Free Ncert Solutions for 12th Class Biology Reproduction In Organisms

1)

Why is reproduction essential for organisms?

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2)

Which is a better mode of reproduction: sexual or asexual? Why?

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3)

Why is the offspring formed by asexual reproduction referred to as clone?

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4)

Offspring formed due to sexual reproduction have better chances of survival, why?

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5)

How does the progeny formed from asexual reproduction are different from those formed by sexual reproduction?

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6)

Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction.

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7)

What is vegetative propagation? Give two suitable examples.

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8)

Define (i) Juvenile phase, (ii) Reproductive phase, (iii) Senescent phase.

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9)

Higher organisms have resorted to sexual reproduction in spite of its complexity, why?

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10)

Explain why meiosis and gametogenesis are always interlinked?

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11)

Identify each part and write whether it is haploid (n) or diploid (2n) : (a) Ovary; (b) Anther; (c) Egg; (d) Pollen; (e) Male gamete; (f) Zygote.

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12)

Define external fertilization. Mention its disadvantages.

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13)

Differentiate between Zoospore and Zygote.

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14)

Differentiate between Gametogenesis and embryogenesis.

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15)

Describe the post fertilization changes in a flower.

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16)

What is a bisexual flower? Collect five bisexual flowers from your neighbourhood and with the help of your teacher find out their common and scientific names.

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17)

Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?

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18)

Why are offspring of oviparous animals are at a greater risk as compared to offspring of viviparous animals?

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19) What happens when a solution of an acid is mixed with a solution of a base in a test tube? (i) The temperature of the solution increases. (ii) The temperature of the solution decreases. (iii) The temperature of the solution remains the same. (iv) Salt formation takes place. (a) Only (i) (b) (i) and (iii) (c) (ii) and (iii) (d) (i) and (iv)

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20) An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change? (a) Baking powder (b) Lime (c) Ammonium hydroxide solution (d) Hydrochloric acid

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21) During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to (a) absorb the evolved gas (b) moisten the gas (c) absorb moisture from the gas (d) absorb ions from the evolved gas

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22) Which of the following salts does not contain water of crystallization? (a) Blue vitriol (b) Baking soda (c) Washing soda (d) Gypsum

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23) Sodium carbonate is a basic salt because it is a salt of (a) strong acid and strong base (b) weak acid and weak base (c) strong acid and weak base (d) weak acid and strong base

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24) Calcium phosphate is present in tooth enamel. Its nature is (a) basic (b) acidic (c) neutral (d) amphoteric

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25) A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue? (a) Lemon juice (b) Vinegar (c) Common salt (d) An antacid

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26) Which of the following gives the correct increasing order of acid strength? (a) Water < acetic acid < hydrochloric acid (b) Water < hydrochloric acid < acetic acid (c) Acetic acid < water < hydrochloric acid (d) Hydrochloric acid < water < acetic acid

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27) If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done? (a) Wash the hand with saline solution (b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate (c) After washing with plenty of water apply solution of sodium hydroxide on the hand (d) Neutralise the acid with a strong alkali

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28) Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved? (i) It turns lime water milky. (ii) It extinguishes a burning splinter. (iii)It dissolves in a solution of sodium hydroxide. (iv) It has a pungent odour. (a) (i) and (ii) (b) (i), (ii) and (iii) (c) (ii), (iii) and (iv) (d) (i) and (iv)

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29) CO2 turns lime water milky, :it is a non-supporter of combustion and is absorbed by strong alkalies like NaOH. Common salt besides being used in kitchen can also be used as the raw material for making (i) washing soda (ii) bleaching powder (iii) baking soda (iv) slaked lime (a) (i) and (ii) (b) (i), (ii) and (iv) (c) (i), (ii) and (iii) (d) (i), (iii) and (iv)

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30) One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is (a) hydrochloric acid (b) tartaric acid (c) acetic acid (d) sulphuric acid

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31) To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is (a) acidic (b) neutral (c) basic (d) corrosive

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32) Which of the following statements is correct about an aqueous solution of an acid and a base? (i) Higher the pH, stronger the acid (ii) Higher the pH, weaker the acid (iii) Lower the pH, stronger the base (iv) Lower the pH, weaker the base (a) (i) and (iii) (b) (ii) and (iii) (c) (i) and (iv) (d) (ii) and (iv)

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33) The pH of the gastric juices released during digestion is (a) less than 7 (b) more than 7 (c) equal to 7 (d) equal to 0

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34) Which of the following phenomena occur, when a small amount of acid is added to water? (i) Ionisation (ii) Neutralisation (iii) Dilution (iv) Formation (a) (i)and(ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (ii) and (iv)

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35) Which one of the following can be used as an acid-base indicator by a visually impared student? (a) Litmus (b) Turmeric (c) Vanilla essence (d) Petunia leaves

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36) Which of the following substances will not give carbon dioxide on treatment with dilute acid? (a) Marble (b) Limestone (c) Baking soda (d) Lime

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37) Which of the following is acidic in nature? (a) Lime juice (b) Human blood (c) Lime water (d) Antacid

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38) In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus (figure) was set up. Which among the following statement(s) is/are correct? (i) Bulb will not glow because electrolyte is not acidic. (ii) Bulb will glow becauseis a strong base and furnishes ions for conduction. (iii) Bulb will not glow because circuit is incomplete. (iv) Bulb will not glow because it depends upon the type of electrolytic solution. (a) (i) and (iii) (b) (ii) and (iv) (c) Only (ii) (d) Only (iv)

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39) Which of the following is used for dissolution of gold? (a) Hydrochloric acid (b) Sulphuric acid (c) Nitric acid (d) Aqua-regia

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40) Which of the following is not a mineral acid? (a) Hydrochloric acid (b) Citric acid (c) Sulphuric acid (d) Nitric acid

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41) Which among the following is not a base? (a) (b) (c) (d)

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42) Which of the following statements is not correct? (a) All metal carbonates react with acid to give a salt, water and carbon dioxide (b) All metal oxides react with water to give salt and acid (c) Some metals react with acids to give salt and hydrogen (d) Some non-metal oxides react with water to form an acid

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43) Match the chemical substances given in Column I with their appropriate application given in Column II.

Column I Column II

A. Bleaching powder B. Baking soda C. Washing soda D. Sodium chloride 1. Preparation of glass 2. Production of H2 andCl2 3. De colourisation 4. Antacid

Codes A B C D (a) 2 1 4 3 (b) 3 2 4 1 (c) 3 4 1 2 (d) 2 4 1 3

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44) Equal volumes of hydrochloric acid and sodium hydroxide solutions of same concentration are mixed and the pH of the resulting solution is checked with a pH paper. What would be the colour obtained? (You may use colour guide given in figure of NCERT Book (Science Class X) on page26). (a) Red (b) Yellow (c) Yellowish green (d) Blue

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45) Which of the following is/are true when HCl (g) is passed through water (i) It does not ionise in the solution as it is a covalent compound. (ii) It ionises in the solution. (iii) It gives both hydrogen and hydroxyl ion in the solution. (iv) It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule. (a) Only (i) (b) Only (iii) (c) (ii) and (iv) (d) (iii) and (iv)

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46) Which of the following statement is true for acids? (a) Bitter and change red litmus to blue (b) Sour and change red litmus to blue (c) Sour and change blue litmus to red (d) Bitter and change blue litmus to red

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47) Which of the following are present in a dilute aqueous solution of hydrochloric acid? (a) (b) (c) (d) Unionized HCI

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48) Identify the correct representation of reaction occurring during chloralkali process. (a) (b) (c) (d)

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49) Match the adds given in Column I with their correct source given in Column II

Column I Column II

A. Lactic acid B. Acetic acid c. Citric acid D. Oxalic acid 1. Tomato 2. Lemon 3. Vinegar 4. Curd

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50) Match the important chemicals given in Column I with the chemical formulae given in Column II.

Column I Column II

A. Plaster of Paris B. Gypsum C. Bleaching powder D. Slaked lime 1. 2. 3. 4.

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51) What will be the action of the following substances on litmus paper? Dry HCl gas, moistened NH3 gas, lemon juice, carbonated soft drink, curd, soap solution.

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52) Name the add present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.

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53) What happens when nitric acid is added to egg shell?

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54) A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since, both the solutions are colourless, how will she distinguish between the two?

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55) How would you distinguish between baking powder and washing soda by heating?

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56) Salt A commonly used in bakery products on heating gets converted in to another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky. Identify A, B and C.

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57) In one of the industrial processes for manufacture of sodium hydroxide, a gas X is formed as by-product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.

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58) Fill in the missing data in the given table.

Name of the salt Formula Salt obtained from

Base Acid

(i) Ammonium chloride ?

(ii) Copper sulphate sodium ? ?

(iii) Sodium chloride ?

(iv) Magnesium nitrate ?

(v) Potassium sulphate ? ?

(v) Calcium sulphate ?

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59) What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.

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60) When zinc metal is treated .with a dilute solution of a strong acid, a gas is evolved, which is utilized in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

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61) In the following schematic diagram for the preparation of hydrogen gas as shown in the figure, what would happen if the following changes are made? (a) In place of zinc granules, same amount of zinc dust is taken in the test tube. (b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken. (c) In place of zinc, copper turnings are taken. (d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

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62) For making cake, baking powder is taken. If at home your mother uses baking soda instead of baking powder in cake. (a) How will it affect the taste of the cake and why? (b) How can baking soda be converted into baking powder? (c) What is the role of tartaric acid added to baking soda?

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63) A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identify X, Y, G and Z.

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64) A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by-product of chlor-alkali process. Identify B, what type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.

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65) A sulphate salt of group 2 element of the periodic table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt and why does it show such a behaviour? Give the reaction involved.

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66) Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.

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67) A few statements describing certain features of reproduction are given below I. gametic fusion takes place. II. transfer of genetic material takes place. III. reduction division takes place. IV. progeny have some resemblance with parents. Select the options that are true for both asexual and sexual reproduction from the options given below (a) I and II (b) II and III (c) II and IV (d) I and III

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68) The term 'clone' cannot be applied to offspring formed by sexual reproduction because (a) offspring do not possess exact copies of parental DNA (b) DNA of only one parent is copied and passed on to the offspring (c) offspring are formed at different times (d) DNA of parent and offspring are completely different

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69) Amoeba and yeast reproduce asexually by fission and budding respectively, because they are (a) microscopic organisms (b) heterotrophic organisms (c) unicellular organisms (d) uninucleate organisms

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70) A few statements with regard to sexual reproduction are given below I. Sexual reproduction does not always require two individuals. II. Sexual reproduction generally involves gametic fusion. III. Meiosis never occurs during sexual reproduction. IV. External fertilization is a rule during sexual reproduction. Choose the correct statements from the options below. (a) I and IV (b) I and II (c) II and III (d) I and IV

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71) A multi cellular, filamentous alga exhibits a type of sexual life cycle in which the meiotic division occurs after the formation of zygote. The adult filament of this alga has (a) haploid vegetative cells and diploid gometangia (b) diploid vegetative cells and diploid gometangia (c) diploid vegetative cells and haploid gometangia (d) haploid vegetative eel Is-and haploid gometangia

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72) The male gametes of rice plant have 12 chromosomes in their nucleus. The chromosome number in the female gamete, zygote and, the cells of the seedling will be, respectively (a) 12, 24, 12 (b) 24, 12,12 (c) 1 2, 24, 24 (d) 24, -12, 24

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73) Given below are a few statements related to external fertilization. I. The male and female gametes are formed and released, simultaneously. II. Only a few gametes are released into the medium. III. Water is the medium in a majority of organisms exhibiting external fertilization. IV. Offspring formed as a result, of external, fertilization have better chances of survival than those formed inside an organism. Choose the correct statements. (a) III and IV (b) I and III (c) II and IV (d) I and IV

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74) The statements given below describe certain features that are observed inthe pistil of flowers. I. Pistil may have many carpels. II. Each carpel may have more than one ovule. III. Each carpel has only one ovule. IV. Pistil have only one carpel. Choose the statements that are true from the options below. (a) I and II (b) I and III (c) II and IV (d) III and IV

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75) Which of the following situations correctly describe the similarity between an angiospermic egg and a human egg? I. Eggs of both are formed only once in a lifetime. II. Both the angiosperm egg and human egg are stationary. III. Both the angiosperm egg and human egg are motile transported. IV. Syngamy in both results in the formation of zygote. Choose the correct answer from the options given below. (a) II and IV (b) only IV (c) III and IV (d) I and IV

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76) Appearance of vegetative propagules from the nodes of plants such as sugarcane and ginger is mainly because (a) nodes are shorter than internodes (b) nodes have meristematic cells (c) nodes are located near the soil (d) nodes have non-photosynthetic cells

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77) Which of the following statements, support the view that elaborate sexual reproductive process appeared much later in the organic evolution. I. Lower groups of organisms have simpler body design. II. Asexual reproduction is common in lower groups. III. Asexual reproduction is common in higher groups of organisms. IV. The high incidence of sexual reproduction in angiosperms and vertebrates. Choose the correct answer from the options given below. (a) I and III (b) I and III (c) II and IV (d) II and III

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78) Offspring formed by sexual reproduction exhibit more variation than those formed by asexual reproduction because (a) sexual reproduction is a lengthy process (b) gametes of parents have qualitatively different genetic composition (c) genetic material comes from parents of two different species (d) greater amount of DNA is involved in sexual reproduction

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79) Choose the correct statement from amongst the following. (a) Dioecious (hermaphrodite) organisms are seen only in animals. (b)Dioecious organisms are seen only in plants. (c) Dioecious organisms are seen in both plants and animals. (d) Dioecious organisms are seen only in vertebrates.

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80) There is no natural death in single celled organisms like Amoeba and bacteria because (a) they cannot reproduce sexually (b) they reproduce by binary fission (c) parental body is distributed among the offspring (d) they are microscopic

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81) There are various types of reproduction. The type of reproduction adopted by an organism depends on (a) the habitat and morphology of the organism (b) morphology of the organism (c) morphology and physiology of the organism (d) the organism's habitat, physiology and genetic makeup

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82) Identify the incorrect statement. (a) In asexual reproduction, the offspring produced are morphologically and genetically identical to the parent. (b) Zoospores are sexual reproductive structures. (c) In asexual reproduction, a single parent produces offspring with or without the formation of gametes. (d) Conidia are asexual structures in Penicillium.

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83) Which of the following is a post-fertilization event in flowering plants? (a) Transfer of pollen grains (b) Embryo development (c) Formation of flower (d) Formation of pollen grains

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84) The number of chromosomes in the shoot tip cells of a maize plant is 20.The number of chromosomes in the microspore mother cells of the same plant shall be (a) 20 (b)10 (c)40 (d) 15

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85) Mention two inherent characteristics of Amoeba and yeast that enable them to reproduce asexually.

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86) Why do we refer to offspring formed by asexual method of reproduction as clones?

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87) Although potato tuber is an underground part, it is considered as a stem. Give two reasons.

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88) Between an annual and a perennial plant, which one has a shorter juvenile phase? Give one reason.

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89) Rearrange the following events of sexual reproduction in the sequence in which they occur in a flowering plant embryogenesis, fertilization, gametogenesis, pollination.

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90) The probability of fruit set in a self-pollinated bisexual flower of a plant is far greater than a dioecious plant. Explain.

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91) Is the presence of large number of chromosomes in an organism a hindrance to sexual reproduction? Justify your answer by giving suitable reasons.

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92) Is there a relationship between the size of an organism and its life span? Give two examples in support of your answer.

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93) In the figure given below the plant bears two different types of flowers marked 'A' and 'B'. Identify the types of flowers and state the type of pollination that will occur in them.

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94) Give reasons as to why cell division cannot be a type of reproduction in multicellular organisms.

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95) In the figure given below, mark the ovule and pericarp.

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96) Why do gametes produced in large numbers in organisms exhibit external fertilization?

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97) Which of the following are monoecious and dioecious organisms? (a) Earthworm.......... (b) Chara.......... (c)Marchantia......... (d) Cockroach ...........

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98) Match the organisms given in column I with the vegetative propagules given in column II.

Column I Column II

A. Bryophyllum B. Agave C. Potato D. Water hyacinth 1. Offset 2. Eyes 3. Leaf buds 4. Bulbils

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99) What do the following parts of a flower develop into after fertilization? (a) Ovary........... (b) Ovules?.......

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100) In haploid organisms that undergo sexual reproduction, name the stage in the life cycle when meiosis occurs. Give reasons for your answer.

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101) The number of taxa exhibiting asexual reproduction is drastically reduced in higher plants (angiosperms) and higher animals (vertebrates) as compared with lower groups of plants and animals. Analyze the possible reasons for this situation.

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102) Honeybees produce their young ones only by sexual reproduction. Inspite of this, in a colony of bees we find both haploid and diploid individuals. Name the haploid and diploid individuals in the colony and analyze the reasons behind their formation.

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103) With which type of reproduction do we associate the reduction division? Analyze the reasons for it.

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104) Is it possible to consider vegetative propagation observed in certain plants like Bryophyllum, water hyacinth, ginger, etc., as a type of asexual reproduction? Give two/three reasons.

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105) 'Fertilisation is not an obligatory event for fruit production in certain plants'. Explain the statement.

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106) In a developing embryo, analyze the consequences if cell divisions are not followed by cell differentiation.

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107) List the changes observed in an angiosperm flower subsequent to pollination and fertilization.

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108) Suggest a possible explanation why the seeds in a pea pod are arranged in a row, whereas those in tomato are scattered in the juicy pulp.

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109) Draw the sketches of a zoospore and a conidium. Mention two dissimilarities between them and atleast one feature common to both structures.

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110) Justify the statement 'vegetative reproduction is also a type of asexual reproduction'.

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111) Enumerate the differences between asexual and sexual reproduction. Describe the types of asexual reproduction exhibited by unicellular organisms.

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112) Do all the gametes formed from a parent organism have the same genetic composition (identical DNA copies of the parental genome)? Analyze the situation with the background of gametogenesis and provide or give suitable explanation.

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113) Although sexual reproduction is a long drawn, energy-intensive complex form of reproduction, many groups of organisms in kingdom-Animalia and Plantae prefer this mode of reproduction. Give atleast three reasons for this.

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114) Differentiate between (a) oestrus and menstrual cycles; (b) ovipary and vivipary. Give an example for each type.

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115) Rose plants produce large, attractive bisexual flowers, but they seldom produce fruits. On the other hand a tomato plant produces plenty of fruits though they have small flowers. Analyze the reasons for failure of fruit formation in rose.

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Column I	Column II
A. Bleaching powder B. Baking soda C. Washing soda D. Sodium chloride	1. Preparation of glass 2. Production of H2 andCl2 3. De colourisation 4. Antacid

Column I	Column II
A. Lactic acid B. Acetic acid c. Citric acid D. Oxalic acid	1. Tomato 2. Lemon 3. Vinegar 4. Curd

Column I	Column II
A. Plaster of Paris B. Gypsum C. Bleaching powder D. Slaked lime	1. 2. 3. 4.

Name of the salt	Formula	Salt obtained from
Name of the salt	Formula	Base	Acid
(i) Ammonium chloride			?
(ii) Copper sulphate sodium	?	?
(iii) Sodium chloride			?
(iv) Magnesium nitrate		?
(v) Potassium sulphate		?	?
(v) Calcium sulphate			?

Column I	Column II
A. Bryophyllum B. Agave C. Potato D. Water hyacinth	1. Offset 2. Eyes 3. Leaf buds 4. Bulbils

done 12th Biology Reproduction In Organisms

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12th Biology Reproduction In Organisms