NCERT Solutions class 10 Science Chapter 8 || How do organism reproduce Solution Class 10 Science Chapter 8 || How do organism reproduce Solution || Biology || Science ||

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Ques 1: Asexual reproduction takes place through budding in  

(a) amoeba.

(b) plasmodium.

(c) yeast.

(d) leishmania.

Ans 1: (c) Asexual reproduction takes place  in yeast through budding.  

Ques 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

Ans 2: (c) Vas deferens is not a part of the female reproductive system, it is present in the male reproductive system in human beings.  

Ques 3: The anther contains  

(a) sepals.

(b) carpel.

(c) ovules.

(d) pollen grains.

Ans 3: (d) The anther contains pollen grains.

Ques 4: What are the advantages of sexual reproduction over asexual reproduction?  

Ans 4: Advantages of sexual reproduction: 

» In sexual reproduction, more variations are produced. Thus, it ensures the survival of species in a population.  

» The new formed individual is having the characteristics of both the parents.

» Variations are more viable in sexual mode than in asexual one. This is because in asexual reproduction, DNA has to function inside the inherited cellular apparatus.  

Ques 5: What are the functions performed by the testis in human beings?  

Ans 5: The testes are the male reproductive organs that are located outside the abdominal cavity  within a pouch known as scrotum.  

Functions of testes:

» Produces sperms

» Produce a hormone called testosterone, which brings about secondary sexual characters in boys.  

Ques 6: Why does menstruation occur?  

Ans 6: Menstruation is a process in which blood and mucous flows out every month through the  vagina of the females. This process occurs every month because one egg is released from the ovary every  month and at the same time, the uterus (womb) inside the female prepares itself to receive the fertilized  egg. Thus, the inner lining of the uterus gets thickened and is supplied with richer blood to nourish the embryo. If the egg does not get fertilised, then the lining of the uterus breaks down slowly and gets released in the form of blood and mucous through the vagina.

Ques 7: Draw a labelled diagram of the longitudinal section of a flower.

Ans 7:


Ques 8:  What are the different methods of contraception?  

Ans 8:  The contraceptive methods can be broadly divided into the following types:
  
» Natural method: In natural method, it involves avoiding the chances of meeting of sperms and ovum. In this method, the sexual act is avoided from day 10th to 17th of the menstrual  cycle because during this period, ovulation is expected and therefore, the chances of fertilization are very high.
  
» Barrier method: In this method, the fertilization of ovum and sperm is prevented 
with the help of barriers. Barriers are available for both males and females. Condoms are barriers made of thin rubber that are used to cover penis in males and diaphragm is the barrier used in vagina by females.  

» Oral contraceptives: In this method, tablets or drugs are taken orally. These  contains the small doses of hormones that prevent the release of eggs and thus  fertilization cannot occur.  

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

Ques 9: How are the modes for reproduction different in unicellular and multicellular organisms?  

Ans 9: In unicellular organisms, reproduction occurs by the d division of the entire cell. The modes of reproduction in in unicellular organisms can be fission, budding, etc. while in  the multicellular organisms, specialised reproductive organs are present. Therefore, they can reproduce by complex reproductive methods such as vegetative propagation, spore formation, etc. In more complex multicellular organisms such as human beings and plants, the mode of reproduction is sexual reproduction.  

Ques 10: How does reproduction help in providing stability to populations of species?  

Ans 10: Living organisms reproduce for the continuation of a p particular species. It helps in  providing stability to the population of species by producing a new individual that resembles the parents. This is the reason w why cats give birth to only cats or dogs give birth to only dogs. Therefore, reproduction provides s stability to populations of dogs or cats or any other species.  

Ques 11: What could be the reasons for adopting contraceptive methods?  

Ans 11: 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 prevent the transfer of sexually transmitted diseases.

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