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Practice all diagram of ncert 5 to 10 times with labelling

Asexual Reproduction in Plants
• Spore formation → eg. Bacteria, fungi
• Budding → eg. Fungi (yeast)
• Fragmentation → eg. Algae, fungi
• Vegetative propagation

(a) Natural method (b) Artificial method

• By roots → eg. Sweet potato • Cutting → eg. Rose
• By stems → eg. Ginger, potato • Layering → eg. Strawberry, lemon
• By leaves → eg. Bryophyllum • Grafting → eg. Mango, rose.
• Micropropagation → eg. Orchids, dahlia

Sexual Reproduction in Plants Asexual Reproduction in Animals

• Flower is the reproductive organ. • Fission
• It has four whorls – Calyx, Corolla, Androecium, Gynoecuim. (a) Binary fission → eg. Amoeba
• Calyx and corolla are accessory parts. (b) Multiple fission → eg. Plasmodium
• Androecium - Male reproductive organ producing pollen grains. • Budding → eg. Hydra
• Gynoecium - Female reproductive organ having ovule (egg). • Regeneration → eg. Planaria, Hydra
• Pollination – Transfer of pollens from anther to stigma for fertilization.
• Fertilization – Fusion of male and female gametes.
• Double fertilization (Triple fusion and syngamy) – unique events in the
embryo sac of ovules.

Sexual Reproduction (Human)

• Human being is heterosexual.

• Reproductive system includes:
(a) Primary sex organs: Testes (males) and ovaries (females)
(b) Secondary sex organs: Genital ducts and glands (males) and fallopian tubes, uterus, vagina (females)
• Male sex hormone is testosterone and female sex hormones are progesterone and estrogen.
• Puberty is attained at the age of 13 – 14 years in males and 10 – 12 years in females.
• The zygote formed after fertilization develops into embryo which gets implanted in uterus.
• Placenta (a disc-like special tissue) develops between uterine wall and embryo for nourishment of the embryo.
• Gestation period in humans is 280 days.

Reproductive Health

• Birth control prevents unwanted pregnancies.

(a) Barrier methods
(b) Chemical methods
(c) Intrauterine contraceptive device
(d) Surgical method
• Sexually transmitted diseases (STD) are caused by bacteria, protozoa and viruses.
• AIDS is an incurable viral disease
 The Learning Tree
Diversity in living Organisms

1. The production of new organisms from the existing organisms of the same species is
known as reproduction.
2. Asexual Reproduction : Modes of sexual reproduction used are binary fission,
multiple fission, Budding, spore formation, regeneration, vegetative propagation, tissue
culture, fragmentation
3. Sexual Reproduction : In sexual reproduction, a male gamete (germ cells) fuses with a
female gamete to form a new cell called ‘zygote’. This zygote then grows and develop
into a new organism in due course of time.
When male gamete and female gamete fuse, they form a zygote and the process is
known as fertilization.
Fertilization is of two types :- External fertilization and Internal fertilization.

4. Sexual Reproduction in Flowering Plants :

Flower is meant essentially for sexual reproduction.
i) Pollination is the process in which pollen grains are transferred from the anther to
stigma of the carpel. It is of two types self pollination and cross-pollination.
ii) In the fertilization process primary endospermic nucleus is formed.
iii)After the fertilization process, ovary develops into the fruit whereas ovules into the
seed.
5. Reproduction in Human Being : The sex organ in males are testes and ova in females.
i) Male reproductive organ consist of a pair of testes, vasdeferens, a pair of epididymis,
a pair of ejaculatory duct, urethra, pairs of accessory gland.
ii) Female reproductive part consist of a pair of ovaries, a pair of fallopian tube, uterus,
vagina, external genitalia, mammary glands and accessory glands. Ovary produces
the female gametes (eggs or ova) and female sex hormone (estrogen).
iii) If sperms are present, fertilization of ovum takes place in the upper end of the
fallopian tube.
iv) Bleeding accompanied by discharge of soft tissue lining the reproductive tract
is menstrual flow. It last for 3-5 days.
v) Secretory phase lasts for 12-14 days.
vi) Fertilization process occurs in fallopian tube. In this process zygote is formed. In this
process umbilical cord is produced which is attached to foetus. During this
vii) process two hormones are produced which are estrogen and progesterone
viii) Progesterone stops mensturation and prevents ovulation. The placenta protects the
body against diseases. Due to contraction of uterine muscles young one is expelled
and the phenomenon is called parturition.
ix) If the egg is not fertilized, it lives for about one day. Since the ovary releases one
egg every month, the uterus also prepares it self every month to recieve a fertilized
egg.
x)After the age of 45-50 years menses stop and process is called menopause.
xi) Fertility control can be done chemically, mechanically or surgically.
6 Reproductive Health Barrier methods
(i) Mechanical barrier method:- They prevent contraception by preventing either
sperms from entering uterus or preventing implantation if fertilization has occurred.
The instruments are condom, cercival cap, diaphragm & ICDU method.
(ii) Hormonal method: They are used by women for suppressing the production of
ovum. i.e. ,oral pills, Implants morning after pills.
(iii) Chemical contraception: They are creams, jellies and foaming tables which are
placed in vagina for killing the sperms at the time of coitus.
(iv) Surgical techniques:—
(a) Vasectomy: — The two vasa deferential of the male are blocked by cutting a small
piece of tying the rest. This prevents the passage of sperms from testes to semen.
(b) Tubectomy:— A portion of both the fallopian tubes is excised to ligated to block the
passage of ovum
7. Sexually Transmitted Diseases (STDs)
It is a group of infections caused by different types of pathogens that are transmitted by
sexual contact between a healthy person and an infected person. The sexually
transmitted diseases are also called venereal diseases (VDs). Some 30 different types
of STDs are known. For example : Gonorrhoea, Syphilis, Trichomonas, Genital warts,
AIDS.

HOW DO ORGANISMS REPRODUCE?

1. What are different methods of reproduction?

2. Name two plants that are bisexual.
3. What is pollination.
4. When does DNA copying occur?
5. How does the embryo get nourishment?
6. What is STD? Name two STDs.
7. Explain process of sexual reproduction in plants.
8. With the help of diagrams explain process of budding in Hydra.
9. Name the one unisexual plant.
10. Name on organism that grows by multiple fission
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HOW DO ORGANISMS REPRODUCE?
PREVIOUS YEAR QUESTIONS

1. Name two plants that are grown by vegetative propagation. (CBSE 2016)
2. What is reproduction? Explain two advantages of sexual reproduction over asexual
reproduction (CBSE 2016)
3. What is reproduction? Mention the importance of DNA copying in reproduction. (CBSE
2008)
4. List any two differences between pollination and fertilization. (CBSE2008)
5. Name two sexually transmitted disease caused due to infection and viral infection. How
it can these be prevented? (AI 2008)
6. Explain the terms:
a. Implantation
b. Placenta
c. What is the average duration of human pregnancy? (CBSE 2009)
7. Why is DNA copying is an essential part of the process reproduction? (AI 2009)
8. List any four methods of contraception used by humans. How does their use have a
direct effect on the health and prosperity of a family? (CBSE 2015)
9. Define the terms pollination and fertilization. Draw a diagram of a pistil showing pollen
tube growth into the ovule and label them:
OR
Describe in brief the role of (i)testis (ii) seminal vesicle, (iii) vas deferens, (iv)ureter and
(v) prostate gland in human male reproductive system (CBSE 2012)
10. (a) Draw a diagram of the longitudinal section of a flower and label on it sepal, petal,
ovary and stigma.
(b)Write the names of male and female reproductive parts of a flower.
OR
(a)What is fragmentation in organisms? Name a multicellular organism which
reproduces by this method.
(b)What is regeneration in organism? Describe regeneration in Planaria with the help of
a suitable diagram. (CBSE 2011)
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HOW DO ORGANISMS REPRODUCE?
TEST

Time taken: 40minutes

Maximum marks: 26 marks

1. Name two nucleic acids? What happens during copying of DNA? Why does
organism reproduce? (3)

2. What is binary and multiple fission? Name the organism in which they occur. (3)

3. How do potato and Bryophyllum plants reproduce vegetatively? What is self and
cross pollination? (5)

4. Devise an experiment to show germination of gram seed. Draw well labeled

diagram of a bisexual flower. (5)
5. State the functions of
a. Testis
b. Ovaries
c. Vas deferens
d. Stamen
e. Pistil (5)
10. What are the different methods of contraception in males and female human
beings? (5)
The Learning Tree

Class X Science
NCERT Solution for How do Organisms Reproduce

NCERT IN-TEXT QUESTIONS SOLVED

Q1. What is the importance of DNA copying in reproduction?
Ans. DNA copying is an important phenomenon of reproduction through which the organisms pass on their characteristics
to their offspring. It maintains the characteristics in different generations of the species. It also produces variations which
are useful for the survival of species for long time.
Q2. Why is variation beneficial to the species but not necessary for the individual?
Ans. Accumulation of variations after several generations results in new set of traits required for survival. As they show
results after many generations so they are not important for individual.
Q3. How does binary fission differ from multiple fission?
Ans. Binauy Fission: An organism is divided into two individuals. Mitotic division takes place resulting in two identical
individuals or daughter cells. e.g., Amoeba.
Multiple Fission: Mitotic division takes place. The nucleus a ii diumrepeatedly to form a number of equal sized and similar
individuals, e.g.,
Q4. How will an organism be benefited if it reproduces through spores?
Ans. During adverse circumstances spore remain coated are means potideve over layer. This helps an organism survive
adverse conditions. Spores are means to tide over bad phases.
Q5. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Ans. More complex organisms cannot give rise to new individuals because:
1. Their body design is highly complicated.
2. There are specific organs to do specific functions.
3. There is a labour division in the body of complex organisms.
4. Exception is lizard, which can regenerate its tail.
Q6. Why is vegetative propagation practised for vowing same types of plants?
Ans. The process by which some plant can reproduce asexually It has their vegetative pars like roots, stems and leaves is
called vegetative propagation.
Plants raised by this method can befit flowers and fruits earlier than those produced from seeds.
Plants that have lost capability to produce seeds like banana, organge, rose and jasmine can be propagated. All plants
produced are genetically similar to the parent plant.
Q7. Why is DNA copying an essential part of the process of reproduction?
Ans. DNA copying is needed because information stored in DNA is used to e make protein. Synthesis of different proteins
will lead to altered body design. Thus, reproduction at its most basic level involves making copies of the blueprints of body
design.
Q8. How is the process of pollination different from fertilization?
Ans. Pollination is the transfer of pollen grains from the anther of a stamen to the stigma of a carpel. These are transferred
by agents such as insects, birds, wind or water.
Fertilization is defined as the fusion of a male gamete (sperm) with a female gamete (ovary) to form a zygote by sexual
reproduction.
Q9. What is the role of seminal vesicles and prostate gland?
Ans. Seminal vesicles are a pair of thin-walled muscular and elongated sacs which secrete a fluid for nourishment of
sperms.
Prostate glands also produce a fluid which is released in the urethra along with secretion of seminal vesicle. It affects the
vaginal pH so that sperms move smoothly inside the vagina.
Q10. What are the changes seen in girls at the time of puberty?
Ans. At the time of puberty, breast size begins to increase, with darkening of the skin of the nipples. Also, girls begin to
menstruate at around this time.
Q11. How does the embryo get nourishment from its mother's body?
Ans. The embryo grows inside the mother's womb and gets nourishment from its mother's blood through placenta. Placenta
contains villi which connects the embryo with the mother's blood. These villi provides a large surface area for glucose and
oxygen to pass from mother to the embryo.
Q12. If a woman is using copper-T, will it help in protecting her front sexually Transmitted diseases?
Ans. No, it will not protect the woman from sexually transmitted diseases as fluid to fluid contact occurs in the vagina.
Q1. Asexilal reprodnction takes place through budding in
(a) amoeba (b) yeast. (c) plasnrodium. (d) leishrnaniia.
Ans. (b) yeast
Q2. Which of the following is not a part of the temule reproductive system in human begins?
(a) Ovary (b) Uterus (c) Vas deferens (d) Fallopian tube
Ans. (c) Vas deferens
Q3. The anther cantains
(a) sepals (b) ovules (c) carpel (d) pollen grains
Ans. (d) pollen grains
Q4. What are the advantage of sexual reproduction acre asexual reproduction?
Ans. In asexual reproduction, the offspring is almost identical to the parent because they have the same gene as their parent.
Thus, variation is not present. Sexual reproduction involves fusion of male and female gametes. The offspring exhibits
diversity of characters because they receive some genes from the mother and some from the father. The mixing of genes in
different combinations, results in genetic variations. This variation leads to the continuous evolution of various species to
produce various organisms.
Q5. What are the functions performed by testis in human beings?
Ans. The function of testis is to produce sperms and male sex hormone called testosterone.
Q6. Why data menstruation occur?
Ans. Menstruation occurs in females when the egg produced inside the cervix is not fertilized. Since the egg does not fuse
with the male gamete, so the thick and soft lining of uterus having a lot of blood capillaries in it are not required. This
unfertilized egg dies within a day and the lining breaks down shedding blood along with other tissues. This comes out of the
vagina in the form of bleeding.
Q7. Draw a labelled diagram of the longihaltnal section of a flower.

Refer to ncert
Q8. What are the different methods of contraception?
Ans. Contraception is the method to avoid pregnancy. Various methods of contraception are as follows:
Physical Barrier Methods: Use of condoms, diaphragms, cervical caps can be used. These prevent the entry of sperms into
the female genital tract by acting as a barrier between them.
Chemical Methods: Oral pills can be used which change the hormonal balance and stop release of egg. Vaginal pills kill
the sperms.
Surgical Methods: This includes vasectomy (sperm duct is removed) in males and tubectomy (removal of small portion of
fallopian tube) in females.
Q9. How are modes of reproduction different in unicellular and multicellular organisms?
Ans. Unicellular organisms have only one cell. There is no separate tissue for reproduction. So, they can reproduce by the
process of fission or budding. Multicellular organisms contain various cells and have separate system for reproduction. So,
they can reproduce by both sexual and asexual methods.
Q10. How does reproduction help in providing stability to the population of species?
Ans. Stability is provided by equalizing the birth and death ratio. Thus, the rate of birth should approximately be equal to
the rate of death.
Q11. What could be the reasons for adopting contraceptive methods?
Ans. The reasons for adopting contraceptive methods could be:
1. Protection from sexually transmitted diseases such as HIV-AIDS, gonorrhoea, syphilis, warts etc.
2. Restricting the number of children.
3. Sufficient gap between successive births.
4. Enjoying a good reproductive health.
5. Controlling population