Notes And Questions For NCERT Class 10 Science How Do Organisms Reproduce

Students should refer to the below How Do Organisms Reproduce Class 10 notes prepared as per the latest curriculum issued by CBSE and NCERT. These notes and questions are really useful as they have been developed based on the most scoring topics and expected questions in upcoming examinations for Class 10. How Do Organisms Reproduce is an important topic in Science Class 10 which if understood properly can help students to get very good marks in class tests and exams.

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How Do Organisms Reproduce Class 10 Notes and Questions PDF Download

Read the notes below which will help you to understand all important and difficult topics in this chapter. There are some topics in How Do Organisms Reproduce chapter which you should understand carefully as many questions can come from those parts. Our team of teachers have designed the revision notes so that its helpful for students to revise entire course prior to the class tests.

Question: Fertilization in plants occurs in the –
a) Embryo sac
b) Style
c) Pollen tube
d) Stigma

Question: Which among the following diseases is not sexually transmitted?
a) syphilis
b) Gonorrhoea
c) HIV – AIDS
d) Hepatitis

Question: In vegetative reproduction, the new individuals are genetically –
a) Similar
b) Dissimilar
c) Abnormal
d) None of these

Question: When an organism breaks into a number of parts and each part develop into an individual, it is called –
a) Budding
b) Binary fission
c) Regeneration
d) Spore formation

Question: During grafting, the portion of plant that is grafted is called –
a) Stock
b) Scion
c) stalk
d) stem

Question: In man, fertilization of ovum takes place in
a) Vagina
b) ovary
c) uterus
d) Fallopian tubes

Question: Characters that are transmitted from parents to offspring during reproduction show
a) only similarities with parents
b) only variations with parents
c) neither similarities nor variations
d) both similarities and variations with parents

Question: Which part of the flower forms the fruit?
a) Whole flower
b) Only stamens and carpel
c) Only ovary
d) Only carpel

Question: Anemophily is the pollination by –
a) Birds
b) Rain
c) insects
d) Wind

Question: Which of this is seminal fluid?
a) Prostate gland
b) Cowper’s gland
c) Seminal vesicle
d) all of these

Question: A common feature of reproduction in Amoeba, spirogyra and yeast is that –
a) Asexual reproduction occurs after sexual reproduction
b) Asexual reproduction occurs before sexual reproduction
c) Asexual reproduction does not involve gametes
d) Asexual reproduction involves only one parent

Question: The normal duration of menstrual cycle is
a) 7 – 8 days
b) 13 – 15 days
c) 3 – 4 days
d) 28 days

Question: Asexual reproduction takes place through budding in
(a) Amoeba
(b) Yeast
(c) Plasmodium
(d) Leishmania.

Question: A common feature of reproduction in Amoeba, spirogyra and yeast is that –
a) They reproduce only sexually
b) They are all unicellular
c) they reproduce asexually
d) They are all multicellular

Question: The anther contains
(a) Sepals
(b) Ovules
(c) Carpel
(d) Pollen grains.

Question: At the time of entering into ovule, pollen tube has
a) three male nuclei
b) two mole nuclei
c) one gamete nucleus
d) four male gametes

Question: Which of the following is an IUCD?
a) copper – T
b) diaphragm
c) oral pills
d) tubectomy

Question: Which of the following is not a part of female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube

Question: Name the structure through which pollen tubes enters the ovule.

Question: What is the product of fertilization?

Question: Name the unicellular organism which caused the disease known as kala-azar.

Question: Which process taking place in the nucleus of a cell leads to variation in the offspring during reproduction?

Question: The simple animals such as planaria can be cut into number of pieces and each piece grows into a complex organism. What is this process known as?

Question: How may male gametes are produced by pollen grains?

Question: Define parthenogenesis.
Answer: Development of organism from an unfertilized egg.

Question: Which type of layering is done in Jasmine?
Answer: Air Layering (Gootee)

Question: What is syngamy?
Answer: Fusion of male gamete with the egg cell is called syngamy.

Question: Name the causative organism, of AIDS?
Answer: HIV – Human Immunodeficiency virus.

Question: Where does fertilization takes place in human female?
Answer: Oviduct (fallopian tube)

Question: What is parturition?
Answer: Parturition – The birth of fully developed foetus in completion of gestation.

Question: How many follicles mature every month during the reproductive phase of human female?
Answer: One egg is produced every month by one of the ovaries

Question: What is puberty?
Answer: Puberty – Age when reproductive system functionally active or starts producing ova or
sperm is called puberty.

Question: What is tubectomy?
Answer: Removal of a section of fallopian tube.

Question: A couple wants to space the birth of their second child. Suggest one preventive method which could be observed 
(a) By the husband (b) By the wife for the same.
Ans. (a) Use of condoms by the husband
(b) Use of oral pills or loop or Copper-T by the wife.

Question: Blue prints of body design are stored in the DNA. Why? 
Ans. The chromosomes present in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA molecule. The DNA is the information source for making proteins. Thus, blueprints of the body design are stored in the DNA.

Question: Protozoan reproduce by binary fission as well as by multiple fission. In your opinion which process is better and why? 
Ans. Multiple fission is better than binary fission because:-
1. More number of individuals is produced.
2. It helps to tide over unfavourable conditions.

Question: A pregnant woman visits a doctor to determine the sex of her child. The doctor refused to perform the test. Why is she being denied? 
Ans. The doctor refused to perform the test in order to prevent female foeticide which leads to an alarming decline in child sex ratio.

Question: Producing individuals by parents consume a lot of energy. So, why should an individual organism waste energy in the process, it does not need to stay alive?
Ans. Reproduction, unlike other life processes is not essential to maintain the life of an individual organism. But it is essential for providing stability to the population of species. Maintaining the species is essential for maintaining balance in nature.

Question: A girl attains her puberty at the age of 11 years and a boy at 13 years but, still they are asked to refrain from sex, why?
Ans. They are asked to refrain from sex because:-
1. They are not physically, emotionally mature enough to be able to bear the responsibility of the child.
2. They may suffer from reproductive tract infections.

Question: What changes occur in girls and boys in the age group of 10 -14 years?
Ans. Changes in males (boys)
1) Widening of shoulder.
2) Deepening of voice
3) Appearance of beard and moustaches
4) Growth of sex organs
Changes in females (girls)
1) Widening of pelvis and hips.
2) High pitch voice.
3) Growth of auxiliary and pubic hair
4) Initiation of menstrual cycle.
5) Growth of mammary glands.

Question: Mention the events taking place when the ovum is fertilized in fallopian tube till it is implanted in the uterus of human female.
Ans. After fertilization, the zygote starts dividing by repeated mitotic divisions called cleavage. In about 4 -5 days after fertilization, zygote becomes a multicellular structure called blastocyst. The blasto cyst gets attached to the lining of uterus is called implantation.

Question: How does the embryo get nourishment inside the mother’s body?
Ans. The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. This is a disc which is embedded in the wall of uterus. It contains finger-like projections villi on the embryo’s side of the tissue. On mother’s sides are blood spaces, which surround the villi. This provides a large surface area for glucose and oxygen to pass the mother to the embryo and waste products from embryo to mother.

Question: Name the surgical methods of birth control in human males and females respectively.
Ans. Surgical methods of birth control are –
a) Castration – Removal of testes from the body of a male
b) Ovariectomy – Removal of ovaries from the body of a female
c) Vasectomy – small pieces of both the vas deferens are cut and removed.
d) Tubectomy – Small pieces of both the fallopian tubes are removed.
e) Laparoscopy – Fallopian tubes are blocked with the help of an instrument called laparoscope

Question: What are the post fertilizational changes in the flower?
Ans. Post – fertilization changes in flowers are –
a) The sepals, petals and stamens wither off
b) Style and stigma degenerate
c) Ovary develops into fruit
d) Ovules grows into seed
e) Integuments of the ovule act as seed coats.
f) Fertilized egg gets converted into embryo which bear plumule, radicle and cotyledons.
g) Fertilized polar nuclei form endosperm which may or may not be consumed during seed development.

Question: What is micropropogation? Mention its advantages.
Ans. Micropropagation – It is a type of artificial vegetative propagation in which an isolated plant part is cultured under aseptic conditions with proper nutrient medium. Advantages of micropropagation.
a) It is a quick method of multiplication of plants.
b) Virus free plants are produced by this method from virus infected plants
c) It can overcome seed dormancy

Question: What are the major factors responsible for population explosion?
Ans. Reason for population explosion –
(i) Better medical facilities – Better medical facilities have resulted in fall of death rate.
(ii) Lack of education and awareness – This is a major factor since people become prey to ignorance
(iii) Religions – For some people, family planning is against the norms set by their religion.
(iv) Control over epidemics – Various medical technologies has made it possible to fight against epidemics.
(v) Sanitary conditions – There is a lot of improvement in sanitary conditions which led to increase in population.

Question: What could be the reasons for adopting contraceptive methods?
Ans. The sexual act always has the potential to lead to pregnancy. Pregnancy will make major demands on the body and the mind of the woman and if she is not ready for it, her health will adversely affected. Therefore, adopting contraceptive methods are essential. Some contraceptive methods like condom also prevent spread of STDs and lethal diseases like HIVAIDS.

Question: What are the advantages of vegetative propagation?
Ans. Advantages of vegetative propagation –
a) It is a rapid, cheap and easy method of reproduction for the multiplication of plants
b) Genetically identical plants (clones) are produced by this method
c) Superior quality fruits or flowers can be produced by grafting.
d) Disease free plants can be produced by this method
e) Early flowering and fruit formation

Question: Describe sexually transmitted diseases (STDs) and mention the ways to prevent them.
Ans. Those infectious diseases which are spread by sexual contact called sexually transmitted diseases (STDs)
Methods for prevention of STDs
a) The people should be educated about various STDs
b) Extra – marital relations should be avoided
c) Sex without proper precaution should be avoided
d) High standard of moral education should be give to the people.

Question: Describe budding in yeast, a fungus
Ans. a) It is a type of asexual reproduction in which an outgrowth (bud) is formed on the parent organism due to single cell division.
b) The bud gradually grows in size and gets detached form the parent body.
c) Detached bud develops into an adult organism, similar to the parent.

Question: What is the importance of reproduction?
Ans. Importance of reproduction –
a) Maintenance of the existence – Organisms are maintaining their existence on the earth since their origin, million year ago, only because of reproduction.
b) Preservation of species – Species (a group of similar organisms) are preserved because of reproduction. It is possible because reproducing organisms produce new individuals which are very similar to themselves.
c) Role in evolution – some variations is produced in the new organisms during reproduction which play an important role in evolution.

Question: What are the different methods of contraception?
Ans. Different methods of contraception are –
a) Barrier method – In this method, a device used to prevent the entry of sperms in the female genital tract example – Condom, Diaphragm, Cervical caps.
b) Chemical method – In this method certain drugs (containing hormones) are used by the females. These drugs are avaiblabe in the form of pills. There are two kinds of pills commonly used for preventing pregnancies – oral pills and vaginal pills or creams.
c) Intrauterine contraceptive devices (IUCD’S) – IUCD like copper – T is placed in the uterus – IUCD prevent implantation of the fertilized ovum inside the uterus.

Question: What are the essential requisites for sexual reproduction?
Ans. Essential requisites for sexual reproduction are –
a) Transfer of germ cells – Specialized germ – cells have to fuse together, which can happen by either of the following modes –
(i) External release of germ cells – In flowering plant
(ii) Internal transfer of germ cells – In animal cells.
Requirement of special organs –
For example –
a) An erectile organ called penis
b) Organs which can carry the baby for long period

Question: What changes occur in ovaries during menstrual cycle?
Ans. Change occurs in ovaries during menstruation
a) 1 – 4 days – Corpus luteum degenerates. The ovary starts preparing for the maturation of a new follicle.
b) 5 – 13 days – Ovarian follicle develops to optimum. Estrogen secreted by ovaries causes thickening of uterine wall.
c) 14 day – Egg gets released from the ovary. It enters the fallopian tube, known as ovulation.
d) 15 to 28 days – After releasing the egg, the follicle part produces corpus luteum which produces progesterone. If pregnancy has not occurred, corpus luteum degenerates corpus luteum. This restarts menstrual cycle once again.

Question: What is AIDS? Name its causal organism. Mention its symptoms.
Ans. AIDS is a sexually transmitted disease. Its full form is acquired immune deficiency syndrome. It is a viral disease, caused by human immune deficiency virus. Its symptoms area) Destroys the immune system of body.
b) Persistent cough and fever.
c) Body attacked by other diseases like pneumonia, TB and certain cancers.

Question: Describe any 3 methods of asexual reproduction
Ans. Methods of asexual reproduction –
a) Primary fission – It is a type reproduction in which one parent organism divides into two new organisms. Firstly nucleus divide and then division of cytoplasm takes place.
b) Spore formation – A spore is a small microscopic structure with a thick wall. Spores are formed in a structure called sporangium. Nucleus inside sporangium divides repeatedly and produces many nuclei. Each nucleus is surrounded by cytoplasm and called spore.
c) Fragmentation – It is the breaking of an organism into two or more parts upon maturation, each of which grows to form a new individual.

Question: Describe triples fusion in plants? Where does it occur? Draw a neat and clean well labeled diagram to support your answer.
Ans. After pollination, the pollen grains germinate n the stigma by producting pollen tube. This pollen tube is formed from inner wall of the pollen grain. It penetrates the stigma and passes through the style and enters the ovule through an opening called male gamete it releases two male gametes in the embryo sac. One male gamete fuses with egg cells and second fuses with two polar nuclei. The fusion of one male gamete with the egg cells is called syngamy. The fusion of second male gamete with two polar nuclei is called triple fusion. This process occurs in ovary.

Question: What is the importance of DNA copying in reproduction?
Ans. DNA contains information for the inheritance of features from parents to next generation. DNA presents in nucleus of cells are the information source for making protein. If information is different, different protein will be made that lead to altered body design.

Question: Blue prints of body design are stored in the DNA. Why?
Ans. The chromosomes present in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA molecule. The DNA is the information source for making proteins. Thus, blueprints of the body design are stored in the DNA.

Question: Draw a well labeled diagram of female reproductive system and mention its part

Ans. a) A pair of ovaries – ovaries produces ova and female sex hormone. One egg is produced every month by one of the ovaries. Ova are picked up by the funnel shaped fallopian tubes.
b) Fallopian tubes – There are two fallopian tubes. It carries ova from ovary to the uterus. Fertilization occurs in fallopian tubes.
c) Uterus – Pear shaped hollow muscular organ. Fertilized ovum remains attached to the uterus wall.
d) Vagina – It is a narrow muscular tube. Its upper end is connected to the cervix of the uterus and lower end opens outside through an opening. It is a place for copulation.

Question: What are the different methods of contraception?
Ans. Various methods used for regulation of child birth can broadly categories as:
(i) Barrier methods: In this method, physical devices such as condom, diaphragm, cervical cap and copper-T are used.
(ii) Chemical method: use of spermicidal jelly by woman, oral pills and vaginal pills.
(iii) Surgical method: In surgical method, a small portion of vas deferens in male and the oviduct of female, is surgically removed or ligated. It is called vasectomy in male and Tubectomy in females.

Question: Can you think of reasons why more complex organism cannot give rise to new individuals through regeneration?
Ans. The reason is that complex organisms are not merely random collection of cells. Specialized cells are organized in them as tissues are organized in organs. These organs have to be placed at definite positions in the body. So, regeneration is not possible in multicellular organism.

Question: Draw a well labeled diagram of male reproductive system and describe its parts.

Ans. a) A pair of testes – Each testis produces sperms and male sex hormone called testosterone. Testes are present in small pouch called scrotum.
b) Epididymis – It is a long coiled tube. The head is connected with testis and tail is connected with vas deferens
c) Vas deferens – It is a long tube which begins from the tail of epididymis
Urethra – It receives the vas deferens from both the testes. It opens outside through penis. It carries both sperms and urine.

Question: Why is vegetative propagation practiced for growing some types of plants?
Ans. (i) Plants raised by vegetative propagation can bear flower and fruits earlier than those produced from seeds.
(ii) Such methods also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds.
(iii) All plants produced by this method are genetically similar enough to the parent plant to have its all characteristics.

Question: Explain vegetative reproduction through layering. Give examples.
Ans. It is a type of artificial vegetative reproduction in which a branch of the parent plant is buried in the soil. The portion of the branch which is in contact with the soil produces roots and this rooted branch is called layer. Layer is then detached form the parent plant which acts as a new plant. Example – Jasmine.

Question: Differentiate between asexual and sexual reproduction.
Ans.

Question: How does binary fission differ from multiple fissions?
Ans. Difference between binary fission and multiple fission:

Question: Why is DNA coping essential part of the process of reproduction?
Ans. DNA contains information for the inheritance of features from parents to next generation. DNA presents in nucleus of cells are the information source for making protein. If information is different, different protein will be made that lead to altered body design.

Question: How does binary fission differ from multiple fissions?
Ans. Difference between binary fission and multiple fission:

Question: Draw a labeled diagram of the longitudinal section of a flower.
Ans.

Question: Why does menstruation occurs.
Ans. When in human female if the egg is not fertilized, it lives for about one day. Since the ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilized egg. Thus, its lining becomes thick and spongy. This would be required for nourishing the embryo if had fertilized. However, this lining is not required any longer. So, the lining slowly breaks and comes out through the vagina as blood and mucous. This cycle takes roughly every month and is known as menstruation.

Question: What is the need of population control?
Ans. Overpopulation leads to a number of problems like –
a) Unemployment – More number of people means more jobs and if sufficient numbers of jobs are not available, it leads to unemployment.
b) Poverty – If there are more persons and the income is less, it becomes poorer with the addition of every child.
c) Food supply – If the population increases and the food production does not increase; this will lead to shortage of food supply.
d) Hygienic condition – more people in small area generally make the condition unhygienic for survival
e) Educational problem – It becomes difficult for the government to provide education to all
f) Housing problem – It also creates housing problem.
g) Pollution – More pollution with increasing population.
h) Decrease in natural resources – More people will decrease the natural resources quickly.

Question: Draw a flow chart showing various types of reproduction with examples.
Ans.

Question: Why is variation beneficial to the species but not necessarily for the individual?
Ans. Variations are useful for the survival of species in changed environment situations. If a population of reproducing organism were suited to a particular niche and if the niche is drastically altered the population could be wiped out. However, some variations are present some species will survive. Thus, variation is useful to species but not the individual.

Question: Producing individuals by parents consume a lot of energy. So, why should an individual
organism waste energy in the process, it does not need to stay alive?
Ans. Reproduction, unlike other life processes is not essential to maintain the life of an individual organism. But it is essential for providing stability to the population of species. Maintaining the species is essential for maintaining balance in nature.

Question: How are spores produced in sporangium of Rhizopus?
Ans. a) A spore is a small microscopic structure with a thick wall.
b) Spores are generally formed in a structure called sporangium which reassembles formed in
a structure called sporangium which resemble blob on – a – stick.
c) Sporangia are formed at the tip of erect fungal hypha.
d) In each sporangium, a nucleus divides several times producing a large number of nuclei. Nuclei get surrounded by a little cytoplasm and develop into thick – walled cells or spores.
e) The wall of sporangium breaks to release the spores in air.
f) On germination in the presence of moist surface, each spore gives rise to a new organism.

Question: What is grafting? Why is it used in horticulture practices?
Ans. In grafting, cutting of a plant stem is attached to another rooted plant. The cutting of stem which is grafted on the other plant is scion and the rooted plant on which the cutting is grafted is called stock. The scion and stock are placed one over other and tied in such a way that there is no gap between them. The cambium activity takes place among them and they get joined. Grafting is used in plants which do not produce extensive roots.

Question: Why is variation beneficial to the species but not necessary for the individual?
Ans. Variation is beneficial to the species as it enables a species for its survival. A favourable variation makes an organism to live better in a changed environment and an unfavourable variation will not. So it is not necessarily true that a variation is beneficial to the individual

Question: Diagrammatically represent binary fission in amoeba
Ans.

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