KSEEB SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce?

KSEEB SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce? are part of KSEEB SSLC Class 10 Science Solutions. Here we have given Karnataka SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce?.

Karnataka SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce?

KSEEB SSLC Class 10 Science Chapter 8 Intext Questions

Text Book Part II Page No. 38

Question 1.
What is the importance of DNA copying in reproduction?
DNA is a chemical or complex compound which works as genetic material found in every cell of. all organisms. Genetic informations are carried by DNA from parental generation to daughter generations. In reproduction, it is very important to create a DNA copy. The DNA in the cell nucleus is the information source for making proteins. Cells undergo different chemical reactions to build copies of their DNA. This creates two copies of the DNA in a single reproducing cell. It is therefore, possible for the organism to produce organism of similar type.

Question 2.
Why is variation beneficial to the species but not necessarily for the individual?
Variations are a kind of change in genotype of an individual. These changes are caused by sudden or slow change in surroundings and other associated factors with individuals or species. It is found that for a species, the environmental conditions change so drastically that their survival becomes difficult. Thus, their internal genotype changes to give offspring resistant to the surrounding and these variants help in the survival of the species. However, variations are not necessary for the individual organisms as preservation of specific species character. Variation has nothing to do with normal life processes.

Text Book Part II Page No. 43

Question 1.
How does binary fission differ from multiple fission?

Binary fission: It is a simple kind of division which formate new individual. In binary fission, a single cell divides into two equal halves but it is possible only with very simple single cell kind. Amoeba and Bacteria divide by binary fission.

Multiple fission: Another type of simple division is multiple fission, in this, a single cell divides into many daughter, cells, e.g., Plasmodium divide by multiple fission.

Binary fission Multiple fission
In this fission, one cell split into two equal halves during cell division.
Eg: Bacteria.
Here one organism divide into many daughter cells simultaneously.
Eg: yeast.

Question 2.
How will an organism be benefited if it reproduces through spores?

One among the best and common types of vegetative reproduction is reproduction through spores. Advantages of spore formation:

  1. Huge numbers of spores are produced at a time.
  2. Distribution of spores are very easy by air to far-off places to avoid competition at one place.
  3. Spores can store genetic informations for very long time as they are covered by thick walls to prevent dehydration and other unfavourable conditions for new ones development.

Question 3.
Can you think of reasons why more complex organisms cannot . give rise to new individuals through regeneration?
The ability to produce new individual organisms from their body parts or give rise to new individual from cut or broken up parts is called regeneration. For example, simple animals like Hydra and Planaria. Higher complex organisms cannot give rise to new individuals through regeneration because regeneration is carried out by very specialised cells which is particular to some very particular species. These cells proliferate and forms mass of cells, which undergo changes to become various cell types and tissues. Every complex organism have multiple level of organization, hence it is very difficult to regenerate complete body capable of growth and development. All the organ systems of their body work together as a unit. They can regenerate their lost body parts such as skin, muscles, blood etc. However, they cannot give rise to new individuals through regeneration.

Question 4.
Why is vegetative propagation practised for growing some types of plants?

  1. Because plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds. Such methods also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds.
  2. Another advantage of vegetative propagation is that all plants produced are genetically similar enough to the parent plant to have all its characteristics.

Question 5.
Why is DNA copying an essential part of the process of reproduction?
Genetic informations are carried by DNA from parental generation to daughter generations. In reproduction, it is very important to create a DNA copy. It determines the body design of an individual. The reproducing cells produce a copy of their DNA through complicated chemical reactions and result in almost equal two copies of DNA. The copying of DNA always takes place along with the creation of additional cellular structure. This process is then followed by division of a cell to form two cells. While copying it preserves the genetic character or genotype of parents and hence, reproduce almost similar looking and working individuals.

Text Book Part II Page No. 50

Question 1.
How is the process of pollination different from fertilisation?
Secretions of the seminal vesicles and the prostate gland make the

Pollination Fertilisation
1. Transfer of, pollen grains to the stigma of a pistil is termed pollination. 1. Fusion of male germ cells or gametes (sperms) with female gametes (ova) is called fertilisation.
2. Pollinating agents like insects, wind or water assist the process. 2. Pollen tube carries male gametes to the female gamete in plants. In animals sperms swim through the body fluids in reproductive tract of female to reach egg.

Question 2.
What is the role of the seminal vesicles and the prostate gland?
Role of the seminal vesicles and the prostate gland is very important in fertilization. Seminal vesicles and prostate glands r.rovide lubrication and a fluid medium for easy transport of sperms. These secretions are also rich in nutrients like form of fructose, calcium and some enzymes.

Question 3.
What are the changes seen in girls at the time of puberty?
The changes (secondary sexual characters) seen in girls at the time of puberty are as follows:

  • A Breast size begins to increase, with darkening of the skin of the nipples at the tips of the breasts.
  • A Menstrual cycle starts.
  • A Thick hair starts growing in the genital area between the thighs and armpits.
  • A Pimples develop on face and widening of hips occurs.
  • The skin frequently becomes oily.

Question 4.
How does the embryo get nourishment inside the mother’s body?
After fertilization, the lining of uterus thickens and is richly supplied with blood to nourish the growing embryo. The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. It is embedded in the uterine wall. Placenta contains villi on the embryo’s side of the tissue and blood spaces on mother’s side surrounding the villi. This provides a large surface from mother to the embryo and waste products from embryo to mother.

Question 5.
If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Copper-T, is inserted in female body to react with semen entering with egg in uterus. Copper ions prevent pregnancy by inhibiting the movement of sperm, because the copper-lon-containing fluids are toxic to sperm. And, if a spermatozoa fertilizes an egg, the copper ion prevents implantation of the fertilized egg, and thus check pregnancy. But, it do not stop entrance of fluids inside the female body. Hence, it will not protect women from sexually transmitted diseases.

KSEEB SSLC Class 10 Science Chapter 8 Textbook Exercises

Question 1.
Asexual reproduction takes place through budding in
(a) amoeba
(b) yeast
(c) plasmodium
(d) leishmania
(b) yeast.

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
(c) Vas deferens.

Question 3.
The anther contains
(a) sepals
(b) ovules
(c) pistil
(d) pollen grains
(d) pollen grains.

Question 4.
What are the advantages of sexual reproduction over asexual reproduction?

Advantages of sexual reproduction:

  • Sexual reproduction is the process of combining two different genetic materials, resulting into offspring that share similar traits with their parents but are genetically diverse.
  • In sexual reproduction, large number of species with variations are produced. Thus, it ensures survival of species in a population.
  • The newly formed individual has characteristics of two genetically different parents.
  • Variations are more viable in sexual reproduction.

Question 5.
What are the functions performed by the testis in human beings?
The male gametes sperms are produced by the gonads-the testes. Testes also produce a hormone called testosterone, which is responsible for secondary sexual characters developing at the time of puberty in males.

Question 6.
Why does menstruation occur?

In female body, blood and mucous flows out every month through the vagina which is termed menstruation. If the egg present inside uterus does not get fertilised, then the lining of the uterus breaks down slowly and comes out in the form of blood and mucous from the vagina. This is complete process of menstruation.

This process occurs every month as one egg is released from the ovary every month and at the same time, the uterus (womb) prepares itself to receive the fertilised egg. Thus, the inner lining of the uterus gets thickened and is supplied with blood to nourish the embryo.

Question 7.
Draw a labelled diagram of the longitudinal section of a flower.
KSEEB SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce Ex Q 5

Question 8.
What are the different methods of contraception?

Contraception or birth control methods include: condoms, the diaphragm, the contraceptive pill, implants, IUDs (intrauterine devices), sterilization and the morning after pill and many more. Some of best methods are given below:

• Natural methods: It involves avoiding the chances of meeting of sperms and ovum. In this method, the sexual intercourse is avoided by the couple from day 10th to 17th of the menstrual cycle of female as in this period, ovulation is expected and therefore, the chances of fertilisation are very high.

• Barrier methods: In this method, the fertilisation of ovum and sperm is checked out with the help of artificially developed barriers. Barriers are developed for both males and females. Most common barriers available in market are condoms.

• Oral contraceptives: In this method, tablets or drugs are taken orally by females to check pregnancy. These contain small doses of hormones in forms of pills that prevent the release of eggs and thus, fertilisation can not occur. .

• Implants and surgical methods: Contraceptive devices are also developed as the loop or Copper-T to prevent pregnancy. Surgical methods are also used to block the gamete transfer. It includes the blocking of vas deferens to prevent the transfer of sperms known as vasectomy. Similarly, in tubectomy in this fallopian tubes of the ’female can be blocked, so that the egg will not reach the uterus.

Question 9.
How are the modes for reproduction different in unicellular and multicellular organisms?

Unicellular organisms

Multicellular organisms

In Unicellular organisms reproduction takes place by fission, and budding etc. In multicellular organisms reproduction takes place by regeneration budding and vegetative propagation, spore formation and sexual reproduction.

Question 10.
How does reproduction help in providing stability to populations of species?
Populations of organisms fill well defined places or niches in the ecosystem. The consistency of DNA copying during reproduction is important for the maintenance of body design features that allow the organism to use that particular niche. Reproduction is therefore linked to the stability of population of species.

Question 11.
What could be the reasons for adopting contraceptive methods?
The reasons for adopting contraceptive methods are,

  1. Couples are not interested to get issues early.
  2. 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 be adversely affected.
  3. There may be pressure to avoid having children from government agencies.

KSEEB SSLC Class 10 Science Chapter 8 Additional Questions and Answers

Question 1.
Draw a neat diagram showing
KSEEB SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce Ad Q 1

Question 2.
Give an example for Fragmentation.

Question 3.
Give examples where Regeneration takes place.
Hydra and Planaria.

Question 4.
Name the plants where vegetative propagation take place.
Sugarcane, roses or grapes etc.

Question 5.
Draw a neat diagram and label the parts showing germination of a seed.
KSEEB SSLC Class 10 Science Solutions Chapter 8 How do Organisms Reproduce Ad Q 5

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