Karnataka SSLC Science Model Question Paper 5 with Answers

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Karnataka State Syllabus SSLC Science Model Question Paper 5 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.
Identify the correct statement among the following with respect to plant hormones.
A) Cytokinin promotes wilting of leaves
B) Auxin inhibits stem elongation
C) Abscisic acid inhibits growth of plants
D) Gibberellin promotes falling of leaves
Answer:
C) Abscisic acid inhibits growth of plants

Question 2.
A heat producing device should be used in an electric circuit. This device should have
A) high resistance and low melting point
B) low resistance and high melting point
C) high resistance and high melting point
D) low resistance and low melting point
Answer:
C) high resistance and high melting point

Question 3.
Observe the figure. The image formed in the figure is

A) Real, inverted, diminished
B) Virtual, erect, diminished
C) Virtual, erect, enlarged
D) Real, inverted, enlarged
Answer:
A) Real, inverted, diminished

Question 4.
Reactive metals are good reducing agents. The most suitable example related to this is
(A) PbO + C → Pb +CO
(B) 3MnO₂ + 4Al → 2Al₂O₃ + 3Mn
(C) ZnO + C → Zn + CO
(D) CuO + H₂ → Cu + H₂O
Answer:
(B) 3MnO₂ + 4Al → 2Al₂O₃ + 3Mn

Question 5.
The traditional method of sustainable natural resource management is
A) Following water harvesting method
B) Minimising the establishment of factories
C) Using fossil fuels abundantly
D) Preventing overgrazing of cattle in forest areas
Answer:
A) Following water harvesting method

Question 6.
The group of compounds which are in homologous series is,
(A) CH₄, C₂H₄, C₂H₂
(B) CH₄, CH₃OH, HCHO
(C) CH₄, C₂H₆, C₃H₈
(D) C₂H₂, C₃H₆, C₄H₁₀
Answer:
(C) CH₄, C₂H₆, C₃H₈

Question 7.
Observe the following table

The correct arrangement is
(A) a – iii, b – i, c – ii
(B) a – ii, b – i, c – iii
(C) a – ii, b – iii, c – i
(D) a – iii, b – ii, c – i
Answer:
(C) a – ii, b – iii, c – i

Question 8.

A) Neutralization reaction because water is released
B) Oxidation reaction because oxygen is removed from the reactant
C) Addition reaction because hydrogen is added to the reactant
D) Dehydration reaction because water is removed from the reactant
Answer:
D) Dehydration reaction because water is removed from the reactant

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

Question 9.
Define one volt (1V) potential difference.
Answer:
One volt is the potential difference between two points in a current carrying conductor when 1 Joule of work is done to move a charge of 1 Coulomb from one point to the other.

Question 10.
Among the flowers A and B, which flower undergoes self pollination? Why?
Answer:

Flower A, undergoes self pollination because stamen is present in flower A, which is male reproductive part and it produces pollen grains.

Question 11.
You are given a copper coil, 6V battery and iron filings. What effects of electric current can you demonstrate using these materials?
Answer:
Magnetic effect of electric current.

Question 12.
Write the formula to calculate the magnification produced by a spherical mirror.
Answer:

Question 13.
What is the meaning of “Repurpose” with respect to conservation of environment?
Answer:
Repurpose is the process by which an object with one use value is transformed or redeployed as an objbect with an alternative use value.

Question 14.
What is an exothermic reaction? Which of the following is an exothermic reaction?
i) Heating calcium carbonate
ii) Adding water to calcium oxide
Answer:
i) The chemical reactions in which heat is evolved (or given out) during the reaction are called exothermic reactions.
ii) Adding water to calcium oxide.

Question 15.
Aqueous solutions of sodium chloride, sodium sulphate and calcium chloride are taken in three separate test tubes. Using aqueous barium chloride how do you identify sodium sulphate?
Answer:
When a solution of sodium sulphate is added to a solution of barium chloride a white precipitate of barium sulphate will be formed immediately. This precipitate is insoluble in dil- Hydrochloric acid and also insoluble in water. This type of reaction is called precipitation reaction as the BaSO₄ precipitate thus formed is of white colour.
Na₂SO_4(aq) + BaCl_2(aq) → BaSO_4(s) + 2NaCl_(aq)
Since, barium sulphate is insoluble in water. So it will precipitate as a solid, whereas the sodium chloride will remain in solution.

Question 16.
Copper when exposed to air for a long time requires a green coat. Why?
Answer:
Because when copper reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface and gains a green coat. This green substance is basic copper carbonate.

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

Question 17.
How does nervous system differ from the endocrine system in forming control and co – ordination in animals?
Answer:
Nervous system

• Components : Neurons, Nerves and Nervous system.
• Action : It can be voluntary or Involuntary.
• Effects : Only for short period.
• Growth and development: Play very little role.
• Response : Quick and limited to those cells that are innervate.
• Sensory receptors : Present

Endocrine system:

• Endocrine glands and their secretions.
• It is involunary
• Lasts for longer periods.
• This system controls growth and development.
• Response is slow and produced by all the cells of the target tissues.
• Absent.

Question 18.
Draw the circuit diagram showing the combination of resistors R₁, R₂ and R₃ in parallel including ammeter and voltmeter and mark the direction of current.
Answer:

Question 19.
What are ionic compounds? Mention any two properties of ionic compounds.
Answer:
The compounds which have bonds formed by loss and gain of electrons are called ionic compounds or electrovalent compounds.

Two properties of Ionic compounds

• Ionic compounds are hard and brittle.
• Ionic compounds have high melting and boiling points.

OR

Name any two metals that react with cold water very quickly. Write the products formed when these metals react with cold wafer.
Answer:
Lithium, Sodium, Potassium, Calcium reacts with cold water very quickly.
All of these metals react vigorously or even explosively with cold water. In each case, a solution of the metal hydroxide is produced together with hydrogen gas.

Question 20.
Draw the diagram of the apparatus used in electrolytic refining of copper and label the electrode where pure copper is deposited.
Answer:

Question 21.
What are the methods used by plants to get rid of excretory products?
Answer:
Plants have completely different strategies for excretion than those of animals. They can get rid of excess water by transpiration. For other wastes, plants use the fact that many of their tissues consists of dead cells and that they can even lose some parts such as leaves. In many plants waste products may be stored in leaves that fall off. Other waste products are stored as resins and gums, especially in old xylem. Plants .also excrete some waste substances into the soil around them.

OR

Mention the importance of transpiration in plants.
Answer:
Transpiration is the process by which the excess of water is released by the plants to the atmosphere. It Happens with the help of guard cells. When the guard cells shrink the stomatal pores open and the excess water is released to the environment.

• It helps the plants to keep cool during hot conditions.
• It helps plants to lose excess water.
• As the excess water evaporates it indirectly helps us to get rain fall.
• Through transpiration all the parts of the plants get water.
• It helps the plants cells to be turgid.

Question 22.
Draw the ray diagram showing the position of the object and image, to get the real inverted image whose size is same as the object using a convex lens.
Answer:

Question 23.
Draw the diagram of the arrangement of apparatus showing the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning and label the soap bubbles filled with hydrogen.
Answer:

Question 24.
Imagine that in an area containing green bushes, almost equal number of brown grasshoppers and green grasshoppers are living. Which grasshoppers would be eaten by the birds easily? Why? Population of which grasshoppers increases gradually? Name the phenomenon which directs evolution here.
Answer:

• The population of green grasshoppers will increase because they will not be visible on green grass as a result, the brown grasshoppers will get eaten.
• The phenomenon involved is natural selection.

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

Question 25.
Define the rule used to identify the direction of induced current in an electric generator. How can we increase the amount of electric current produced in the electric generator? Mention the property of the current produced by AC generator. Mention an important advantage of this type of current.
Answer:
Fleming’s right hand rule shows the direction of induced current when a conductor attached to a circuit moves in a magnetic field. The maximum potential difference or current can be increased by increasing the rate of rotation increasing the strength of the magnetic field increasing the number of turns on the coil.

Electromagnetic conduction is the property of the current produced by the AC generator. The major advantage that AC electricity has over DC electricity is that AC voltages can be readily transformed to higher or lower voltage levels, while it is difficult to do that with DC voltage. Since high voltages are more efficient for sending electricity to great distances, AC electricity has an advantage over DC.

OR

On what principle an electric motor works? Define the rule used to identify the direction of force on the conductor in an electric motor. Explain the parts used in a commercial motor.
Answer:
The principle of an electric motor is based on the fact that current carrying conductor produces a magnetic field around it. A current carrying conductor placed perpendicular to magnetic field experiences a force.
Flemings left hand rule used is to determine direction.

The commercial motors use:

• An electromagnet in place of permanent magnet.
• Large number of turns of the conducting wire in the current carrying coil.
• The soft iron core, on which the coil is wound plus the coils is called armature.

Question 26.
Explain the flow of energy and harmful chemicals in an ecosystem.
Answer:
Flow of energy is unidirectional. The energy that is captured by the autotrophs does not revert back to the solar input and the energy which passes to the herbivores does not come back to autotrophs. As it moves progressively through the various trophic levels it is no longer available to the previous level. The energy available at each trophic level gets diminished progressively due to loss of energy at each level.

In the same way the harmful chemicals enter our bodies through the food chain. As there chemicals are not degradable they get accumulated progressively at each trophic level. As human beings occupy the top level in any food chain the maximum concentration of these chemicals get accumulated in our bodies, this phenomenon is known as biological magnification.

Question 27.
What is nuclear energy? What are the hazards of nuclear power generation?
Answer:
The energy produced during a nuclear reaction such as nuclear fision or fusion is called nuclear energy.
Nuclear wastes contains radioactive substances which emit harmful nuclear radiations. There is a high risk of environment contamination.

The radiations emitted 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 and animals have also been observed.

OR

List the four characteristics of a good source of energy. Name any two sources of energy which are dependent on solar energy.
Answer:
Characteristics of good source of energy are :

• Provide large amount of continuous supply . of energy per unit mass or volume.
• Cheap and easily available.
• Safe to store and easy to transport.
• Economical and should not pollute the environment.

The two major types of solar energy that make it to Earth are heat and light.

Question 28.
When sulphuric acid is added to lg solid sodium chloride taken in a test tube, which gas is released? What changes do you observe when you test the gas with dry and wet litmus paper? What conclusion do you draw by this experiment?
Answer:
The gas produced is HCL.
Dry blue litmus paper does not change colour but wet litmus paper changes its colour to red. Dry HCl gas is not acidic but HCl solution is acidic. This is because in the presence of water, HCl dissociates to give H⁺ ions.

OR

The pH values of four solutions A, B, C and D are 5, 12, 8 and 9 respectively. Arrange them in the increasing order of their hydroxyl ion concentration. Which solution among them has strong acidic property? Explain what happens if our mouth contains the pH of solution ‘A’.
Answer:

• 12 > 9 > 8 > 5 or B > D > C > A
• In solution ‘A’ has strong acidic property.
• When the p^H in the mouth is 5(A) tooth decay starts. Bacteria present in the mouth produces acid by degradation of sugar and food particles which remain in the mouth after eating. This can lead to tooth decay. Therefore we should brush our teeth with toothpaste because it contain base.

Question 29.
Write the functions of Forebrain, Medulla and Cerebellum in human brain.
Answer:
Fore brain :

• It is the major thinking part of the brain.
• It has regions to receive sensory impulses from various receptors, for hearing, smell sight and so on.
• Decision made is sent to the motor areas which send messages to the effector organ muscles to respond.

Cerebellum :

• Precision of voluntary actions such as walking in a straight line, riding a bicycle, picking up a pencil are possible because of cerebellum.
• It also help in maintaining the posture and balance of the body.

Medulla :
Involuntary actions such as maintaining blood pressure, salivation and vomiting.

Question 30.
The molecular formula of three fatty acids A, B, and C present in oil or fat C₁₂ H₂₉ COOH, C₁₅ H₂₉ COOH and C₁₆H₂₉COOH. Which of these is derived from i) Alkane ii) Alkene and iii) Alkyne? Which of them becomes rancid earlier? How can we increase its shelf life?
Answer:
Derived from
i) Alkane – C₁₄ H₂₉ COOH
ii) Alkene – C₁₅ H₂₉ COOH
iii) Alkyne – C₁₆ H₂₉ COOH
C₁₆H₂₉COOH is unsaturated undergoes rancidity earlier.
By hydrogenation we can increase shelf life.

Question 31.
A tall plant with red flowers (TrRr) is self pollinated. Represent the plants obtained in F2 generation with the help of a checker board (Punnet square). The traits which are not found in the parental plants are expressed in the offspring. Why?
Answer:
i) TtRr

PR : 9 : 3 : 3 : 1
GR : 1 : 2 : 2 : 4 : 1 : 2 : 1 : 2 : 1

ii) Due to variation (mixing up of genes) new traits are formed.

Question 32.
Observe the following figure. AB is light ray travelling from liquid to air. BC and BD are refracted rays.

i) Which is the refracted ray if the liquid taken is benzene?
ii) Which is the refracted ray if the liquid taken is water?
Justify your answer. (The absolute refractive index of water and benzene are 1.33 and 1.5 respectively)
Answer:
i) The ray BC is the refracted ray if the liquid taken benzene.
ii) BD is the refracted ray if the liquid taken water.
As speed of light in water is 2.25 × 10⁸ ms^-1
As speed of light in benzene is 2 × 10⁸ ms^-1
So the refractive index of benzene is more compared to water.

OR

An object 2 cm tall is kept on the principal axis of a converging lens of focal length 8 cm. Find the position, nature and size of the image formed if the object is at 12 cm from the lens. Also find the magnification produced by the lens.
Answer:
Given : h₀ = 2 cm, f = 8 cm, u = -12 cm, v = ?

Question 33.
Explain the three types of decomposition reaction with the help of balanced chemical equation for each.
Answer:
I. Thermal Decomposition

II. Photo chemical decomposition

III. Electrolytic decomposition

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

Question 34.
Draw the diagram showing the structure of human alimentary canal and label the following parts.
a) The part which stores bile juice
b) The longest part of the alimentary canal
Answer:

Question 35.
How did Mendeleev arrange the elements? He left empty places in his periodic table. Why? Explain the limitations of Mendeleev classification.
Answer:
1) Mendeleev realized that the physical and chemical properties of elements were related to their atomic mass in a “periodic” way and arranged them so that groups of elements with similar properties fell into vertical columns in his table.
2) Gaps were left for undiscovered elements in the Mendeleev’s periodic table.
3) Limitations of Mendeleev classification :

• Position of hydrogen was not justified.
• Increasing order of atomic mass could not be maintained.
• Isotopes have similar chemical properties but different atomic masses, they cannot be given separate places.
• Mendeleev could not explain the cause of periodicty.

Question 36.
There are two metallic wires of the same thickness made from iron and silver. If the length of iron wire is 12cm, what should be the length of silver wire which is equal to the resistance of iron wire?
Data : Resistivity of iron = 10 × 10^-8 Ω m
Resistivity of silver = 16 × 10^-8 Ω m
l_(s) = 12 cm
l_(s) = ?
S_(i) = 10 × 18^-8 Ω m
S_(s) = 10 × 18^-8 Ω m

l_(s) = 7.5 cm

Question 37.
a) Explain why variations are observed in the offsprings formed by sexual reproduction?
Answer:
During sexual reproduction two different parent i.e, male and female take part as a result of which the newly formed zygote possess genetic material of both parents. It leads to interchange of genetic information between two gamete which is passed to the progeny and develops variation. Offspring produced as a result of sexual reproduction are genetically different from the parents due to the process of meiosis, during which crossing over takes place which creates recombination.

b) What are the advantages of vegetative propagation?
Answer:
Advantages of vegetative propagation :

• It is used to grow a plant in which viable seeds are not formed or very few seeds are produced such as orange, banana, pineapple.
• It helps to introduce plants in new areas
• where the seed germination fails to produce mature plant due to change in environmental factors and the soil.
• It is more rapid, easier and cheaper method.
• By this method a good quality of a race or variety can be preserved.

OR

a) Write the structure and functions of placenta.
Answer:
Placenta is a disc which is embedded in the uterine wall. It contains villi on the embryo’s side of the tissue. On the mother’s side are blood spacer, which surround the villi. This provides large surface area for glucose and oxygen to pass from mother to the embryo. The waste generated in the embryo is removed by transferring them into the mother’s blood through the placenta.

b) What are the changes that occur in a flower after fertilization.
Answer:
Pollen grain develops pollen tube containing two male gametes, travels from stigma to style to reach the ovule for fertilization to take place. Male and female gametes fuse in the ovule and after fertilization, zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and is gradually converted into a seed. The ovary grows rapidly and ripens to form a fruit.

Meanwhile, the petals, sepals, stamens, style and stigma may shrivel and fall off. The seed contains a seed coat, an embryo with plumule – future shoot, radicle, future root and one or two catyledons which supply food to the germinating seed at a later stage.

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

Question 38.
Stars appear to be twinkling but planets do not twinkle Why? Explain why the colour of the clear sky during day appears blue and during sunset appears red.
Answer:
Stars twinkle due to atmospheric refraction of starlight. As the stars are very far away, they behave as almost point source of light. But planets are much closer to the earth and are seen as extended sources so, a planet may be considered as a collection of a large number of point size light sources. Although light coming from individual point sized sources flicker but the total amount of light entering our eye from all the individual point sized sources average out to be constant. There by planets appear equally bright and there is no twinkling of planets.

The colour of clear sky appear blue during day because the particles in air of Earth’s atmosphere scatter the blue light in all directions. The scattering of blue light is more than other colours. That is the reason we can see the blue sky most of the time as other colour like red are scattered less. Smoke particles are also there which are responsible for blue colour.