STD-6, CHAPTER-7: THE WORLD OF LIVING, EXERCISE QUESTION ANSWER

 A.     FILL IN THE BLANKS.

1.      Plants, animals and human beings are collectively known as ______.

Ans: living things

2.      Amoeba is a ______ organism.

Ans: unicellular

3.      The process, used by plants to synthesise their own food, is known as ____.

Ans: photosynthesis

4.      All living organisms respond to various kinds of ______.

Ans: Stimuli

5.      _____ are very small plants.

Ans: Herbs

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Amoeba is a plant. - FALSE

2.      Living organisms exhibit many variations due to their habitats and habits. - TRUE

3.      Many non-living things can be moulded in different forms or shapes. - TRUE

4.      All living things die. - TRUE

5.      Lotus is an example of a hydrophyte. - TRUE

6.      Invertebrates do not possess a backbone. - TRUE

     

C.      TICK THE CORRECT OPTION.

 

1.      Which of these statements is true for plants?

(a)   Non-green plants are autotrophic

(b)   Green plants are autotrophic

(c)    All plants are heterotrophic

(d)   All non-green plants are saprophytes       

      Ans: green plants are autotrophic

2.      Which of the following plants belongs to the category of shrubs?

(a)   mango              (b)  rose             (c)  neem             (d) tulsi

      Ans: rose

3.      Which one among these is not a flowering plant?  

(a)    grasses            (b)  algae            (c) rose                (d) mango

       Ans: algae

4.      Biennial plants are those plants which live for–

(a)   Many years                                   (b)  three years

(c)    Two years                                      (d)  one year

      Ans: two years

5.      All living organisms have-

(a)   bones                                     

(b)   feathers

(c)    cells

(d)   stems

      Ans: cells

6.      Which of these is an invertebrate?

(a)   snail                                       (b)  sparrow

(c)    cobra                                      (d)  frog

      Ans: snail

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      Name any three important characteristics of living beings.

Ans: Three important characteristics of living beings are,

i) They are made up of cells

ii) They show response to various stimuli

iii) They can reproduce

2.      State the difference between autotrophs and heterotrophs.

Ans: AUTOTROPHS: Plants which can prepare their own food by the process of photosynthesis are called autotrophs. They have chlorophyll on them.

HETEROTROPHS: Plants or animals which cannot prepare their own food, but depend on others for their nutrition are called heterotrophs. They lack chlorophyll.

3.      Give two examples each of annual, biennial and perennial plants.

Ans: Annual Plants: Rice plant, wheat plant

Biennial Plants: Carrot and Raddish plant

Perennial Plants: Mango and Neem plant

4.      Give two examples each of animals which reproduce (i) by laying eggs and (ii) by giving birth to young ones.

Ans: (i) Animals who reproduce by laying eggs – Fish and Tortoise

(ii) Animals who reproduce by giving birth to young ones – Rat and Cow

5.      Give two examples each of vertebrates and invertebrates.

Ans: Vertebrates – Fish, Lizard

Invertebrates – Star fish, earthworm

6.      Write the names of any four useful products obtained from plants.

Ans: Four useful products obtained from plants are - wood, rubber, paper and cotton

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      ‘All living things respond to external stimuli’.

Justify this statement with examples.

Ans: All living organisms respond to different stimuli, such as touch, light, heat and sound.

Example: i) The ‘touch-me-not’ plant closes it leaves in a response to the touch stimulus.

ii) Earthworm moves away from light and saline media.

2.      A cloud is considered as non-living even though it can move and grow bigger. Explain why?

Ans: A cloud is made up of water droplets. Clouds can move and also grow bigger due to the accumulation of more water droplets. But they don’t show all the characteristics of living things. For example, it cannot breathe, reproduce or excrete. So, it is considered as non-living.

3.      Write two points of differences between,

(i) herbs and shrubs

(ii) shrubs and trees

Ans: (i) herbs and shrubs

HERBS	SHRUBS
Herbs are very small plants.	Shrubs are medium sized plants.
They have soft and green stems.	They have a hard woody stem.

 

(ii) shrubs and trees

SHRUBS	TREES
Shrubs are medium sized plants usually having a height of one metre to about three metres.	Trees are tall and large plants.
They have a hard woody stem.	They have strong and woody stems.

 

4.      State the differences between biennial and perennial plants.

Ans:

BIENNIAL PLANTS	PERENNIAL PLANTS
These plants live for two seasons.	These plants live for many years.
In the first year, they have full vegetative growth and in the second year, they bear flowers and fruits.	They produce flowers and fruits many times in their life time.
Examples: carrot, raddish and turnip plants	Examples: Mango, guava and neem plants

 

5.      Name two types of terrestrial plants. How do they differ on the basis of their habitat and water requirements?

Ans: Two types of terrestrial plants are, mesophytes and xerophytes.

	MESOPHYTES	XEROPHYTES
Habitat	These plants grow on land.	These plants grow in deserts.
Water requirements	They need moderate amount of water supply for their survival.	They need very small amounts of water for their survival.

 

6.      How are vertebrates different from invertebrates?

Ans:

VERTEBRATES	INVERTEBRATES
They have a backbone, which is made up of several small ring-like bones, called vertebrae.	They do not have a backbone.
These animals are well-developed and have a bony skeleton.	These animals have a soft body.
Examples are, human beings, fish, frog etc.	Examples are, earthworm, cockroach, snail etc.

 

7.      Write any four uses of animals in our daily life.

Ans: i) Animals, like camel and horse, are used for transportation of humans and materials.

ii) We get many products like, leather, wool and silk from animals.

iii) Animal excreta is used as manure and for producing gobar gas.

iv) Many edible products, like milk, honey, eggs and meat, are obtained from animals.

STD-6, CHAPTER-5: CHANGES AROUND US, EXERCISE QUESTION ANSWERS

 A.     FILL IN THE BLANKS.

1.      All irreversible changes bring a ______ change in a substance.

Ans: permanent

2.      A change, in which the substance produced can get back to the original form, is called a ______ change.

Ans: reversible

3.      Bending of an iron rod is a ______ change.

Ans: physical

4.      Burning of fuel is a _______ chemical change, whereas rusting of iron is a ______ chemical change.

Ans: fast, slow

5.      In chemical change, new substances with ______ properties are formed.

Ans: different

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Glowing of an electric bulb is a fast change - TRUE

2.      Deforestation is a reversible change. - FALSE

3.      Burning of paper is a temporary change. - FALSE

4.      Cutting of an apple is a chemical change. - FALSE

5.      Making of fruit salad is a chemical change. - FALSE

6.      Changing milk into curd is a physical change. - FALSE

 

C.      TICK THE CORRECT OPTION.

 

1.      Which of the following can be considered as a fast change?

(a)    Growth of a child

(b)   Germination of seeds

(c)    Bursting of a fire cracker

(d)   Cooking of food      

      Ans: bursting of a fire cracker

2.      Evaporation of water is a-

(a)   Physical change

(b)   Fast change

(c)    Irreversible change

(d)   Chemical change            

      Ans: Physical change

3.      Which one of these changes is a reversible change?  

(a)   Burning of a candle

(b)   Inflating a balloon

(c)    Baking of chappati

(d)   Grinding of wheat grains into flour      

       Ans: inflating a balloon

4.      Which one of these is an irreversible change?

(a)   Growth of a child

(b)   Stretching a rubber band

(c)    Evaporation of water

(d)   Formation of ice from water

      Ans: growth of a child

5.      A piece of paper undergoes a chemical change, when it is-

(a)   cut

(b)   folded

(c)    reshaped into a paper toy

(d)   burned

      Ans: burned

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

1.      Define the following terms.

(a)   Reversible change

(b)   Chemical change

(c)    Physical change

Ans: a) Reversible Change: a change, in which substance produced, can be brought back into its original form is called as a reversible change.

b) Chemical change: a change, in which a new substance is formed is called as a chemical change.

c) Physical change: a change, in which no new substance is formed is called a physical change.

2.      Distinguish between fast and slow changes. Give two examples of each type.

Ans: Fast change: A change that takes place in a shorter duration of time is called a fast change. Example: bursting of a balloon, lighting of a bulb

Slow Change: A change that takes place over a longer duration of time, is called a slow change.

Example: change of seasons, growth of a plant

3.      Give two examples each of reversible and irreversible change.

Ans: Reversible Change: stretching a rubber band, evaporation of water

Irreversible Change: Baking of chappati, growth of a child

4.      State some of the irreversible biological changes that take place in nature.

Ans: Some of the irreversible biological changes that take place in nature are,

i) germination of a seed

ii) growth of animals

iii) forest fire

iv) burning of fuels

5.      Give one example of a physical change in which (i) energy is given out, (ii) energy is absorbed.

Ans: (i) Energy is given out during burning of a fuel

(ii) Energy is absorbed during boiling of water

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Give two differences between reversible and irreversible changes.

Ans: Reversible Change: i) A change, in which substance produced, can be brought back into its original form, is called as a reversible change.

ii) These are temporary changes.

Examples: stretching a rubber band, evaporation of water

Irreversible Change: i) A change, in which the substance produced cannot get back to the original form, is called an irreversible change.

ii) These are permanent changes.

Examples: Baking of chappati, growth of a child

2.      ‘Formation of curd is an irreversible as well as a chemical change.’ Justify this statement.

Ans: i) Milk is a liquid. After curdling, it changes into a semi-solid material which has a different taste. As, a new substance is formed, the formation of curd is a chemical change.

ii) Again, the process cannot be reversed and we cannot get back milk from curd. So, it is also an irreversible change.

3.      Water cycle is a natural change. Classify it as a (i) physical or chemical change,  (ii) a reversible or irreversible change. Also, justify your answer.

Ans: Water cycle is a natural change. In this cycle, water changes its states due to difference in temperature. 

i) It is a physical change. Because in this cycle no new substance is formed. Water only changes its state.

ii) It is a reversible change as we can get back the original substance by changing temperature. For example, liquid water changes into water vapour on heating and the same water vapour again changes into liquid form on cooling.

4.      How can we say that burning of candle is a chemical change but the glowing of bulb is a physical change?

Ans: i) After burning the candle produces smoke and the thread in the candle changes into ash. Thus new substances are formed. So we can say that burning of candle is a chemical change.

       ii) When the switch is on, the electric bulb starts glowing. And when it is switched off it          stops glowing. No new substance is formed. So, it is a physical change.