Malayalam👈

Basic Science (Part I) Questions and Answers

Chapter 1: Towards A Hundredfold Yield

1. Identify the statement which does not suit organic fertilizers.

   • Answer: c. Destroy soil structure. (Excess use of chemical fertilizers destroys soil structure, whereas organic fertilizers are not harmful to soil).

2. Match the following:

   • Answer:
     • a. Apiculture - Rearing of honey bees.
     • b. Cuniculture - Rearing of rabbits.
     • c. Sericulture - Rearing of silkworm.
     • d. Pisciculture - Rearing of fish.

3. You have learned about layering.

   • a. Identify the type of layering shown in the figure.
     • Answer: Serpentine Layering.
   • b. While layering in this way, at which position should we cut the plant, A, B or C?
     • Answer: C (To separate the rooted plantlet from the mother plant).

4. Look at the picture (Grafting setup).

   • a. Identify stock and scion from A and B.
     • Answer: A is the Root stock (the plant with roots); B is the Scion (the stem which is joined to the root stock).
   • b. What is the advantage of attaching the stem of Malgoa to the local variety of mango tree?
     • Answer: The sapling will grow well in local soil (from the local variety root stock).
     • It will yield mangoes of the superior Malgoa variety (from the Malgoa scion).
   • c. Is there any merit in attaching the stem of a local variety of mango tree to the same variety?
     • Answer: Yes. This helps in early flowering and fruiting because the stem used as scion is of the same age as the mature mother plant.

5. List different methods of pest control. Give examples for each type.

   • Answer:
     1. Biological Control: Using natural agents that feed on pests.
        • Examples: Lady bug, Trichogramma, Frog, Mabuya, Calotes, Bug.
     2. Mechanical Control: Controlling pests manually or using traps.
        • Examples: Pheromone trap, destroying flies attracted by crushed basil leaves.
     3. Pesticides: Using substances (chemical or organic) to kill pests.
        • Examples (Organic): Tobacco decoction, neem oil emulsion, garlic-kanthari (Chilli) mixture.

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Chapter 2: Acids and Bases

1. Which among the following can be used as an indicator of acid?

   • Answer: c. Red litmus paper (Though acids turn blue litmus red, red litmus paper is generally used as part of the litmus test).

2. Which acid is used in automobile batteries?

   • Answer: c. Sulphuric acid.

3. Among the liquids in the three beakers placed on the table, the first one is water, the second is an acid and the third is a base. Is it right to identify them by touching, tasting or smelling? Why? Suggest a method to identify each of them.

   • Answer:
     • Identification Method: It is not right to identify them by touching, tasting, or smelling.
     • Reason: Strong acids and bases are dangerous. Strong acids can absorb water, liberate heat, and cause severe burns if spilled.
     • Suggested Method (Using Litmus/Indicators):
       1. Use Blue Litmus paper: The liquid that turns blue litmus red is the Acid.
       2. Use Red Litmus paper: The liquid that turns red litmus blue is the Base.
       3. The liquid that causes no change in either litmus paper is Water.

4. In the laboratory metalic caps are not used for glass bottles containing acids. Explain the reason for this.

   • Answer:
     • Acids react with metals.
     • This reaction produces hydrogen gas.
     • The reaction would damage the metal cap and could potentially lead to the release of flammable hydrogen gas.

5. Examine the statements given below. Classify them on the basis of properties of acids and bases.

   • Answer:
     • Properties of Acids:
       • a. Has sour taste.
       • d. Turns to pink when methyl orange is added.
       • g. Reacts with metals to produce hydrogen.
     • Properties of Bases:
       • b. Turns to pink when phenolphthalein is added.
       • c. Slippery.
       • e. Turns the colour of Pathimugam water into yellow.
       • f. Red litmus turns blue.
       • h. Has alkaline taste.

6. You have learnt about various indicators to identify acids and bases. Complete the table below.

   • Answer:
     • Indicators of Acids: Natural: Paper rubbed with Hibiscus flower; Used in lab: Methyl Orange.
     • Indicators of Bases: Natural: Turmeric; Used in lab: Phenolphthalein.

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Chapter 3: The World of Electricity

1. What is the energy change in a battery when it is connected to an emergency lamp?

   • Answer: c. Chemical energy changes first into electrical energy and then into light energy.

2. Of the following, which is in an open circuit?

   • Answer: b) A damaged bell is switched on. (An open circuit is incomplete, so the device cannot work).

3. From where do the artificial satellites get electricity for its working?

   • Answer: a) Solar panel. (Solar cells/panels convert solar energy into electrical energy).

4. Sometimes there is power shortage in Kerala during summer season. Why?

   • Answer: Power is largely generated by hydroelectric power stations. Power shortage occurs because the water stored in reservoirs may be insufficient to operate the generators/turbines, particularly during the summer season.

5. A person is standing in water. An electric line breaks and falls into the water. Is the person likely to get an electric shock? Give reason.

   • Answer:
     • Likely to get a shock: Yes.
     • Reason: Water is an electric conductor. The human body is also an electric conductor. The current passes through the water and through the person, causing an electric shock.

6. Observe the diagram of an open circuit. Convert it to a closed circuit using appropriate symbols and draw it.

   • Answer (Conceptual): The drawing must show the circuit components (Battery, Bulb, Wire) connected in a continuous loop using the correct symbols. A closed circuit is complete, allowing electricity to flow and the device to work.

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Chapter 4: When Light Reflects

1. Examine the following table and find the odd one out.

   • Note: Since the table structure is not provided in the assessment, the answer highlights the necessary classifications of the listed materials.
     • Transparent Objects: Clear water, Air.
     • Translucent Objects: Box filled with smoke, Screen guard of a mobile phone, Turbid water, Fog.
     • Opaque Objects: Soil, Tiles, Stone, Mirror, Hardboard.

2. Observe the pictures. Which type of reflections do you see here? Explain both views based on the reflection of light.

   • Answer:
     • Regular Reflection: Occurs when light falls on smooth surfaces (e.g., a still mirror or water) and reflects with regularity.
     • Diffused Reflection (Irregular Reflection): Occurs when light falls on rough surfaces (e.g., sandpaper or rough wall) and gets scattered in different directions.

3. Observe the following situations. Find out which type of reflection takes place in each.

   • Answer:
     • Ornaments shine: Regular Reflection.
     • We get light inside the home during day time: Diffused Reflection.
     • A polished furniture shines: Regular Reflection.
     • See reflection of trees on stagnant water: Regular Reflection.

4. (Based on the setup showing incident/reflected rays):

   • Answer: Based on the Law of Reflection (Angle of incidence = Angle of reflection):
     • Light from Child A will be reflected towards Child D.
     • Light from Child D will be reflected towards Child A.
     • Light from Child B will be reflected towards Child C, and vice versa.
     • If the torch is lighted from X (the Normal), the reflected light will fall back towards X (since the angle of incidence is zero, the angle of reflection is also zero).

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Chapter 5: Human Body: A Wonder (Digestion and Respiration)

1. Which of the following combination is correct?

   • Answer: c. Man, Hen, Monkey, Peacock (Omnivores).

2. In which of the following organ digestion is completed?

   • Answer: b. Small intestine.

3. What are the precautionary steps to be taken to prevent tooth decay?

   • Answer:
     1. Brush teeth in the morning before breakfast and at night after dinner.
     2. Always clean the mouth whenever something is eaten.
     3. Clean the mouth well, especially after consuming sweets.
     4. Prevent food particles from getting stuck between teeth, which leads to lactic acid production and enamel damage.

4. Compare the dentition of a six year old child and that of an adult.

   • Answer:
     • Child (Six years old): Has Milk Teeth (temporary teeth). Total number is 20 (ten in each jaw).
     • Adult: Has Permanent Teeth. Total number is 32 (including Incisors, Canines, Premolars, and Molars). Permanent teeth do not regrow if broken or lost.

5. A person is lying down and eating food. Do you think the food will reach the stomach? Why?

   • Answer:
     • Yes, the food will reach the stomach.
     • Reason: Food is moved through the oesophagus by Peristalsis. This is a wave-like movement of the muscular wall that pushes food down to the stomach, independent of gravity or body position.

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Chapter 6: Heat in Everyday Life

1. Consider some situations in everyday life.

   • a. Which property of matter with respect to heat is evident in the above two cases (electric wires sagging, PVC pipes being joined by heating)?
     • Answer: Thermal Expansion of Solids. (Solids expand when heated and contract on cooling).
   • b. Based on this, can you explain why a fully inflated balloon bursts when exposed to sunlight?
     • Answer: Gases expand on heating. The air inside the balloon expands when exposed to sunlight, increasing pressure until the balloon bursts.

2. Observe the arrangement of an experiment shown in the picture (Injection bottle with water in hot water bath).

   • a. What do you observe?
     • Answer: The water level in the attached refill tube rises.
   • b. What inference can be drawn from this?
     • Answer: Liquids expand on heating.

3. Classify and tabulate the following materials on the basis of thermal conductivity.

   • Materials: Iron, Paper, Bakelite, Copper, Wood, Steel, Aluminium, Cloth.
   • Answer:
     • Good Conductors (Allow heat to pass well): Iron, Copper, Steel, Aluminium.
     • Poor Conductors (Do not allow heat to pass well): Paper, Bakelite, Wood, Cloth.

4. What is the difference between the materials used to make the utensil and its handles? Explain this on the basis of thermal conductivity.

   • Answer:
     • Utensil Body: Made of Good Conductors (e.g., metals).
     • Handles: Made of Poor Conductors (e.g., wood).
     • Explanation: Good conductors are used for the main body to allow heat transmission for cooking. Poor conductors are used for handles to prevent heat from transferring to the hands via conduction.

5. Hot tea of same quantity is kept in an open steel tumbler and in a closed glass tumbler of same size. Tea in which tumbler stays hot longer? Explain your finding on the basis of heat transmission.

   • Answer:
     • The tea in the closed glass tumbler stays hot longer.
     • Explanation: Keeping the glass tumbler closed reduces heat loss through convection (air movement). Furthermore, the glass material may minimize heat loss through conduction compared to steel.

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Chapter 7: Human Body- A Wonder (Circulation, Excretion and Nervous Co-ordination)

1. Which among the following organs does not perform the function of excretion?

   • Answer: c. Heart. (Kidneys, Liver, and Lungs all play a role in excretion).

2. Which of the following statements is correct?

   • Answer: a. Pulse rate increases while running.

3. What should be done to prevent urinary infections?

   • Answer:
     1. Ensure adequate intake of water.
     2. Urinate regularly.
     3. Avoid delaying urination for a long time to prevent pathogen multiplication in the bladder and urethra.

4. What are the physical discomforts that may occur during menstruation?

   • Answer:
     1. Severe abdominal pain.
     2. Vomiting.
     3. Back pain and leg cramps.
     4. Excessive anger and anxiety.

5. The most important organ in the human body is the brain. Substantiate.

   • Answer:
     1. The brain controls movements and coordinates all activities of the body.
     2. It gives instructions to the cells.
     3. It is the centre of vision, hearing, memory, intelligence, imagination, and emotions.
     4. It is protected inside the skull.

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Chapter 8: Wonders of Sky

1. Observe the picture (Moon's orbit around Earth). Check the orbital path of the Moon around the Earth and complete the table below.

   • Answer:
     • The starting position of the lunar eclipse: When the Moon enters the Earth’s shadow.
     • The position of complete lunar eclipse: When the Moon enters completely in the Earth’s shadow.
     • The position where the lunar eclipse ends: When the Moon comes out of the Earth’s shadow.

2. Observe the picture and complete the table by matching the boxes appropriately.

   • Answer:
     • When the Moon reaches the position D: Half Moon.
     • When the Moon reaches the position E: Full Moon.
     • When the Moon reaches the position F: New Moon.

3. Some statements are given below. Tick () the correct ones.

   • Answer:
     • A Full Moon is the day when the part of the Moon on which the sunlight falls, is completely visible from the Earth. (✓)
     • Solar eclipse occurs only on New Moon day. (✓)
     • Lunar eclipse occurs only on Full Moon day. (✓)

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Chapter 9: Hurt not the Environment

1. Observe the diagrams given below. Find out how the air is gets polluted in each situation and complete the table.

   • Answer (Based on Pollution Causes):
     • Situation (Burning Waste/Plastic): Releases chemical substances like Carbon monoxide, Dioxins, Sulphur dioxide, Nitrogen dioxide, and Particulate matter.
     • Consequences: Causes cardiovascular and respiratory diseases, lung cancer, headache, fatigue, and memory loss.
     • Situation (Automobiles): Releases Sulphur dioxide, Nitrogen dioxide, Carbon monoxide, and particulate matters.
     • Consequences: Causes air pollution by mixing with atmospheric air.

2. Prepare posters calling for the prevention of environmental pollution.

   • (Activity requiring poster creation. Measures include the 3 R's, Smoke Testing, and using Electric Vehicles).

3. Identify the correct statements regarding plastic waste management from those given below.

   • Answer:
     • b) Plastic products should be recycled as much as possible. (✓)
     • c) Plastic products should be reused as much as possible. (✓)
     • d) Use of plastic products should be minimised (Reduce). (✓)

4. Which method of purification can be adopted to separate freshwater from seawater?

   • Answer: c) Distillation. (Distillation removes dissolved components).

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Chapter 10: Safe Food

1. Which adulterant can probably be added to pepper?

   • Answer: c. Papaya seed. (Adulteration involves adding similar, cheap, and poor quality substances).

2. Can the ice cubes used in fish markets be used to prepare cool drinks? Why?

   • Answer: No.
   • Reason: A chemical substance called Ammonium Chloride is often added to the ice to prevent melting. Ammonium Chloride is harmful to our body.

3. What are the things to be taken care of while you purchase fruits from shops?

   • Answer (Selecting Fruits):
     1. The outer skin should be undamaged.
     2. Ensure the marketplace is hygienic.
     3. Check that the vendors maintain hygiene (e.g., wear gloves and masks).

4. Milk, tomato, fish, cucumber, lady’s finger and meat are to be kept in the refrigerator. Out of these:

   • u Which are to be kept in freezer?
     • Answer: Fish and Meat.
   • u Which are to be stored in compartments other than the freezer?
     • Answer: Milk, Tomato, Cucumber, and Lady’s finger.