NEET Biology Structure And Events Of Pre Fertilisation Multiple Choice Question And Answers

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Biology MCQs with answers for NEET Structure and Events of Pre-Fertilisation-2

Question 1. Identify the labels A to E in the below diagram of carpel.

NEET Biology Structure and Events of Pre-Fertilisation 2 Question 1 Carpel.

  1. A–Style, B–Ovary, C–Thalamus, D–Ovules, E–Stigma
  2. A–Ovary, B–Filament, C–Ovules, D–Style, E–Stigma
  3. A–Thalamus, B–Cycle, C–Stigma, D–Ovary, E–Ovules
  4. A–Stigma, B–Style, C–Ovules, D–Ovary, E–Thalamus

Answer: 4. A–Stigma – Landing ground for pollen grains

B–Style – Passage for pollen tube C–Ovule – Formation of seed D–Ovary – Embryo sac/fruit E–Thalamus – Receptacle for ovary

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Question 2. Megasporangium is equivalent to

  1. Fruit
  2. Nucellus
  3. Ovule
  4. Embryo sac

Answer: 3. Ovule

  • Ovule is also called integumented megasporangium. it develops into seed after fertilisation in spermatophytes.
  • These occur singly or in a cluster inside ovary with parenchymatous cushions called placenta.

Question 3. The ovule of angiosperms might evolve from

  1. Megagametangium
  2. Integumented megasporangium
  3. Megasporangium
  4. Microgametangium

Answer: 2. Integumented megasporangium

  • Ovule of angiosperms evolved from integumented megasporangium containing a mature megagametophyte.
  • Integuments are specialised protective coverings around megasporangium which vary in number.

“gamete transfer “

Question 4.  Point out the odd one?

  1. Nucellus
  2. Embryo sac
  3. Micropyle
  4. Pollen grain

Answer: 4. Pollen grain

All of given structures are found in ovule, i.e. nucellus, embryo sac and micropyle, while pollen grain is male gametophyte

Question 5. The body of the ovule is fused within the funicle at

  1. Micropyle
  2. Nucellus
  3. Chalaza
  4. Hilum

Answer: 4. Hilum

  • The attachment point of funicle and body of ovule is known as hilum. it is the point where ovule attaches to the base.
  • it is generally present as an eye of the seed as it is present as a scar.

Biology MCQs with answers for NEET

NEET Biology Structure And Events Of Pre Fertilisation Multiple Choice Question And Answers

Question 6. Chalazal pole is present

  1. Opposite to micropyle
  2. At the origin of integuments
  3. Opposite to nucellus
  4. Near the embryo sac

Answer: 1. Opposite to micropyle

Chalazal pole is present just opposite to the micropylar end and chalaza represents the basal part of the ovule.

Question 7. The stalk of ovule is called

  1. Pedicel
  2. Petiole
  3. Funicle
  4. Hilum

Answer: 3. Funicle

A fully mature ovule consists of the stalk or funicle and the body. One end of the funicle is attached to the placenta and the other end to the body of the ovule.

Question 8. Nucellus is

  1. Basic tissue of ovary
  2. Basic tissue of ovule
  3. Basic tissue of embryo
  4. Basic tissue of seed

Answer: 2. Basic tissue of ovule

  • Nucellus is the basic tissue of ovule. it contains the embryo sac and have abundant reserve food materials.
  • It is enclosed by the integuments. in certain flowering plants, it may persist after fertilisation and provide nutrients for the embryo.

Question 9. Integument

  1. Provides protection to nucellus and embryo sac
  2. After fertilisation becomes the seed coat
  3. Provides nutrition to the embryo sac
  4. Both 1 and 2

Answer: 4. Both 1 and 2

  • Integument is the part of the ovule in seed plants that encloses the nucellus. The ovules of a number of plants have one integument, while others, particularly in the monocotyledonous plants, have two.
  • After fertilisation, the integument turns into a seed coat. integument provides protection to the nucellus and to the developing embryo sac.

Biology MCQs with answers for NEET

Question 10.  Ovule without integuments is called

  1. Unitegmic
  2. Bitegmic
  3. Ategmic
  4. Tritegmic

Answer: 3. Ategmic

Ovules that lack integuments are known as ategmic ovules. These occur in Santalum, Loranthus and Olax. Ovule with one integument is called unitegmic and ovule with two integuments is called bitegmic.

“events of fertilization “

Question 11. Crassinucellate means

  1. Thin nucellus
  2. Elongated nucellus
  3. Massive nucellus
  4. Rough nucellus

Answer: 3. Massive nucellus

Crassinucellate ovule consists of a massive nucellus. In crassinucellate ovules, there is a well-developed parietal tissue and the megaspore mother cell is separated from the nucellar epidermis by one or several layers of cells.

Question 12.  Identify the various parts A to E in the given diagram of an ovule.

NEET Biology Structure and Events of Pre-Fertilisation 2 Question 12 Ovule.

  1. A–Chalazal end, B–Embryo sac, C–Nucellus, D–inner integuments, E–Outer integuments
  2. A–inner integuments, B–Nucellus, C–Embryo sac, D–Chalazal end, E–Hilum
  3. A–Hilum, B–Funicle, C–Micropyle, D–Nucellus, E–Embryo sac
  4. A–Micropylar end, B–Embryo sac, C–Funicle, D–Hilum, E–Outer integuments

Answer: 3. A– Hilum, B–Funicle, C–Micropyle, D–Nucellus, E–Embryo sac

Question 13. A micropyle is a

  1. Small pore through which water enters
  2. Small aperture where no integuments are present
  3. Small pores needed for seed existence
  4. All of the above

Answer: 4. All of the above

A micropyle is a small aperture where no integuments are present. it is essential for seed existence because through this pore, the water enters inside to facilitate germination and gaseous exchange takes place through this pores only.

Biology MCQ For NEET With Answers

Question 14. Which of these cells is the largest cell of the ovule?

  1. Antipodal cell
  2. Central cell
  3. Megaspore mother cell
  4. The size of the cells varies from species to species and none of the given above can be treated as largest

Answer: 3. Megaspore mother cell

Ovules generally differentiate a single Megaspore Mother Cell (MMC) in the micropylar region of the nucellus.

it is a largest cell containing dense cytoplasm and
a prominent nucleus.

Question 15. Match the items in Column 1 with those in Column 2 and choose the correct answer.

NEET Biology Structure and Events of Pre-Fertilisation 2 Match Following Column Question 15

Answer:  A–2, B–3, C–v, D–4, E–i

Question 16. Consider the following statements.

  1. The ovule is attached to the placenta by means of a stalk called filament.
  2. The ovule fuses with the stalk in the region called hilum.
  3. The two protective envelopes of ovule are called integuments.
  4. The small opening in the tip of ovule is called germ pore.

Choose the correct option.

  1. 1 and 4
  2. 1 and 3
  3. 2 and 4
  4. 2 and 3
  5. 3 and 4

Answer: 4. 2 and 3

  • Statements(2) and (3) are correct. Other statements are incorrect, which can be corrected as Ovule is attached to the placenta by a small stalk called funicles.
  • A small opening at the apex of the ovule is called the micropyle. The germ pore is the prominent aperture on pollen grain where sporopollenin is absent.

“events of fertilization “

Question 17. What is the correct sequence of the formation of female gametophytes in angiosperms?

  1. Nucellus, megaspore tetrad, megaspore mother cell, megaspore, female gametophyte
  2. Megaspore tetrad, nucellus, megaspore mother cell, megaspore, female gametophyte
  3. Nucellus, megaspore mother cell, megaspore tetrad, megaspore, female gametophyte
  4. Megaspore mother cell, megaspore tetrad, megaspore, nucellus, female gametophyte

Answer: 3. Nucellus, megaspore mother cell, megaspore tetrad, megaspore, female gametophyte

  • In angiosperms, the body of the ovule consists of a mass of parenchymatous cells called nucellus. In the hypodermal region of nucellus towards the micropylar end, a primary archesporial cell develops, which by further division forms a diploid megaspore mother cell.
  • The latter undergoes meiosis to form a megaspore tetrad. Usually, the chalazal megaspore remains functional while the other three degenerate. The functional megaspore is the first cell of female gametophyte (embryo sac).

Thus, option (3) is correct.

Biology MCQ For NEET With Answers

Question 18. What is the direction of micropyle in anatropous ovule?

  1. Upward
  2. Downward
  3. Right
  4. Left

Answer: 2. Downward

  • In anatropous ovule (completely inverted), the micropyle comes very close to hilum and becomes downward and the chalaza is upwardly directed.
  • This type is very common in dicotyledonous and monocotyledonous families.

Question 19. An ovule, where chalaza, micropyle and embryo sac lie along vertical line is called

  1. Campylotropous ovule
  2. Hemianatropous ovule
  3. Orthotropous ovule
  4. Circinotropous ovule

Answer: 3. Orthotropous ovule

  • Depending upon the shape and orientation, the ovules of angiosperms are classified into the following types Orthotropous–the micropyle, chalaza and funicle lie in a straight or vertical line.
  • This is the most primitive type of ovule found in the betel, piper, polygonum. Hemianatropous ovule-turn at a 90º angle upon the funicle, the body of ovule is at right angle to the funicle.
  • Campylotropous ovule-circle more or less at a right angle to the funicle. The micropyle end is bent down slightly. Circinotropous ovule-the funicle is long creating nearly a full circle around the ovule with micropyle pointing in an upward direction.

Question 20. The wall curvature is more pronounced and embryo sac becomes horse-shoe shaped the ovule is

  1. Anatropous
  2. Amphitropous
  3. Campylotropous
  4. Orthotropous

Answer: 2. Amphitropous

In amphitropous ovule, curvature is more pronounced or effective in the nucellus and due to this effect of the nucellus, embryo sac becomes horseshoe-shaped. Micropyle comes close to the hilum.

Question 21. Given below are the different types of ovules. identify A to F.

NEET Biology Structure and Events of Pre-Fertilisation 2 Question 21 Different Types Of Ovules

  1. A–Circinotropous, B–Amphitropous, C–Campylotropous, D–Hemianatropous, E–Anatropous, F–Orthotropous
  2. A–Campylotropous, B–Anatropous, C–Hemianatropous, D–Amphitropous, E–Circinotropous, F–Orthotropous
  3. A–Orthotropous, B–Anatropous, C–Hemianatropous, D–Campylotropous, E–Amphitropous, F–Circinotropous
  4. A–Anatropous, B–Campylotropous, C–Hemianatropous, D–Amphitropous, E–Circinotropous, F–Orthotropous

Answer: 3. A–Orthotropous, B–Anatropous, C–Hemianatropous, D–Campylotropous, E–Amphitropous, F–Circinotropous

Question 22. In angiosperms, microsporogenesis and megasporogenesis

  1. Involve meiosis
  2. Occur in ovule
  3. Occur in anther
  4. Form gametes without further divisions

Answer: 1. Involve meiosis

  • In angiosperms, microsporogenesis, i.e. formation of microspores (or pollen grains) occurs by the meiotic divisions of the diploid microspore mother cell (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.

Question 23. In a flowering plant, the archegonium

  1. Encloses the sperm
  2. Gives rise to only the wall of the sporangium
  3. Encloses the ovum
  4. Gives rise to seed wall

Answer: 3. Encloses the ovum

The archegonium encloses the ovum. The male gamete enters the archegonium through the tubular end containing the neck cells.

Biology MCQ For NEET With Answers

Question 24. The haploid cell which divides by mitosis to form embryo sac is

  1. Megaspore mother cell
  2. Microspore mother cell
  3. Functional megaspore
  4. Non-functional megaspore

Answer: 3. Functional megaspore

In megasporangium, diploid megasporocyte divides by meiosis to produce 4 haploid megaspores, one becomes functional and other three degenerate. The functional megaspore divides by mitosis to form a multicellular embryo sac.

“events of fertilization “

Question 25. Generally, archesporium of an ovule is

  1. Single-celled and hypodermal in origin
  2. Single-celled and lies in the centre of the ovule
  3. Single-celled and terminal in origin
  4. Many called and lie in the centre

Answer: 1. Single-celled and hypodermal in origin

  • In the ovule or megasporangium, during the process of megasporogenesis, hypodermal cell functions as a archesporium cell and becomes more prominent because of large size, denser cytoplasm and large nucleus.
  • In tenuinucellate ovules, archesporial cell directly functions as MMC while in crassinucellate ovules, archesporial cell divides periclinal to form an outer parietal cell and inner primary sporogenous cell that functions as MMC. Hence, a single hypodermal cell in the nucellus functions as the archesporium.

Question 26. In majority of angiosperms

  1. Egg has a filiform apparatus
  2. There are numerous antipodal cells
  3. Reduction division occurs in the megaspore mother cell
  4. A small central cell is present in the embryo sac

Answer: 3. Reduction division occurs in the megaspore mother cell

Megaspore mother cell of megasporangium undergoes meiosis (reductional division) and forms megaspore tetrad, out of which one megaspore is functional. Central cell of embryo sac is the large cell consisting of two polar nuclei.

Synergids, the flanking cells of the egg cell, have finger-like projections of the wall in their cytoplasm, the filiform apparatus. An embryo sac has three antipodal cells which provide nutrition to developing embryo.

Question 27. Functional megaspore in an angiosperm develops into

  1. Ovule
  2. Endosperm
  3. Embryo sac
  4. Embryo

Answer: 3. Embryo sac

Functional megaspore in an angiosperm develops into the embryo sac. it undergoes free nuclear mitosis to form 8-nucleated and 7-celled
embryo sac.

NEET Biology Mcq

Question 28. Embryo sac is also known as

  1. Microgametophyte
  2. Microsporangium
  3. Megagametophyte
  4. Megasporangium

Answer: 3. Megagametophyte

The female gametophyte specifically termed a megagametophyte. it is also called embryo sac. The megagametophyte produces an egg cell for the purpose of fertilisation.

Question 29. identify the type of cell division A to D in the following flowchart.

NEET Biology Structure And Events Of Pre-Fertilisation 2 Question 29 Flow Chart

  1. A–Meiosis-i, B–Mitosis, C–Mitosis, D–Meiosis
  2. A–Meiosis-i, B–Meiosis-2, C–No division, D–Mitosis
  3. A–Mitosis, B–No division, C–Meiosis-2, D–Meiosis-i
  4. A–Mitosis, B–Mitosis, C–Meiosis-i, D–Meiosis-i

Answer: 3. A– Meiosis-i, B– Meiosis-2, C–No division, D–Mitosis

Question 30. Select the correct statement.

  1. Integuments begin to form below the nucellus and grow upwards.
  2. The central part of oVule is parenchymatous mass of cells.
  3. Majority of angiosperms have bitegmic ovules.
  4. All of the above

Answer: 4. All the given statements are correct.

Question 31. How many meiotic divisions would be required to produce i0i female gametophytes in an angiosperm?

  1. 26
  2. 101
  3. 127
  4. None of these

Answer: 1. 26

  • In angiosperms, the female gametophyte is produced inside megasporangium after meiotic cell division in megaspore mother cell.
  • When meiosis occurs in megaspore mother cell, three of the four megaspores degenerate and only one, called functional megaspore, develops further.
  • The functional megaspore forms ovule inside which develops female gametophyte or the embryo sac. Because three megaspore produced after reduction division degenerate, the number of meiotic cell divisions required to produce i0i female gametophytes will be 101.

NEET Biology Mcq

Question 32. The arrangement of megaspores in a tetrad in an angiosperm is

  1. Decussate
  2. Tetrahedral
  3. linear
  4. Isobilateral

Answer: 3. A linear tetrad of 4 cells lying in an axial row is formed during the development of angiosperms.

Question 33. In angiosperms, the functional megaspore of a linear tetrad is the

  1. First nearest to the micropyle
  2. Second from micropyle
  3. Third from micropyle
  4. Fourth from micropyle

Answer: 4. Fourth from micropyle

The sporogenous cell acts as megaspore mother cell. it undergoes meiosis and forms four haploid megaspores. The megaspore which is present farthest from the micropylar end or the one which is fourth from the micropylar end becomes the functional megaspore while the three on top disintegrate.

Question 34. Primary archaesporial cell develops from the cells of

  1. Nucellus towards micropylar end
  2. Inner integument towards micropylar end
  3. Nucellus towards chalazal end
  4. Outer integument towards chalazal end

Answer: 1. Nucellus towards micropylar end

In angiosperms, during megasporogenesis, the primary archaesporial cell develops in the hypodermal region of nucellus towards the micropylar end of the ovule. it grows in size, develops a prominent nucleus and undergoes further divisions.

Question 35. Assertion (A) Megaspore mother cell undergoes meiosis to produce four haploid gametes. Reason (R) Megaspore mother cell is 2n, meiosis gives haploid structure.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true, but R is not the correct explanation of A
  3. A is true, but R is false
  4. Both A and R are false

Answer: 1. Both A and R are true and R is the correct explanation of A.

Diploid megaspore mother cell (MMC) is developed inside the nucellus. it then undergoes meiotic division to form four haploid megaspore. MMC is diploid and megaspores are haploid.

NEET Biology Mcq

Question 36.  The embryo sac of an angiosperm is made up of

  1. 8 cells
  2. 7 cells and 8 nuclei
  3. 8 nuclei
  4. 8 cells and 7 nuclei

Answer: 2. 7 cells and 8 nuclei

Embryo sac of an angiosperm contains 8 nuclei and 7 cells. it contains 2 synergids, 3 antipodals, one egg cell and central cell. The central cell is the largest cell and contains two polar nuclei.

Question 37. The arrangement of the nuclei in a normal embryo sac in the dicot plants is

  1. 3+2+3
  2. 2+3+3
  3. 3+3+2
  4. 2+4+2

Answer: 1. 3+2+3

The arrangement of nuclei in normal embryo sac in a dicot plant is 3 +2 +3. Three at micropylar end [2 synergids, one egg cell], two in central region [2 polar nuclei] and three at chalazal end [3 antipodals].

Question 38. 8-nucleated embryo sac are

  1. Monosporic
  2. Bisporic
  3. Tetrasporic
  4. Any of the above

Answer: 4. Any of the above

The 8-nucleate embryo sac can be monosporic, bisporic or tetrasporic. The final organization of embryo sacs in all these types is 8-nucleate only.

Question 39. The number of nuclei migrating from each of the micropylar quartet and chalazal quartet to the centre of the normal embryo sac is

  1. One
  2. Two
  3. Four
  4. Number not fixed

Answer: 1. One

One nucleus from each quartet proceeds towards the centre of the embryo sac and then these two nuclei fuse to form secondary nucleus. The three nuclei remained at the micropylar region form the egg apparatus.

Question 40.

NEET Biology Structure and Events of Pre-Fertilisation 2 Question 40

In the diagram given above, parts labelled A, B, C, D, E and F are respectively identified as

  1. Synergids, polar nuclei, central cell, antipodals, filiform apparatus and egg
  2. Polar nuclei, egg, antipodals, central cell, filiform apparatus and synergies
  3. Egg, synergids, central cell, filiform apparatus, antipodals and polar nuclei
  4. Central cell, polar nuclei, filiform apparatus, antipodals, synergids and egg
  5. Filiform apparatus, polar nuclei, egg, antipodals, synergids and central cell

Answer: 1. A – Synergids, B – Polar nuclei, C – Central cell, D – Antipodals, E – Filiform apparatus, F – Egg.

“events of fertilization “

Question 41. Which of the following has only four nuclei in its embryo sac?

  1. Peperomia
  2. Carica
  3. Oenothera
  4. Pogostemon

Answer: 3. Oenothera

  • In Oenothera type embryo sac, the megaspore nucleus divides twice and produces four nuclei at the micropylar end.
  • Three of them act as egg apparatus while the fourth one is the polar nucleus. The second polar nucleus and the antipodal nuclei are absent.

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Question 42.  A pseudo embryo sac is seen in the members of the family

  1. Poaceae
  2. Podostemaceae
  3. Both 1 and 2
  4. Santalaceae

Answer: 2. Podostemaceae

Pseudoembryo sac contains several free nuclei and dense cytoplasm which are generally consumed by the developing embryo, e.g. Podostemaceae.

Question 43. Which one of the following pairs of plant structures has haploid number of chromosomes?

  1. Nucellus and antipodal cells
  2. Egg nucleus and secondary nucleus
  3. Megaspore mother cell and antipodal cells
  4. Egg cell and antipodal cells

Answer: 4. Egg cell and antipodal cells

Egg cells and antipodal cells have haploid number of chromosomes. in angiosperms, a single diploid megaspore mother cell matures. Through meiosis, it gives rise to four haploid megaspores

Question 44. Consider the following statements

  1. Megaspore mother cell is the last cell of female sporophytic (2n) generation.
  2. Haploid functional megaspore represents the first cell of female gametophytic generation.

Choose the correct option.

  1. Statement 1 is correct, but 2 is incorrect
  2. Statement 1 is incorrect, but 2 is correct
  3. Both statements 1 and 2 are correct
  4. Both statements 1 and 2 are incorrect

Answer: 3. Both statements 1 and 2 are correct.

Question 45. Consider the following statements

  1. Fritillaria type of tetrasporic embryo sac is 8-nucleated.
  2. Allium type of diasporic embryo sac is 8 nucleated.

Choose the correct option.

  1. Statement 1 is correct, but 2 is incorrect
  2. Statement 1 is incorrect, but 2 is correct
  3. Both statements 1 and 2 are correct
  4. Both statements 1 and 2 are incorrect

Answer: 3. Both statements 1 and 2 are correct

Question 46. in the angiospermic ovule, the synergids are

  1. Haploid
  2. Diploid
  3. Haploid before fertilisation and diploid after fertilisation
  4. Both (1) and (3)

Answer: 1. Haploid

Synergid cells are two specialised cells that lie adjacent to the egg cell in the female gametophyte. Synergids are haploid in nature as these are formed from the MMC by meiosis.

Question 47. Through which cell of the embryo sac, does the pollen tube enter the embryo sac?

  1. Egg cell
  2. Central cell
  3. Persistent synergid
  4. Degenerated synergid

Answer: 4. The pollen tube enters the embryo sac through the micropylar end. it can enter directly through the synergid or can enter from the space between the egg cell and synergid. So, the answer is 4 degenerated synergid.

NEET Biology Mcq

Question 48. Filiform apparatus is characteristic

  1. Cellular thickening at antipodal cell
  2. Cellular thickening at micropylar end
  3. Cellular thickening at synergid cells
  4. Cellular thickening at nuclear end

Answer: 3. Cellular thickening at synergid cells

Filiform apparatus are the special finger like cellular thickening of synergid cells. It guards the pollen tube inside the ovule towards the embryo sac.

Question 49. What does the filiform apparatus do at the entrance into ovule?

  1. It brings about opening of the pollen tube
  2. It guides pollen tube from a synergid to egg
  3. It helps in the entry of pollen tube into a synergid
  4. It prevents entry of more than one pollen tube into the embryo sac

Answer: 3. It helps in the entry of pollen tube into a synergid

  • Filiform apparatus is defined as the prolongation of the synergids by and the summit of the embryo sac. The function of the filiform apparatus is that it helps the pollen tubes to enter the ovule through synergids.
  • This is an important process during fertilisation in the angiosperms.

Thus, correct answer is option (3).

Question 50. Assertion (A) Synergids play an important role in directing the pollen tube growth. Reason (R) Because synergids secrete some chemotropically active substance.

  1. Both A and R are true and R is the correct explanation of the A
  2. Both A and R are true, but R is not the correct explanation of A
  3. A is true, but R is false
  4. Both A and R are false

Answer: 1. Both A and R are true and R is the correct explanation of A.

  • Synergids are part of the egg apparatus along with the egg cell.
  • The pollen germinates on the stigma to form the pollen tube. The pollen tube reaches the egg cell by chemotropism. A chemical stimulus is produced by synergids.
  • This stimulus allows the movement of the pollen tube towards the micropylar end of the ovule through which the pollen tube enters the ovule.

Question 51. In a mature embryo sac, the central cell is

  1. Single nucleate
  2. Binucleate
  3. Four nucleate
  4. Eight nucleate

Answer: 2. Binucleate

Embryo sac is present at the centre of the nucellus of the ovule. It is 7 celled and 8-nucleated structure which is composed of three celled egg apparatus, three antipodals and a binucleated central cell or secondary nucleus.

Question 52. Antipodal nuclei in a typical angiospermic embryo sac are found towards

  1. Micropylar end
  2. In the middle (polar) region
  3. Chalazal end
  4. On the lateral sides

Answer: 3. Chalazal end

Antipodal cells are haploid in nature. These three haploid cells in the embryo sac of flowering plants are situated at the chalazal region (end).

Question 53. Egg apparatus is present at

  1. Micropylar end
  2. Chalazal end
  3. Hilum
  4. Funicle

Answer: 1. Micropylar end

The egg apparatus is located at the end of the embryo sac closer to the micropylar end.

Question 54. Secondary nucleus is formed by the fusion of

  1. Egg apparatus
  2. Two polar nuclei
  3. Degeneration synergides
  4. Antipodal cells

Answer: 2. Two polar nuclei

  • The secondary nucleus is formed by the fusion of two polar nuclei Vegetative nucleus and generative nucleus are present in the young pollen grain when the microspore divides mitotically to form a large vegetative cell and a small generative cell.
  • Primary endosperm nucleus is formed by the fusion of male gamete with a diploid secondary nucleus.

Question 55. The egg apparatus of angiosperm comprises

  1. An egg cell and two antipodals
  2. An egg cell and two synergids
  3. An egg cell and two polar nuclei
  4. An egg cell and the central cell

Answer: 2. An egg cell and two synergids

  • The three micropylar cells in the embryo sac are collectively known as egg apparatus. One middle cell is larger and is called egg or oosphere.
  • It has a central or micropylar Vacuole and a nucleus towards the chalazal end. The remaining two cells are called synergids help cells.

Question 56. Assertion (A) The three cells of the egg apparatus are arranged in a triangular fashion. Reason (R) The degenerating synergid forms the seat for pollen tube discharge in the embryo sac.

  1. Both A and R are true and R is the correct explanation of the A
  2. Both A and R are true, but R is not the correct explanation of A
  3. A is true, but R is false
  4. Both A and R are false

Answer: 2. Both A and R are true, but R is not the correct explanation of A.

  • The three cells in the egg apparatus are arranged in a triangular fashion as it enables the easy entry of male gametes.
  • These enter the embryo sac within pollen tube through synergids. The synergids degenerate after the male gametes are discharged in the embryo sac

Question 57. Most common type of embryo sac reported in angiosperm is of

  1. Polygonum
  2. Oenotherna
  3. Adoxa
  4. Plumbago

Answer: 1. Polygonum

The most common type of embryo sac found in angiosperms are monosporic, i.e. 8-nucleated and 7-celled or Polygonum type. The embryo sac is formed from the chalazal megaspore in the tetrad and is eight-nucleate.

Question 58.  Which is the most common type of embryo sac in angiosperms?

  1. Tetrasporic with one mitotic stage of divisions
  2. Monosporic with three sequential mitotic divisions
  3. Monosporic with two sequential mitotic divisions
  4. Bisporic with two sequential mitotic divisions

Answer: 2. Monosporic with three sequential mitotic divisions

The embryo sacs may present a diversity of developmental pathways, however the most common is the monosporic Polygonum type, in which the functional megaspore passes through three mitotic divisions to produce a seven-celled and 8-nucleated embryo sac.

Question 59. Oenothera type of female gametophyte is always

  1. 8 nucleate and 7 celled
  2. 16 nucleate and i3 celled
  3. 8 nucleate and 8 celled
  4. 4 nucleate and 4 celled

Answer:  4. 4 nucleate and 4 celled

  • Oenothera type of embryo sac (monosporic 4-nucleate) develops from the micropylar megaspore. The megaspore nucleus divides twice and forms only four nuclei
  • Of these three organise into 3- celled egg apparatus and the fourth functions as uninucleate polar cell. Thus, Oenothera type of embryo sac does not have any antipodals.

Question 60. What would be the chromosome number of endosperm if it developed from Oenothera type of embryo sac possessing chromosome number equal to 16 (haploid)?

  1. 32 (diploid)
  2. 48 (triploid)
  3. 16 (haploid)
  4. None of these

Answer: In Oenothera, the endosperm is diploid. Hence, the number of chromosomes in endosperm will be 2n = 2 ×i6 = 32 (diploid).

“events of fertilization “

Question 61.  Match the following columns.

NEET Biology Structure and Events of Pre-Fertilisation 2 Match Following Column Question 62

Answer: A–1, B–2, C–3, D–4

Question 62. The plant part consists of two generations, one within the other

  1. Pollen grains inside the anther.
  2. Germinated pollen grain with two male gametes.
  3. Seed inside the fruit.
  4. Embryo sac inside the ovule.

Choose The Correct Answer

  1. 1, 2 and 3
  2. 3 and 4
  3. 1 and 4
  4. Only 1

Answer: 3. 1 and 4

  • The plant part which consists of two generations one within the other are pollen grains inside the anther and embryo sac inside the ovule.
  • This can be explained as: In an ovule of megasporangia (2n ) there occurs an embryo sac or female gametophyte which consists of an egg cell (n). This egg cell or female gamete is part of the next generation which forms the zygote after syngamy.
  • Likewise, an anther (2n ) is a male reproductive structure of a plant. As the anther matures and dehydrates, it forms pollen grains via microsporogenesis.
  • These pollen grains represent the male gametophyte comprising male gametes (n). So in this way, there are two generations one with the other.

Question 63. An ovule which becomes curved, so that the nucellus and embryo sac lie at right angles to the funicle is

  1. Hemianatropous
  2. Campylotropous
  3. Anatropous
  4. Orthotropous

Answer: 1. Hemianatropous

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