3 – Life Processes in Living Organisms | Part 3 | Science II | Class 10

The blog presents the short Questions and Answers of the Chapter 3, Life Processes in Living OrganismsPart 2, from Science Part II of Class 10 from Maharashtra State Board. These can be very useful for students preparing for SSC Board exams as well as competitive exams, as it includes the objective type basic concepts & fundamentals.

1. What is fertilization in humans ?

Ans. Formation of zygote by union of sperm and ovum is called as fertilization.

2. How do the sperm complete their journey for fertilization ?

Ans. Sperms, in the numbers of few millions start their journey by the route of vagina – uterus – oviduct. One of those few million sperms fertilize the only ovum present in the oviduct.

3. What is the chromosome number in germ cells producing gametes?

Ans. The chromosome number in germ cells producing the gametes are diploid i.e. 2n. It includes 22 pairs of autosomes and 1 pair of sex-chromosomes i.e. (44 + XX or 44 + XY).

4. After meiosis what are the types of sperm and oocytes formed ?

Ans. These germ cells divide by meiosis. Due to this, gametes contain only haploid (n) number of chromosomes i.e. (22 + X or 22 + Y). Two types of sperms are produced as (22 + X) or (22 + Y) whereas oocytes are produced of only one type as (22 + X).

5. When is the meiotic division complete for the sperms and oocytes?

Ans. Both, sperms and oocytes are produced by meiosis. In case of sperms, process of meiotic division is completed before the sperms leave male reproductive tract. However, in case of oocytes, process of meiotic division completes after ovulation; during fertilization in oviduct.

6. Name the organ formed for supply of food material during growth in uterus ?

Ans. An organ called as placenta is formed for supply of food material during the growth in uterus.

7. In a couple, a man is totally responsible to have a boy or a girl, explain ?

Ans. During zygote formation, man contributes either X or Y chromosome to the next generation, but woman contributes only X-sex chromosome to the next generation. At the time of fertilization, if X-chromosomes comes from male, the child will be a girl and if Y-chromosome comes then the child will be a boy. Thus a man is totally responsible, whether the couple will have a boy or a girl child.

8. What is menstrual cycle ?

Ans. Female reproductive system undergoes some changes at puberty and those changes repeat at the interval of every 28 – 30 days. These repetitive changes are called as menstrual cycle.

9. Name the four harmones controlling menstrual cycle ?

Ans. Menstrual cycle is a natural process, controlled by four hormones:
(a) follicle stimulating hormone (FSH)
(b) luteinizing hormone (LH)
(c) estrogen
(d) progesterone

10. What is ovulation ?

Ans. (i) One of the several follicles in the ovary starts to develop along with the oocyte present in it, under the effect of follicle stimulating hormone.
(ii) This developing follicle secretes estrogen.
(iii) Endometrium of the uterus starts to develop (during first cycle) or regenerate (during subsequent cycles) under the effect of estrogen.
(iv) Meanwhile, developing follicle completes its development and bursts under the effect of luteinizing hormone and oocyte is released. This is called as ovulation.

11. What is menstruation ?

Ans. (i) If oocyte is not fertilized within 24 hours, corpus luteum becomes inactive and transforms into corpus albicans.
(ii) Due to this, secretion of estrogen and progesterone stops completely.
(iii) Endometrium starts to degenerate in absence of these two hormones.
(iv) Tissues of degenerating endometrium and unfertilized ovum are discarded out through vagina.
(v) This is accompanied with continuous bleeding that continues approximately for five days. This is called as menstruation.

12. Why there is need of rest along with special personal hygiene form women during mestrual cycle?

Ans. (i) Menstrual cycle is a natural process and the women experience severe pains during this period.
(ii) Severe weakness is felt due to heavy bleeding.
(iii) There is higher possibility of infections too during this overall period.
Due to all such reasons, there is need of rest along with special personal hygiene.

13. What are the various reasons for many couples not to have children ?

Ans. Many couples cannot have children due to various reasons as follows :
(i) In case of women, irregularity in menstrual cycle, difficulties in oocyte production, obstacles in the oviduct, difficulties in implantation in uterus and many other reasons are responsible for this.
(ii) Absence of sperms in the semen, slow movement of sperms, anomalies in the sperms are the reasons in case of males.

14. What is In Vitro Fertilization (IVF) technique ?

Ans. (i) IVF technique is used for having the child in case of those childless couples who have problems like less sperm count, obstacles in oviduct, etc.
(ii) In this technique, fertilization is brought about in the test-tube and the embryo formed is implanted in uterus of woman at appropriate time.

15. What is surrogacy and who is a surrogate mother ?

Ans. (i) Surrogacy is a technique in which a oocyte is collected from the ovary of the woman having problem in implantation in uterus.
(ii) That oocyte is fertilized in test-tube with the help of sperms collected from her husband.
(iii) The embryo formed from such fertilization is implanted in the uterus of
some other woman having normal uterus.
(iv) Such a woman, in whose uterus the embryo is implanted, is called as surrogate mother.

16. What is a sperm bank ?

Ans. (i) A sperm bank is the aid of modern medical technique through which a childless couple can have a child.
(ii) A sperm bank is a concept similar to blood bank.
(iii) In sperm bank the semen ejaculated by the desired men is collected after their thorough physical and medical check-up and stored in the sperm bank.
(iv) As per the wish of needful couple, oocyte of woman of the concerned couple is fertilized by IVF technique using the semen from sperm bank.
(v) Resultant embryo is implanted in the uterus of same woman. Name of the semen donor is strictly kept secret as per the law.

17. What are twins and their main types ?

Ans. When two embryos develop simultaneously in the same uterus two offsprings are delivered simultaneously. Such offsprings are called as twins. There are two main types of twins:
(a) monozygotic twins
(b) dizygotic twins

18. What are monozygotic twins ?

Ans. (i) Monozygotic twins are formed from single embryo.
(ii) During early period of embryonic development (within 8 days of zygote formation), cells of that embryo divide into two groups.
(iii) Those two groups develop as two separate embryos and thus monozygotic twins are formed.
(iv) Since monozygotic twins are genetically exactly similar to each other such twins are exactly similar in their appearance and gender. i.e. both will be either boys or girls.

19. What are conjoined twins ?

Ans. In case of monozygotic twins, if the embryonic cells are divided into two groups 8 days after the zygote formation; there is high possibility of formation of conjoined twins (Siamese twins).
(ii) Such twins are born with some parts of body joined to each other and some organs are common in such twins.

20. What are dizygotic twins ?

Ans. (i) Occasionally, two oocytes are released from the ovary of woman and
both oocytes are fertilized by two separate sperms and thus two zygotes are formed.
(ii) Two embryos are formed from those two zygotes and both of those embryos are separately implanted in the uterus and thus dizygotic twins are delivered after complete development.
(iii) Such twins are genetically different and may be same of different by gender.

21. Define health ?

Ans. A person’s state of being physical, mental and social strongness is called as health.

22. Name two sexual diseases and their symptoms ?

Ans. Two sexual diseases caused by bacteria are: Syphilis and Gonorrhoea.
(i) Symptoms of Syphilis : Occurrence of chancre (patches) on various parts of body including genitals, rash, fever, inflammation of joints, alopecia, etc.
(ii) Symptoms of Gonorrhoea : Painful and burning sensation during urination, oozing of pus through penis and vagina, inflammation of urinary tract, anus, throat, eyes, etc.



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