BLE Model Set 03

Basic Level Examination Preparation, Day: 03

Question paper for 8th grader students of Suryodaya

Science and Environment

Class: 8                                        Full marks: 75

Time: 2 hrs. 15 min.                            Pass marks: 30

Group A (Physics)

1. a) What is mass? Write two differences between fundamental and derived units.

   b) What will be the final velocity of vehicle, if it started from rest and accelerates at 4m/s² after 5 second?

2. a) Define: i) Mechanical advantage      ii) velocity ratio        iii) efficiency

   b) Prove that, liquid pressure (P)=hdg.

3. a) Define work and power, write the relationship between them.

   b) Write any two differences between clinical and simple thermometer.

4. a) What is refraction of light? Which type of mirror is used as side mirror in vehicles and why?

   b) what is unit of frequency? Write any two differences between echo and reverberation.

5. a) Draw the diagram to show the arrangement of molecular magnet in magnet and magnetic substance.

   b) Why we use dry cell in torch light? Write any three reasons.

Group B (Chemistry)

6. a) Write the molecular formula of salt. Write the word equation of following chemical equation.

Hydrogen + Oxygen ➡️ Water

   b) Draw the electronic configuration of Magnesium atom.

7. a) What is chromatography? Which type of mixture is separated from it?

   b) Write any one use of sulphur and copper each.

8. a) What effect do acid, base and salt have on different indicators? Show in table.

   b) How can you detect hardness of water collected from different sources?

Group C (Biology)

9. a) Draw a labelled diagram of virus.

   b) Why does modification of root occur? Write any two causes or uses.

10. a) Write the relationship between cells, tissue and organs in human body.

   b) Write the name of tissue found in animals.

11. a) What do you mean by vegetative propagation? Write the name of two plants which is reproduced from this process.

   b) What is photosynthesis? How can you demonstrate that plants prepares their food on its leaves? Write with an experiment.

Group D (Astronomy and Geology)

12. a) What is soil erosion? Which region of Nepal does rain fall more? Why?

   b) What is phases of moon? Write any three reasons for the existence of living being on earth.

Group E (Environmental Science)

13. a) What can human being get from nature? Write any three with examples.

   b) Write the difference between national park and wild life reserve.

14. a) Write any four reasons of water pollution. Give any one measure that mitigates for minimizing water pollution in your region.

   b) What is climate change? Write two effects of climate change.

15. a) What is biodiversity? Write its types.

   b) What can you do in your residencial area for protection of Environment? Write any four points.

BLE Science Model 04

Group (Physics)

1. (a) What is demagnetization? How can you demagnetize a magnet? [2]

Answer

The process of losing magnetic property of a magnet is called demagnetization.

Some of the processes to demagnetize a magnet are:
a)    By dropping or striking a magnet.
b)    By heating the magnets.
c)    By rubbing similar poles of the magnet.
 

(b) What are the differences between fundamental units and derived units? [2]

Answer

The differences between fundamental units and derived units are;

	Fundamental units	Derived units
Definition	Fundamental units are the units of measurement which are independent of each other or any other units.	Derived units are the units of measurement which are dependent on each other and other units for their existence.
Derivation	Fundamental units cannot be derived from any other units.	Derived units can be derived from other basic units.

2. (a) What is terrestrial magnetism? Write some evidences to support terrestrial magnetism. [3]

Answer

Our planet, Earth is supposed to be a big magnet and this magnetic property of the earth as a whole is known as terrestrial magnetism. 

Some of the evidences to support terrestrial magnetism are:
a)    A freely suspended bar magnet always shows the geographical N-S direction due to terrestrial magnetism.
b)    The ores of iron or any other buried magnet show magnetic property.
c)    The angle of inclination and angle of declination are shown by a magnetic needle.
d)    In the magnetic field of a magnet, the neutral point can be formed.
 

(b) What is a dry cell? How is a dry cell made? [3]

Answer

A dry cell is a portable cell. A dry cell consists of a zinc container whose base acts as the negative electrode. The carbon rod placed at the centre with a brass cap (metal cap) acts as the positive electrode. This is surrounded by a mixture of manganese dioxide and charcoal in a muslin bag. The electrolyte uses is a moist paste of ammonium chloride. The outer body (excluding the base) of the zinc container is insulated with cardboard. 

When the dry cell is connected in a circuit comprising a bulb, current flows in the circuit due to the chemical reaction that takes place in the cell. This makes the bulb glow. The dry cell is a primary cell and it cannot be recharged.

 

3. (a) Calculate the area and volume of a book whose length is 18 centimetres, breadth is 8 centimetresand height is 5 centimetres. Convert the value of area and volume of the book in terms of their SI units? [3]

Answer

Here, we have to calculate the area and volume of a book.

For that, let us collect the given information.

The information given are;

The length of a book (let us represent it by l) is equal to 18 centimetres.

          Length (l) = 18 cm

The breadth of the book (let us represent it by b) is equal to 8 centimetres.

          Breadth(b) = 8 cm

The height of the book (let us represent it by h) is equal to 5 centimetres.

          Height (h) = 5 cm

Now, we have to calculate the area of the book (let us represent it by A)

          Area (A) =?

And we have to calculate the volume of the book (let us represent it by V).

          Volume (V) =?

We know,

Area of book (A) is the product of its length (l) and breadth (b).

          A = l × b

Substituting the given values in the formula

          A = l × b

We get,

A is equal to

          Let us write 18 in the place of ‘l’ and 8 in the place of ‘b’.

Remember that it is not necessary to write the units while performing the calculations. 

          A = 18× 8

Multiplying 18 and 8 together, we get 144.

          A = 144

Remember that we should not forget to write the unit while writing the final answer.

So, let us write the unit of area (square centimetre) in the final answer.

Therefore, the area of the book is equal to 144 square centimetres.

∴       A = 144cm2

Now, let us convert the value of area of the book in terms of its SI unit i.e. square metre.

We know,

1 square metre is equal to 10000 square centimetres.

          1 m2= 10000cm2

As we need to convert the square centimetre value of areain terms of square metre, let us write the square centimetre value at first.

10000square centimetres is equal to 1 square metre.

          10000cm2= 1 m2

Now, we can apply simple unitary method to get the value of 1 square centimetre in terms of metre.

1 square centimetre is equal to ten thousandth square metre

          1 cm2 = 110000m2

As we need the area of the book (i.e. 144 square centimetres) in terms of its SI unit, let us multiply 144 by the unit value of square centimetre in terms of square metre.

          144 cm2 = 144 × 110000m2

Dividing 144 by 10000, we get 0.0144.

Therefore, the area of the book in terms of its SI units is equal to 0.0144 square metres.

          Area = 0.0144 m2

              

Now, let us calculate the volume of the book (V).

We know,

Volume of book (V) is the product of its length (l), breadth (b) and height (h).

V= l × b × h

Substituting the given values in the formula

V= l × b × h

We get,

V is equal to

          Let us write 18 in the place of ‘l’, 8 in the place of ‘b’ and 5 in the place of ‘h’.

Remember that it is not necessary to write the units while performing the calculations. 

          V = 18× 8 × 5

Multiplying 18, 8 and 5 together, we get 720.

          V = 720

Remember that we should not forget to write the unit while writing the final answer.

So, let us write the unit of volume (cubic centimetre) in the final answer.

Therefore, the volume of the book is equal to 720 cubic centimetres.

∴       V = 720 cm3

Now, let us convert the value of volume of the book in terms of its SI unit i.e. cubic metre.

We know,

1 cubic metre is equal to one million cubic centimetres.

          1 m3= 1,000,000cm3

As we need to convert the cubic centimetre value of volume in terms of cubic metre, let us write the cubic centimetre value at first.

One million cubic centimetres is equal to 1 cubic metre.

          1000000cm3= 1 m3

Now, we can apply simple unitary method to get the value of 1 cubic centimetre in terms of cubic metre. This gives us

1 cubic centimetre is equal to one millionth cubic metre

          1 cm3 =11,000,000m3

As we need the volume of the book (i.e. 720cubic centimetres) in terms of its SI unit, let us multiply 720 by the unit value of cubic centimetre in terms of cubic metre.

          720 cm3= 720 ×11,000,000m3

Dividing 720 by 1,000,000, we get 0.000720.

Therefore, the volume of the book in terms of its SI units is equal to 0.000720 cubic metres.

          Volume = 0.000720 m3

Hence, the area and volume of the given book are 0.0144 m2and 0.00072m3 respectively. 

(b) State the principle of the simple machine. What do you mean by mechanical advantage of a lever is 4.  [3]

Answer

The principle of levers states that 'If there is no friction, in the balanced condition of s lever, work output and work input are equal.'

Mathematically,

Work output = Work input (In a balanced state of a lever)

Or, L х Ld = E х Ed

We have,

MA = LoadEffort

Mechanical advantage of a machine is 4 which means that the machine can lift load four times greater that the applied force.

4. (a) 1 m long lever is used to lift the load of 600 N by using an effort of 200 N. If load 20 cm far from the fulcrum then calculate mechanical advantage, velocity ratio and efficiency.  [3]

Answer

Load (L) = 600 N
Load distance (Ld) = 20 cm = 20 = 0.2 m
Effort (E) = 200 N
Effort distance (Ed) = 80 cm = 0.8 m
Mechanical advantage (MA) =?
Velocity ratio (VR) =?
Efficiency (ɳ) =?

We have,
MA = L/(E ) = 600 = 3

Again, VR = EdLd = 0.8 = 4

Finally,
Efficiency = MAVR х 100% = 3 х 100% = 75%

Hence, MA, VR, and efficiency of the lever is 3, 4 and 75% respectively.

(b) Define conventional and actual direction of current with figure. [3]

Answer

Before 18th century the scientists thought that charge (electrons) flows from positive terminal to negative terminal. But it has been revealed that the charge flows from negative terminal to positive terminal. The representation of flow of charge from positive to negative terminal is called conventional direction of current and the representation of flow of charge from negative to positive terminal is called actual direction of current. The direction of current flow in both cases is shown in figure below:

5. (a) What is one joule work? What kinds of energy are present in rotating fan and stretched rubber?  [2]

Answer

We have,
Work (W) = Force (F) х Displacement (d)

Force is expressed in N and distance is expressed in metre, then, work done is expressed in Nm. Newton metre is also called Joule. In short, it is represented by 'J'.

If   F = 1N and d = 1 m,then,
W = 1 N х 1 m = 1 Nm = 1J

Hence, 1 joule of work is said to be done if a force of 1 N displaces a body by 1 m distance in the direction of force applied.

Rotating fan and stretched rubber contains kinetic energy and potential energy respectively.
 

(b)  Astronauts wear special device on their ear, why? Define wavelength.  [3]

Answer

Sound wave is mechanical wave i.e. it need a material medium to for their propagation. In space there is vacuum i.e. no air is present for the propagation of sound, so astronauts cannot communicate with each other. Hence, astronauts wear special device on their ear for communication.

The distance between two consecutive compressions or rarefactions of a sound wave is called wavelength of that wave. It is denoted by 'ʎ'. 

 

Group (Chemistry)

6. (a) What is acid? Write any one application of sulphuric acid. Write down molecular formula of sodium hydroxide. [3]

Answer

An acid is a chemical compound which gives hydrogen ion (H+) when dissolved in water.
Application of sulphuric acid
It is used in manufacture of chemical fertilizers, like ammonium sulphate, superphosphate.
Molecular formula of sodium hydroxide is NaOH.

(b) What is chemical equation? Hydrogen and oxygen react to give water, write the word equation and chemical equation for it. [3]

Answer

A chemical reaction which is expressed by using molecular formulae of reactants and products is called chemical equation.
Word equation-
Hydrogen + Oxygen →  Water
Chemical equation-
2H2 + O2 → 2H2O

7. (a) Write the names of two type of chromatography. [2]

Answer

Types of chromatography-
i.   Paper chromatography
ii.  Adsorption chromatography

(b) Differentiate between electron and proton by two points. What is electric charge? [3]

Answer

Differences between electrons and protons are as followings.

Protons	Electrons
They are positively charged particles.	They are negatively charged particles.
They are found in nucleus.	They revolve around nucleus.

 Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.

8. (a) What is the pH value of strong acid, strong base and salt? Why sulphuric acid is called an acid? [3]

Answer

The pH value of strong acid is 0, pH value of strong base is 14 and pH value of salt is 7.
Acid is a chemical compound which gives hydrogen ion (H+) when dissolved in water. One molecule of sulphuric acid gives two hydrogen ions (2H+) when dissolved in water. Hence, sulphuric acid is called an acid.

(b) By what name Group IA elements are denoted? The valency of nitrogen is 3, clarify it. [2]

Answer

Group IA elements are also known as alkali metals. The valency of nitrogen is 3. This means that combining capacity of nitrogen is 3. The number of electron present is valence shell of nitrogen is 5. So, it gains 3 more electrons from other atom during chemical reaction to form stable electronic configuration.

Group (Biology)

9. (a) Epithelium and Meristematic tissue are not similar, why? [2]

Answer

Epithelium is formed of cells which have lost their ability to divide and are concerned with the functions of protection, conduction and support. Meristematic tissue is a type of plant tissue formed of young living cells capable of continuous cell division and is responsible for the growth of the plant. So, Epithelium and Meristematic tissue are not similar

(b) What is vegetative propagation? Write any two examples [2]

Answer

The process of reproduction by the vegetative parts such as root, stem and leaves are called vegetative propagation. Potato and ginger are the two example of vegetative propagation.

10. (a) Where does the epithelial tissue lie? Write any two function of it.  [3]

Answer

The epithelial tissue lies in Animal tissue.

 The two function of epithelial tissue are:
i.     To protect skin.
ii.     Absorption of intestinal lining. 

(b) Write two organs of nervous system with two functions.  [2]

Answer

The two organs of nervous system are:
i.     Brain
       a.  Thinking or cognition
       b.  Perception or sensing

ii.     Spinal cord
        a.    Reflexes
        b.    walking
 

11. (a) What is asexual reproduction? Write the name of reproduction process that occurs in tapeworm. [3]

Answer

A type of reproduction that occurs without the fusion of male and female gametes is called asexual reproduction. Regeneration is the name of reproduction process that occurs in tapeworm.

(b) Explain, how could you prove experimentally that, oxygen gas is released during photosynthesis by green plants.  [3]

Answer

Material required:
    Beaker, funnel, test tube, hydrilla plant.

Procedure:
    Take some healthy, fresh branches of hydrilla plant in a funnel and invert in a beaker. Put water in the beaker till the end of the funnel is under water as shown in figure. Take a test tube full of water and close its mouth with a thumb. Then invert it over the stem of funnel and release the thumb. Such method is applied so as to keep the test tube free of air. Keep the set undisturbed in the sunlight for a while. 

Observation:
    After a short time some bubble of gas in the test tube is produced. The gas so evolved is collected at the top of test tube. Take it out and bring burning match stick near the tube. The test-tube will steak light.
    Figure in copy
    Fig: Oxygen is evolved during photosynthesis.

Result
    The evolved gas is oxygen which helps in burning.

Conclusion
    O2 is evolved during photosynthesis.
 

Group (Astronomy and Geology)

12. (a) What is monsoon? How does monsoon enter in Nepal? [3]

Answer

Monsoon was the term first used by British India and neighbouring countries to refer to the big seasonal winds flowing from the Bay of Bangal and Arabian Sea in the southwest bringing heavy rainfall to this area.

In Nepal monsoon comes from south east of Nepal. During the summer, the water vapour rising from Bay of Bangal enters to Nepal from eastern part and flows towards the north and the west. When this vapour reaches in northern hills, it turns into rain and causes rainfall. Due to which eastern part of Nepal receives more rain that western in summer.
 

(b) Write any four characteristics of minerals. [2]

Answer

Four characteristics of minerals are as follows:

i)  Minerals are crystalline in form.
ii)  Every mineral has its own colour. For example, hematite has red-brown colour whereas chalcopyrite has golden green colour.
iii)  Minerals are hard solid substances.
iv)  Minerals shine according to their properties.

Group (Environment Science)

13. (a) How is biodiversity conserved by sustainable development? [3]

Answer

 One of the main principles of sustainable development is conservation of biodiversity. It promotes the use of renewable energy sources. These types of sources can be used repeatedly and replaced naturally. It helps to understand the limitation of natural resources and make development plans accordingly. Hence, sustainable development is a must for biodiversity conservation.
 

(b) Write importance of forest in human life. [3]

Answer

Some of the importance of forest in human life is as follows:
i.    Forest protects us from bad weather and unpleasant consequences.
ii.   Forest provides shelter and food to wildlife.
iii.  Human beings depend upon forest for firewood, fodder, medicinal herbs, etc.
iv.  Industries get their raw materials from the forest.
 

14. (a) Development and amount of minerals are closely related. Why? [2]

Answer

For any development activities to be carried out, we need minerals like coal, petroleum products, copper, iron, steel etc. If they are present in large amount, number of development activities can also be increased. So, development and amount of minerals are closely related.
 

(b) During the winter season, a green house is made of plastic, why? [2]

Answer

A greenhouse is mainly made of plastic or glasses. They are made specially to trap sunlight. The trapping of sunlight maintain the heat inside the greenhouse in spite of the cold weather outside. So, green house is made of plastic.
 

15. (a) What is greenhouse effect? Write few green house gases. [2]

Answer

The greenhouse effect is a process by which thermal radiation from planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Major gases that contribute to the greenhouse effect are:
i.    Water vapour
ii.   Carbon dioxide 
iii.  Methane
iv.  Ozone
 

(b) What do you mean by soil profile? Draw a labeled diagram of soil profile. [3]

Answer

A clear structure showing internal adjustment of the different layers of soil from up to down is called soil profile.

A labeled diagram of soil profile is as follows:

                               Fig: Soil profile

BLE Science Preparation: Model Set 02

Group (Physics)

1. (a) What is transverse wave? Write one effect of reverberation. [2]

Answer

 If the particles medium vibrate perpendicular to the direction of the motion of the wave, such a wave is called transverse wave.

Due to effect of reverberation, original sound gets reflected  and reflected sound mixes with original sound and prolongation of sound occurs. 
 

(b) What is magnetic induction? Magnets are not hammered or rubbed, why? [3]

Answer

The process in which a piece of magnetic material acquires the magnetic properties temporarily due to the presence of magnet near or in contact with it is called the magnetic induction. 
       
Magnets are not hammered or rubbed because 
i.    If a magnet is rubbed on hard substances it’s loses its magnetism.
ii.   On hammering, the vibration caused by the impact on the magnetic molecules within the magnet, forcing them out of order and destroying the long-range order of the unit                   magnet. As a result, the magnet gets demagnetized.
 

2. (a) What are the differences between MKS system and FPS system? [2]

Answer

The differences between MKS system and FPS system are;
 

	MKS system	FPS system
Definition	The system of measurement in which length is measured in 'metre', mass in 'kilogram' and time in 'second' is called MKS system.	The system of measurement in which length is measured in 'foot', mass in 'pound' and time in 'second' is called FPS system.
Full-form	In MKS system, MKS is the abbreviated form of units; Metre, Kilogram and Second.	In FPS system, FPS is the abbreviated form of units; Foot, Pound and Second.

(b) Write two differences between heat and temperature.  [2]

Answer

Differences between heat and temperature are as followings:
 

Heat	Temperature
It is a form of energy that gives sensation of warmth.	It is the degree of hotness and coldness of a body.
It is a cause of change of temperature.	It is an effect of heat.

3. (a)  Sound can travel without medium. Write on the basis of following points: 

i.  Materials required
ii. Procedure
iii.Conclusion
  [3]

Answer

Sound cannot travel without medium.

Materials required
•  Electric bell
•  Glass bell jar
•  Vacuum pump


















An experiment showing sound cannot travel without medium

Procedure
An electric bell is suspended inside a glass bell jar as shown in figure below. When the switch is pressed on, the hammer hits the gong and sound is heard. Then, the air present inside the bell jar is allowed to escape through the vacuum pump. Now, the sound becomes fainter and fainter and finally no sound can be heard though the hammer hits the gong continuously.

Observation
It is observed that the hammer hits the gong continuously but we hear no sound after the air is taken out from the bell jar.

Conclusion
From above experiment it can be concluded that sound does not travel through vacuum, it requires material medium to travel.


 

(b) What is output work?  [2]

Answer

The efficiency of a simple machine is 80%, it means that only 80% of input work applied to the machine can do output work, remaining 20% input work is wasted due to friction.

4. (a) What is magnetic induction? [2]

Answer

The property of a magnet by virtue of which it is transferred to another body which is attracted by it for a while is called a magnetic induction. It is a temporary process because of which magnetic materials in contact with the magnet acquires temporary magnetic properties.
 

(b)  Alcohol thermometer cannot be used to measure the boiling point of water, why?  [2]

Answer

Alcohol thermometers are filled with alcohol. Water has boiling point 100ᵒC. The boiling point of alcohol is 78ᵒC, so alcohol thermometer cannot measure the temperature greater than 78ᵒC. Hence,alcohol thermometer cannot be used to measure the boiling point of water.

5. (a) The distance from Thapathali to Koteshwor is 4 kilometres. Convert this value in terms of metre. [3]

Answer

Here, we have to convert the kilometre value of length into metre.

For that, we need to remember the relationship between kilometre and metre.

We know the relationship between kilometre and metre is;

One kilometre is equal to 1000 metres.
           

1 km = 1000 m
 

The distance from Thapathali to Koteshwor is equal to 4 kilometres.
           

Distance = 4 km
 

As we need the value of 4 kilometres in terms of metres, let us multiply 4 by the unit value of kilometre in terms of metre.
           

4 km = 4×1000 m
 

Multiplying 4 and 1000 together, we get 4000.

Therefore,4 kilometres is equal to 4000 metres.
           

∴ 4 km = 4000 m
 

Hence, the distance from Thapathali to Koteshwor in terms of metre is equal to 4000 metres.  

(b) What are the differences between mass and weight? [2]

Answer

The differences between mass and weight are;
 

	Mass	Weight
Definition	Mass is the quantity of matter which is contained in a body.	Weight is the force acting on the mass of a body due to gravity.
Measuring device	Mass is measured using 'beam balance'.	Weight is measuredusing 'springbalance'.
Uniformity	Mass does not vary from place to placei.e. the mass of a body is always constant in every place of the universe.	Weight varies from place to place i.e. the weight of a body measured in a place is different from the weight measured in another place of the universe.
Type of quantity	Mass is a scalar quantity.	Weight is a vector quantity.

Group (Chemistry)

6. (a) What is semi-conductor? Write any two properties of aluminium. [2]

Answer

Those substances which are bad conductor of heat and electricity are termed as semiconductors.
Properties of aluminium are as followings:
•    They possess metallic lustre when they are freshly cut.
•    They are good conductor of heat and electricity.
 

(b) Write any one use of copper and aluminium. [2]

Answer

Uses of copper and aluminium-
•    Aluminium is used in a huge variety of products including cans, foils, kitchen utensils, window frames, beer kegs and aeroplane parts.
•    Copper is used in electrical equipment such as wiring and motors.

7. (a) Show two differences between sodium carbonate and sodium bicarbonate. [2]

Answer

Differences between sodium carbonate and sodium bicarbonate are as followings:

Sodium carbonate	Sodium bicarbonate
Sodium carbonate is commonly known as ash soda and washing soda.	Sodium bicarbonate is commonly known as baking soda.
Sodium carbonate is used in manufacturing glass and soap.	It is used in food industries.

(b) Which acids are found in lemon and milk? Give any two properties of base. [3]

Answer

Citric acid is found in lemon and lactic acid is found in milk.
Properties of base are as followings:
i.    Bases have bitter taste and they are soapy to touch.
ii.   Bases have a pH value greater than 7.

8. (a) Write any one difference between mixture and compound. Mention the charge of proton and electron. [2]

Answer

Difference between mixture and compound is as following:

Mixture	Compound
A mixture is a material made up of two or more different substances which are mixed but are not combined chemically.	A substance made from the chemical reaction of two or more atoms of elements in a fixed proportion by weight is called compound.

Proton contains positive charge while electrons contain negative charge.

(b) Write about position of metals, metalloids and non-metals in periodic table. What is sulphur? [3]

Answer

In periodic table metals are placed in group IA(except hydrogen) and IIA, non-metals are placed in left side of periodic table (group IIIA, VA, VIA and VIIA) and metalloid are kept in group IVA of periodic table.

Group (Biology)

9. (a) Write one function each of RBC, WBC and platelets.  [3]

Answer

RBC: The function of RBC is to transport oxygen and carbon dioxide in our body.
WBC: The function of WBC is to fight against germs that cause diseases.
Platelets: The function of platelets is to protect the body from loss of blood. 
 

(b) Explain, how could you prove experimentally that, oxygen gas is released during photosynthesis by green plants.  [3]

Answer

Material required:
    Beaker, funnel, test tube, hydrilla plant.

Procedure:
    Take some healthy, fresh branches of hydrilla plant in a funnel and invert in a beaker. Put water in the beaker till the end of the funnel is under water as shown in figure. Take a test tube full of water and close its mouth with a thumb. Then invert it over the stem of funnel and release the thumb. Such method is applied so as to keep the test tube free of air. Keep the set undisturbed in the sunlight for a while. 

Observation:
    After a short time some bubble of gas in the test tube is produced. The gas so evolved is collected at the top of test tube. Take it out and bring burning match stick near the tube. The test-tube will steak light.
    Figure in copy
    Fig: Oxygen is evolved during photosynthesis.

Result
    The evolved gas is oxygen which helps in burning.

Conclusion
    O2 is evolved during photosynthesis.
 

10. (a) Where does the epithelial tissue lie? Write any two function of it.  [3]

Answer

The epithelial tissue lies in Animal tissue.

 The two function of epithelial tissue are:
i.     To protect skin.
ii.     Absorption of intestinal lining. 

(b) What is a system? Mention a name of any one system of human body? [2]

Answer

A group of different organs which conducts a particular life process is called system. The name of one system of human body is skeletal system.

11. (a) What is vegetative propagation? Write any two examples [2]

Answer

The process of reproduction by the vegetative parts such as root, stem and leaves are called vegetative propagation. Potato and ginger are the two example of vegetative propagation.

(b) What is asexual reproduction? Write the name of reproduction process that occurs in tapeworm. [3]

Answer

A type of reproduction that occurs without the fusion of male and female gametes is called asexual reproduction. Regeneration is the name of reproduction process that occurs in tapeworm.

Group (Astronomy and Geology)

12. (a) How many types of soil are there on the basis of colour, size and composition? Describe them in brief. [3]

Answer

There are three types of soil on the basis of colour, size and composition. They are:

i)    Loam soil: Loam soil is the combination of sand, clay and humus in good proportion. It is fertile soil which is good for cultivation of crops.

ii)   Clay soil: Clay soil is the soil which has small and tightly packed particles. Water does not flow freely through this soil.

iii)  Sandy soil: Sandy soil is the soil which contains high proportion of sand particles. Water can easily pass through this soil.
 

(b) Why do erosion and deposition take place side by side? Write any four effects of erosion. [3]

Answer

Erosion and deposition take place side by side because on process of them is a must for or after another process.

Four effects of erosion are as follows:
i)    Erosion causes landslide.
ii)   Erosion forms plains, plateaus and Residual Mountain like landscapes.
iii)  Erosion decreases the soil fertility.
iv)  Erosion may cause water pollution.
 

Group (Environment Science)

13. (a) What is acid rain? Write some impacts of acid rain. [3]

Answer

Rain with high levels of nitric and sulphuric acids is called acid rain. Some of the impacts of the acid rain are as follows:
i.    Acid rain damages forests and kills the trees.
ii.   Soil loses fertility so the crops are destroyed or not able to grow.
iii.  Houses, statues, monuments made out of limestone, sandstone and marbles are destroyed because acid rain can melt such items.
iv.  Fishes of lake, streams and rivers are affected because acid rain causes lack of oxygen. 
 

(b) How many types of forest are there in Nepal? Write them. [2]

Answer

There are mainly two types of forest in Nepal. They are:
a)    Government Managed Forest:
       i.    Community Forest 
       ii.   Leasehold Forest
       iii.  Protected Forest
       iv.  Religious Forest
b)    Private Forest ( managed by individual households )

14. (a) How can we conserve biodiversity? [2]

Answer

The things we can do to conserve biodiversity are as follows:
i.    Do not do things that could cause fire in the forest or any other places.
ii.   Follow the rules and regulations strictly.
iii.  Go for wise use of natural resources.
iv.  Report any mishap or wrong doings if seen or found, to the authority.  
 

(b) Write some importance of medicinal plant. [3]

Answer

Some of the importance of the medicinal plants is as follows:
i.    They are chief raw materials for the manufacture of present age drugs and medicines.
ii.   They are comparatively safe, eco-friendly and locally available.
iii.  As herbs are natural products, they are free from side effects.
iv.  They have a great traditional value in our culture and religion.
 

15. (a) Write some activities of ICIMOD. [3]

Answer

 ICIMOD stands for International Centre for Integrated Mountain Development. Some of the activities of ICIMOD are as follows:
i.    Provide training facilities to improve the skills and the technical knowledge of farmers.
ii.   Conduct research for applied/practical conservation.
iii.  Investigate the impact of climate change on biodiversity and livelihoods.
iv.  Manage biodiversity as a resource of income for local communities as well as a heritage for society. 
 

(b) Write short note on 
i.    Genetic diversity
ii.   Proper use of resources
  [2]

Answer

i.    Genetic diversity: 
Genetic diversity is the variation in the hereditary unit that transfers parental characteristics to their offspring. It depends on the population of the organism.

ii.    Proper use of resources : 
The need to increase efficiency and productivity while preserving natural resources, especially water and soil, is great. In light of these realities, growers are under pressure to produce more, pollute less, fulfill consumer preferences, and make a living.