Class 10 Science Chapter 8 How Do Organisms Reproduce? The answer to each chapter is provided in the list so that you can easily browse throughout different chapters NCERT Class 10 Science Chapter 8 How Do Organisms Reproduce? and select need one.
Class 10 Science Chapter 8 How Do Organisms Reproduce?
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Higher-Order thinking questions
Q.1. There are four tiny organisms A , B , C and D. The organism A is a parasitic protozoan which causes a disease known as Kala – azar . The organism B is a microscopic single called animal which causes malaria disease in human beings . The organism C is a unicellular animal which can change its body shape according to need , it has no fixed shape . The organism D is also a unicellular animal which is shipper shaped having a large number of tiny hair all around its body .
( a ) Name the organisms A , B , C and D.
( b ) Name one characteristic body feature of organism A.
( c ) Name the insect which carries organism B and transmits it from one person to another .
( d ) What name is given to the asexual method of la reproduction of
( i ) Organism A and
( ii ) Orgamism B ?
( e ) Where do organisms C and D live ?
Ans :- ( a ) A is leishmania . B is plasmodium . C is Amoeba dn Dis Paramecium .
( b ) Organism A ( leishmania ) has a whip – like structure called flagellum at its one end .
( c ) Female Anopheles mosquito .
( d ) ( i ) Binary fission.
( ii ) Multiple fission .
( e ) In pond water.
Q.2. Two very small organisms X and Y both reproduce by the method of buddieg . Organism X is industrially overy important because it is used in making alcohol from sugar . It is also used in making bread . organism Y lives in freshwater If organism Y gets cut into a number of parts accidently , each cut part can grow to from complete organism .
( a ) What are the organisms X and Y ?
( b ) What is the name of the process in which X converts sugar into alcohol ?
( c ) To which class of organisms does X belong ?
( c ) Name an important body feature of organism Y.
( d ) Which organism is multicellular and which one is unicellular ?
Ans :- ( a ) X is yeast and Y is HYdra.
( b ) Fermentation.
( c ) Fungi.
( d ) Y has tentacles.
( e ) Y is multicellular whereas X is unicellular .
Q.3. When a moist slice of bread was kept aside for a few days then some organism grew on it to form a white cottony mass which later turned black . When this slice of bread was observed through a magnifying glass , then fine thread like projection and thin stems having bulb like structures at the top where sun .
( a ) What is the common name and scientific name of the organism which grew on the moist slice of bread ?
( b ) How did the organism grow on the moist slice of bread automatically ?
( c ) What are the fine , thread like projections on the surface of slice of bread known as ?
( d ) What name is given to the knob like structures and what do they contain ?
( e ) What is the name of this method of reproduction .
( f ) Name one unicellular organism which reproduces by this method .
( g ) Name two non – flowering plants which reproduce by this method .
Ans :- ( a ) Bread mould ; Rhizopus .
( b ) Sporse of bread mould plant are always present around us . One such spore landed on moist slice of bread and finding the conditions favourable grew into bread mould .
( c ) Hyphae .
( d ) Sporangia , Spores .
( e ) Spore formation .
( f ) Bacteria .
( g ) Ferns and Mossed .
Q.4. The stem of fruit tree X fixed in soil is cut in a slanting way . The upper part of stem of anoter fruit tree Y of different variety of same species is also cut in a slanting way . The cut stem of thee Y , without roots but having some leaves , is placed over the rooted cut stem of tree X in such a way that their cut surfaces fit together property . While joining the two cut stems , care is taken to make sure that the layer Z of one cut stem is incontact with layer Z of the other cut stem . The joint of cut stem is bound tightly with a piece of cloth and covered properly with polythene . Soon the cut heals and the two stems grow together and become one fruit tree producing leaves , flowers and fruits .
( a ) What is the name of this method of producing plants or trees ?
( b ) What name is given to the cut stem of tree X having roots ?
( c ) What name is given to the cut stem of tree Y which has no roots but has some leaves ?
( d ) Name the layer Z.
( e ) Why should the layer Z of one cat stem be in contact with the layer Z of the other cut stem ?
( f ) Name any four fruit trees which are usually bred by this technique .
( g ) State any one advantage of producing fruit trees by this technique .
Ans :- ( a ) Grafting .
( b ) Stock.
( c ) Scion.
( d ) Cambium layer.
( e ) Because the layer Z in the stem is responsible for growth .
( f ) Apple , peace , apricot and pear trees .
( g ) It enables us to combine the most desirable characteristics of the two plants in fruits .
Q.5. When a broken piece of the stem of a plant X is planted in the soil , a new plant grows from it in a week’s time . The leaves of plant X also have many small entities Y in their margins which can fall to he ground alone or along with leaves and grow into new plants .
( a ) Name of plant which X could be.
( b ) What are the entities Y present on the leaves of X known as ?
( c ) Name a plant other than X which can be reproduced from its leaves .
( d ) Name a common plant grown in many homes which can be propagated from its broken stems like plant X.
( e ) Name a kind of dormant organs present in dry of old grass plants lying in the fields which get activated and produce green plant after the rains .
Ans :- ( a ) Bryophyllum.
( b ) Buds.
( c ) Begonia.
( d ) Money plant.
( e ) Buds.
Q.6. The flask – shaped oryan A at the centre of a flower is surrounded by a number of little stalks B having swollen tops which lie just inside the ring of petals.
( a ) Name A what are the various parts of A ?
( b ) Which part of A contains gametes ?
( c ) Name B what is the swollen top of B known as ?
( d ) What does the swollen top of B contain ?
( e ) Out of A and B , which one is
( i ) Male part , and
( ii ) Female part of the flower ?
Ans :- ( a ) A is corpel ( orpistil ) , stigma , syle and ovary.
( b ) Overy.
( c ) B is stamen , Anther.
( d ) Pollen grains.
( e ) ( I ) B ( ii ) A
Q.7. When a human female reaches a certain age then veginal bleeding occurs for a few days regular time intervals .
( a ) What is this process known as
( i ) in scientific terms and
( ii ) in every day language .
( b ) At what approximate age this process starts in human females ? What is the human female said to have attained at this stage ?
( c ) After how much time is this process repeated ? For how many days this process usually lasts ?
( d ) What does the onset of this process in human females signify ?
( e ) At which particular event in the life of a human female . This process stops temporarily but starts again ?
( f ) Al which approximate age of human female this process stops permanently ?
Ans :- ( a ) ( i ) Menstruation.
( ii ) periods.
( b ) 10 to 12 years puberty.
( c ) 28 days ; About 3 to 5 days.
( d ) That the reproductive system of human female has started working .
( e ) Beginning of pregnancy .
( f ) About 4th to 50 years .
Q.8. A woman uses pills A as a method of birth control ( or 8 . preventing pregnancy ) . The pills A stop the ovaries from releasing ovum into ovid vets . Another woman uses pills B as a method of birth control . The pills B kill the sperms and prevent pregnancy .
( a ) What do the pills A contain ?
( b ) What is the common name of pills A ?
( c ) What do the pills B contain ?
( d ) What is the common name of pills B ?
( e ) What is the general name of these methods of birth control ?
Ans :- ( a ) Hormones .
( b ) Oral pills .
( c ) Spermicides.
( d ) Viginal pills.
( e ) Chemical methods.
Q. 9. A woman uses a device X made of a common metal for preventing pregnancy . This device works by preventing the implantation of fertilised egg cell ( or embryo ) in the female organs Y.
( a ) What are the two name of device X ?
( b ) Name the organ Y ?
( c ) Can this method of contraception protect a woman from acquiring a STD ?
Ans :- ( a ) Copper – T and IUCD.
( b ) Uterus ( or womb )
( c ) No
Q.10. A , B and C are three common STDs . A and care caused by bacteria where as B is caused by a virus D. The virus D reduces the immunity of the infected person to such a low level that the person can die of even every mild disease .
( a ) What could A and C be ?
( b ) What is B ?
( c ) Name the virus D ?
( d ) How can A , A , B and C be caused ?
( e ) Out of A , B and C. Which one does not have a definite cure as yet ?
Ans :- ( a ) Syphilis and Gonorrhoea .
( b ) AIDS .
( c ) HIV .
( d ) By sexual contact with an infected person .
( e ) B ( AIDS ) .
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