NOTES/SOLVED EXERCISES: GENERAL SCIENCE 5 PCTB LAHORE PAKISTAN (2016-17)

NOTES/SOLVED EXERCISES: GENERAL SCIENCE CLASS 5 PTB LAH PAK 2015-16

 

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CLASSIFICATION OF LIVING THINGS ….

MICROORGANISMS …………………….

 SEEDS: STRUCTURE AND GERMINATION

ENVIRONMENTAL POLLUTION ………….

 MATTER & CHANGES IN ITS STATES

FORCES & MACHINES ……………..

PROPERTIES AND BEHAVIOUR OI LIGHT

 ELECTRICITY AND MAGNETISM ……….

SOILS …………………………………….

SOLAR SYSTEM …………………………

 

 Unit: 01 CLASSIFICATION OF LIVING THINGS Page:

Exercise

ANSWER THE QUESTIONS.

  1. Define classification. Why do we need to classify living things?

ANSWER. Classification means to separate or sort out organisms on the basis of similarities and differences present in them.                                                                  Scientists classify organisms in order to study them easily. They also give scientific names to the organisms to identify them.

  1. What are the main kingdoms into which living things can be divided?

ANSWER. The living things are classified into five major groups. They are:

(i) Bacteria  (ii) Algae (iii) Fungi (iv) Animals (v) Plants

  1. 3. You see some organisms with thread-like bodies. They live at damp places and use dead materials as food. What we are talking about?

ANSWER. The organisms with thread like bodies and living at damp places and eating dead materials are fungi.

  1. What is the difference between vertebrates and invertebrates?

ANSWER. Following table shows differences between invertebrates and vertebrates.

INVERTEBRATES VERTEBRATES
(i) They do not

(ii) They do not have bony skeleton for support.

(iii) They have small body size.

(iv) They usually move slowly.

(i) They have backbone.

(ii) They have bony

Bony skeleton for support.

(iii) They have relatively large body size.

(iv) They are active and move efficiently.

 

  1. Write the characteristics of the main groups of vertebrates.

ANSWER.

(i) FISHES:                                                                                                                                  i-  Fishes have fins.                                                                                                                       Ii- They are all aquatic animals.                                                                                                      Iii- Their bodies are mostly covered with scales.                                                                  Iv- They have no legs.                                                                                                                     V- All fishes breathe through gills.                                                                                          Vi- They swim in water with the help of fins on their bodies.                                      EXAMPLES: trout, finger fish, etc.

 (II) AMPHIBIANS:

  1. Amphibians are the second group of vertebrates.
  2. They live on land, but reproduce in water.
  3. They lay eggs in water.
  4. Each egg hatches to produce larva.
  5. Larva grows to adult which comes on land to live. EXAMPLES: toads, frogs, salamanders, etc.

(iii) REPTILES:

  1. Reptiles make the third group of vertebrates.
  2. They have tough scales all over their bodies.
  3. They may live on land or in water.
  4. They use lungs for breathing.
  5. They lay eggs on land. Their eggs are enclosed in hard shells.
  6. They crawl on land with the help of four

EXAMPLES: Crocodiles, turtles, snakes lizards, etc.

(iv) BIRDS

  1. Birds make fourth group of vertebrates.
  2. All birds have feathers on their skin.
  3. A bird has two legs and two wings.
  4. Birds can fly with the help of feathers and wings.
  5. Birds have hollow bones which are light in weight. lt also help them in flight.
  6. Birds have lungs for breathing.
  7. Birds have no teeth but they have; beaks to get food.
  8. Birds lay eggs and their eggs are covered with hard shells.
  9. Some birds have weak wings and they cannot fly. They are ostrich, penguin, etc.

Examples: pigeon eagle, sparrow etc.

(v) MAMMALS:

  1. This is the most advanced group of vertebrates.
  2. Mammals have hair on their body.
  3. They do not lay eggs but give birth to young ones.
  4. They feed their babies on mother’s milk.
  5. They use lungs for breathing. ‘
  6. Most mammals live on land but some live in water.                                               Examples: Land mammals human being, cow, elephant cat, etc. water, mammals whales, dolphins, etc.
  7. What two characters will help you to identify a bird?

ANSWER. BIRDS                                                                                                                               All birds have feathers on their skin.                                                                                                      A bird has two legs and two wings.                                                                                          Birds can fly with the help of feathers and wings.

  1. Seed contains the embryo of plant. The embryo grows to make new plant. From where embryo gets food in dicot and monocot seeds?

ANSWER. Embryo is the most important part in a  seed. It grows into a new plant. For its growth, embryo needs food. In monocot seeds, food is stored in the form of endosperm. During its growth embryo uses this stored food. While in dicots, food is stored in two cotyledons which is used by embryo during its growth.

  1. All of the following statements are false. Correct the statements.

ANSWER.

(i) An animal has feathers on its skin and lives in water.

ANSWER. A bird has feathers on its skin and lives on land.

(ii) All fishes have fins which help them to breather in water.

ANSWER. All fishes have fins which help them to swim in water.

(iii) The scales on the skin of amphibians help them in dry season.

ANSWER. The moist skin of amphibians help them in dry season.

(iv) All mammals have backbones while fishes, amphibians, reptiles and birds do not have.

ANSWER. All mammals have backbones like fishes, amphibians, reptiles and birds.

CHOOSE THE ANSWERS.

Bacteria are unicellular. Their cells do not have:

  1. a) cell membrane b) nuclei c) cell wall d) chromosome

All the animals given below are invertebrates except:

  1. a) snail b) leech snake d) mosquito

lf you can open the seed of mango, how many cotyledons you will find?

  1. a) 1 b)2 c) 3 or multiple of 3 d) 4 or multiple of4

Whale appears fish-like but is not grouped in fishes, because:

  1. a) it feeds its young ones on milk b) it can crawl on land c) it has feathers on its skin d) it has scales on skin

What is true about all invertebrates?

  1. a) have wings b)do not have backbone c) have jointed legs  d) have cylinder-like bodies
  2. vi) Find the correct statement about all the groups of invertebrates.
  3. a) worms are invertebrates but insects are vertebrates
  4. b) insects have jointed legs but worms do not have
  5. c) worms can fly but insects cannot
  6. d) insects are invertebrates but worms are vertebrates

Answer: (i-b)(ii-c)(iii-b)(iv-a)(v-b)(vi-b)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

U: 02 MICROORGANISMS P:

EXERCISE:

ANSWER THE QUESTIONS.

  1. What are microorganisms? Can you see them? ‘How?

ANSWER. The group of extremely small organisms which cannot be seen and observed with naked eye, are known as Microorganisms.                                                                          Their body consists of only a single cell.                                                                 Microorganisms can be seen only with the help of a micro-scope                               EXAMPLES: Bacteria, virus, some fungi.

  1. How a virus is different from all other living things?

ANSWER. Viruses are different from all other organisms in the following ways; i

(i) Their body is not made of cell.                                                                                                   (ii) A virus can survive in the outer environment but in order to reproduce,  it has to enter in the body of a living thing.                                                                                           (iii) it is always harmful and cause diseases in other organisms.

  1. Viruses are always harmful for our health. Give examples.

ANSWER. Viruses are always harmful for our health as they cause various diseases inhuman beings.

EXAMPLES:

(i) Common cold in human beings is caused by a virus.

(ii) Hepatitis which is a fatal disease, is caused by a virus.

(iii) Polio, which can make a person disabled for whole life is also caused by

a virus.

  1. Many bacteria are useful for us. Give examples.

ANSWER. Bacteria are not always harmful.

Some bacteria are useful such as:

(i) Decomposer bacteria break down the dead materials and make them the part of soil. In this way we get rid of garbage and dirt.

(ii) Some bacteria are present in our digestive system which help in digestion of food.

(iii)Some bacteria are helpful in the preparation of yogurt, cheese and other  dairy products.

(iv) Bacteria are also used to make antibiotics and vaccines.

  1. What is germ? How can you protect yourself from germs? ’

ANSWER. Disease causing microorganisms are called germs. They can enter our bodies through mouth, nose or wounded‘ skin. Germs include some bacteria, some fungi and all viruses

Protection against germs:

We can protect ourselves against germs by taking some precautionary measures.

(i) We should boil water before drinking as tap water always contains germs.

(ii) Houseflies and mosquitoes carry germs from one person to another. Kill them  and stop their breeding possibly.

(iii) Always wash your hands before eating.

(iv) Make the environment clean and tidy.

(v) Wash your hands before handling raw fish, meat or use gloves.

  1. If you keep a piece of bread in open space, it gets mouldy. why? B

Answer. When we keep a piece of bread in open place, it becomes mouldy because the spores of fungi are always in air. These spores fall on the bread and grow there. ln this way the piece of bread becomes mouldy.

  1. What do you mean by infection?

ANSWER. When germs enter in our body, they attack the cells of different parts of body. Here, they reproduce and increase their number. ln this way cells are destroyed. lt results in disease. This condition is called infection.

  1. Why you should wash your hands after using the toilet?

ANSWER. After using toilet, our hands may have germs. lt is necessary to wash our hands so that these germs are not transmitted to ourselves or to other people.                                                                                                                                                                                    Below is a list of different complaints. For each complaint put a tick if it is caused by microorganism or put a cross if it is not caused by a microorganism.

ANSWER. Flu / Bleeding in gumsX Bruise in skin X Bone fracture X

Pneumonia / Nose bleeding)/ Headache X Athlete’s foot /

Observe the following chart and enlist the ways by which an infection is transmitted from one person to another.

ANSWER. List of ways by which an infection is transmitted from one person to another:

(i) By using common tooth brush, shaving blades etc.

(ii) Through blood donation

(iii) By reusing injection syringe

(iv) Through surgical instruments

(v) Through cough, sneeze or body fluid of infected persons

(vi) Through water, air or food

CHOOSE THE ANSWERS.

  1. i) All of these are microorganisms, except:
  2. a) bacteria b) viruses c) yeasts mushrooms
  3. ii) Which type of bacteria can cause infections in humans?

a)decomposer becteria b)bacteria which can prepare their food c)bacteria that depend on living things d)bacteria normally present in our body

iii) Which microorganisms we use to prepare yoghurt?

  1. a) bacteria b) viruses c) yeasts d) mushrooms
  2. iv) Which microorganisms act as decomposers of dead material?
  3. a) bacteria and viruses b) fungi and viruses bacteria and fungi d) fungi only
  4. v) The infection pneumonia may be caused by:
  5. a) a bacterium b) a virus c) a fungus all of these

Answer: (i-d)(ii-d)(iii-a)(iv-c)(v-d)

 

 

 

 

 

 

 

 

 

 

 

 

U:03 SEEDS: STRUCTURE AND GERMINATION P:

EXERCISE:

ANSWER THE QUESTIONS:

  1. YOU SEE A SMALL PLANT GROWS INTO A TREE. CAN YOU CALL IT GERMINATION? IF NOT, WHAT IS GERMINATION?

ANSWER: We see a small plant growing into tree. This process is not called germination, rather, it is called growth.                                                               GERMINATION: The growth of a new tiny plant from the embryo in the seed is called germination.

2 WHAT IS COTYLEDON‘? WRITE ITS FUNCTION.

ANSWER: Cotyledon is a part of embryo which is present inside a seed. Monocot seeds have one cotyledon while dicot seeds have two cotyledons.                           FUNCTION: In monocots cotyledons does not store food. Food is stored in endosperm. Cotyledon takes food from endosperm and provides it to embryo. in dicots, there are two cotyledons which store food for embryo.

  1. WHAT IS THE DIFFERENCE BETWEEN A MONOCOT AND DICOT SEED? DRAW DIAGRAMS TO SUPPORT YOUR ANSWER.

ANSWER:                                                                                                                                                => Monocot seeds have only one cotyledon. This single cotyledon does not store food. Food is stored in Endosperm.                                                                                =>Dicot seeds have two cotyledons which store food for embryo.                                                                                                =>In Monocots, after germination cotyledon does not come out but remains under the soil.                                                                                                                                                    => in dicots, during germination, both the cotyledons come out with plumule.

  1. DRAW DIFFERENT STAGES OF SEED GERMINATION.
  2. WHAT IS THE FUNCTION OF MICROPYLE?

ANSWER:  Micropyle is a small hole young seed coat. Through micropyle; water enters into seed and helps in the germination of seed.

  1. WHAT IS THE FUNCTION OF SEED COAT?

ANSWER: Seed coat is a tough and hard covering over seed. lt protects embryo and stored food so that -seed can be safe till it germinates.

  1. LABEL THE PARTS OF FOLLOWING SEEDS. ALSO WRITE THE NAMES OF SEEDS.

ANSWER:

CHOOSE THE ANSWERS.

  1. i) The process by which seed grows into a new plant is called:
  2. a) germination b) photosynthesis c) respiration d) circulation
  3. ii) The root of a new plant grows from:
  4. a) plumule b) cotyledon c) radicle d) micropyle

iii) A dicot seed has two cotyledons which;

  1. a) prepare food b) digest food c) store food          d) require sfood
  2. iv) Embryo of a plants present in the:
  3. a) seed b) flower) c) shoot  d) root
  4. v) What is false about the roles of the parts of plant seeds?
  5. a) radicle forms the first root b) cotyledons form the leaves of the plant.
  6. c) plumule forms the shoot d) seed coat protects the embryo

Answer: (i-a)(ii-c)(iii-c)(iv-a)(v-b)

 

U:04 ENVIRONMENTAL POLLUTION P:

EXERCISE:

ANSWER THE QUESTIONS:

1- WHAT IS POLLUTION?

ANSWER: The addition of unwanted and harmful materials in the environment is ‘called “pollution.”

2- ENLIST THE CAUSES OF AIR, WATER AND LAND POLLUTION.

ANSWER:

(1) CAUSES OF AIR POLLUTION:

Air pollution is caused by the following factors:                                                                      (i) The smoke from vehicles and factories is full of harmful gases which cause air         pollution.                                                                                                                                      (ii)Dust added in air by different human activities is also a cause of air pollution.              (iii)Volcanoes are another cause of air pollution.                                                              (2)WATER POLLUTION                                                                                                                                                    Water pollution takes place in the following ways.                                                                      (i)When water canals pass through the agricultural areas, fertilizers and pesticides mix with water.                                                                                                                    (ii)When water goes underground and passes through the housing colonies,               untreated sewage mixes in it. Water becomes polluted.                                                    (iii)Waste materials of factories are also thrown into the rivers and streams and                    also waste water from industry and homes mixes with rivers and streams                         which make the water polluted.                                                                                                     (3) CAUSES OF LAND POLLUTION:                                                                                                     Land pollution takes place as under:                                                                                              – When people dump home and factory wastes in soil, then land pollution takes 1 A place.                                                                                                                                                – When the people also dump sewage in soil, and plastic bags are not properly disposed of and are thrown here, and there land is polluted.                                                                                                        – Over-use of pesticides and other chronicles also cause land pollution.

  1. WHY TRAFFIC SMOKE IS HARMFUL TO YOUR ENVIRONMENT?

ANSWER:                                                                                                                                                  – Traffic smoke contains harm gases.                                                                                                   – These gases pollute the environment                                                                                              – Lungs, eyes and skin diseases are; caused by the traffic smoke.                                                   – Traffic smoke also causes acid rains.                                                                                                  so, Traffic smoke is harmful to environment

  1. PLANTS ARE USEFUL TO PROTECT OUR ENVIRONMENT. JUSTIFY THIS STATEMENT.

ANSWER: Plants are useful to protect our environment in the following ways.                   (i) Plants add oxygen into environment for 5 the respiration of all animals.                           (ii) Plants use carbon dioxide in their food making process. Thus help to reduce pollution.                                                                                                                                            (iii) Plants add water vapours into the environment and decrease temperature of atmosphere.

(iv) Plants are producers. They directly or in directly provide food to all living things. so, plants are useful to protect our environment.

  1. HOW WATER CANAL IS POLLUTED WHEN IT PASSES THROUGH AGRICULTURAL LAND?

ANSWER: When water canals pass through agricultural areas, pesticides and; fertilizers are added in the canal water.

ln this way, the water is polluted.

  1. Write the kinds of pollution caused by industries.

ANSWER: lndustries mostly cause all the three  types of pollution Le. air pollution. land pollution and water pollution.

  1. DIFFERENTIATE BETWEEN BIO-DEGRADABLE AND NON-BIODEGRADABLE MATERIALS?

ANSWER: BIODEGRADABLE MATERIALS:                                                                                                The material rots which is decomposed by micro-organisms i.e fungi and cloth  animal bacteria and dung. Such process breaks into simpler compounds is called biodegradable material.                                                                                                            Example: Food items, paper.

NON-BIODEGRADABLE MATERIALS:

The material which cannot be broken down into simpler compounds by micro-organisms is called non-biodegradable materials.                                                                                        Example: Shopping bags, plastics etc.

  1. WHAT IS THE IMPACT OF NON-BIODEGRADABLE MATERIALS ON ENVIRONMENT?

ANSWER:– The chemicals used in insect-killers sprays are non-biodegradable. They can cause harmful and dangerous diseases.                                                                   Plastic bags are a major cause of land pollution.                                                                                   Non-degradable materials make huge piles on ground and occupy a lot of space.            When non-biodegradable materials stored underground, they block the growth of plant roots.                                                                                                                                                At high temperatures, plastic begins to melt. When it happens plastic releases dangerous gases in the air.                                                                                                  Plastic wastes are thrown in the ocean, where they are responsible for the deaths of fish and other animals.                                                                                                         Land animals also swallow such materials and it results in their death.

CHOOSE THE ANSWERS.

(i) Which is the cause of pollution?

a)burning fuels in vehicles and industry b)mixing of untreated sewage in under ground water and rivers c)over-use of non-biodegradable materials (iv)all of these

  1. ii) Which is the main reason of acid rain?

air pollution b) land pollution c) water pollution d) all of these

iii) Which is non-biodegradable?

  1. a) paper b) bread c) cloth glass
  2. iv) A disease caused by polluted water is:
  3. a) polio b) small pox (c ) cholera d) athlete’s foot
  4. v) What is a proper way to dispose of used tyres?
  5. a) burn them openly b) dig soil and bury them c) recycle them to make new rubber d) collect them and make a big pile
  6. vi) Which is a way to reduce pollution?
  7. a) drive less and walk more b) recycle the non-biodegradable materials c) treat sewage before releasing it into rivers d)  all of these

Answer: (i-d)(ii-a)(iii-d)(iv-c)(v-c)(vi-d)

 

 

 

 

U:05 MATTER & CHANGES IN ITS STATES P:

EXERCISE:

ANSWER THE QUESTIONS:

1- WRITE THE STATES OF MATTER IN THE FOLLOWING CHART:

Matter

Fixed Shape  -No fixed shape

occupies definite space  -Does not occupy definite space

ANSWER:

SOLID – LIQUID – GAS

  1. WHY IS IT EASY TO POUR A LIQUID?

ANSWER: lt is easy to pour a liquid from one                                                                              (i) container to another for two reasons:                                                                          Particles of liquids are attracted to each Other with a relative weak force. They                   neither stop each other nor break away. So form a continuous pattern while pouring.                                                                                                                                           (ii) These particles are not closely packed.                                                                           They are at some distance from one another.                                                                       These two factors make the pouring of liquids easy.

  1. WHY IS IT DIFFICULT TO COMPRESS ANY SOLID?

ANSWER: There is almost no space between the particles of solids so they cannot come any closer to one another. That is why, solids cannot be compressed.

  1. EXPLAIN WHY A GAS CAN BE COMPRESSED.

ANSWER:                                                                                                                                                      A gas can be compressed for the following reasons:                                                            (i) Gas particles are very far away from each other.                                                              (ii) They have enough space, between them.                                                                     (iii)They attract each other with weak forces so, the gases can be compressed easily.

  1. DEFINE MELTING, BOILING AND FREEZING?

ANSWER:                                                                                                                                           (i) Melting: The process of changing a solid into a liquid on heating is called “Melting”.                                                                                                                             (ii) Boiling: The process of changing a liquid into vapour state on heating is called “Boiling.”                                                                                                                                   (iii)Freezing: On continuous cooling, a liquid changes to solid state. This process is called “Freezing.”

  1. WHICH PROCESS IS OPPOSITE TO FREEZING?

ANSWER:                                                                                                                                        The process of melting is opposite to freezing.                                                                      In melting, solid changes to liquid. While in freezing liquid changes to solid.

  1. HOW ARE CLOUDS FORMED?

ANSWER:                                                                                                                                        Clouds are formed in the following way:                                                                        Water from water bodies evaporates due to the heat of sun                                               The water vapours rise up and go on height                                                                                    On height, due to low temperature, the process of condensation starts.                               Water vapours due to condensation change into water droplets.                                These water droplets form clouds.

  1. WRITE DOWN THE STEPS INVOLVED IN WATER CYCLE.

ANSWER: Following are the -main steps in water cycle.                                                   Water evaporates from water bodies due the heat of sun.                                          Vapours rise up, become cool and process of condensation starts.

  1. WHAT IS THE DIFFERENCE BETWEEN DEW AND RAIN?

ANSWER:                                                                                                                                         (i) Dew: In the morning and at night. water vapours condense to form small droplets of water. These droplets come down in the form of dew.                        Rain.                                                                                                                                                      ln case of rain, water vapours condense to form bigger drops which fall in the form of rain.

CHOOSE THE ANSWERS.

i-What is correct about the particles in milk?

  1. a) they are arranged in a regular manner b) they only vibrate about their fixed positions c) they are for apart from one another they are free to move but they move to short distances

ii-In a state of matter, the particles are moving around each other. Then they become regularly arranged and vibrate in fixed position. What this process is called?

  1. a) boiling b) W freezing c) evaporation d) melting

iii-One of the following substances is not a solid.

(a) wood (b) iron mercury(d)gold

iv- Liquids do not have:

  1. a) fixed shape b) definite volume c) definite mass d) closely held particles

v- When you place an ice cube in a glass, it changes to water after few minutes. This change is called:

  1. a) boiling b) freezing c) evaporation d) melting

vi- Dew drops are formed from water vapours in the air by:

  1. a) evaporation (b)melting c)condensation (d)freezing

Answer: (i-d)(ii-b)(iii-c)(iv-a)(v-d)(vi-c)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

U:06 FORCES & MACHINES P:

EXERCISE

ANSWER THE QUESTIONS:

  1. What is gravitational force?

Compare gravitational forces of the Earth and the Moon.

ANSWER:                                                                                                                     GRAVITATIONAL FORCE:  The force with- which Earth attracts other objects towards its centre, is called Gravitational force.                                                                                             Gravitational force is present between all the objects of universe.                                                          EXAMPLE: Planets are moving around the Sun due to the gravitational force of the Sun.                                                                                                                                 Comparison of Gravitational Forces of the Earth and the Moon:                           Gravitational force of Earth is greater than the gravitational force of Moon because the earth is much bigger than the Moon.

  1. How would you define friction? Does it always give advantages? If no, give some examples.

ANSWER: Friction is a force between two surfaces that slows moving objects.                   lt acts when one object rubs against the other.                                                                 Friction always acts in opposite direction of movement of objects.                       ADVANTAGES OF FRICTION: Following are advantages of friction:                                   (i) Friction between feet or shoes and ground helps us to walk.                                (ii)Friction keeps the wheels of vehicle on road.                                                                 (iii) Friction between wheel disk and brakes help to stop vehicle.                                         (iv) Friction helps us to write on paper.                                                                                             DISADVANTAGES OF FRICTION: Following are disadvantages of friction.                                  (i) Friction wears down parts of machine.                                                                           (ii)Friction wears away surface of tyres and soles of shoes.                                                (iii) Machines and car engines become hotter due to friction.                                               (iv) Due to friction engines of vehicles and machines consume more fuel.                       (v) Noise is also produced in machines due to friction.

  1. If the bicycle mechanic tells you that the machinery of your bicycle is getting worn due to extra friction between gears, what methods would you use to reduce friction?

ANSWER: We will use a lubricant (oil, grease) sun: between the parts (gears) to reduce friction.

  1. What is meant by balanced and unbalanced forces? Give examples from your classroom observation.

ANSWER: The forces which are equal in size and opposite in direction are called balanced forces. The forces which are not equal in size or not opposite in direction are called unbalanced forces.

  1. What is inertia?

ANSWER: Every material object opposes the change in its state of motion or rest.  This property of matter is called inertia.

  1. Someone says: “Give me 500 grams salt”. What has been told? Weight of salt or mass?

ANSWER: When some body demands 500g of salt, he is talking about the mass of salt.

  1. Write four points to explain that mass and weight are two different things.

ANSWER:

=> Mass does not change at different locations of earth but in weight there is less gravitational force.                                                                                                                      => Units of mass is kilo-gram or gram while unit of weight is Newton(N).                                               => Mass is a quantity while weight is a force.

  1. What is a lever? What are different kinds of levers. Give examples.

ANSWER: Lever is a simple machine used to pull, push or lift heavy things. it is a bar which turns about a fixed point or line called fulcrum.                                                 Levers decrease the amount of effort needed to lift a load.

  1. How do wedge and inclined plane make our work easier? Give examples from your daily life.

ANSWER: Wedge and inclined planes make our work easy in the following way.                    (i) Inclined planes help us to lift heavy loads easily e.g. Loading unloading heavy objects in trucks.                                                                                                               (ii)Wedge helps as to cut or tear objects e.g. We can tear wood easily by using wedge.

  1. Write the kinds of levers for the following:

ANSWER:                                                                                                                                   First kind of lever – Second kind of lever –  3rd kind of lever

 FILL IN THE BLANKS.

  1. i) In the first kind of lever, fulcrum is between effort and load.
  2. ii) The larger the mass of an object, the more inertia it has.

iii) Levers turn about a fixed point or line called Fulcrum.

  1. iv) Friction can be reduced by oiling and lubricating moving parts of machines.
  2. v) There is always a force of attraction between two objects. This force is called Gravitational force.

Answer: (i-first)(ii-mass)(iii-fulcrum)(iv-oiling , lubricating)(v-gravitational force)

 CHOOSE THE ANSWERS.

  1. i) Weight is a force and is measured in:

Newtons b) kilograms c) metres d) litres

  1. ii) Where would you feel heaviest?
  2. a) the Earth b) the Moon c) ocean d) same everywhere

iii) Which of these is not a force?

  1. a) friction b) weight height d) gravity
  2. iv) How many kinds of levers are there?
  3. a) one b) two c) three d) five
  4. v) Which type of simple machine is shown in this diagram?
  5. a) lever b) inclined Plane c) wedge  d) pulley

Answer: (i-a)(ii-a)(iii-c)(iv-c)(v-b)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

U: 07 PROPERTIES & BEHAVIOUR OF LIGHT P:

EXERCISE

ANSWER THE QUESTIONS:

  1. Define and give examples of: (a) Luminous objects (b) Non-luminous objects(c) Opaque objects (d) Transparent objects (e) Translucent objects

Answer:                                                                                                                                              (A) LUMINOUS OBJECTS: The objects which give out light of their own are called “luminous objects”.                                                                                                          EXAMPLEES: The Sun, bulb, candle etc.                                                                                          (B) NON-LUMINOUS OBJECTS: The objects that do not give out light of their own are called non-luminous objects.                                                                                  EXAMPLEES: Moon, book, hand etc.                                                                                                   (C) OPAQUE OBJECTS: The objects that do not allow light to pass through them, are called opaque objects.                                                                                                                                   EXAMPLEES: Wood, cardboard, brick etc.                                                                                            (D) TRANSPARENT OBJECTS:  The objects that allow almost all light to pass through them, are called transparent objects.                                                            EXAMPLEES: Clear water, clear glass etc.                                                                                           (E) TRANSLUCENT OBJECTS: The objects that allow some light to pass through them are called translucent objects                                                                                     EXAMPLEES: Plastic cup, Tracing paper tissue paper etc.

  1. WHAT IS A PINHOLE CAMERA? GIVE ITS CONSTRUCTION AND WORKING.

ANSWER:                                                                                                                                    PINHOLE CAMERA:  It is a simplest camera.                                                                             lt consists of a box having a hole in the middle of one wall.                                               The inner side of opposite wall to pinhole acts as a screen.                                                    WORKING                                                                                                                                   Light from the object enters the camera through the pinhole.                                                                    i. lt goes to the screen where it forms an inverted and small image.                                             Ii. it The image has the same colour as the object.                                                                               Iii. Smaller is the pinhole, sharper will be the image.                                                                          lf the pinhole is large, many images will be formed on the screen instead of a sharp image and final image will be blurred.

  1. DESCRIBE THREE IMPORTANT PROPERTIES OF LIGHT.

ANSWER: Following are some properties of ‘light.                                                                       (i) Light travels in a straight line.                                                                                            (ii) Light forms shadows.                                                                                                                     (iii)When light coming from the Sun is blocked, eclipses are formed.

  1. WHAT ARE PHASES OF THE MOON? Explain them.

ANSWER: The Moon seems to be changing all the time. These changing shapes and sizes are called phases of the Moon.                                                                           There are 8 phases of the Moon, ranging from phase A1 to phase 8.                               PHASE 1: The Sun, the Moon and the Earth are in the same line. The sun light shines on one side of the Moon. The Earth is on the other side of it. The Moon looks very dark.                                                                                                                                                                                   PHASE 2: During this phase, a bright crescent is visible on the Moon.                           PHASE 3: During this phase, the Moon is half bright and half dark.                              PHASE 4: During this phase, most of the right side is bright.                                              PHASE 5: lt is also called full Moon. The sunlight shines the side of the Moon facing the Earth.                                                                                                                                   PHASE 6: The right edge appears dark. lt is opposite to phase 4.                                             PHASE 7: During this phase, the Moon looks as half Moon. The bright side is opposite where it was in phase 3.                                                                                           PHASE 8: Bright crescent is visible on the left of the Moon.

  1. RECALL YOUR PREVIOUS KNOWLEDGE ABOUT HOW PEOPLE USED TO MEASURE TIME BEFORE THE INVENTION OF CLOCKS. WHICH PROPERTY OF LIGHT THEY USED FOR MEASURING TIME?

ANSWER: Before the invention of clocks, people used to measure time by observing the shadows of objects and the position of the Sun in the sky. They used the fact that light travels in straight line.

  1. THE SUN GIVES US LIGHT DURING DAYTIMES. DOES THE SUN STOP PRODUCING LIGHT WHEN IT IS NIGHT WHERE WE ARE LIVING?

ANSWER: The Sun does not stop producing light at night but during its movement the part of the Earth, we are living on, is not in the position to receive sunlight.     So, it is dark in our part of Earth at night.

  1. THE MOON DOES NOT PRODUCE LIGHT. WHY DOES IT APPEAR BRIGHT?

ANSWER: The Moon is a non luminous object.  lt has no light of its own. It looks bright because it reflects the light of the Sun which falls on it.

FILL IN THE BLANKS.

  1. i) Light is a form of useful energy.
  2. ii) When an opaque object blocks light, shadow is formed.

(iii) When the Moon comes between the Sun and the Earth, it is called solar eclipse.

(iv) The objects which give out light of their own are called luminous objects.

(v) The objects which allow some light to pass through, are called translucent objects.

CHOOSE THE ANSWERS.

(i) Which of the following cannot be seen during a total solar eclipse?

the Sun (b)the Moon (c) the Earth (d)all of these

(ii) The luminous objects:

(a) do not allow light to pass (b) allow all light to pass (c) allow some light to pass d) produce their own light

(iii) Air is:

transparent (b)translucent (c) opaque (d)luminous

(iv) Light travels in:

(a) curved lines (b) perpendicular lines straight lines (d)scattered lines

(v) By looking the shadow of an object, we get information about its:

(a) shape (b) colour(c)weight(d) smell

Answer: (i-a)(ii-d)(iii-a)(iv-c)(v-a)

 

 

 

 

 

 

 

 

 

 

 

 

 

U: 08 ELECTRICITY & MAGNETISM P:

ANSWER THE QUESTIONS:

  1. Give two ways to increase strength of an electromagnet.

ANSWER: We can make an electromagnet strong by two ways.

(i) by increasing the current in the coil

(ii) by increasing the number of turns of wire in the coil

  1. Define electric current.

ANSWER: The flow of electrons in a circuit or through a wire is called electric current.

The electric current is measured in amperes (A).

  1. WHAT IS MAGNETIC COMPASS USED FOR?

ANSWER: A magnetic compass is a device which sailors use to find their way at sea. It shows the directions.                                                                                                                                WORKING: A magnetic compass have a magnetic needle. The needle spins freely but stays in North-South direction. Compass has a circular scale around the needle. On this scale, our directions are marked.

  1. WHAT IS AN ELECTROMAGNET? DESCRIBE AN EXPERIMENT TO MAKE IT.

ANSWER: lf we wrap a wire around an iron bar and run electric current through the wire, strong magnet can be created. Such a magnet is called an electromagnet.                                                                                                               EXPERIMENT:                                                                                                                                      – Take a copper wire and wrap it around a nail.                                                                                                                                                                 – Connect the ends of wires to battery.                                                                                              – Try picking up some pins using nail.                                                                                                                                             – Pins will stick to the nails as it has become an electromagnet.                                                                 -Now disconnect the battery. Pins will no more remain stick to nail.

  1. STATE FEW USES OF ELECTROMAGNETS?

ANSWER: The uses of electro-magnets are as under.                                                                                       (i) They are used in door bells.                                                                                                                                   (ii) They are used in earpieces of telephones.                                                                                    (iii) They are used in special cranes to lift heavy loads;                                                                    (iv) They are used in fans to rotate them.                                                                                         (v) They are used in electric motors.                                                                                                                                   

  1. Explain the phenomenon of lightning?

ANSWER: LIGHTNING: When oppositely charged clouds come close to each other, they attract with much force and a spark is produced. It is called as lightning.                                                              LIGHTNING STRIKES: When positive charge of the ground attracts, the negative charge from the clouds then it occurs a lightning strike.                                                                                                                     LIGHTENING PRODUCES HEAT: This heat causes the surrounding air to explode out ward with a sound called thunder.

FILL IN THE BLANKS.

  1. Electric current is the flow of charges / electrons.
  2. Electric current is measured by an instrument called ammeter.
  3. Battery is a source of electrical
  4. Electromagnets are used in telephone ear pieces to convert electric current into sound.
  5. A fuse is a device in which a wire melts if too much electric current flows through it.

CHOOSE THE ANSWERS.

  1. i) Electric current means the flow of: a) atoms b) neutrons c) charge d) protons
  2. ii) Which of these is not necessary for electric circuit?
  3. a) battery b) fuse c) wires d) electric device

iii) The magnetic needle always stays:         a)north-south b) east-west c) south-east d) north-west

  1. iv) Earth’s magnetic field is strongest at
  2. a) centre b) east and west poles c) deep layers d)north and south poles
  3. v) Sudden and high power of electricity can damage our electrical devices. Which the following save our devices?
  4. a) batteries b) fuses c) electromagnets d) wires

Answer: (i-a)(ii-b)(iii-a)(iv-d)(v-b)

U: 09 SOILS P:

EXERCISE

ANSWER THE QUESTIONS:

  1. EXPLAIN WHY SOIL IS CALLED “THE FOUNDATION OF LIFE.

ANSWER: Soil is called “The foundation of life” because nearly every thing we eat, drink and use comes from soil, grows in soul or built on soil.

  1. HOW CAN YOU DESCRIBE THE PARTICLE SIZE, AIR SPACES AND WATER HOLDING POWERS OF DIFFERENT TYPES OF SOIL?

ANSWER: There are three basic types of soil.                                                                                        (i) Sand (ii) Clay (iii) Silt                                                                                                                                     Most soils are made of the combination of three types.                                                                                        (i) SAND: Sand consists of large particles and large air spaces.                                                      Water moves through sand very fast.                                                                                            This soil does not hold water very well.                                                                                              (ii) CLAY: Clay consists of fine particles that cling together.                                                 It contains small air spaces.                                                                                                   Water moves through it very slowly.                                                                                       This soil holds lot of water.                                                                                                        When it is dry, it is very hard.                                                                                                      (iii)SILT: Silt is in between sand and clay.                                                                                 The particles of silt are medium sized.                                                                                               lt has largest air spaces.                                                                                                                       It feels smooth and powdery.                                                                                                            Water flows through it with medium speed.                                                                                 It holds water more than sand.

  1. LIVING ORGANISMS DIE AND THEIR BODIES MIX WITH SOIL. AFTER SOME TIME THEIR BODIES VANISH. WHAT HAPPENS TO THE DEAD BODIES?

ANSWER: After their death, living organisms mix up with soil. After some time, their dead bodies vanish. Actually, decomposer bacteria and fungi act on their dead bodies and break them into simpler substances. These simpler substances become the part of soil.

  1. Write an experimental plan to compare the absorption of water by different types of soil.

ANSWER: Take three small cups and make small holes in their bottom.                               Put equal amounts of different soils (sand, clay, silt) in them.                                            Place these cups inside larger cups for collecting water.                                                      Pour equal amount of water into each cup and observe.                          CONCLUSION:(i)Sand does not absorb water.                                                                  Clay holds lot of water.                                                                                                                     Silt holds water more than sand but less than clay.

  1. YOU KNOW SAND, SILT AND CLAY ARE THE TYPES OF SOIL. YOU SEE A SAMPLE OF SOIL IS COMPOSED OF 50% SAND AND 50% CLAY. WHAT WILL YOU CALL IT?

ANSWER: The mixture of 50% sand and 50% clay is called loam. lt contains the particles of both sizes. So, it holds more water than sand and less water than clay.

 FILL IN THE BLANKS.

  1. i) Soil provides nutrients and water to growing plants.
  2. ii) The type of soil which has maximum air spaces is

iii) Red soil means it has more iron.

  1. iv) Loam is a mixture of sand and clay.
  2. v) The type of soil which has the largest sized particles is sand.

CHOOSE THE ANSWERS.

  1. i) Organic matter from dead plants and animals is also called:
  2. a) clay b) rock c) silt d) humus
  3. ii) The smallest particles are present in:
  4. a) silt clay c) sand d) loam

iii) Plants grow very well in:

  1. a) silt b) clay c) sand loam
  2. iv) Plants need many minerals for their growth. They get minerals by:
  3. a) absorbing from air b) absorbing from soil c) absorbing from sunlight d) making by themselves
  4. v) Important decomposers in soil are:
  5. a) bacteria and fungi b)bacteria only c) fungi only d) roots of plants

Answer: (i-d)(ii-b)(iii-d)(iv-b)(v-a)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

U:10 SOLAR SYSTEM P:

EXERCISE

ANSWER THE QUESTIONS:

  1. WRITE DIFFERENCES BETWEEN STAR AND A PLANET. GIVE EXAMPLES.

ANSWER: Following are the differences between a star and a planet.

STAR

=>  Star produces its own.                                                                                                              => A star does not  rotate.                                                                                                                           => A star is a huge ball of rock of hot gases.                                                                  Example: The Sun

PLANET

-Planet has no light of its own light. They take light from stars.                                                                                       -A planet rotates around a star.                                                                                                            -A planet is a spherical ball of rocks or gases                                                                            Example :The Earth, The Mars etc.

  1. WHY WE CANNOT SEE STARS DURING THE DAY?

ANSWER: The stars shine all the time but we cannot see them during the day because the light coming from the Sun is much brighter.

  1. WHAT IS SOLAR SYSTEM? WHAT IS IT MADE UP OF?

ANSWER: Our Solar system is made up of all the planets moving around the Sun.  – The Sun is the centre of our Solar system.                                                                                     – The solar system contains the following different types of objects.                                                (i) A star – The Sun                                                                                                                      (ii) Planets that go around the Sun.                                                                                                 (iii) Satellites which go around the planets.                                                                               (iv) Smaller objects e.g. comets and asteroids.

  1. NAME THE PLANETS OF THE SOLAR SYSTEM.

ANSWER: Following are the planets of our solar system .                                                            (i) Mercury (ii) Venus (iii) Earth (iv) Mars (v) Jupiter (vi) Saturn (vii)Uranus (viii) Neptune

  1. WHAT IS NATURAL SATELLITE OR MOON? How is it different from a planet?

ANSWER: The large bodies which move around the planets are called moons or natural satellites.                                                                                                                           The difference between moon and planet is; the moon revolves around planet and planet revolve around sun.

  1. DRAW A TABLE TO SHOW THE DISTANCE OF THE PLANETS FROM THE SUN WITH PLANET NEAREST TO THE SUN AT THE TOP.

ANSWER:

  1. MATCH THE CORRECT NUMBERS OF MOONS IN COLUMN A WITH ITS NAMES IN COLUMN B.
column A Column B: Column C.
Earth

Jupiter

Mars

Mercury

63

None

02

01

01

63

02

None

FILL IN THE BLANKS.

  • A star is a huge ball of very hot gases.
  • The closest star to Earth is Sun.
  • There are planets in the solar system of the Sun is hydrogen.
  • The gravitational force of the Sun is greater than the Earth because the Sun has more bigger than Earth.

CHOOSE THE ANSWERS.

(i)Our Earth is a:

(a) galaxy (b) universe (c)star d) planet

(ii) The planet nearest to the Sun is:

(a) Venus (b)Jupiter c)Mercury(d)Neptune

(iii)The biggest planet in our Solar;

(a) Venus  b) Jupiter (c) Mercury (d)Neptune

(iv) The larger bodies which orbit around planets are called:

  1. a) natural satellites(b)artificial Satellites (c) moons (d) all of above

Answer: (i-d)(ii-c)(iii-b)(iv-a)

===========THE END =============

 

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