Reproduction is a fundamental process that ensures the continuation of life on Earth. It is the ability of living organisms to produce offspring of their own kind. In Class 10 Science Chapter 7, “How Do Organisms Reproduce?”, we explore the various mechanisms and processes through which different organisms reproduce. From asexual reproduction in unicellular organisms to sexual reproduction in multicellular organisms, this chapter delves into the intricate details of reproductive strategies. Understanding how organisms reproduce is essential for comprehending the diversity and adaptability of life forms. This chapter also sheds light on the importance of reproduction in maintaining the genetic continuity and survival of species.
Table of Contents
Question 1: What is the importance of DNA copying in reproduction?
Answer- DNA (Deoxyribonucleic acid) determines the body design of an individual. DNA transfers inherited properties from parents to offsprings. DNA copying is also responsible for variations, which are necessary for development.
Question 2: Why is variation beneficial to the species but not necessarily for the individual?
Answer- Because sometimes for a species, the environmental conditions change so drastically that their survival becomes difficult. So due to variations some individuals will adapt according to the conditions, and will survive. Thus, these variants help in the survival of the species. However, all variations are not necessarily beneficial for the individual organisms.
Question 3: How does binary fission differ from multiple fission?
Answer- In binary fission, a single cell divides into two equal halves. Amoeba and Paramecium divide by binary fission. In multiple fission, a single cell divides into many daughter cells simultaneously. Plasmodium divide by multiple fission.
Question 4: How will an organism be benefited if it reproduces through spores?
Answer- Spores are distributed easily by air to far-off places to avoid competition at one place. Spores aremcovered by thick walls to prevent dehydration under unfavourable conditions.
Question 5: Can you think of reasons why more complex organisms cannot give rise to new individualsmthrough regeneration?
Answer- complex organisms have organ-system level of organization. All the organ systems of their body work together as an interconnected unit. So new complete organism cannot be regenerated from any body part.
Question 6: Why is vegetative propagation practised for growing some types of plants?
Answer- Some plants which cannot produce seeds or produce dormant seeds are produced by vegetative propagation
Question 7: Why is DNA copying an essential part of the process of reproduction?
Answer- DNA (Deoxyribonucleic acid) determines the body design of an individual. DNA transfers inherited properties from parents to offsprings. DNA copying is also responsible for variations, which are necessary formdevelopment.
Question 8: How is the process of pollination different from fertilization?
Answer- Pollination Fertilization
| Pollination | Fertilisation |
| 1. Pollination is the process of transfer of pollens from anther to stigma. | 1. Fertilization is the fusion of the male and female gametes. |
| 2. It is of two types: Self- pollination and cross- Pollination | 2. It is of two types: Internal and external fertilization. |
Question 9: What is the role of the seminal vesicles and the prostate gland?
Answer- The secretions from seminal vesicles and prostate glands lubricate the sperms and provide a fluid medium for easy transport of sperms. Their secretion also provides nutrients to sperms.
Question 10: What are the changes seen in girls at the time of puberty?
Answer- (1) Increase in breast size and darkening of skin of the nipples present at the tips of the breasts.
(2) Appearance of hair in the genital area.
(3) Appearance of hair in other areas of skin like underarms, face, hands, and legs.
(4) Maturity in the reproductive organs.
(4) Beginning of menstrual cycle.
(5) More secretion of oil from the skin, which results in the appearance of pimples.
Question 11: How does the embryo get nourishment inside the mother’s body?
Answer- Embryo get nutrients from blood of mother. Inside the uterus, the outer tissue surrounding the embryomdevelops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. Also, there is a special tissue called placenta, which is embedded in the uterine wall. The embryo receives the oxygen and nutrients from the mother’s blood via the placenta. The waste materials produced by the embryo are also removed through the placenta.
Question 12: If a woman is using a copper-T, will it help in protecting her from sexually transmitted
diseases?
Answer- No, because it is only contraceptive. It does not prevent the entry of semen.
EXERCISE
Question1: Asexual reproduction takes place through budding in
(a) amoeba. (b) yeast. ✓
(c) plasmodium. (d) leishmania.
Question 2: Which of the following is not a part of the female reproductive system in human beings?
(a) Ovary (b) Uterus
(c) Vas deferens ✓ (d) Fallopian tube
Question 3: The anther contains
(a) sepals. (b) ovules.
(c) carpel. (d) pollen grains. ✓
Question 4: What are the advantages of sexual reproduction over asexual reproduction?
Answer- (1) In sexual reproduction, more variations are produced. Thus, it ensures survival of species in a population.
(2) The new formed individual has characteristics of both the parents.
Question 5: What are the functions performed by the testis in human beings?
Answer- Testes produce sperms and a hormone called testosterone, which brings about secondary sexual characters in boys.
Question 6: Why does menstruation occur?
Answer- Menstruation is a process in which blood and mucous flows out every month through the vagina. This process occurs every month because one egg is released from the ovary every month and at the same time, the uterus (womb) prepares itself to receive the fertilized egg. Thus, the inner lining of the uterus gets thickened and is supplied with blood to nourish the embryo. If the egg does not get fertilized, then the lining of the uterus breaks down slowly and gets released in the form of blood and mucous from the vagina.
Question 7: Draw a labelled diagram of the longitudinal section of a flower
.Answer
Question 8- What are the different methods of contraception?
Answer- Contraceptive methods-
(i) Physical methods like condom, copper-T and loop etc can prevent fertilization.
(ii) Oral contraceptive tablets or drugs can prevent the release of egg, thus can stop fertilization.
(iii) Surgical methods like vasectomy in man and tubectomy in woman can stop fertilization.
Question 9: How are the modes for reproduction different in unicellular and multicellular organisms?
Answer- Unicellular organism reproduce only by asexually reproduction, but most of multicellular organism reproduce by sexual reproduction.
Question 10: How does reproduction help in providing stability to populations of species?
Answer- With reproduction an organism produce new individuals that resemble the parents. Also sexual reproduction causes variations, which are necessary for the survival of a species in drastic environmental changes.
Question 11: What could be the reasons for adopting contraceptive methods?
Answer- Contraceptive methods are mainly adopted because of the following reasons:
(i) To prevent unwanted pregnancies.
(ii) To control population rise or birth rate.
(iii) To keep appropriate gap between children for good health.
(iv) To prevent the transfer of sexually transmitted diseases.
PSEB 10th Class Science Important Questions Chapter 8 How do Organisms Reproduce?
Multiple Choice Questions
Question 1. Reproduction in Amoeba is by:
(A) Binary fission
(B) Multiple fission
(C) Budding
(D) Regeneration.
Answer:(A) Binary fïssion
Question 2. Biyophyllum in nature is reproduced by :
(A) Foliar adventitious buds
(B) Seeds
(C) Roots
(D) None of these.
Answer: (A) Foliar adventitious buds
Question 3. In which organism can we see budding?
(A) BrvophyHurn
(B) Hydra
C) Yeast
(D) All of above.
Answer: (B) Hydra
Question 4. In which of the following regeneration take place?
(A) Hydra
(B) Planaria
(C) Both A & B
(D) Human.
Answer:
(D) Human.
Question 5. In which of the following asexual reproduction take place through spore formation?
(A) Plasmodium
(B) Leishmania
(C) Spirogvra
(D) Rhizopus.
Answer:
(D) Rhizopus.
Question 6. In man why testes are located outside the abdominal cavity in scrotum?
(A) For security reasons
(B) Because sperms formation needs lower temperature than normal body temperature
(C) For proper delivery of sperms to the female vaginal tract during copulation
(D) None of the above.
Answer:
(B) Because sperms formation needs lower temperature than normal body temperature
Question 7. If the egg is not fertilized then lining of which of the following breaks and come out as blood?
(A) Cervix
(B) Oviduct
(C) Vagina
(D) None of these.
Answer:
(D) None of these.
Question 8. Which of the following shrivel and fall off when ovary risens to form fruit :
(A) Sepals
(B) Petals
(C) Stamen
(D) All of the above.
Answer:
(D) All of the above.
Question 9. Placenta is embedded in:
(A) Cervix
(B) Uterus
(C) Vagina
(D) Oviduct.
Answer:
(B) Uterus
Answer:
- Insects
- Frog
- Birds.
Question 57. Name two types of pollination.
Answer:
- Self-pollination
- Cross-pollination.
Question 58. Name three parts of pistil.
Answer:
- Ovary
- Style
- Stigma.
Question 59. What is foetus?
Answer:
A 12 week old embryo in the genital tract (uterus) of mother in viviparous animals is called foetus.
Question 60. List two characters which start developing in girls during puberty.
Answer:
- Growth of mammary glands.
- Growth of public hairs.
Question 61. State any two characters which appear during.puberty in boys.
Answer:
- Appearance of beard.
- Growth of public hairs.
Question 62. What is semen?
Answer:
Sperms and seminal plasma constitute semen.
Question 63. What is placenta?
Answer:
Placenta is an organ of attachment between an embryo and the uterine wall of mother w hich is for med jointly by them.
Question 64. Define pregnancy.
Answer:
The duration for whic h embryo remain implanted inibhe wall of uterus is called pregnancy or period of gestation.
Question 65. Name the organs of human male reproductive system.
Answer:
- 1. Testes
- Scrotum
- Epididymes
- Vasa deferntiai
- Urethra
- Reproductive glands (seminal vesicles prostate gland and and Cowper’s glands).
Question 66. Name the organs of human female reproductive system.
Answer:
- Ovariea
- Oviducts (Fallopian tubes)
- Uterus
- Vagina
- Vulva
- Female reproduct ive glands (Mammary glands).
Question 67. What is ovulation?
Answer:
Ovulation is release of mature ovum by bursting the mature follicle of ovary.
Question 68. Supply the scientific term for the following :
(i) Release of ovum from ovary.
Answer:
Ovulation
(ii) Onset of menstrual cycle in female.
Answer:
Puberty.
Question 69. What is the function of sperm duct?
Answer:
Sperm duct (vas deferens). It conducts sperms from testes to urethra.
Important Key Points and Notes
→ The female germ cells or eggs are made in the ovaries.
→ The fertilized egg, the zygote, gets implanted in the lining of the uterus and starts dividing.
→ The embryo gets nutrition from the mother’s blood with the help of a special tissue called the placenta.
→ Since the ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilized egg.
→ If the egg is not fertilized, the uterus lining slowly breaks and comes out through the vagina as blood and mucus. This cycle takes place roughly every month and is known as menstruation. It usually lasts for about two to eight days.
→ The process of sexual maturation is gradual.
→ Gonorrhea and syphilis and viral infections such as warts and HIV-AIDS are sexually transmitted diseases.
→ The sexual act always has the potential to lead to pregnancy.
→ Many mechanical, hormonal, and surgical methods are used to avoid pregnancy.
→ Pre-natal sex determination has been prohibited by law.
→ Because of reckless female foeticides, the child sex ratio is declining at an alarming rate.
→ Population explosion is raising problem in our country.
→ Birth control is an attempt to control the number of births in a family so that a couple may not have more children than required.
→ Physical barriers include the use of condoms, diaphragm, and cervical caps.
→ Chemical methods include the use of specific drugs by females i.e. oral pill and vaginal pill.
→ The use of IUCD (Copper-T) is very effective.
→ Surgical methods include vasectomy and tubectomy.
→ The communicable diseases occurring due to sexual contact are called sexually transmitted diseases such as gonorrhea, syphilis, and AIDS.
→ Reproduction: It is the process of producing new organisms by existing organisms of a species.
→ Sexual reproduction: The production of offspring by the fusion of male and female gametes is called sexual reproduction. It is biparental.
→ Asexual reproduction: The production of progeny without the fusion of male and female gametes is called asexual reproduction. It is uniparental.
→ Fission: The division of an organism into two or more individuals is called fission.
→ Budding: The process of development of an outgrowth due to repeated cell division at one specific site which grows into a tiny individual is called budding.
→ Vegetative propagation: The process of development of the new individual from any part of the body is called vegetative propagation.
→ Grafting: The technique of joining the different parts of two different plants to grow into one plant.
→ Unisexual: When the male and female are separate individuals, they are called unisexual.
→ Bisexual/Hermaphrodite: The organisms having male and female in a single individual are called bisexual/hermaphrodite.
→ Scion: A stem piece of good quality plant is grafted to grow into a new plant is called the scion.
→ Layering: The production of a new plant by covering the leaned branches of a plant under the soil.
→ Pollination: The transfer of pollen from another to stigma.
→ Fertilization: The fusion of male and female gametes is called fertilization.
→ Syngamy: The fusion of male gamete with female gamete is called syngamy.
→ Double fertilization: When the fertilization occurs two times (with ovum and polar cell) in angiosperms the process is called double fertilization.
→ DNA Replication: Duplication of DNA molecule by copying from a molecular template of DNA.
→ Regeneration: The formation of the lost part is called regeneration.
→ Gamete: Haploid sex cell is called gamete.
→ Zygote: Diploid fertilized egg is called a zygote. If undergoes cleavage (non-motile division) to form a complete organism.
→ Sperm: Haploid male gamete is called sperm.
→ Ovum: Haploid female gamete is ailed ovum.
→ Ovule: A structure in the ovary of a seed plant that develops into a seed after fertilization.
→ Puberty: The process of becoming sexually mature.
→ Ovulation: The release of the ovum from the ovary.
→ Implantation: The fixation of the embryo in the uterus is called implantation.
→ Placenta: It is the connection between mother and embryo.
→ Parturition: The process of giving birth to foetus is called parturition