Monday, 29 June 2020

Chemical reactions and equations


1. Which of the following is a displacement reaction?
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 1
Answer/ Explanation
Answer: b
Explaination: Reason: Here sodium (Na) displaces to form sodium hydroxide.
2. Magnesium ribbon is rubbed before burning because it has a coating of
(a) basic magnesium carbonate
(b) basic magnesium oxide
(c) basic magnesium sulphide
(d) basic magnesium chloride
Answer
Answer: a
3. Which of the following statements about the given reaction are correct?
3Fe (s) + 4H2O (g) → Fe3O4 (s) + 4 H2 (g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent
(a) (i), (zi) and (iii)
(b) (in) and (iv)
(c) (i), (ii) and (iv)
(d) (ii) and (iv)
Answer
Answer: c
4. Which of the following are exothermic processes?
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Answer/ Explanation
Answer: a
Explaination: Reason: In both the cases, heat energy is evolved.
5. Oxidation is a process which involves
(a) addition of oxygen
(b) addition of hydrogen
(c) removal of oxygen
(d) removal of hydrogen
Answer
6. The process of reduction involves
(a) addition of oxygen
(b) addition of hydrogen
(c) removal of oxygen
(d) removal of hydrogen
Answer
7. Three beakers labelled as A, B and C each containing 25 ml of water were taken. A small amount of NaOH, anhydrous CuSO4and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solution contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?
(i) In beakers A and B, exothermic process has occurred.
(ii) In beakers A and B, endothermic process has occuBftd.
(iii) In beaker C exothermic process has occurred.
(iv) In beaker C endothermic process has occurred.
(a) (i) only
(b) (ii) only
(c) (i) and (iv)
(d) (iv), (ii) and (iii)
Answer
8. Give the ratio in which hydrogen and oxygen are present in water by volume.
(a) 1:2
(b) 1:1
(c) 2:1
(d) 1:8
Answer
9. Which among the following statement(s) is (are) true?
Exposure of silver chloride to sunlight for a long duration turns grey due to
(i) the formation of silver by decomposition of silver chloride
(ii) sublimation of silver chloride
(iii decomposition of chlorine gas from silver chloride
(iv) oxidation of silver chloride
(a) (i) only
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iv) only
Answer
10. MnO2 + 4HCl → 2 + 2H2O + Cl2
Identify the substance oxidized in the above . equation.
(a) MnCl2
(b) HCl
(c) H2O
(d) MnO2
Answer/ Explanation
11. A substance ‘X’ is used in white-washing and is obtained by heating limestone in the absence of air. Identify ‘X’.
(a) CaOCl2
(b) Ca (OH)2
(c) CaO
(d) CaCO3
Answer/ Explanation
12. When Ag is exposed to air it gets a black coating of
(a) AgNO3
(b) Ag2S
(c) Ag2O
(d) Ag2CO3
Answer
13. Which of the following is an endothermic process?
(a) Dilution of sulphuric acid
(b) Sublimation of dry ice
(c) Condensation of water vapours
(d) Respiration in human beings
Answer
14. In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?
(a) Lead sulphate (insoluble)
(&) Lead acetate
(c) Ammonium nitrate
(d) Potassium sulphate
Answer
15. What type of chemical reactions take place when electricity is passed through water?
(a) Displacement
(b) Combination
(c) Decomposition
(d) Double displacement
Answer/ Explanation
16. Select the oxidising agent for the following reaction:
H2S + I2 > 2HI + S
(a) I2
(b) H2S
(C) HI
(d) S
Answer
17. A substance added to food containing fats and oils is called:
(a) Oxidant
(b) Rancid
(c) Coolant
(d) Antioxidant
Answer
18. The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called:
(a) antioxidation
(b) reduction
(c) rancidity
(d) corrosion
Answer
19. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:
(a) 1 : 1
(b) 2:1
(c) 4:1
(d) 1:2
Answer
20. When S02 gas is passed through saturated solution of H2S, which of the following reaction occurs?
(a) SO2 + 2H2S → 2H20 + 3S
(b) SO2 + 2H2S → H20 + 3S
(c)SO2 + H2S → H2O + S
(d) SO2 + H2O → SO3 + H2
Answer
21. Name the products formed when iron filings are heated with dilute hydrochloric acid
(a) Fe (III) chloride and water
(b) Fe (II) chloride and water
(c) Fe (II) chloride and hydrogen gas
(d) Fe (III) chloride and hydrogen gas
Answer/ Explanation
22. Pb + CuCl2 → PbCl2 + Cu
The above reaction is an example of:
(a) combination
(b) double displacement
(c) decomposition
(d) displacement
Answer
23. Which of the following gases can be used for storage (a) Carbon dioxide or Oxygen
(b) Nitrogen or Oxygen
(c) Carbon dioxide or Helium
(d) Helium or Nitrogen
Answer
24. A dilute ferrous sulphate solution was gradu¬ally added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disap¬pears. Which of the following is the correct explanation for the observation?
(a) KMnO4 is an oxidising agent, it oxidises FeSO4.
(b) FeSO4 acts as an oxidising agent and oxidises KMNO4.
(c) The colour disappears due to dilution; no reaction is involved.
(d) KMnO4 is an unstable compound and de-composes in presence of FeSO4. to a colourless compound.
Answer
25. In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
(a) 2H2 (l) + O2 (l) > 2H2O(g)
(b) 2H2 (g) + O2 (l) > 2H2O (l)
(c) 2H2 (g) + O2 (g) > 2H2O (l)
(d) 2H2 (g) +O2 (g) > 2H2O (g)
Answer
26. When green coloured ferrous sulphate crystals are heated, the colour of the crystal changes because
(a) it is decomposed to ferric oxide
(b) it loses water of crystallisation
(c) it forms SO2
(d) it forms SO3
Answer
27. 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O; is an example of
(i) displacement reaction
(ii) double displacement reaction
(iii) neutralisation reaction
(iv) combination reaction.
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Answer
28. Burning Magnesium ribbon is brought in the gas jar of carbon dioxide. Which of the following is correct ?
(i) It keeps on burning
(ii) It gets extinguished
(iii) Although CO2 is non-supporter of combustion but burning magnesium breaks CO2 into carbon and oxygen, oxygen helps in burning.
(iv) Carbon dioxide is supporter of combustion.
(a) (i) and (iv)
(b) (i) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)
Answer
29. What is observed when a solution of potassium iodide is added to silver nitrate solution ?
(a) No reaction takes place
(b) White precipitate of silver iodide is formed
(c) yellow precipitate of Agl is formed
(d) Agl is soluble in water.
Answer
30. Identify ‘x’, ‘y’ and ‘z’ in the following balanced reaction
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 1
(a) 2, 4, 2
(b) 2, 2, 4
(c) 2, 4, 4
(d) 4, 2, 2
Answer
31. Which of the following is precipitation as well as double displacement reaction?
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 2
Answer
32. Which of the following reactions will not take place ?
(a) Zn + CuSO4 → ZnSO3 + Cu
(b) 2KBr + Cl2 → KCl + Br2
(c) Zn + MgSO4 → ZnSO4 + Mg
(d) Mg + FeSO4 → MgSO4 + Fe
Answer
33. Which of the following involves combination of two elements ?
(a) N2(g) + 3H2(g) → 2NH3(g)
(b) CaO(s) + CO2(g) → CaCO3(g)
(c) 2SO2(g) + O2(g) → 2SO3f(g)
(d) NH3(g) + HCl(g) → NH4Cl(s)
Answer
34. In the reaction Hg2Cl2 + Cl2 → 2HgCl2The reducing agent is
(a) Hg2Cl2
(b) Cl2
(c) HgCl2
(d) Both Cl2 and HgCl2
Answer
35. Oxidation involves
(i) gain of electron
(ii) loss of electron
(iii) addition of oxygen or electronegative element
(iv) removal ofhydrogenorelectropositive element
(a) (i), (ii), (iii)
(b) (ii), (iii), (iv)
(c) (i), (iii), (iv)
(d) (i), (ii), (iv)
Answer
36. The formula of Ammonium phosphate is
(a) NH4PO4
(b) (NH4)2PO4
(c) (NH4)3PO4
(d) (NH4)3(PO4)2
Answer
37. Which of the following is a thermal decomposition reaction ?
(a) 2H2O → 2H2 + O2
(b) 2AgCl → 2Ag + Cl2
(c) ZnCO3 → ZnO + CO2
(d) H2(g) + Cl2(g) → 2HCl(g)
Answer
38. The following reaction is an example of a
4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)
(i) displacement reaction
(ii) combination reaction
(iii) redox reaction
(iv) neutralisation reaction [NCERT Exemplar Problems]
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (iii) and (iv)
Answer
39. Which of the following statements about the given reaction are correct ?
3Fe(s) + 4H2O(g) → Fe3O4(g) + 6H2(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as an oxidising agent [NCERT Exemplar Problems]
(a) (i), (ii) and (iii)
(b) (iii) and (iv)
(c) (i), (ii) and (iv)
(d) (ii) and (iv)
Answer
40. Which of the following are exothermic processes?
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals) [NCERT Exemplar Problems]
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (iii) and (iv)
Answer
41. Which among the following is (are) double displacement reactions ? [NCERT Exemplar Problems]
(i) Pb + CuCl2 → PbCl2 + Cu
(ii) Na2SO4 + BaCl2 → BaSO4 + 2NaCl
(iii) C + O2 → CO2
(iv) CH4 + 2O2 → CO2 + 2H2O
(a) (i) and (iv)
(b) (ii) only
(c) (i) and (ii)
(d) (iii) and (iv)
Answer
42. Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved ? [NCERT Exemplar Problems]
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction
(iv) Double displacement reaction
(a) (i) only
(b) (ii) only
(c) (iv) only
(d) (ii) and (iv)
Answer
43. Electrolysis of water is a decomposition reaction. The molar ratio of hydrogen and oxygen gases liberated during electrolysis of water is [NCERT Exemplar Problems]
(a) 1 : 1
(b) 2 : 1
(c) 4 : 1
(d) 1 : 2
Answer
44. Which of the following is (are) an endothermic process(es) ? [NCERT Exemplar Problems]
(z) Dilution of sulphuric acid
(ii) Sublimation of dry ice
(iii) Condensation of water vapours
(iv) Evaporation of water
(a) (i) and (iii)
(b) (ii) only
(c) (iii) only
(d) (ii) and (iv)
Answer
45. Which of the following gases can be used for storage of fresh sample of an oil for a long time? [NCERT Exemplar Problems]
(a) Carbon dioxide or oxygen
(b) Nitrogen or oxygen
(c) Carbon dioxide or helium
(d) Helium or nitrogen
Answer
46. The following reaction is used for the preparation of oxygen gas in the laboratory
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 3
Which of the following statement(s) is (are) correct about the reaction ? [NCERT Exemplar Problems]
(a) It is a decomposition reaction and endothermic in nature
(b) It is a combination reaction
(c) It is a decomposition reaction and accompanied by release of heat
(d) It is a photochemical decomposition reaction and exothermic in nature
Answer
47. Which one of the following processes involve chemical reactions ? [NCERT Exemplar Problems]
(a) Storing of oxygen gas under pressure in a gas cylinder
(b) Liquefaction of air
(c) Keeping petrol in a china dish in the open
(d) Heating copper wire in presence of air at high temperature
Answer
48. In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature ? [NCERT Exemplar Problems]
(a) H2(l) + O2(l) → 2H2O(g)
(b) H2(g) + O2(l) → 2H2O(l)
(c) H2(g) + O2(g) → 2H2O(l)
(d) H2(g) + O2(g) → m2O(g)
Answer
49. The brown gas evolved on heating of copper nitrate is
(a) O2
(b) NO2
(c) N2
(d) NO
Answer/Explanation
50. Zinc reacts with silver nitrate to form which compounds?
(a) Zn(NO3)2 + Ag
(b) ZnNO3 + Ag
(c) AgNO3 + Zn(NO3)2
(d) Ag + Zn(NO3)3
Answer/Explanation
51. MnO2 + 4HCl → MnCl2 + H2O + Cl2 The oxidising agent is
(a) MnO2
(b) HCl
(c) MnCl2
(d) Ag + Zn(NO3)3
Answer/Explanation
52.
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 4
The colour of iodine is
(a) green
(b) purple
(c) brown
(d) pink
Answer/Explanation
Direction (Q53 to Q57): In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
(a) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
(b) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
(c) Assertion is true but the Reason is false.
(d) The statement of the Assertion is false but the Reason is true.
53. Assertion: AgBr is used on photographic and x-ray film.
Reason: AgBr is photosensitive and changes to Ag and bromine in presence of sunlight and undergoes decomposition reaction.
Answer/Explanation
54. Assertion: Magnesium ribbon keeps on burning in atmosphere of nitrogen. Reason: Magnesium reacts with nitrogen to form magnesium nitrides and this reaction is combination reaction.
Answer/Explanation
55. Assertion: Zinc reacts with sulphuric acid to form zinc sulphate and hydrogen gas and it is displacement reaction.
Reason: Zinc reacts with oxygen to form zinc oxide.
Answer/Explanation
56. Assertion: MnO2 + 4HCl → MnCl2 + Cl2+ 2H2O is redox reaction.
Reason: MnO2 oxides HCl to Cl2 and gets reduced to MnCl2.
Answer/Explanation
57. Assertion: A lead nitrate on thermal decomposition gives lead oxide, brown coloured nitrogen dioxide and oxygen gas. Reason: Lead nitrate reacts with potassium iodide to form yellow ppt of lead iodide and the reaction is double displacement as well as precipitation reaction.
Answer/Explanation
58. The colour of FeSO4 crystal before ___________ heating is and after heating is ___________ .
Answer/Explanation
59. SO2 + 2H2S → 2H2O + 3S; SO2 is ___________ acting as agent.
Answer/Explanation
60. The reaction Cu + xHNO3 (cone.) → Cu(NO3)2 + yNO2 + zH2O The values of x, y and z are ___________ , ___________ and ___________ .
Answer/Explanation
61. A balanced chemical equation has equal masses of various elements in ___________ and ___________ .
Answer/Explanation
62.
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 5
is an example of ___________ reaction.
Answer/Explanation
63. All combustion reactions are oxidation reactions. [True/False]
Answer/Explanation
64. Displacement reaction can be redox reaction also. [True/False]
Answer/Explanation
65. In H2S + Cl2 → 2HCl + S, Cl2 is oxidising agent and H2S is reducing agent. [True/False]
Answer/Explanation
66. CaO + 2HCl → CaCl2 + H2O is neutralisation reaction. [True/False]
Answer/Explanation
67. Chemical reactions are those processes where new substances with old properties are formed. [True/False]
Answer/Explanation
Direction: Match Column I with Column II.
68.
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 6
Answer/Explanation
69. State one basic difference between a physical change and a chemical change. [CBSE 2011]
Answer/Explanation
70. What is meant by a chemical reaction? [CBSE 2011]
Answer/Explanation
71. On what basis is a chemical equation balanced?
Answer/Explanation
72. Balance the given chemical equation:
Al(s) + CuCl2(ag) → AlCl(aq) + Cu(s)
Answer/Explanation
73. Balance the given chemical equation:
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 7
Answer/Explanation
74. Balance the given chemical equation:
Answer/Explanation
75. AgNO3(aq) + NaCl(aq) → AgCl(g) ↓ + NaNO3(aq)
FeS + H2SO4 → FeSO4 + H2S ↑
Consider the above mentioned two chemical equations with two different kinds of arrows ( ↑ and ↓) along with product. What do these two different arrows indicate? [CBSE 2011]
Answer/Explanation
76. Hydrogen being a highly inflammable gas and oxygen being a supporter of combustion, yet water which is a compound made up of hydrogen and oxygen is used to extinguish fire. Why? [CBSE 2011]
Answer/Explanation
77. What happens chemically when quicklime is added to water filled in a bucket?
MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers 10
Answer/Explanation
78. What change in colour is observed when white silver chloride is left exposed to sunlight? State the type of chemical reaction in this change.
Answer/Explanation
79. How will you define a reducing agent?
Answer/Explanation
80. Potato chips manufacturers fill the packet of chips with nitrogen gas. Why? [DoE]
Answer/Explanation
81. Why do gold and platinum not corrode in moist air?
Answer/Explanation
82. Write two characteristics associated with rancid food.
Answer/Explanation
83. How will you indicate the following effect in a chemical equation? A solution made in water.
Answer/Explanation
84. Give reason for the following:
The burning of natural gas is an exothermic reaction.
Answer/Explanation
85. Give one example of a redox reaction which is also a combination reaction.
Answer/Explanation
86. Balance the given chemical equation:
HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
Answer/Explanation
Fill in the Blanks
1. The addition of oxygen to a substance is called …………. whereas removal of oxygen is called …………. .
2. The addition of hydrogen to a substance is called …………. whereas removal of hydrogen is called …………. .
3. Precipitation reactions produce insoluble …………. .
4. Reactions in which energy is given out are known as …………. .
5. Reaction in which an element displaces another element from its compound is called …………. .
6. Two antioxidants which are usually added to fat and oil containing foods to prevent rancidity, are …………., …………. .
7 …………. is the process in which metals are eaten up gradually by the action of air, moisture or a chemical on
their surface.
8. 2 FeSO4 → Fe2O3 + SO2 + ………….
9. Na2SO4 + BaCl2 → …………. + 2NaCl
10. Complete the missing components/variables given as x and y in the following reactions:
(a) Pb (NO3)2 (aq) + 2KI (aq) → Pbl2 (x) + 2KNO3 (y)
(b) Cu (s) + 2AgNO3 (aq) → Cu (NO3)2 (aq) + x (s)
on No comments:

Saturday, 6 June 2020


on No comments:

Reproductive health

Reproductive Health | Biology Notes for NEET/AIIMS/JIPMER

INTRODUCTION

According to the World Health Organisation (WHO), reproductive health means a total well-being in all aspects of reproduction, i.e., physical, emotional, behavioural and social.

REPRODUCTIVE HEALTH PROBLEMS AND STRATEGIES

  • India was amongst the first countries in the world to initiate the programmes called ‘family planning’ in 1951 which were periodically assessed over the past decades.
  • Reproductive health in a society forms a crucial part of general health. Some crucial concerns are as follows-
    • complication of pregnancy, childbirth and unsafe abortion.
    • maximum infection rates of sexually transmitted diseases (including HIV/AIDS) among the young people (15 to 24 years).
    • less education and lower future income for young mothers due to early pregnancy and child bearing.
  • Improved programmes covering wider reproduction-related areas are currently in operation under the popular name ‘Reproductive and Child Health Care (RCH) programmes’.
  • Health and education of young people and marriage and childbearing during more mature stages of life are important attributes to the reproductive health of a society.
  • Reproductive health programmes :
    • create awareness in both males and females about various reproduction related aspects with the help of audio-visual and print media.
    • provide sex education in schools to save the young school goers from myths and misconceptions about the sex related issues.
    • provide proper information about reproductive organs, adolescence and safe hygienic sexual practices.
    • educate the fertile couples and those in marriageable age group about birth control measures, prenatal and post natal care of mothers and child etc.

POPULATION EXPLOSION AND BIRTH CONTROL

  • The rapid increase  in human population size over a relatively short period is called human population explosion. 
  • Population growth rate depends on factors like fertility, natality, mortality, migration, age and sex structure.
  • The regulation of conception by preventive methods or devices to limit the number of offsprings is called birth control.
  • A birth control method which deliberately prevents fertilization is referred to as contraception.
  • Contraceptive methods are preventive methods and are of 
    2 types - temporary and permanent.
  • Temporary methods includes natural method, chemical method, mechanical means, physiological devices or hormonal methods and permanent method includes sterilization.
  • Natural methods work on the principle of avoiding chances of ovum and sperm meeting. It includes safe period, abstinence, coitus interruptus and lactational amenorrhea. 
  • A week before and a week after menses is considered as safe period (rhythm method) for sexual intercourse. The idea is based on the following facts-
    • Ovulation occurs on the 14th day of menstruation.
    • Ovum survives for about 2 days.
    • Sperms remain alive for about 3 days.
  • Periodic abstinence is one such method in which the couples avoid or abstain from coitus from day 10 to 17 of the menstrual cycle when ovulation could be expected. As chances of fertilization are very high during this period, it is called the fertile period.Therefore, by abstaining from coitus during this period, conception could be prevented.
  • Withdrawal or coitus interruptus (oldest method) is another method in which the male partner withdraws his penis from the vagina just before ejaculation so as to avoid insemination. This method has some drawbacks like male produces some lubricating fluid containing some sperm from his cowper's gland before ejaculation.
  • Lactational amenorrhea (absence of menstruation) method is based on the fact that ovulation and therefore the cycle do not occur during the period of intense lactation following parturition. Therefore, as long as the mother breast feeds the child fully, chances of conception are almost nil. 
  • Chemical methods means spermicides (such as lactic acid, citric acid, boric acid, potassium permanganate and zinc sulphate). Foams, jellies, pastes and creams, if introduced before sexual intercourse into the vagina, adhere to the mucous membrane and immobilize and kill the sperm by inhibiting oxygen intake. 
  • In mechanical methods, ovum and sperm are prevented from physically meeting with the help of barriers. Such methods are available for both males and females. 
  • Mechanical  methods are of following types condom, diaphragm, cervical caps, vaults and intrauterine devices (IUDs).
  • Condoms are barriers made of thin rubber/latex sheath that are used to cover the penis in the male just before coitus so that the ejaculated semen would not enter into the female reproductive tract. This can prevent conception. 
  • Diaphragms, cervical caps and vaults are rubber that are inserted into the female reproductive tract to cover the cervix during coitus. These prevent conception by blocking the entry of sperm through the cervix. These are reusable. Spermicidal creams, jellies and foams are usually used along with these barriers to increase their contraceptive efficiency.
  • IntraUterine Devices (IUDs) are inserted by doctors in the uterus through vagina. These Intra Uterine Devices are presently available as the non-medicated IUDs (e.g., Lippes loop), copper releasing IUDs (CuT, Cu7, Multiload 375) and the hormone releasing IUDs (Progestasert, LNG-20). 
  • IUDs increase phagocytosis of sperm within the uterus and the Cu ions released suppress sperm motility and fertilizing capacity of sperm. The hormone releasing IUDs, in addition, making the uterus unsuitable for implantation and the cervix hostile to the sperm. 
  • IUDs are ideal contraceptives for the females who want to delay pregnancy and/or space children. It is one of the most widely accepted methods of contraception in India.
  • Physiological (oral) devices (hormonal) includes birth control pills. Oral administration of small doses of either progestogens or progestogen–estrogen combination is another contraceptive method used by the females. These are used in the form of tablets and hence are popularly called the pills. 
  • Birth control pills check ovulation by inhibiting the secretion of FSH and LH that are necessary for ovulation.
  • Saheli –the new oral contraceptive for the females contains a non-steroidal preparation. It was developed by scientists at Central Drug Research Institute (CDRI) in Lucknow, India.
  • Pill Mala D is taken daily, and the pill Saheli is taken weekly.
  • Progestogens alone or in combination with estrogen can also be used by females as injections or implants under the skin.
  • Surgical methods, also called sterilization, are generally advised for the male/female partner as a terminal method to prevent any more pregnancies. Surgical intervention blocks gamete transport and thereby prevent conception. Sterilization procedures in the male is called ‘vasectomy’ and that in the female, ‘tubectomy’. 
  • In vasectomy, a small part of the vas deferens is removed or tied up through a small incision on the scrotum whereas in tubectomy, a small part of the fallopian tube is removed or tied up through a small incision in the abdomen or through vagina. 
Fig. : Vasectomy and Tubectomy

Table : Method of Birth Control

AMNIOCENTESIS

  • Amniocentesis is a pre-natal diagnostic technique to determine.
    • Sex of the developing baby.
    • Genetically controlled congenital diseases.
    • Metabolic disorders in foetus.
  • Process of amniocentesis involves the following steps :
    • Location of the foetus is determined by a technique called sonography (using high frequency ultrasound waves) to prevent accidental damage to the foetus.
    • A fine hollow needle is passed through the abdominal and uterine wall of a pregnant female (about 14th to 15th week after conception) into the amniotic cavity.
    • A small amount of amniotic fluid is withdrawn. It contains foetal skin cells and a number of proteins, especially enzymes. The cells can be cultured in vitro for further examination.  
Fig. : Amniocentesis

SIGNIFICANCE OF AMNIOCENTESIS

SEX DETERMINATION
  • The somatic cells of foetal skin drawn with the amniotic fluid are stained to determine the presence of sex chromatin (barr body). 
  • Presence of barr body indicates that the developing foetus as female is with 2 X-chromosomes out of which one X-chromosome is active, while other X-chromosome is heterochromatized into a darkly stained barr body.

CONGENTIAL DISEASE
  • By karyotypic studies of somatic cells, abnormalities due to changes in chromosome number like Down's syndrome, Turner's syndrome, Klinefelter's syndrome etc. can be determined.

METABOLIC DISORDER
  • By the enzyme analysis of amniotic fluid, different types of inborn metabolic disorders like phenylketonuria, alkaptonuria etc. can be detected.
  • These inborn errors are caused by the absence or inactivity of specific enzymes due to gene mutations. So with the help of amniocentesis, if it is confirmed that the child is likely to suffer from some incurable, congenital defect, the mother can go for abortion.

DRAWBACKS OF AMNIOCENTESIS

  • However, these days, the amniocentesis is being misused also. Mothers even get their normal foetus aborted if it is a female. This is just equivalent to killing of a normal child. So Govt. of India enforced the Pre-natal Diagnostic Techniques (Regulation and Prevention of Misuse) Act, 1994, since January 1, 1994 under which all genetic counselling centres and laboratories are required to apply for registration.
  • The violation of this act can bring a fine of ` 50,000 and imprisonment for two years.
  • The doctor's registration is also cancelled till the complaint is disposed of.

CHORIONIC VILLUS SAMPLING (CVS)

  • Amniocentesis is possible without a chance of injuring the foetus with the needle only after the sixteenth week of pregnancy. At this time, abortion is not safe. A new technique, named Chorionic Villus Sampling (CVS), can be done during the eighth to tenth week of pregnancy when abortion is safe for the woman. For CVS, cells are sucked into a catheter passed through the cervix. CVS technique provides a mass of rapidly dividing foetal cells, thus facilitating the examination of chromosomal disorders.
Fig:Chorionic Villus Sampling(CVS)

MEDICAL TERMINATION OF PREGNANCY (MTP)

  • Intentional or voluntary termination of pregnancy before full term is called medical termination of pregnancy (MTP) or induced abortion. 
  • Nearly 45 to 50 million MTPs are performed in a year all over the world which accounts to 1/5th of the total number of conceived pregnancies in a year.
  • Government of India legalised MTP in 1971 with some strict conditions to avoid its misuse. 
  • MTPs are considered relatively safe during the first trimester, i.e., upto 12 weeks of pregnancy. 
  • Misoprostol (a prostaglandin) along with mifepristone (anti progesterone) is an effective combination. Vacuum aspiration and surgical procedure are adapted thereafter.
  • MTP is used to get rid of unwanted pregnancies and where continuation of the pregnancy could be harmful or even fatal either to mother or to the foetus or both.

SEXUALLY TRANSMITTED DISEASES (STDs)

  • Diseases which are transmitted through sexual intercourse are collectively called sexually transmitted diseases (STD) or venereal diseases (VD) or reproductive tract infections (RTI). 
  • These disease are caused by a widerange of bacterial, viral, protozoan, fungal agents and ectoparasites.
Table : Some STDs and their pathogens

  • These disease lead to complication later like pelvic inflammatory disease (PID), abortions, still births, ectopic pregnancies, infertility and even cancer of reproductive tract.
  • Some of these infections like hepatitis–B and HIV can also be transmitted by sharing of injection needles, surgical instruments, etc., with infected persons, transfusion of blood, or from an infected mother to the foetus too. 
  • Except for hepatitis-B, genital herpes and HIV infections, other diseases are completely curable if detected early and treated properly.
  • Transmission of sexually transmitted disease can be avoided by-
    • Avoiding sex with multiple partners or unknown partner.
    • Using condoms during coitus.
    • Consulting qualified doctors for early detection and get complete treatment if diagnosed with disease.

INFERTILITY

  • Inability to conceive or produce children even after 2 years of unprotected sexual cohabitation is called infertility. 
  • Various methods are now available to help such couples. 
  • Assisted reproductive technology (ART)includes all fertility treatment in which both sperms and eggs are handled. Art procedure involves surgically removing eggs from a mothers ovaries, combining them with sperm in the laboratory and returning them to the woman's body or donating them to another woman.
  • The main ART-techniques include:
    • In vitro fertilization (IVF)
    • Zygote intra fallopian transfer (ZIFT)
    • Intra cytoplasmic sperm injection (ICST).
    • Gamete intra fallopian transfer (GIFT).
    • Surrogacy or surrogate motherhood.
  • In vitro fertilization followed by transfer of embryo into the female genital tract is one such method and is commonly known as the ‘Test Tube Baby’ Programme.
  • First attempt to produce a test tube baby was made by a Italian scientist, Dr. Petrucci (1959 A.D.). Although this human embryo survived for only 29 days, but his experiment opened a new file of  biological science. The first test tube baby was born to Lesley and Gilbert Brown on July 25, 1978, in Oldham, England. Mrs. Brown had obstructed fallopian tubes. Dr.Patiricke Steptoe and Dr. Robert Edward both from England experimented on Mrs. Brown successfully. 
The world's first test tube baby (a baby girl) was named as Louise Joy Brown. Later, test-tube babies were also born in Australia, United States and some other countries. India's first test tube baby was born Durgaon 3rd October, 1978 in Kolkata. Her parental name was Kanupriya Aggarwal and was created by Dr. Subash Mukherjee.

  • In test-tube baby programme, ova from the wife/donor (female) and sperms from the husband/donor (male) are collected and are induced to form zygote under simulated conditions in the laboratory. The zygote or early embryos (with upto 8 blastomeres) could then be transferred into the fallopian tube (ZIFT–Zygote Intra Fallopian Transfer) and embryos with more than 8 blastomeres, into the uterus (IUT – Intra Uterine Transfer), to complete its further development. Embryos formed by in-vivo fertilization (fusion of gametes within the female) also could be used for such transfer to assist those females who cannot conceive.
  • Intra cytoplasmic sperm injection (ICSI) is another specialised procedure to form an embryo in the laboratory in which a sperm is directly injected into the ovum. 
  • Infertility cases either due to inability of the male partner to inseminate the female or due to very low sperm counts in the ejaculates, could be corrected by artificial insemination (AI) technique. In this technique, the semen collected either from the husband or a healthy donor is artificially introduced either into the vagina or into the uterus (IUI – intra-uterine insemination) of the female.
  • Gametic Intra-Fallopian Transfer (GIFT) is the latest technique to produce the child. Sperm (obtained by masturbation/electro ejaculation) and ovum obtained by laproscopy are injected into the mid part of the oviduct by a separate catheter in a cycling female (in proliferative stage).
  • Surrogate motherhood is a by product of the artificial insemination. It means that a woman allows a fertilized ovum of another couple to be infected into her womb. Then she carries to its full term for other couple.
<1>
This is the last page
on No comments:
Subscribe to: Posts (Atom)