CBSE Class 10 Biology How Do Organisms Reproduce Worksheet Set B

MULTIPLE CHOICE QUESTIONS:

Question. The two oviducts in a human female unite into an elastic bag like is known as
a. Vagina
b. Uterus
c. Fallopian tube
d. Cervix
Answer. B

Question. Which of the following disease is transmitted sexually?
a. Kala azar
b. Jaundice
c. Cholera
d. Syphilis
Answer. D

Question. Which of the following is a contraceptive?
a. Copper t
b. Condom
c. Diaphragm
d. All of these
Answer. D

Question. When a animal is cut into pieces and each piece grows into a complex organism. What is the process?
a. Budding
b. Fragmentation
c. Spore formation
d. Regeneration
Answer. D

Question. Which is the portion on which grafting is done it provides the roots?
a. Stock
b. Scion
c. Both a and b
d. None of these
Answer. A

Question. Where does fertilization occur in human females?
a. Uterus
b. Cervix
c. Oviduct
d. None of these
Answer. C

Question. Growing fetus derive nutrition from mother’s blood through
a. Uterus
b. Fallopian tube
c. placenta
d. cervix
Answer. C

Question. What is the puberty age in human males?
a. 8-10
b. 10-12
c. 12-14
d. 14-16
Answer. C

Question. Fruits are formed from
a. Stamen
b. Stigma
c. Ovary
d. Ovule
Answer. C

Question. IUCD is for
a. Vegetative propagation
b. Contraception
c. Increasing fertility
d. Avoiding miscarriage
Answer. B

Question. Which among the following is a unicellular organism that reproduces by budding?
(a) Hydra
(b) Planaria
(c) Yeast
(d) Spirogyra
Answer. C

Question. Which among the following does not reproduce by spore formation:
(a) Penicillium fungus
(b) Yeast fungus
(c) Mucor fungus
(d) Rhizopus fungus
Answer. C

Question. The rapid spreading of bread mould on slices of bread are due to:
(i) Presence of large number of spores in air
(ii) Presence of large number of thread-like branched hyphae
(iii) Presence of moisture and nutrients
(iv) Formation of round shaped sporangia
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (i) and (ii)
(d) (iii) and (iv)
Answer. A

Question. The asexual reproduction in the Spirogyra involves:
(a) Breaking up of filaments into smaller bits
(b) Division of a cell into many cells
(c) Division of a cell into two cells
(d) Formation of a large number of buds
Answer. A

Question. Reason for the greater similarities among the off springs produced by asexual reproduction, is:
(i) Asexual reproduction involves only one parent
(ii) Asexual reproduction involves two parents
(iii) Asexual reproduction involves gametes
(iv) Asexual reproduction does not involve gametes
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iv)
(d) (i) and (iv)
Answer. D

Question. The process of the division of cell into several cells during reproduction in Plasmodium is termed as:
(a) Fragmentation
(b) Budding
(c) Multiple fission
(d) Binary fission
Answer. C

Question. The number of chromosomes in parents and off springs of a particular species remains constant due to:
(a) Doubling of chromosomes after zygote formation
(b) Halving of chromosomes during gamete formation
(c) Doubling of chromosomes after gamete formation
(d) Halving of chromosomes after gamete formation
Answer. B

Question. A Planaria worm is cut horizontally in the middle into two halves P and Q such that the part P contains the whole head of the worm. Another Planaria worm is cut vertically into two halves R and S in such a way that both the cut pieces R and S contain half head each. Which of the cut pieces of the two Planaria worms could regenerate to form the complete respective worms?
(a) Only P
(b) Only R and S
(c) P, Rand S
(d) P, Q, R and S
Answer. D

Question. The number of chromosomes in both parents and off s prings of a particular species remains constant because:
(a) Chromosomes get doubled after zygote formation
(b) Chromosomes get doubled after gamete formation
(c) Chromosomes get halved during gamete formation
(d) Chromosomes get halved after gamete formation
Answer. C

Question. An organism capable of reproducing by two asexual reproduction methods one similar to the reproduction in yeast and the other similar to the reproduction in Planaria is:
(a) Spirogyra
(b) Hydra
(c) Bryophyllum
(d) Paramecium
Answer. B

ASSERTION REASON QUESTIONS:-

DIRECTION: Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Question. Assertion (A): Spores are unicellular bodies.
Reason(R) : The parent body simply breaks up into smaller pieces on maturation.
Answer. C

Question. Assertion(A) : Asexual reproduction is a primitive type of reproduction.
Reason (R) : Asexual reproduction involves only mitotic cell division.
Answer. B

Question. Assertion(A) : The offspring produced by sexual reproduction is likely to adjust better in environmental fluctuation.
Reason (R) : During the fusion of gametes there is mixing of genetic material from Two parents.
Answer. A

Question. Assertion (A): Testes lie in penis outside the body.
Reason (R): Sperms require temperature lower than the body temperature for development
Answer. C

Question. Assertion (A): Unisexual flowers have separate male and female flowers whereas a typical monocot embryo comprises an embryonal axis with single cotyledon.
Reason (R): Cucumber, pumpkin and water melon are example of unisexual flowers.
Answer. B

CASE STUDY BASED QUESTION

Q.1. Read the following and answer the questions:

Preeti is very fond of gardening. She has different flowering plants in her garden. One Day few naughty children entered her garden and plucked many leaves of Bryophyllum plant And threw them here and there in the garden. After few days, Preeti observed that new Bryophyllum plants were coming out from the leaves which fell on the ground.

Question. What does the incidence sited in the paragraph indicate?
(a) Bryophyllum leaves have special buds that germinate to give rise to new plant.
(b) Bryophyllum can propagate vegetatively through leaves.
(c) Bryophyllum is a flowering plant that reproduces only asexually
(d) Both (a) and (b).
Answer. D

Question. Which of the following plants can propagate vegetatively through leaves like Bryophyllum?
(a) Guava
(b) Begonia
(c) Ginger
(d) Mint
Answer. B

Question. Do you think any other vegetative part of Bryophyllum can help in propagation? If yes, then which part?
(a) Roots
(b) Stems
(c) Flowers
(d) Fruits
Answer. B

Question. Which of the following plant is artificially propagated (vegetatively) by stem cuttings in horticultural practices?
(a). Potato
(b) Snake plant
(c) Rose
(d) Water hyacinth
Answer. C

2. Read the following and answer the questions:

Menstrual cycle is the cycle of events taking place in female reproductive organs, under the control of sex hormones, in every 28 days. At an interval of 28 days, a single egg is released from either of two ovaries. Regular Menstrual cycle stopped abruptly in a married women. She got herself tested and was happy to discover that she is pregnant with her first baby.

Question. Why menstruation stops in a pregnant female?
(a) The egg gets fertilised so need not to be expelled out of body
(b) Ovulation stops during pregnancy and so do menstruation
(c) Thick uterine lining is needed for proper development of embryo, so that it is retained
(d) All of these
Answer. D

Question. Select the correct sequence of acts that leads to pregnancy in a female.
A. Fertilisation of egg
B. Ovulation
C. Formation of zygote
D. Implantation
(a) D ⇒⇒C ⇒⇒B ⇒⇒A
(b) B⇒⇒ A⇒⇒C⇒⇒D
(c) A ⇒⇒ B⇒⇒ C⇒⇒ D
(d) D⇒⇒ C⇒⇒ A ⇒⇒B
Answer. B

Question. How is a zygote different from embryo?
(a) Zygote is formed by repeated division of embryo
(b) Zygote is formed by fusion of sperm and egg whereas embryo is formed by fusion of zygote with other zygote
(c) Zygote is single celled but embryo is multicellular
(d) Zygote is formed by fertilisation but embryo is formed without fertilization
Answer. C

Question. What change takes place in the uterus of a pregnant female?
(a) Uterine lining becomes thick and vascular
(b) Placenta develops which links the embryo to mother through umbilical cord
(c) Uterus lining containing lots of blood capillaries breaks down
(d) Both (a) and (b)
Answer. D

3. Read the following and answer the questions:

The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which
organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not necessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of population.

Question. What are common signs of sexual maturation in boys
a) Broadening of shoulders
b) Development of mammary glands
c) Broadening of waist
d) High pitch of voice
Answer. A

Question. Common sign of sexual maturation in girls is
a) Low pitch voice
b) Appearance of moustaches and beard
c) Development of mammary glands
d) Broadening of shoulders
Answer. C

Question. Which contraceptive method changes the hormonal balance of the body
a) Condoms
b) Diaphragms
c) Oral pills
d) Both a) and b)
Answer. C

Question. What should be maintained for healthy society
a) Rate of birth and death rate
b) Male and female sex ratio
c) Child sex ratio
d) None of these
Answer. B

4. Read the following and answer the questions:

The male reproductive system consist of portions which produce the germ-cells and other portions that deliver the germ-cells to the site of fertilisation. Testes are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than normal body temperature.
It also has a role of secretion of male sex hormone which brings changes in appearance seen in boys at the time of puberty. Vas deferens unites with a tube coming from urinary bladder. Urethra is a common passage for sperms and urine. Prostate gland and seminal vesicles add their secretions so that sperms are now in fluid.

Question. Name the sex hormone associated with males.
(a) Testosterone
(b) Progesterone
(c) Oestrogen
(d) None of these
Answer. A

Question. Which of the following statements is incorrect ?
(a) Sperms are present in a fluid
(b) Fluid provides nutrition to sperms
(c) Fluid makes easier transportation of sperms
(d) Fluid helps to bind the sperms together
Answer. D

Question. Testes are located outside the abdominal cavity in scrotum because
(a) sperms formation requires higher temperature than body temperature
(b) sperms formation requires lower temperature than body temperature
(c) it is easier to transport sperms from the scrotum
(d) None of these
Answer. B

Question. Which of the following statement is incorrect?
(a) Sperms and urine has a common passage from urethra.
(b) Sperms have long tail that helps them to move forward.
(c) Sperms contain genetic material.
(d) Sperms formation requires 1–3°C higher temperature than normal body temperature.
Answer. D

Question. What is the nature of semen?
(a) slightly acidic
(b) Neutral
(c) Slightly basic
(d) Strongly basic
Answer. C

Q.5. Read the following and answer the questions:

Reproduction is necessary for living things because it enables them to create offspring and continue their population. Through reproduction, they pass on their genetic information to the next generation. This ensures that their species continues to exist on Earth. The DNA copying mechanism is very necessary for the reproduction process as the copying of DNA can help in the transfer of the characters or information from the parents to the offspring. It can also generate the variations at the time of sexual reproduction. This variation is the reason behind the evolution.The DNA is the information site for making proteins and each specific type of protein leads to a specific type of body design and if DNA is not copied properly then offspring might face some serious abnormalities or might not even develop.

Question. Incorrect DNA copying mechanism can lead to
a. Abnormalities of body.
b. Speeding the process of reproduction
c. Formation of same blueprint of body design
d. Production of same type of proteins
Answer. A

Question. Choose the correct statements:
i. Human beings are bisexual organisms.
ii. Bisexual flower has both pistil and stamen.
iii. Plants bearing unisexual flower has only one type of flowers
iv. Both eggs and sperms are produced in one individual in hermaphrodite animal
a. i) and ii)
b. ii) and iii)
c. ii) and iv)
d. iii) and iv)
Answer. C

Question. Monoeciousspecies have both male and female sexual organs or flowers. These male and female parts are located at different locations on the plant. Dioecious species have separate male and female plants. They do not have the male and female flowers on the same plant.
Choose the correct statement
Assertion: Monoecious and Dioecious plant bears unisexual flowers.
Reason: Monoecious species has only one type of plant and dioeciousspecies has two types of plant.
a. If both the assertion and the reason are true and the reason is a correct explanation of the assertion.
b. If both the assertion and the reason are true and the reason is not a correct explanation of the assertion.
c. If the assertion is true but the reason is false.
d. If both the assertion and reason are false.
Answer. B

Question. Hari planted 100 Papaya plants. After few years he observed 75 plants have different pattern of flowering from the other 25 plants. He also found out that 75 plants having the same flowering pattern bear papaya fruits while the other 25 plants having the same pattern of flowering do not
produce fruit. What may be the reason?
Answer. Papaya plant is a dioecious plant having male and female reproductive organs in separate individuals. 75 papaya plants bear pistillate flowers and hence bear fruitswhile the remaining 25 plants bear staminate flowers and do not bear fruit.

Very Short answer type question -

Question. Define vegetative propagation.
Answer. Vegetative propagation is an asexual method of plant reproduction that occurs in its leaves,roots and stem.

Question. What are the agents of pollination?
Answer. Pollinating agents can be animals such as insects, birds, and bats; water; wind; and even plants themselves,

Question. Name the vegetative parts used in Bryophyllum and sugarcane for propagation.
Answer. Reproduction in Bryophyllum occurs asexually through vegetative propagation by leaves. The leaf of Bryophyllum is broad and has notches at its margins. ... Sugarcane has a thick, tillering stem which is clearly divided into nodes and internodes.

Question. Name any two organisms that reproduce by spores.
Answer. Rhizopus, mushroom etc., reproduce by spore formation

Question. Name two sex hormones.
Answer. The two main sex hormones — estrogen and testosterone

Short answer type question –

Question. Define the terms unisexual and bisexual giving one example of each.
Answer. Unisexual is the plant whose flowers contain either stamens or carpels but not both. Example Papaya, watermelon.
Bisexual is the plant whose flowers contain both stamens and carpels. Example : Hibiscus,Mustard.

Question.How does leishmania and Planaria reproduce differently ?
Answer. Leishmania reproduces by binary fission and Plasmodium reproduce by multiple fission.
ii ) Binary fission- It occurs under favourable conditions and gives rise to two individuals .
multiple fission - It occurs under both favourable and unfavourable conditions and forms several individual.

Question. How does bryophyllum produce new plants?
Answer. Bryophyllum can be reproduced by vegetative propagation by using either a piece of its stem or leaves. The leaves of a Bryophyllum plant have special buds in their margins which may get detached from the leaves, fall to the ground and then grow to produce a new plant.

Question. How does rhizopus reproduce?
Answer. Fungi and some algae reproduce asexually through spores. Rhizopus is a fungus and is commonly called bread mould.
Rhizopus grows as fine thread-like projections known as hyphae. Present on the top of hyphae is a blob-like structure, called sporangia. Sporangia produce numerous reproductive bodies called spores. Spores germinate under moist conditions to grow into new Rhizopus species.

Question. Exlain how human embryo get nourished in mother body?
Answer. The embryo gets nourishment inside the mother body through a special tissue called placenta. The embryo grows inside the mother's womb and gets nourishment from mother's blood through the tissue called placenta. The placenta is a temporary organ that develops in the uterus during pregnancy.

Question. What changes occur in the flower after fertilisation? 
Answer. After fertilisation the flower withers. The sepals and the petals dry up, the ovary converts into fruit, the ovule forms the seed and the zygote forms the embryo which is enclosed in the seed.

Question. How do potato and Bryophyllum plants reproduce vegetatively?
Answer. Potato tuber has depressions called ‘‘eyes’’ on its surface. These eyes have vegetative buds in them which germinate to produce a new potato plant. Similarly the fleshy leaves of Bryophyllum bear vegetative buds in the notches along the leaf margin. These buds germinate to form small plantlets which form new plants on being detached.

Question. What is the significance of sexual reproduction?
Answer. (a) A sexual reproduction results in new combination of characters and increases genetic variations.
(b) It promotes diversity of characters in the offspring.
(c) It speeds up the process of making variations in the population.

Question. What is regeneration? Name two organisms that can reproduce by regeneration.
Answer. Many fully differentiated organisms have the ability to give rise to new organisms from their body parts by being cut or broken into many pieces. This is known as regeneration. All organisms do not have the capacity to reproduce by regeneration.
Hydra and Planaria can reproduce by the process of regeneration.

Question. State the changes that occur in human males and females at puberty.
Answer. Puberty is the state of sexual maturiy in humAnswer : The changes that take place in males during puberty are growth of hair on the body, appearance of beard and moustache and the voice becomes hoarse. Females show development of breasts, and beginning of menstruation.

Question. State the advantages of seed formation in plants.
Answer. The seed contains the future plant or embryo which can develop into a seedling under appropriate conditions. The seed is in a state of dormancy and can be kept in secure state for long period of time.

Question. What is puberty?
Answer. Puberty is the age at which the gametes start forming in the male and female human beings. At this age boys and girls become sexually mature.

Question. Name the agents of pollination.
Answer. The agents that bring about pollination are wind, water, birds and insects.

Question. Name the following:
(i) Name two plants that cannot produce seeds.
(ii) An organism that reproduces by budding and regeneration.
(iii) An organism that grows by multiple fission
(iv) One unisexual flower.
Answer. (i) Bryophyllum, Banana (ii) Hydra (iii) Paramecium (iv) Maize flower

Question. State the functions of the human male and female sex hormones.
Answer. The human male sex hormone testosterone regulates the formation of the male gamete, the sperms and brings about changes in appearance seen in boys at the time of puberty.
The human female sex hormone estrogen brings about the changes occurring in girls at puberty and progesterone controls the uterus changes occurring during the menstrual cycle and also helps in maintaining the pregnancy.

Question. Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can these be prevented?
Answer. Bacterial infection: gonorrhoea
Viral infection: warts and HIV-AIDS
Prevention: Use of condoms by male.

Question. What is germination of seed?
Answer. When the seed gets the right conditions the embryo within it starts growing to form the shoot and the root. When the embryo emerges out of the seed to form a new seedling it is called the germination of seed.

Question. What happens when the egg is fertilised?
Answer. When the egg is fertilised zygote is formed, it starts dividing and gets implanted in the lining of the uterus.

Question. (a) Explain the terms:
(i) Implantation (ii) Placenta
(b) What is the average duration of human pregnancy?
Answer. (a) (i) Implantation: The zygote when fixes itself on the inner thick wall of uterus for further development is called implantation.
(ii) Placenta: It is the special tissue in the form of a disc which is embedded in the uterus wall. It provides large surface area for glucose and oxygen to pass from mother to the embryo. The waste generated by the embryo also passes into the mother’s blood through this placenta
(b) It takes nine months for the human pregnancy.

Question. (a) Name the parts labelled A, B, C, D, and E
(b) Where do the following functions occurs?
(i) Production of an egg
(ii) Fertilisation
(iii) Implantation of zygote
(c) What happens to the lining of uterus
(i) before release of fertilised egg.
(ii) if no fertilisation occurs.

Answer : (a) A → Fallopion tube
B → Ovary
C → Uterus
D → Cervix
E → Vagina
(b) (i) Production of an egg — ovary
(ii) Fertilisation — fallopian tubes
(iii) Implantation of zygote — lining of the uterus
(c) (i) Before release of fertilized egg – the uterus wall becomes thick.
(ii) If no fertilisation occurs – the lining of uterus slowly breaks down and comes
out in the form of bleeding.

Long answer type questions -

Question. Draw a well labelled diagram of the female reproductive system in humans.
Answer. 

Question. State the functions of the following:
(a) testis (b) ovaries (c) vas deferens (d) stamen (e) pistil
Answer. (a) Testis: Form the male gametes the sperms and secrete the male sex hormone testosterone
(b) Ovaries: Form the female gamete ovum or the egg cell and secrete the female sex hormones estrogen and progesterone.
(c) Vas deferens: Transport the sperms from the testis to the exterior.
(d) Stamen: Form the pollen grains in flowers. The pollen grains bear the male gametes.
(e) Pistil: The ovary forms the egg and the stigma helps in attracting the pollen grains for fertilisation.

Question. Illustrate the following with the help of a suitable diagrams:
(i) Regeneration in Planaria
(ii) Budding in Hydra (AI CBSE 2008)
Answer. (i) Regeneration in Planaria
Planaria: If it is divided into 3 parts a, b and c, each part grows as a new individual

Question. Draw a human male reproductive system of a human and label the parts. Mention the function of vas deferens and ureter?
Answer. 

Vas deferens:The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation.
The ureters are the part of the urinary system, whose function is to filter blood and create urine as a waste product. The ureters' role in the process is to carry urine from the kidneys to the bladder.

Question. List the advantages of vegetative propagation
Answer : The advantages of vegetative propagation are as follows
• It helps in the easy propagation of non–flowering plants.
• It helps in producing hybrids of various plants, with improved qualities.
• It helps in the propagation of a large number of populations in a very short duration.
• It helps in the propagation of plants that do not produce seeds or produce them in very small quantities 

Question. What are the limitations of the asexual mode of reproduction? Differentiate between asexual reproduction and sexual reproduction.
Answer : In asexual reproduction very little variation occurs within a generation. Asexual reproduction has a lesser significance for evolution of species. Asexual reproduction involves only a single individual. It does not require two sexes.
Sexual reproduction involves two different individuals, male and female sexes.
The offspring is produced due to fission of male and female gamet

Question. Explain various steps of budding in yeast.
Answer : Budding is a form of asexual reproduction usually observed in yeast.
• During this process, a small protrusion appears on the upper portion of the body of the organism. This bulge is called a bud.
• The bud gradually grows in size and forms an individual cell.
• From this newly budded cell, another bud appears at the tip.
• This process continues and many chains of buds are formed

Question. What is the importance of variation in the survival of individuals?
Answer : Variations help in survival of the organism by many different ways-
(i) It helps a species to survive
(ii) It also helps organisms to adapt to their environment as well as to changes which do occur in the environment.
(iii) It also helps a species to emerge strongly favoured by natural selection.
(iv) Variation helps a species to be resistant to diseases.

Question. Draw a diagram of human female reproductive system and label the parts?
Answer. 

Question. Describe various methods of asexual reproduction in organisms with suitable examples?
Answer. Asexual reproduction:
1. It is a form of reproduction in which a single parent produces a new offspring.
2. The new individuals developed are exact copies of their parents.
3. They are clones of their parents.
Various methods of asexual reproduction:
Vegetative propagation
1. In vegetative propagation, new plants are produced from roots, stems, leaves, and buds.
2. It is a form of asexual reproduction.
3. Examples- Tuber of potato, the rhizome of ginger
Budding
1. Bud is a small outgrowth that grows and gets detached from the parent body.
2. The new detached bud grows, matures, and produces more buds.
3. Examples- Hydra
Fragmentation
1. In this mode of reproduction, the growth is done by rapidly breaking down into more fragments.
2. When resources (water and nutrients) are available these fragments grow into new individuals.
3. Examples- Algae
Fission
1. Unicellular organism splits into new organisms.
2. There are two types of fission:
i. Binary fission (Amoeba, paramecium, etc.)
ii. Multiple fission (Plasmodium)
Spore Formation
1. Reproduction is done by spores.
Under favorable conditions germinate and develop into a new individual.

Question. Name and explain any three methods of contraception?
Answer. Three different methods of contraception:
1. Barrier method: Physical devices like condoms, diaphragm and cervical caps are used. The prevent entry of sperm in female genital tract, so, act as a barrier between them.
2.Chemical method: They act by changing hormonal balance of body so that eggs are not released and fertilisation cannot occur. Females use two types of pills for preventing pregnancies, that is oral pills and vaginal pills.
Oral pills has hormones that stop ovaries from releasing ovum into fallopian tube. It is also called oral contraceptives. Other contraceptive devices are loop or copper-T, are placed in uterus to prevent pregnancy.
3. Surgical method: They are carried out in males and females. In males, a small portion of the sperm duct (vas deferens) is blocked by surgical operation. It prevents the eggs to reach the uterus.
In females, fallopian tubes are cut and tied.

Question. Mention the site and product of fertilization in a flower. Draw labelled diagram of a pistil showing the following parts: Stigma, Style and Ovary.
Answer. 

Site of fertilization: Ovary
Product of fertilization: Zygote

Question. Name the mode of reproduction of the following organisms and state the important feature of each mode :
I. Planaria
II. Hydra
III. Rhizopus
a) We can develop new plants from the leaves of Bryophyllum. Comment.
b) List two advantages of vegetative propagation over other modes of reproduction. (2020)
Answer : (i) Planaria – Regeneration
Regeneration of organism from its cut body parts occurs by the process of growth and development. 
Regeneration is an asexual mode of reproduction common in lower plants and animals.
(ii) Hydra – Budding
In budding, a small part of the body of the parent organism grows out as a bud which on detaching forms a new organism.
Budding occurs in yeast, some protozoans and certain lower animals.
(iii) Rhizopus – Spores
Spores are usually produced in sporangia. 
Spore formation is a common method of an asexual reproduction in bacteria and most of the fungi.
a) The leaves of a Bryophyllum have special type of buds in their margins.
These buds may get detached from the leaves, fall to ground and then grow to produce new Bryophyllum plants. The buds can also drop to the ground together with the leaf and then grow to produce new plants.
b) Advantages of vegetative propagation are
: It is a quick method of propagation.
The new plants produced by artificial vegetative propagation are exactly like the parent plants 

More Important Questions For How Do Organisms Reproduce

Question. Name the method by which spirogyra reproduces under favourable conditions. Is this method sexual or asexual?
Answer. Under favourable conditions spirogyra reproduces by a process known as fragmentation. This is an asexual mode of reproduction.

Directions: In the following questions, a statement of assertion(A) is followed by a statement of reason(R).
Mark the correct choice as:
(a)Both assertion (A) and reason(R)are true and reason(R)is the correct explanation of assertion(A)
(b)Both assertion (A) and reason(R) are true but reason (R) is not the correct explanation of assertion (A)
(c)Assertion (A) is true but reason(R) is false
(d)Assertion (A) is false but reason (R)is true

Question. Draw a labeled diagram of a human male reproductive system.
Answer.

Question.Which of these life processes of an organism helps in the growth of its population?
(a)Nutrition
(b) Respiration
(c) Reproduction
(d) Excretion

Answer : (c) Reproduction

Question.How will an organism benefit if it reproduces through spores?
Answer. The reproduction by spores takes place in plants. Spores are covered by hard protective coat which enables them to survive in unfavorable conditions such as lack of food, water and extreme temperatures. When the conditions are favorable the spores can grow to produce new plants. Thus reproduction by spores’ benefits the plant because by surviving under adverse conditions, the spores make these plants live forever.

Question.The number of chromosomes in parents and offspring of a particular species remains constant due to—
(a)doubling of chromosomes after zygote formation
(b) halving of chromosomes during gamete formation
(c) doubling of chromosomes after gamete formation
(d) halving of chromosomes after gamete formation

Answer.  (b) halving of chromosomes during gamete formation

Question. Define pollination. Explain the different types of pollination. List two agents of pollination. How suitable pollination does leads to fertilization?
Answer. Pollination: -Transfer of pollen from anther to stigma of the flower.

Types of pollination:
(a) Self Pollination: Transfer of pollen from anther to stigma occurs in the same flower.

(b) Cross Pollination: Pollen is transferred from anther of one flower to stigma of another flower.

Agents of pollination: Wind, Water, Insects and Animals

Agents of pollination: Wind, Water, Insects and Animals

A tube grows out of the pollen grain and travels through the style, to reach the female germ cell in the ovary to cause fertilization.

Class 10 Science How Do Organisms Reproduce Notes and Questions

Short Answer Questions 

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. Name the part of Bryophyllum where the buds are produced for vegetative propagation.
Answer : Bryophyllum propagates vegetatively by the buds produced at the margins of leaves.

Question. Name the method by which Spirogyra reproduces under favourable conditions. Is this method sexual or asexual?
Answer : The method by which Spirogyra reproduces under favorable conditions is fragmentation. This is an asexual mode of reproduction.

Question. Name the causative agent of the disease “kala- azar” and its mode of asexual reproduction
Answer : Causative agent of the disease Kala-azar is Leishmania. It reproduces asexually by binary fission.

Question. Name an organism which reproduces by spore formation. List three conditions favourable for spores to germinate and grow
Answer : Rhizopus reproduce by the method of spore formation.
The three conditions favourable for spores to germinate and grow are moisture, suitable temperature and food (nutrition).

Question. How does Plasmodium reproduce. Is this method sexual or asexual?
Answer : Plasmodium reproduces through multiple fission method. In this method, the parent organism splits to form many new organisms at the same time. This is an asexual method of reproduction.

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.
Answer. (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? 
Answer. 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? 
Answer. 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? 
Answer. 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?
Answer. 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?
Answer. 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?
Answer. 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.
Answer. 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?
Answer. 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.
Answer. 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?
Answer. 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.
Answer. 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?
Answer.. 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.

VERY SHORT ANSWER TYPE(1 MARK)

Q1) Name a plant where buds develop on the leaves to produce new plants.
Q2) A large variety of plants like banana, rose and sugarcane are grown by vegetative means.Give reasons.
Q3) What do we call the undifferentiated mass of cells formed during tissue culture?
Q4) Mention a disadvantage of vegetative propagation.
Q5) Describe fragmentation in Spirogyra with the help of diagram.
Q6) How does sexual reproduction result in variation /diversity of characters in the offspring?
Q7) How many male gametes are formed by a pollen grain?
Q8) What is ovulation?
Q9) Why are petals scented and coloured?
Q10) Which organ enables the developing foetus to obtain nourishment from the mother’s blood?
Q11) Name the structure formed after fertilization of ovum by the sperm.
Q12) What is menopause?
Q13) Name the causative organism of AIDS.
Q14) Name the female gonad and female gametes.
Q15) Name two biotic agents of pollination.
Q16) Name two abiotic agents of pollination.
Q17) What happens if the mature ovum is not fertilized in a female?
Q18) What does the term ‘menarche’ signify?
Q19) Write name of one male and one female sex hormone.

SHORT ANSWER TYPE-1(2MARKS)

Q1)Define reproduction.why is it important?
Q2)Mention two features of asexual reproduction.
Q3)Mention the two most common methods of asexual reproduction in plant.
Q4)Name the type of reproduction involved in the following;
(i) a slice of bread has greenish –yellow patches.
(ii) Potato in the store-room starts sprouting.
Q5)Mention two fungi that reproduce asexually by spore formation.(Rhizopus,yeast)
Q6)How do organisms reproduce by budding?
Q7)Give the name of a unicellular and a multicellular organism which reproduce by budding.(hintyeast, hydra)
Q8)Name any two curable sexually transmitted diseases?
Q9)Give two reasons why frequent pregnancies must be control.
Q10_How do barrier methods prevent fertilization?
Q11)Describe surgical methods of birth control?
Q12)Reproduction is linked to stability of population of a species.Justify this statement.
Q13)Why changes are observed in the uterus if fertilization doesnot take place?
Q14)Why changes are observed in the uterus subsequent to implantation of young embryo?
Q15)Give two reasons for the appearance of variation among the offspring formed by sexual reproduction.

SHORT ANSWER TYPE-11(3 MARKS)

Q1) Describe the different methods of natural vegetative propagation.
Q2) How does plasmodium reproduce by multiple fission?
Q3) Describe budding in yeast?
Q4) Describe asexual reproduction. How do the following organisms reproduce?
a) Amoeba b)Plasmodium c)Hydra