NEET AIPMT Biology Chapter Wise Solutions – Sexual Renroduction in Flowering Plants
1. Filiform apparatus is characteristic feature of
(a) aleurone cell
(c) generative cell
(d) nucellar embryo. (AIPMT 2015)
2. In angiosperms, microsporogenesis and mega- sporogenesis
(a) involve meiosis
(b) occur in ovule
(c) occur in anther
(d) form gametes without further divisions. (AIPMT 2015)
3. Flowers are unisexual in
(a) china rose
(d) cucumber. (AIPMT 2015)
4. Coconut water from a tender coconut is
(a) innermost layers of the seed coat
(b) degenerated nucellus
(c) immature embryo
(d) free nuclear endosperm. (AIPMT 2015)
5. Which one of the following fruits is parthenocarpic?
(d) Apple (AIPMT 2015)
6. Male gametophyte in angiosperms produces
(a) single sperm and two vegetative cells
(b) three sperms
(c) two sperms and a vegetative cell
(d) single sperm and a vegetative cell. (AIPMT 2015)
7. Which of the following are the important floral rewards to the animal pollinators ?
(a) Floral fragrance and calcium crystals
(b) Protein pellicle and stigmatic exudates
(c) Colour and large size of flower
(d) Nectar and pollen grains (AIPMT 2015, Cancelled)
8. Which one of the following may require pollinators, but is genetically similar to autogamy?
(d) Xenogamy (AIPMT 2015, Cancelled)
9. Which one of the following statements is not true?
(a) The flowers pollinated by flies and bats secrete foul odour to attract them.
(b) Honey is made by bees by digesting pollen collected from flowers.
(c) Pollen grains are rich in nutrients, and they are used in the form of tablets and syrups.
(d) Pollen grains of some plants cause severe allergies and bronchial afflictions in some people. (AIPMT 2015, Cancelled)
10. The hilum is a scar on the
(a) fruit, where style was present
(b) seed, where micropyle was present
(c) seed, where funicle was attached
(d) fruit, where it was attached to pedicel. (AIPMT 2015, Cancelled)
11. Transmission tissue is characteristic feature of
(a) dry stigma
(b) wet stigma
(c) hollow style
(d) solid style. (AIPMT2015, Cancelled)
12. Which one of the following shows isogamy with non-flagellated gametes?
(d) Spirogyra (AIPMT 2014)
13. Geitonogamy involves
(a) fertilization of a flower by the pollen from another flower of the same plant
(b) fertilization of a flower by the pollen from the same flower
(c) fertilization of a flower by the pollen from a flower of another plant in the same population
(d) fertilization of a flower by the pollen from a flower of another plant belonging to a distant population. (AIPMT 2014)
14. An aggregate fruit is one which develops from
(a) multicarpellary syncarpous gynoecium
(b) multicarpellary apocarpus gynoecium
(c) complete inflorescence
(d) multicarpellary superior ovary. (AIPMT 2014)
15. Pollen tablets are available in the market for
(a) in vitro fertilization
(b) breeding programmes
(c) supplementing food
(d) ex situ conservation. (AIPMT2014)
16. Function of filiform apparatus is to
(a) recognize the suitable pollen at stigma
(b) stimulate division of generative cell
(c) produce nectar
(d) guide the entry of pollen tube. (AIPMT 2014)
17. Non-albuminous seed is produced in
(d) pea. (AIPMT 2014)
18. Meiosis takes place in
(d) conidia. (NEET 2013)
19. Seed coat is not thin, membranous in
(d) coconut. (NEET 2013)
20. Perisperm differs from endosperm in
(a) being a diploid tissue
(b) its formation by fusion of secondary nucleus with several sperms
(c) being a haploid tissue
(d) having no reserve food (NEET 2013)
21. Advantage of cleistogamy is
(a) no dependence on pollinators
(c) higher genetic variability
(d) more vigorous offspring. (NEET 2013)
22. Megasporangium is equivalent to
(c) embryo sac
(d) fruit (NEET 2013)
23. Which one of the following statements is correct?
(a) Endothecium produces the microspores
(b) Tapetum nourishes the developing pollen
(c) Flard outer layer of pollen is called intine
(d) Sporogenous tissue is haploid (NEET2013)
24. Product of sexual reproduction generally generates
(a) new genetic combination leading to variation
(b) large biomass
(c) longer viability of seeds
(d) prolonged dormancy. (NEET 2013)
25. Animal vectors are required for pollination in
(d) maize. (Karnataka NEET 2013)
26. Albuminous seeds store their reserve food mainly in
(d) perisperm. (Karnataka NEET 2013)
27. Megaspores are produced from the megaspore mother cells after
(a) mitotic division
(b) formation of thick wall
(d) meiotic division. (Karnataka NEET 2013)
28. Which one of the following statements is correct?
(a) Cleistogamous flowers are always autogamous.
(b) Xenogamy occurs only by wind pollination.
(c) Chasmogamous flowers do not open at all.
(d) Geitonogamy involves the pollen and stigma of flowers of different plants. (Karnataka NEET 2013)
29. Which of the following statements is correct?
(a) Sporopollenin can be degraded by enzymes.
(b) Sporopollenin is made up of inorganic materials.
(c) Sporopollenin can withstand high temperatures as well as strong acids and alkalis.
(d) Sporopollenin can withstand high temperatures but not strong acids. (Karnataka NEET2013)
30. Both, autogamy and geitonogamy are prevented in
(d) maize. (Prelims 2012)
31. An organic substance that can withstand environmental extremes and cannot be degraded by any enzyme is
(d) cellulose. (Prelims 2012)
32. Which one of the following is correctly matched?
(d) Yeast-Zoospores. (Prelims 2012)
33. Even in absence of pollinating agents seed-setting is assured in
(d) fig (Prelims 2012)
34. What is the function of germ pore?
(a) Emergence of radicle.
(b) Absorption of water for seed germination.
(c) Initiation of pollen tube.
(d) Release of male gametes. (Mains 2012)
35. Which one of the following statements is wrong?
(a) When pollen is shed at two-celled stage, double fertilization does not take place.
(b) Vegetative cell is larger than generative cell.
(c) Pollen grains in some plants remain viable for months.
(d) Intine is made up of cellulose and pectin. (Mains 2012)
36. Plants with ovaries having only one or a few ovules, are generally pollinated by
(d) wind. (Mains 2012)
37. Filiform apparatus is a characteristic feature of
(d) zygote (Prelims 2011)
38. Nucellar polyembryony is reported in species of
(d) Brassica (Prelims 2011)
39. Which one of the following pollinations is autogamous?
(d) cleistogamy (Prelims 2011)
40. The “eyes” of the potato tuber are
(a) root buds
(b) flower buds
(c) shoot buds
(d) axillary buds (Prelims 2011)
41. Wind pollination is common in
(d) orchids (Prelims 2011)
42. In angiosperms, functional megaspore develops into
(a) embryo sac
(d) pollen sac (Mains 2011)
43. What is common between vegetative reproduction and apomixis?
(a) both are applicable to only dicot plants
(b) both bypass the flowering phase
(c) both occur round the year
(d) both produce progeny identical to the parent. (Mains 2011)
44. Apomictic embryos in Citrus arise from
(b) maternal sporophytic tissue in ovule
(c) antipodal cells
(d) diploid egg. (Predims 2010)
45. Transfer of pollen grains from the anther to the stigma of another flower of the same plant is called
(d) autogamy. (Prelims 2010)
46. Wind pollinated flowers are
(a) small, brightly coloured, producing large number of pollen grains
(b) small, producing large number of dry pollen grains
(c) large producing abundant nectar and pollen
(d) small, producing nectar and dry pollen. (Prelims 2010)
47. Examine the figures (A-D) given below and select the right option out of (a – d), in which all the four structures A, B, C and D are identified correctly
48. Vegetative propagation in Pistia occurs by
(d) sucker (Mains 2010)
49. Vegetative propagation in mint occurs by
(d) runner (Prelims 2009)
50. Which one of the following pairs of plant structures has haploid number of chromosomes?
(a) nucellus and antipodal cells
(b) egg nucleus and secondary nucleus
(c) megaspore mother cell and antipodal cells
(d) egg cell and antipodal cells. (Prelims 2008)
51. What does the filiform apparatus do at the entrance into ovule?
(a) it brings about opening of the pollen tube
(b) it guides pollen tube from a synergid to egg
(c) it helps in the entry of pollen tube into a synergid
(d) it prevents entry of more than one pollen tube into the embryo sac. (Prelims 2008)
52. Unisexuality of flowers prevents
(a) geitonogamy, but not xenogamy
(b) autogamy and geitonogamy
(c) autogamy, but not geitonogamy
(d) both geitonogamy and xenogamy. (Prelims 2008)
53. Which one of the following is resistant to enzyme action?
(a) pollen exine
(b) leaf cuticle
(d) wood fibre. (Mains 2008)
54. Male gametes in angiosperms are formed by the division of
(a) generative cell
(b) vegetative cell
(c) microspore mother cell
(d) microspore. (2007)
55. Two plants can be conclusively said to belong to the same species if they
(a) have more than 90 per cent similar genes
(b) look similar and possess identical secondary metabolites
(c) have same number of chromosomes
(d) can reproduce freely with each other and form seeds. (2007)
56. Which one of the following is surrounded by a callose wall?
(a) male gamete
(c) pollen grain
(d) microspore mother cell. (2007)
57. Parthenocarpic tomato fruits can be produced by
(a) treating the plants with phenylmercuric acetate
(b) removing androecium of flowers before pollen grains are released
(c) treating the plants with low concentrations of gibberellic acid and auxins
(d) raising the plants from vernalized seeds (2006)
58. In a cereal grain the single cotyledon of embryo is represented by
(d) prophyll (2006)
59. The arrangement of the nuclei in a normal embryo sac in the dicot plants is
(a) 3 + 3 + 2
(b) 2 + 4 + 2
(c) 3 + 2 + 3
(d) 2 + 3 + 3 (2006)
60. What type of placentation is seen in sweet pea?
(d) free central (2006)
61. In which one pair both the plants can be vegetatively propagated by leaf species?
(a) Agave andKalanchoe
(b) Bryophyllum and Kalanchoe
(c) Asparagus and Bryophyllum
(d) Chrysanthemum and Agave. (2005)
62. In a type of apomixis known as adventive embryony, embryos develop directly from the
(a) nucellus or integuments
fc) synergids or antipodals in an embryo sac
(d) accessory embryo sacs in the ovule. (2005)
63. Which one of the following represents an ovule, where the embryo sac becomes horse-shoe shaped and the funiculus and micropyle are close to each other?
(d) anatropous. (2005)
64. Through which cell of the embryo sac, does the pollen tube enter the embryo sac?
(a) egg cell
(b) persistant synergid
(c) degenerated synergids
(d) central cell. (2005)
65. When a diploid female plant is crossed with a tetraploid male, the ploidy of endosperm cells in the resulting seed is
(d) triploidy. (2004)
66. An ovule which becomes curved so that the nucellus and embryo sac lie at right angles to the funicle is
(d) orthotropous. (2004)
67. Which of the following propagates through leaf-tip?
(a) walking fern
(b) sprout-leaf plant
(d) moss. (2004)
68. Anthesis is a phenomenon which refers to
(a) reception of pollen by stigma
(b) formation of pollen
(c) development of anther
(d) opening of flower bud. (2004)
69. In a flowering plant, archesporium gives rise to
(a) only the wall of the sporangium
(b) both wall and the sporogenous cells
(c) wall and the tapetum
(d) only tapetum and sporogenous cells (2003)
70. In angiosperms pollen tube liberate their male gametes into the
(a) central cell
(b) antipodal cells
(c) egg cell
(d) synergids. (2002)
71. In angiosperm all the four microspores of tetrad are covered by a layer which is formed by
(d) sporopollenin. (2002)
72. What is the direction of micropyle in anatropous ovule?
(d) left. (2002)
73. Adventive embryony in Citrus is due to
(c) zygotic embryo
(d) fertilized egg. (2001)
74. In grasses what happens in microspore mother cell for the formation of mature pollen grains?
(a) one meiotic and two mitotic divisions
(b) one meiotic and one mitotic divisions
(c) one meiotic division
(d) one mitotic division. (2001)
75. Anemophily type of pollination is found in
(b) bottle brush
(d) coconut. (2001)
76. Endosperm is formed during the double fertilization by
(a) two polar nuclei and one male gamete
(b) one polar nuclei and one male gamete
(c) ovum and male gamete
(d) two polar nuclei and two male gametes. (2000)
77. Eight nucleated embryosac is
(a) only monosporic
(b) only bisporic
(c) only tetrasporic
(d) any of these (2000)
78. The endosperm of gymnosperm is
(d) haploid. (1999)
79. Type of placentation in which ovary is syncarpous unilocular and ovules are on sutures is called
(a) marginal placentation
(b) superficial placentation
(c) apical placentation
(d) parietal placentation. (1999)
80. An interesting modification of flower shape for insect pollination occurs in some orchids in which a male insect mistakes the pattern on the orchid flower for the female species and tries to copulate with it, thereby pollinating the flower. This phenomenon is called
(d) pseudocopulation. (1998)
81. The embiyo in sunflower has
(a) two cotyledons
(b) many cotyledons
(c) no cotyledon
(d) one cotyledon. (1998)
82. The role of double fertilization in angiosperms is to produce
(d) integuments. (1998)
83. If an angiospermic male plant is diploid and female plant tetraploid, the ploidy level of endosperm will be
(d) triploid. (1997)
84. The role of double fertilization in angiosperms is to produce
(d) hormones. (1996)
85. If there are 4 cells in anthers, what will be the number of pollen grains?
(d) 4. (1996)
86. The anthesis is a phenomenon, which refers to
(a) development of anthers
(b) opening of flower bud
(c) stigma receptors
(d) all of these. (1995)
87. In an angiosperm, how many microspore mother cells are required to produce 100 pollen grains?
(d) 50. (1995)
88. The polyembryony commonly occurs in
(d) turmeric. (1995)
89. When pollen of a flower is transferred to the stigma of another flower of the same plant, the pollination is referred to as
(d) allogamy. (1994)
90. Embryo sac represents
(d) megagamete. (1994)
91. Number of meiotic divisions required to produce 200/400 seeds of pea would be
(d) 250/500. (1993)
92. Double fertilization is characteristic of
(d) bryophytes. (1993)
93. Ovule is straight with funiculus, embryo sac, chalaza and micropyle lying on one straight line. It is
(d) amphitropous. (1993)
94. Study of formation, growth and development of new individual from an egg is
(d) cytology. (1993)
95. A population of genetically identical individuals, obtained from asexual reproduction is
(d) aggregate. (1993)
96. Meiosis is best observed in dividing
(a) cells of apical meristem
(b) cells of lateral meristem
(c) microspores and anther wall
(d) microsporocytes. (1992)
97. Double fertilization is fusion of
(a) two eggs
(b) two eggs and polar nuclei with pollen nuclei
(c) one male gamete with egg and other with synergid
(d) one male gamete with egg and other with secondary nucleus. (1991)
98. Syngamy means
(a) fusion of gametes
(b) fusion of cytoplasms
(c) fusion of two similar spores
(d) fusion of two dissimilar spores. (1991)
99. Point out the odd one
(b) embryo sac
(d) pollen grain (1991)
100. Which of the following pair have haploid structures
(a) nucellus and antipodal cells
(b) antipodal cells and egg cell
(c) antipodal cells and megaspore mother cell
(d) nucellus and primary endosperm nucleus (1991)
101. Embryo sac occurs in
(b) axis part of embryo
(d) endosperm. (1991)
102. Pollination occurs in
(a) bryophytes and angiosperms
(b) pteridophytes and angiosperms
(c) angiosperms and gymnosperms
(d) angiosperms and fungi. (1991)
103. Cellular totipotency was demonstrated by
(a) Theodore Schwann
(d) Robert Hooke. (1991)
104. Entry of pollen tube through micropyle is
(d) pseudogamy (1990)
105. Sperm and egg nuclei fuse due to
(a) base pairing of their DNA and RNA
(b) formation of hydrogen bonds
(c) mutual attraction due to differences in electrical charges
(d) attraction of their protoplasts. (1990)
106. Female gametophyte of angiosperms is represented by
(b) megaspore mother cell
(c) embryo sac
(d) nucellus. (1990)
107. Male gametophyte of angiosperms/monocots is
(d) stamen. (1990)
108. Which ones produce androgenic haploids in anther cultures
(a) anther wall
(b) tapetal layer of anther wall
(c) connective tissue
(d) young pollen grains. (1990)
109. Which is correct
(a) gametes are invariably haploid
(b) spores are invariably haploid
(c) gametes are generally haploid
(d) both spores and gametes are invariably haploid. (1989)
110. Generative cell was destroyed by laser but a normal pollen tube was still formed because
(a) vegetative cell is not damaged.
(b) contents of killed generative cell stimulate pollen growth
(c) laser beam stimulates growth of pollen tube
(d) the region of emergence of pollen tube is not harmed. (1989)
111. Nucellar embryo is
(a) amphimictic haploid
(b) amphimictic diploid
(c) apomictic haploid
(d) apomictic diploid. (1989)
112. Development of an organism from female gamete/ egg without involving fertilization is
(a) adventitive embryony
(d) parthenogenesis. (1989)
113. Perisperm is
(a) remnant of endosperm
(b) persistent nucellus
(c) peripheral part of endosperm
(d) disintegrated secondary nucleus. (1989, 88)
114. Double fertilization and triple fusion were discovered by
(b) Nawaschin and Guignard
(d) Strasburger. (1988)
115. Total number of meiotic divisions required for forming 100 zygotes/100 grains of wheat is
(d) 50. (1988)
116. Male gametophyte of angiosperms is shed at
(a) four celled pollen grain
(b) three celled pollen grain
(c) microspore mother cell
(d) anther. (1988)
117. Parthenogenesis is
(a) development of embryo without fertilization
(b) development of fruit without fertilization
(c) development of fruit without hormones
(d) development of embryo from egg without fertilization. (1988)
118. Formation of gametophyte directly from sporophyte without meiosis is
(d) amphimixis. (1988)
1. (b) :
Filliform apparatus is a mass of finger like projections of the wall into the cytoplasm. It is present in synergids (help cells) of the embryo sac, in the micropylar region. It guards the pollen tube inside the ovule towards the embryo sac.
2. (a) :
In angiosperms, microsporogenesis i.e., formation of microspores (or pollen grains) occurs by the meiotic divisions of diploid microspore mother cells (or pollen mother cells). Microsporogenesis takes place in the anther. Megasporogenesis i.e. formation of megaspores occurs by the meiotic divisions of diploid megaspore mother cells. Megasporogenesis takes place in the ovule.
3. (d) :
In cucumber, unisexual flowers i.e., separate male and female flowers are present on the same plant (Monoecious plant).
4. (d) :
In Cocos nucifera (coconut), the coconut water represents free-nuclear endosperm and the surrounding kernel represents the cellular endosperm. The primary endosperm nucleus (PEN) first undergoes a number of free nuclear divisions without wall formation to form a large number of free nuclei (free nuclear endosperm). When the fruit is about 50 mm long, the embryo sac gets filled with a clear fluid in which float numerous nuclei of various sizes. At a later stage (about 100 mm long fruit), the suspension shows, in addition to free nuclei, several cells each enclosing a variable number of nuclei. Gradually these cells and free nuclei start settling at the periphery of the cavity, and layers of cellular endosperm start appearing. This forms the coconut meat. The quantity of the cellular endosperm increases further by divisions of the cells.
5. (b) :
Parthenocarpic fruits are the fruits which are formed without fertilisation. These fruits are naturally seedless, e.g., banana.
6. (c) :
The protoplast of the male gametophyte divides mitotically to produce two unequal cells — a small generative cell and a large vegetative cell. The generative cell divides later into two non-motile male gametes (or sperms). Thus, the male gametophyte in angiosperms produces two sperms and a vegetative cell. The vegetative cell, later on, grows to produce pollen tube.
8. (c) :
Geitonogamy involves transfer of the pollen from one flower of a plant to the stigma of another flower of the same plant. As the pollen has to move from one flower to another flower, it requires a pollinating agent. Yet it is genetically similar to autogamy, as both the flowers of the plant, share the same genotype of the plant.
Honey is made from nectar through a process of regurgitation and evaporation. Honey bees transform saccharides (carbohydrates) into honey by regurgitating it a number of times, until it is partially digested. The bees do the regurgitation and digestion as a group. After the last regurgitation, the aqueous solution is still high in water, the process continues by evaporation of much of the water and enzymatic transformation. Honey is produced by bees as a food source.
10. (c) :
Ovule is an integumented megasporangium found in spermatophytes which develops into seed after fertilization. An angiospermic ovule is typically an ovoid and whitish stmcture. It occurs inside ovary where it is attached to a parenchymatous cushion called placenta either singly or in a cluster. The ovule is stalked. The stalk is called funiculus or funicle. The point of attachment of the body of the ovule with the funiculus is known as hilum. It is present as a scar on a mature seed.
Style is traversed by the pollen tube to reach the ovule.lt is of two types – hollow and solid. In hollow styles, the stylar canal is lined by glandular cells, which are usually multinucleate and polyploid whereas solid style has a core of transmitting tissue, composed of thin walled cells, through which, the pollen tube moves.
12. (d) :
Sexual reproduction in algae takes place through fusion of two gametes. In Spirogyra, the gametes are similar in size (isogamy) and non- flagellated (non-motile).
13. (a) :
Geitonogamy is the pollination taking place between the two flowers of the same plant or genetically similar plant. Hence, genetically it is self pollination but since the agency is involved, it is ecologically, cross pollination.
14. (b) :
An aggregate fruit or etaerio is a group of simple fruitlets that develop from free ovaries (apocarpus condition) of a single flower (single gynoecium).
Pollen grains are believed to be rich in nutrients (protein 7-26 % carbohydrates 24-48%, fats 0.9-14.5%). They are taken as tablets or syrups to improve health. They also enhance performance of athletes and race horses.
16. (d) :
In the ovule, the pollen tube is attracted by secretions of synergids. Usually the pollen tube enters the embryo sac by passing into one of the two synergids and is guided by the filiform apparatus of the synergids in their movement. Pollen tube then breaks open and releases its contents in the embryo sac. Antipodals and synergids later degenerate.
17. (d) :
In majority of dicot seeds, including pea, the endosperm is consumed during seed development and the food is stored in cotyledons and other regions. They are called non-endospermic or exalbuminous seeds.
Gemmule and conidia are asexual propagules thus no meiosis takes place in them. Megaspores are haploid which are formed as a result of meiosis of diploid megaspore mother cell. Meiocyte is any cell that undergoes meiosis.
20. (a) :
Both perisperm and endosperm are nutritive layers. Perisperm is residual persistent nucellus of seed prior to fertilization while endosperm develops when one of the sperm cells fuses with two haploid polar nuclei. Thus perisperm is diploid while endosperm is a triploid tissue.
21. (a) :
Cleistogamy is the process of pollination and fertilization before the flower has opened. In such flowers, the anther and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma. Cleistogamous flowers produce assured seed-set even in the absence of pollinators.
In angiosperms, body of the ovule consists of a mass of parenchymatous cells called nucellus, which is equivalent to megasporangium. A megasporangium alongwith its protective integuments is called as an ovule.
A microsporangium is generally surrounded by four wall layers – the epidermis, endothecium, middle layers and the tapetum. The outer three wall layers perfom the function of protection and help in dehiscence of anther to release the pollen. The innermost wall layer is the tapetum. It nourishes the developing pollen grains. Cells of the tapetum are food rich and possess dense cytoplasm and generally have more than one nucleus. They disintegrate to liberate the contents which is absorbed by the developing spores.
24. (a) :
Sexual reproduction always involves meiosis (zygotic in case of haploid individuals and gametic in case of diploid individuals). Meiosis results in crossing over between chromosomes during prophase I generating new recombinations. Besides, sexual reproduction generally involves combination of genes from two different organisms. Thus, sexual reproduction generates new genetic combinations leading to variations.
25. (c) :
In Vallisneria, water pollination occurs while mulberry and maize undergo wind pollination. In cucumber, animal pollination is observed.
26. (a) :
In some seeds, the endosperm persists in the seed as food storage tissue. Such seeds are called endospermic or albuminous, e.g., castor, maize, wheat, barley, rubber, coconut.
27. (d) :
One hypodermal nucellar cell of the micropylar region of ovule differentiates as the sporogenous cell. It forms a diploid megaspore mother cell or megasporocyte. The megaspore mother cell undergoes meiosis and forms a row of four haploid megaspores. Only the chalazal megaspore remains functional while the other three degenerate.
28. (a) :
In cleistogamy, as the flowers never open so there is no alternative of self pollination. It is invariably autogamous. In xenogamy, pollination takes between two flowers of different plants (genetically and ecologically).
Chasmogamy occurs when the flowers’expose their mature anther and stigma to the pollinating agents.
Geitonogamy is the pollination taking place between the two flowers of the same plant or genetically similar plant. Genetically, it is self pollination but as the agency is involved it is ecologically cross pollination.
29. (c) :
Pollen grain is a haploid, unicellular body. It is cuticularised and the cutin is of special type called sporopollenin, which is resistant to chemical and biological decomposition. It can withstand high temperatures as well as strong acids and alkalis. This is why, pollen wall is preserved for long periods in fossil deposits. In addition pollen wall possesses proteins for enzymatic and compatability reactions.
30. (a) :
Autogamy and geitonogamy are two forms of self pollination. In autogamy, pollen falls on stigma of the same flower. While in geitonogamy pollens from a flower fall on the stigma of some other flower on the same plant. Papaya is a dioecious plants thus both autogamy and geitonogamy are prevented in it.
31. (b) :
Sporopollenin is a major component of the tough outer (exine) walls of spores and pollen grains. It is chemically very stable and is usually well preserved in soils and sediments. It can withstand environmental extremes and cannot be degraded by enzymes and strong chemical reagents.
32. (a) :
Yeast and other ascomycetes characteristi- cally produce ascospores. Chlamydomonas is an alga and conidia are not found in algae. Ginger propagates by rhizome not by sucker. Onion propagates by bulb ‘ which is an underground, modified stem.
33. (a) :
Some plants such as Viola (common pansy), Oxalis, and Commelina produce two types of flowers- chasmogamous flowers which are similar to flowers of other species with exposed anthers and stigma, and cleistogamous flowers which do not open at all. In such flowers, the anthers and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma. Cleistogamous flowers produce assured seed-set even in the absence of pollinators.
34. (c) :
In a pollen grain, exine is thin or absent at certain places. These areas may have thickened intine or deposition of callose. They are called germ pores (if rounded) or germinal furrows (if elongated). After pollination, the pollen grain on the stigma absorbs water and nutrients from the stigmatic secretion through its germ pores. The tube or vegetative cell enlarges and comes out of pollen grains through germ pore to form a pollen tube.
35. (a) :
In 60% of flowering plants, the pollen grains are shed at two-celled stage (tube cell + generative cell). Further, development of male gametophyte (pollen grain) occurs on stigma. Pollen grain gives rise to pollen tube which absorbs nourishment from the cells of style for its growth. Generative cell divides to give rise to two male gametes. Out of these, one fuses with the egg to form diploid zygote (generative fertilization or syngamy) whereas the second male gamete fuses with the two haploid polar nuclei or diploid secondary nucleus of the central cell to form primary endosperm nucleus (vegetative fertilization or triple fusion). These two acts of fertilization occur in the same embryo sac and are referred to as double fertilization.
36. (d) :
Anemophily is an abiotic means of pollination by wind and, being non-directional, a wasteful process as the pollen would reach the stigma through wind is a hit-or-miss affair. During the transit of pollen through wind, a considerable amount of pollen is lost because it never reaches a proper stigma. To stand this loss, anemophilous plants have to produce enormous quantities of pollen. Anemophily is also associated with reduction in the number of ovules per ovary. Some models predict that plants benefit from numerous inexpensive flowers distributed throughout the inflorescence, each with a single ovule or a few ovules. In grasses there is just one ovule per ovary. This is to increase the probability of successful pollination of each ovule.
37. (c) :
In angiosperms, the female gametophyte is called embryo sac. It contains 8 nuclei but 7 cells — 3 micropylar, 3 chalazal and one central. The three micropylar cells are collectively known as egg apparatus. One middle cell is larger and is called egg or oosphere. The remaining two cells are called synergids or help cells. Each of them (synergids) bears a filiform apparatus in the micropylar region, a lateral hook, chalazal vacuole and a central nucleus.
38. (a) :
In nucellar polyembryony, some of the nucellar cells surrounding the embryo sac start dividing. Then it protrudes into the embryo sac and develop into the embryos. In such species, each ovule contains many embryos. Occurrence of more than one embryo in a seed is referred as polyembryony. Nucellar polyembryony is found in many of the citrus and mango varieties.
39. (d) :
Autogamy is a kind of pollination in which the pollen from the anthers of a flower are transferred to stigma of the same flower. Cleistogamy, homogamy, bud pollination are three methods of the autogamy.Cleistogamy occurs in those plants, which never open and ensure complete self-pollination. E.g., Commelina bengalensis, Oxalis, Viola etc.
40. (d) :
Potato is the common example of stem-tuber. It stores starch as reserve food material. The potato- tubers are used for vegetative propagation. These possess axillary buds over their nodes or eyes. The buds produce new plantlets when a stem-tuber or a part of it having an eye is placed in the soil.
41. (c) :
Anemophily is pollination of a flower in which the pollen is carried by the wind. Examples of anemophilous flowers are those of grasses and conifers.
42. (a) :
Embryo sac is a cell that develops in the ovule of flowering plants. It is equivalent to the female gametophyte of lower plants, although it is very much reduced. Typically it contains eight nuclei formed by division of the megaspore mother cell. Megaspore mother cell divides by meiosis to give rise to four haploid megaspores. One of the megaspores develops into the embryo sac; the others abort.
43. (d) :
Apomixis is a reproductive process in plants that superficially resembles normal sexual reproduction but in which there is no fusion of gametes. The embryos develop simply by division of a diploid cell the ovule. So, the progenies produced are identical to the parent. In vegetative reproduction also progenies produced are identical to the parent.
44. (b) :
Apomixis is abnormal kind of sexual reproduction in which egg or other cells associated with egg (synergids, antipodals, etc.) develop into embryo without fertilization and meiosis. Development of embryos directly from sporophytic tissues like nucellus and integuments is called adventive embryony which is also a type of apoximis. E.g., Citrus, mango.
45. (b) :
Geitonogamy is the transfer of pollen grains from the anther to stigma of another flower on the same plant or genetically similar plant, e.g., in maize.
46. (b) :
Pollination by wind is called anemophily and such plants in which pollination occurs by wind are called anemophilous plants. Anemophilous plants are characteristized by small flowers, pollens present in large number which are small, dry and light in weight (carried upto 1300 Km by wind), number of ovules generally reduced in ovary (biological significance), feathery or brushy stigma (to receive the pollen). Grasses and palms are generally anemophilous.
47. (c) :
A – offset of water hyacinth (Eichhornia)
B – Antheridiophore of Marchantia
C – Antipodals of the mature embryo sac
D – Oogonium of Chara
48. (b) :
In Pistia (water lettuce) vegetative propagation occurs by offset where one intemode long runners grows horizontally along the soil surface and gives rise to new plants either from axillary or terminal buds.
49. (c) :
Vegetative propagation in mint occurs through sucker.
50. (d) :
Megaspore is the initial cell or beginning of female gametophyte or embryo sac. The nucleus of megaspore undergoes divisions and gives rise to embryo sac or female gametophyte, which is called megagametogenesis. During development, the single nucleus of functional megaspore (of chalazal end) undergoes 3 mitotic divisions to form 8 nuclei. Out of these 8 nuclei, 4 are present at micropylar end and 4 at chalazal end. One nucleus from each group comes in centre to form 2 polar nuclei. Remaining 3 nuclei at micropylar end constitute egg apparatus and remaining 3 nuclei at chalazal end constitute 3 antipodal cells or antipodals. So it is 3 + 2 + 3 arrangement.
so fully developed normal type of female gametophyte or embryo sac is 8-nucleated and 7-celled structure.
51. (b) :
Within the embryo sac three cells are grouped together at the micropylar end and constitute the egg apparatus. The egg apparatus, in turn, consists of two synergids and one egg cell. The synergids have special cellular thickenings at the micropylar tip called filiform apparatus, which plays an important role in guiding the pollen tubes into the synergid. Three cells are at the chalazal end and are called the antipodals. The large central cell, has two polar nuclei.
52. (c) :
Unisexuality or dicliny is a condition in which two types of unisexual flowers are present i.e., staminate (male flower) and pistillate (female flower). The plant may be monoecious or dioecious. This is a device for cross pollination (or xenogamy). Both xenogamy and geitonogamy (i.e. transfer of pollen from anther of one flower to stigma of another flower of either the same or genetically similar plant) are included under allogamy/cross pollination. Autogamy or self pollination (i.e. transfer of pollen from anther to stigma of the same flower) occurs in bisexual flower.
53. (a) :
Refer answer 31.
54. (a) :
In the pollen sac (microsporangium) of the anther, haploid microspores are formed by mitosis. Mitosis then follows to produce a two-celled pollen grain with a small generative cell and a large vegetative cell. This generative cell will undergo further mitosis to form two male gametes (nuclei). The pollen tube grows through a spore in the pollen grain, with the tube (vegetative) nucleus at its tips and the male nuclei behind.
55. (d) :
If two plants can reproduce freely with each other and form seeds, they are concluded to belong to same species. Plants belonging to same species have mostly every character common and will be able to reproduce freely with each other to produce new generations.
56. (d) :
Anther consists of microsporangia or pollen sacs. The archesporium gives rise to parietal cells and primary sporogenous tissue. Sporogenous cells divide to form pollen grain or microspore mother cells. They are diploid and connected by plasmodesmata. The microspore, mother cells consists of a callose wall inner to the cell wall. The mother cell then undergoes meiosis and forms tetrads of microspores. Finally the wall of the mother cell degenerates and pollen grains are separated.
57. (c) :
Development of fruits without fertilization is called parthenocarpy and such fruits are called parthenocarpic fruits. Parthenocarpic fruits are seedless. A flower is emasculated and auxins are applied to the stigma of the flower, it forms a parthenocarpic fruit. For parthenocarpy induction by auxins, these should be applied after anthesis (first opening of flower) and by gibberellins, these should be applied earlier i.e., at anthesis.
58. (c) :
The cotyledons are known as seed leaves, they are attached to the embryonic axis. Dicotyledons typically have two cotyledons and monocotyledons have only one cotyledon. The single shield shaped cotyledon in grains is known as scutellum.
Tire scutellum does not contain food and its function is to absorb food from the endosperm and transfer it to the growing parts of the embryo. The plumule consists of growing tip of the shoot along with few young leaf primordia. It is covered by a sheath called coleoptile. The radicle which lies at the base of the grain is also covered with a sheath called coleorhiza. The hypocotyl is very short and is represented by a short axis in between radicle and plumule.
59. (c) :
Refer answer 50.
60. (a) :
The arrangement of ovules inside the ovary on placenta is called placentation. Sweet pea or Lathyrus odoratus belongs to family leguminosae or fabaceae and in all the members of this family the placentation is marginal in which ovary is unilocular and ovules are borne on margin.
61. (b) :
Leaves of a number of plants develop or possess adventitious buds for vegetative propagation e.g. Bryophyllum, Kalanchoe, Adiantum caudatum etc.
62. (a) :
Normal type of sexual reproduction having two regular features, i.e., meiosis and fertilization, is called amphimixis. But in some plants, this normal sexual reproduction (amphimixis) is replaced by some abnormal type of sexual reproduction called apomixis.
Apomixis may be defined as, ‘abnormal kind of sexual reproduction in which egg or other cells associated with egg (synergids, antipodals, etc.) develop into embryo without fertilization and with or without meiosis’.
Adventive embryony is a type of apomixis in which development of embryos directly from sporophytic tissues like nucellus and integuments takes place, e.g., in Citrus, mango, etc.
63. (a) :
Depending upon position of micropyle in
relation to chalaza, ovules are of 6 types in angiosperms. In amphitropous type the curvature is observed both in body of ovule and embryo sac. The embryo sac assumes horse shoe-shape. Micropyle is directed downwards. It is commonly found in families papaveracerae, alismaceae and butomaceae.
Circinotropous ovule is characteristic of family cactaceae. Here the ovule is straight first but due to more growth on one side gets inverted and later becomes straight again.
Orthotropous ovule is the most primitive and of simplest type. It is also known as atropous or straight ovule.
Anatropous ovule is the most common type of ovule found in angiosperms. Here the body of the ovule gets inverted and micropyle is on lower side.
64. (c) :
The pollen tube enters into the embryo sac at the micropylar end. This entry may be between egg and one synergid or between wall of embryo sac and synergid or through one synergid. So one synergid is always degenerated to allow the entry of the pollen tube.
65. (a) :
Endosperm is formed due to fusion of the haploid male gamete with the polar nucleus of the embryo sac. But in this case the male plant is tetraploid so that its gametes would be diploid. When these diploid gametes fuse with two polar nuclei of the embryo sac the resultant endosperm would be tetraploid.
66. (a) :
In hemianatropous or hemitropous ovule, the nucellus and integuments are at right angles to stalk or funiculus so that the ovule becomes curved. It is commonly found is primulaceae and Ranunculus. In campylotropous ovule the body of the ovule gets curved and micropyle is directed downwards. Atropous ovule is erect and micropyle, chalaza and funiculus are in the same straight line. Anatropous ovule is the most common type of ovule in angiosperms. In this the body of the ovule gets inverted and the micropyle is on lower side.
67. (a) :
In Adiantum caudatum, adventitious buds develop at the leaf tips. When such leaf tips happen to touch the soil, they form new plant. This process helps in propagation of this fern to a large area. Adiantum caudatum is commonly called as walking fern.
68. (d) :
Anthesis is the process of opening floral buds. Reception of pollen by stigma is called pollination. Formation of pollen is called microsporogenesis.
69. (b) :
In flowering plants, archaesporial cells are vertical rows of hypodermal cells at four angles of anther. These undergo periclinal (transverse) division to form an outer primary parietal cell and inner sporogenous cell. Primary parietal wall after few more periclinal divisions forms anther wall and sporogenous cells give rise to sporogenous tissue.
70. (d) :
On reaching of pollen tube inside the embryo sac, the 2 male gametes are discharged through a sub¬terminal pore in pollen tube. The contents of pollen tube are discharged in the synergid and the pollen tube does not grow beyond it in the embryo sac. Further the cytoplasm of pollen tube is restricted to chalazal end of this synergid cell.
71. (a) :
Each microspore or pollen is having a two layered wall. Outer layer is thick tough cuticularized called exine, which is chiefly composed of a material called ‘sporopollenin’. Inner layer is thin, delicate and smooth called intine, which is made of pectocellulose. Exine is not uniform but is thin at one or more places in the form of germ pores. Whereas intine made of pectocellulose covers the entire surface of pollen grains.
72. (b) :
Anatropus ovule is the most common type of ovule found in angiosperms. Here the body of the ovule gets inverted and micropyle is on lower side. It comes very close to the hilum and the chalaza is upwardly directed.
73. (a) :
Presence of more than one embryo inside the seed is called polyembryony. It is more common in gymnosperms than angiosperms. In angiosperms, it is generally present as an unusual feature in few cases like Citrus, mango etc.
In Citrus many embryos are formed from the structures outside the embryo (like nucellus). This is commonly called adventive polyembryony. In Citrus upto 10 nucellar embryos are formed.
74. (b) :
Grass is a monocot plant. Primary sporogenous cell gives rise to microspore mother cells or pollen mother cells. Each MMC on reduction division gives rise to 4 microspores or pollens and
this formation of microspores or pollens is called microsporogenesis. Karyokinesis is of successive type. The successive type of cytokinesis is common in monocots. Here both meiotic I and II nuclear divisions are followed by wall formation and it leads to isobilateral tetrad.
75. (d) :
Anemophily is the pollination by wind. Anemophilous plants are characterized by small flowers, pollens present in large number which are small, dry and light in weight, number of ovules generally reduced in ovary, feathery or brushy stigma to recieve the pollen. All these features are shown by coconut flower.
In Vallisneria pollination occurs outside water called epihydrophily. Callistemon (Bottle brush) is pollinated by birds and is an example of omithophily. Salvia is insect pollinated and is an example of entomophily.
76. (a) :
Double fertilization is the simultaneous occurrence of syngamy and triple fusion. Syngamy involves fusion of one male gamete with egg cell to form zygote. The result of syngamy is zygote (2n) which ultimately develops into embryo.
The second male gamete fuses with 2 polar nuclei or secondary nucleus to form triploid primary endosperm nucleus and this is called triple fusion. This primary endosperm nucleus (3n) ultimately develops into a nutritive tissue for developing embryo called endosperm.
77. (d) :
On the basis of number of megaspore nuclei taking part in development of female gametophyte or embryo sac, there are 3 types of embryo sacs-
(i) Monosporic type – In this type the single nucleus of functional megaspore undergoes 3 mitotic divisions to form 8 nuclei, 7 cells.
(ii) Bisporic type – Here embryo sac develops from 2 megaspore nuclei out of 4 nuclei formed after reduction division of MMC. It is also 8 nucleated.
(iii) Tetrasporic type – Here all the 4 megaspore nuclei formed after reduction division of megaspore mother
cell are functional and take part in development of embryo sac. It is further of different types. Fritillaria type, Plumbago type and Adoxa type are 8 nucleated.
78. (d) :
The endosperm of gymnosperms is haploid. It is a pre-fertilization tissue and is equivalent to female gametophyte, hence it is haploid in nature but in angiosperms it is post-fertilization tissue and is generally triploid in nature.
79. (a) :
Arrangement of ovules inside the ovary on placenta is called placentation. In marginal placentation ovary is unilocular and the placenta develops along the junction of the two margins of the carpel, called the ventral suture. It occurs in pea, wild pea, gram etc. In superficial placentation ovary is multilocular and ovules are borne on inner surface or partition walls as in water lily. In parietal placentation the ovary is unilocular and the ovules are borne on periphery as in Brassica, Argemone etc.
80. (d) :
In an orchid Ophrys speculum, there is most interesting and unique mechanism of pollination. Here pollination occurs by a wasp called Culpa aurea. In this orchid, pollination occurs by act of pseudocopulation. The appearance and odour of Ophrys is similar to female wasp and are mistake by male wasps and they land on Ophrys flowers to perform act of pseudo-copulation and thus pollination takes place. This plant-insect relationship is useful only to plant.
81. (a) :
Sunflower (Helianthus) belongs to family asteraceae of dicotyledons. A dicot embryo has an embryonal axis and 2 cotyledons attached to it laterally. So the number of cotyledons in sunflower will be two.
82. (c) :
Refer answer 76.
83. (b) :
If the female plant is tetraploid, then the central cell of embryo sac, which is a fused polar nuclei, will also be tetraploid. Fusion of the tetraploid central cell to the haploid male gamete forms a pentaploid endosperm in the given example.
84. (c) :
Refer answer 76.
85. (a) :
Pollen grains or microspores are formed inside anther, which is the fertile portion of stamen or microsporophyll. Inside the anther, primary sporogenous cell gives rise to microspore mother cells or pollen mother cells (MMC or PMC). Each MMC on reduction division gives rise to 4 microspores or pollens. So these four cells will give rise to 4 x 4 = 16 pollen grains.
86. (b) :
Anthesis refers to opening of a flower bud. It is the duration of life of a flower from the opening of the bud to setting of the fruit.
87. (c) :
Pollen grains or microspores are formed inside anther, which is the fertile portion of stamen or microsporophyll. The formation of microspores or pollens is called microsporogenesis. The primary sporogenous cell gives rise to microspore mother cells or pollen mother cells. Each microspore mother cell on reduction division gives rise to 4 microspores or pollens. So for the formation of 100 pollen grains, 25 MMC are required. It inolves karyokinesis followed by cytokinesis.
88. (c) :
Refer answer 73.
89. (b) :
Refer answer 45.
90. (b) :
Refer answer 50.
91. (d) :
Number of meiotic divisions required to produce 200/400 seeds of pea would be 250/500. 200 seeds of pea would be produced from 200 pollen grains and 200 eggs. 200 pollen grains will be formed by 50 microspore mother cell while 200 eggs will be formed by 200 megaspore mother cell so 250/500.
92. (a) :
Double fertilization is the characteristic feature of angiosperms. This phenomenon first observed by Nawaschih, 1898 in Lilium and Fritillaria. In angiosperms one male gamete fuses with the two polar nuclei to form triploid primary endosperm nucleus. The process is called triple fusion. These two acts together are known as double fertilization.
93. (a) :
Orthotropous ovule is straight with funiculus, embryo sac, chalaza and micropyle lying on one straight line. It is an Polygonum type ovule in which body of the ovule is straight. Funiculus, chalaza, embryo sac and micropyle lie in the same vertical axis.
94. (b) :
Study of formation, growth and development of new individual from an egg is embryology. Study of an individuals life cycle after the fertilization takes place till it develops into a new organism.
95. (b) :
A population of genetically identical individuals, obtained from asexual reproduction is clone. Cloning is a technique by which genetically same individuals can be produced without including any sexual reproduction, e.g. Dolly, the cloned sheep.
96. (d) :
Meiosis is best observed in dividing microsporocytes. Microsporocytes or microspore mother cell after meiosis give rise to microspore. Other cells do not divide by meiosis.
97. (d) :
Refer answer 76.
98. (a) :
Syngamy means fusion of gametes. Syngamy is the phenomenon in which male gamete fuses with the egg.
99. (d) :
Pollen grain is odd one among all the other three. Pollen grain in a male gametophytic structure. Whereas all the other three are found inside ovule (nucellus, micropyle and embryo sac).
Antipodal cells and egg cell are haploid structures as they are after meiosis while the others nucellus, megaspore mother cell and primary endosperm nucleus are diploid structures.
Embryo sac occurs in ovule. Ovule is integumented megasporangium. It consists of nucleus covered by one or two integuments, mounted on a funicle, chalaza and micropyle. The ovule is vascularised.
The term pollination refers to the transfer of pollen from anther to stigma. Because pollens are found only in angiosperms and gymnosperms so this phenomenon relates to angiosperms and gymnosperms only.
Cellular totipotency was demonstrated by F.C. Steward. Cellular totipotency is the technique of regeneration or development of complete plant from explant or cell or tissue of the plant.
In most of the plants the pollen tube enters the ovule through the micropyle and the phenomenon is called as porogamy. Entry through chalaza is chalazogamy and through integuments or funiculus is mesogamy.
The two gametes i.e., sperm released by pollen tube and egg move in opposite direction by an unknown mechanism but most probably by streaming currents of cytoplasm i.e., due to attraction of their protoplasts. The nucleus of one male gamete fuses with the egg nucleus and the phenomenoft is called fertilization.
Female gametophyte of angiosperms is represented by embryo sac. The polygonum type of embryo sac is eight nucleate and seven celled. It is found in more than 80% plant families. The nucleus of megaspore undergoes division and give rise to embryosac or female gametophyte by the process of megagametogenesis.
Male gametophyte of angiosperms is microspore. Microspore is haploid, uninucleate, minute spores produced in large numbers as a result of meiosis in microspore mother cell inside the microsporangia. These are the first cell of gametophytic generations in angiosperms.
Young pollen grains produce androgenic haploids in anther cultures. Because rest all i.e., anther wall, tapetal layer of anther wall and connective tissue are the diploid tissue as they are part of anther pollen grains are produced by meiosis.
Gametes are invariably haploid. Spores are formed in lower plants by mitotic division and they may be diploid but gametes are always be made by meiosis and they are always haploid.
Generative cell was destroyed by laser but a normal pollen tube was still formed because vegetative cell is not damaged. Each microspore divide by mitotic division making a smaller generative cell and a larger vegetative cell or tube cell. If generative cell is damaged then the normal pollen tube will be formed because pollen tube is formed by vegetative cell not by generative cell of microspore.
111. (d) :
Nucellar embryo is apomictic diploid. Substitution of usual sexual reproduction by a form of reproduction which does not include meiosis and syngamy is called apomixis. In this technique embryo is developed by some other tissue without fertilization e.g., nucellus or integuments or infertilized egg. Nucellus in a diploid tissue so nucellar embryo is apomictic diploid.
112. (d) :
Development of an organism from female gamete/egg without involving fertilization is parthenogenesis and when a fruit is developed by this technique it is called parthenocarpy.
Perisperm is persistent nucellus. Endosperm formation is accompanied by degeneration of nucellus.
114. (b) :
Double fertilization and triple fusion were discovered by Nawaschin and Guignard in Fritillaria and Lilium. In angiosperms one male gamete fuses with the two polar nuclei to form triploid primary endosperm nucleus. The process is called triple fusion. These two acts together are known as double fertilization.
115. (c) :
For formation of 100 zygotes, 100 male gametes and 100 female gametes (eggs) are required. 100 male gametes are developed from 100 microspores (from 25 meiotic divisions) and 100 eggs are developed from 100 megaspores (from 100 meiotic division).
Hence, number of meiotic divisions necessary for 100 zygotes formation = 25 + 100 = 125.
116. (b) :
The male gametophyte or microspore is shed at 3-nucleate stage. The microspore undergoes only two mitotic divisions.
117. (d) :
Parthenogenesis is the phenomenon of development of embryo from egg without fertilization. It is of two types haploid and diploid parthenogenesis. It usually occurs due to defective meiosis that results in egg nucleus having unreduced number of chromosomes.
118. (a) :
Formation of gametophyte directly from sporophyte without meiosis and spore formation is apospory. The gametophyte thus has diploid number of chromosomes. Such gametophyte may form viable gametes which fuse to form tetraploid sporophyte. Apogamy is development of sporophyte directly from gametophytic tissue without fusion of gametes. Amphimixis is normal sexual reproduction. Parthenogenesis is development of embryo from egg without fertilization.