated.
Answer:
i) 2KBr_(aq) + BaI_2(aq) → 2KI_(aq) + BaBr_(aq)
ii)

b) Which coloured fumes are obtained when lead nitrate is heated? Write the balanced chemical equation for this reaction. Name the type of this chemical reaction.
Answer:
On heating white powder of lead nitrate we observe the emission of brown fumes of nitrogen dioxide and a yellow residue of lead oxide. This is due to the decomposition reaction.

Question 37.
a) What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?
Answer:
The advantages of connecting electrical devices in parallel with the battery are as follows:

Each devices gets the full battery voltage.
The parallel circuit divides the current through the electrical devides the current through the electrical devices. Each device gets proper current depending on its resistance.
If one device is switched off / on others are not affected.

b) According to Joule’s law of heating, mention the factors on which heat produced in a resistor depends. According to this law write the formula used to calculate the heat produced.
Answer:
Heat produced in a resistor is

Directly proportional to the square of current for a given resistance.
Directly proportional to resistance for a given current and
Directly proportional to the time for which the current lows through the resistor.
H = I²Rt.

VI. Answer the following question. ( 1 × 5 = 5 )

Question 38.
What is the role of concentrated H₂SO₄ in th esterification reaction?
Draw the structures of the following compounds
a) Ethanoic acid
b) Bromopentane
c) Butanone
Answer:
In esterification reaction a carboxylic acid reacts with alcohol to form ester and water in the presence of concentrated sulpuric acid. This reaction is revrsible and this reverse reaction is called ester hydrolysis.

Concentrated sulphuric acid being a strong dehydrating agent removes water from the reaction mixture. As a result, the reaction proceeds only is the forward direction to form ester.

i) Ethanoic acid

ii) Bromopentane
CH₃CH₂CH₂CH₂CH₂Br

iii) Butanone