CBSE Class 12 Biology Sexual Reproduction in Flowering Plants Assignment

Important Questions for NCERT Class 12 Biology Sexual Reproduction in Flowering Plants

Question. From outer to inner what is the sequence of wall layers in anther lobes?
(a) Epidermis, middle layers, tapetum, endothecium
(b) Epidermis, endothecium, tapetum, middle layers
(c) Epidermis, endothecium, middle layer, tapetum
(d) Tapetum, middle layers, endothecium, epidermis
Answer : C

Question. Due to which of the following chemical deposition pollen grains are well preserved as fossils
(a) Pollenkitt
(b) Callose
(c) Sporopollenin
(d) Pectocellulose
Answer : C

Question. Which of the following is not involved in post fertilisation events
(a) Endosperm and embryo development
(b) Maturation of ovules into seed
(c) Maturation of ovary into fruit
(d) Degeneration of nucellus
Answer : D

Question. The structure in which few leaf primordia and shoot apex of monocot embryo remain enclosed is
(a) Coleoptile
(b) Coleorhiza
(c) Epiblast
(d) Epicotyl
Answer : A

Question. Which of the following is not a pollen grain caused disease?
(a) Asthma
(b) Bronchitis
(c) Hayfever
(d) Malaria
Answer : D

Question. The number of ovules in an ovary may be
(a) One
(b) Many
(c) Two
(d) One to many
Answer : D

Question. Each ovule has one or two protective envelopes called
(a) Micropyle
(b) Integuments
(c) Hilum
(d) Chalaza
Answer : B

Question. Regarding to number of ovules in ovary select out the odd one
(a)Wheat
(b) Orchids
(c) Paddy
(d) Mango
Answer : B

Question. What would be the genetic nature of apomictic embryo?
(a) n
(b) 3n
(c) 2n
(d) n or 2n like mother plants
Answer : D

Question. Five kingdom system of classification suggested by R.H. Whittaker is not based on
(a) presence or absence of a well defined nucleus
(b) mode of reproduction
(c) mode of nutrition
(d) complexity of body organisation.
Answer: D

Question. Maximum nutritional diversity is found in the group
(a) fungi
(b) animalia
(c) monera
(d) plantae. 
Answer: A

Question. In the five kingdom classification, Chlamydomonas and Chlorella have been included in
(a) protista
(b) algae
(c) plantae
(d) monera. 
Answer: B

Question. In which kingdom would you classify the archaea and nitrogen-fixing organisms, if the five kingdom system of classification is used ?
(a) Plantae
(b) Fungi
(c) Protista
(d) Monera 
Answer: D

Question. In five kingdom system, the main basis of classification is
(a) structure of nucleus
(b) mode of nutrition
(c) structure of cell wall
(d) asexual reproduction.
Answer: B

Question. In the five kingdom system of classification, which single kingdom out of the following can includeblue-green algae, nitrogen fixing bacteria and methanogenic archaebacteria?
(a) Plantae
(b) Protista
(c) Monera
 (d) Fungi
Answer: C

Question. BGA (blue green algae) are included in which of the following groups?
(a) Bryophytes
(b) Prokaryotes
(c) Protista
(d) Fungi 
Answer: D

Question. An important criterion for modern day classification is
(a) resemblances in morphology
(b) anatomical and physiological traits
(c) breeding habits
(d) presence or absence of notochord. 
Answer: D

Question. Match the organisms in column-I with habitats in column-II.
Column-I                           Column-II
A. Halophiles                     (i) Hot springs
B. Thermoacidophiles       (ii) Aquatic environment
C. Methanogens                (iii) Guts of ruminants
D. Cyanobacteria              (iv) Salty area
Select the correct answer from the options given below.
(a) A-(iv), B-(i), C-(iii), D-(ii)
(b) A-(i), B-(ii), C-(iii), D-(iv)
(c) A-(iii), B-(iv), C-(ii), D-(i)
(d) A-(ii), B-(iv), C-(iii), D-(i) 
Answer: B

Question. Which of the following are found in extreme saline conditions?
(a) Eubacteria
 (b) Cyanobacteria
(c) Mycobacteria
(d) Archaebacteria
Answer: A

Question. Which among the following are the smallest living cells, known without a definite cell wall, pathogenic to plants as well as animals and can survive without oxygen?
(a) Pseudomonas
(b) Mycoplasma
(c) Nostoc
 (d) Bacillus 
Answer: B

Question. Which of the following components provides sticky character to the bacterial cell?
(a) Nuclear membrane
(b) Plasma membrane
(c) Glycocalyx
(d) Cell wall 
Answer: A

Question. DNA replication in bacteria occurs
(a) within nucleolus
(b) prior to fission
(c) just before transcription
(d) during S phase. 
Answer: C

Question. Methanogens belong to
(a) eubacteria
(b) archaebacteria
(c) dinoflagellates
(d) slime moulds.
Answer: B

Question. The primitive prokaryotes responsible for the production of biogas from the dung of ruminant animals, include the
(a) methanogens
(b) eubacteria
(c) halophiles
(d) thermoacidophiles.
Answer: A

Question. Archaebacteria differ from eubacteria in
(a) cell membrane structure
(b) mode of nutrition
(c) cell shape
(d) mode of reproduction. 
Answer: C

Question. Which of the following are likely to be present in deep sea water?
(a) Blue-green algae
 (b) Saprophytic fungi
(c) Archaebacteria
(d) Eubacteria
Answer: C

Question. Pigment containing membranous extensions in some cyanobacteria are
(a) pneumatophores
(b) chromatophores
(c) heterocysts
(d) basal bodies.
Answer: B 

Question. Identify A to E in the diagram given below.

(a) A–Antipodal, B–2 polar nuclei, C–Central cell, D–Egg, E–Synergids
(b) A–Antipodal, B–Central cell, C–2 polar nuclei, D–Egg, E–Synergids
(c) A–2 polar nuclei, B–Central cell, C–Antipodal cell, D–Egg, E–Synergids
(d) A–Synergids, B–Egg, C–Central cell, D–2 polar nuclei, E–Antipodal cell
Answer : D 

Question. In embryo sac, the number of synergid® egg cell→ central cell→ antipodal cell follows the order
(a) 1–1–2–3
(b) 2–1–3–2
(c) 2–1–1–3
(d) 3–2–1–2
Answer : C 

Question. Identify A to F in the diagram given below.

(a) A–Egg, B–Filiform apparatus, C–Synergid,D–Antipodals, E–Polar nuclei, F–Central cell
(b) A–Egg, B–Synergid, C–Filiform apparatus,D–Antipodals, E–Central cell, F–Polar nuclei
(c) A–Central cell, B–Egg, C–Synergid, D–Antipodals,E–Filiform apparatus, F–Polar nuclei
(d) A–Filiform apparatus, B–Synergid, C–Egg, D–Central cell, E–Polar nuclei, F–Antipodals
Answer : D 

Question. Filiform apparatus are
(a) special cellular thickenings at antipodal cell
(b) special cellular thickenings at the micropylar end
(c) special cellular thickenings at synergid cells
(d) special cellular thickenings at nuclear end
Answer : C 

Question. Function of filiform apparatus is to
(a) recognise the suitable pollen at stigma
(b) stimulate division of generative cell
(c) produce nectar
(d) guide the entry of pollen tube
Answer : D 

Question. How many nuclei are found in female gametophyte?
(a) 8
(b) 7
(c) 6
(d) 5
Answer : A 

Question. How many cells are found in female gametophyte?
(a) 6
(b) 8
(c) 7
(d) 5
Answer : C 

Question. Two nuclei within a single cell is
(a) antipodal cell
(b) chalazal cell
(c) central cell
(d) synergid cell
Answer : C 

Question. Egg apparatus consists of
(a) 2 synergids + 2 eggs
(b) 2 synergids + 2 eggs
(c) 2 synergids + 1 egg
(d) 2 synergids + 4 eggs
Answer : C 

Question. In an embryo sac of anatropous ovule, cells present at chalazal end are called
(a) nucellar cells
(b) synergids
(c) antipodal cells
(d) None of these
Answer : C 

Question. In an angiospermic anatropous ovule, the embryo sac contains certain cells at the micropylar end. These are called
(a) synergids
(b) antipodal cells
(c) nucellar cells
(d) None of these
Answer : A  

Pollination 

Question. Autogamy stands for
(a) pollination in same flower
(b) pollination between different plants
(c) pollination in two flowers of same plant
(d) division in embryo
Answer : A 

Question. Cleistogamous flowers are strictly autogamous because they remain
(a) always open
(b) always close
(c) always fragrance
(d) are brighty coloured
Answer : B 

Question. Identify the type of flower A and B.

(a) A–Cleistogamous; B–Chasmogamous
(b) A–Homogamous; B–Heterogamous
(c) A–Chasmogamous; B–Cleistogamous
(d) A–Heterogamous; B–Homogamous
Answer : C 

Question. In chasmogamy pollination takes
place in
(a) open flower
(b) closed flower
(c) large flower
(d) geitonogamy flower
Answer : A 

Question. Advantage of cleistogamy is 
(a) higher genetic variability
(b) more vigorous offspring
(c) no dependence on pollinators
(d) vivipary
Answer : C 

Question. Even in the absence of pollinating agents seed-setting is assured in
(a) Commelina
(b) Zostera
(c) Salvia
(d) Fig
Answer : A 

Question. Geitonogamy involves 
(a) fertilisation of a flower by the pollen from another flower of the same plant
(b) fertilisation of a flower by the pollen from the same flower
(c) fertilisation of a flower by the pollen from a flower of another plant in the same population
(d) fertilisation of a flower by the pollen from a flower of another plant belonging to a distant population
Answer : A 

Question. Transfer of pollen grains from the anther to stigma of another flower of different plant is called
(a) geitonogamy
(b) xenogamy
(c) chasmogamy
(d) cleistogamy
Answer : B 

Question. The most common abiotic pollinating agency in flowering plant is/ are
(a) water
(b) wind
(c) Both (a) and (b)
(d) None of these
Answer : B 

Question. Characteristic of wind pollinated pollens is, they are
(a) non-sticky
(b) light
(c) produced in large number
(d) All of the above
Answer : D 

Question. The feathery long stigma is found in
(a) rice
(b) maize
(c) sugarcane
(d) None of these
Answer : B 

Question. Flowers, which have single ovule in the ovary and are packed into inflorescence are usually pollinated by
(a) water
(b) bee
(c) wind
(d) bat
Answer : C 

Question. Wind pollination is common in 
(a) lilies
(b) grasses
(c) orchids
(d) legumes
Answer : B 

Question. Pollination in water hyacinth and water lily is brought about by the agency of 
(a) water
(b) insects or wind
(c) birds
(d) bats
Answer : B 

Question. What type of pollination takes place in Vallisneria?
(a) Pollination occurs in submerged condition by water
(b) Flowers emerge above surface of water and pollination occurs by insects
(c) Flowers emerge above water surface and pollen is carried by wind
(d) Male flowers are carried by water currents to female flowers at the surface of water
Answer : D 

Question. Pollen grain of water pollinated plants are coated by covering to prevent it from wetting
(a) mucilage
(b) cuticle
(c) exine
(d) intine
Answer : A 

Question. Wind pollinated and water pollinated flowers
(a) are colourful
(b) are non-colourful
(c) are small in size
(d) produce nectar
Answer : B 

Question. Pollenkitt is present in
(a) anemophily
(b) entomophily
(c) malacophily
(d) zoophily
Answer : B 

Question. Attractants and rewards are required for 
(a) anemophily
(b) entomophily
(c) hydrophily
(d) cleistogamy
Answer : B 

Question. Which one of the following plants shows a very close relationship with a species of moth, where none of the two can complete its life cycle without the other?
(a) Banana
(b) Yucca
(c) Hydrilla
(d) Viola
Answer : B 

Question. Continued self-pollination results in
(a) inbreeding depression
(b) out breeding depression
(c) hybrid vigour
(d) better result in offspring
Answer : A 

Question. Device to discourage self-pollination or increase cross-pollination is
(a) pollen release and stigma receptivity are not synchronised
(b) anther and stigma placed at different position
(c) same height of stamen and stigma
(d) Both (a) and (b)
Answer : D 

Question. A dioecious flowering plant prevents both
(a) autogamy and xenogamy
(b) autogamy and geitonogamy
(c) geitonogamy and xenogamy
(d) cleistogamy and xenogamy
Answer : B 

Question. In which of the following, both autogamy and geitonogamy are prevented?
(a) Wheat
(b) Papaya
(c) Castor
(d) Maize
Answer : B 

Question. Identify A to F in the given diagram.

(a) A–Pollen tube, B–Ovary, C–Ovule,D–Antipodal cell, E–Pollen grain,F–Polar nuclei
(b) A–Polar nuclei, B–Antipodal cell,C–Ovule, D–Ovary, E–Pollen tube,F–Pollen grain
(c) A–Pollen grain, B–Pollen tube,C–Ovary, D–Ovule, E–Antipodal cell,F– Polar nuclei
(d) A–Antipodal cell, B–Ovule, C–Ovary,D–Polar nuclei, E–Pollen grain,F–Pollen tube
Answer : C 

Question. Generally pollen tube enters through
(a) micropylar region
(b) antipodal region
(c) chalazal end
(d) nuclear region
Answer : A 

Question. The ability of the pistil to recognise the pollen followed by its acceptance or rejection is the result of a continuous dialogue between pollen grain and the pistil.
Which of the following chemicals mainly takes part in this interaction.
(a) Nucleotides
(b) Proteins
(c) Minerals
(d) Lipid or Inulin
Answer : B 

Question. The process of removal of anther from the flower bud before it dehisces is called as 
(a) emasculation
(b) bagging
(c) embryo rescue
(d) budding
Answer : A 

Question. For artificial hybridisation experiment in bisexual flower, which of the sequence is correct?
(a) Bagging → Emasculation → Cross-pollination → Rebagging
(b) Emasculation → Bagging → Cross-pollination → Rebagging
(c) Cross-pollination → Bagging → Emasculation → Rebagging
(d) Self-pollination → Bagging → Emasculation → Rebagging
Answer : B 

Double Fertilisation and Development of Endosperm 

Question. Double fertilisation is 
(a) fusion of two male gametes with one egg
(b) fusion of one male gamete with two polar nuclei
(c) fusion of two male gametes of pollen tube with two different eggs
(d) syngamy and triple fusion
Answer : D 

Question. Double fertilisation is exhibited by
(a) gymnosperms
(b) algae
(c) fungi
(d) angiosperms
Answer : D 

Question. I. Antipodal cell    II. Egg cell
III. Synergid cell                  IV. Polar nuclei
V. Male gamete                     VI. Nucellar cell
VII. Central cell
Out of the seven names given above, find out haploid cells.
(a) I, II, IV and V
(b) II, IV, VI and VII
(c) I, II, III and V
(d) II, IV, III and I
Answer : C 

Question. What is the fate of the male gametes discharged in the synergid? 
(a) All fuse with the egg
(b) One fuses with the egg, other(s) fuse(s) with synergid nucleus
(c) One fuses with the egg and other fuses with central cell nuclei
(d) One fuses with the egg other(s) degenerate(s) in the synergid
Answer : C 

Question. How many number of nuclei are involved in fertilisation?
(a) 1
(b) 1 + 1
(c) 2 + 1
(d) None of these
Answer : B 

Question. The total number of nuclei involved in triple fusion is/are
(a) 2
(b) 3
(c) 4
(d) 1
Answer : B

POINT TO REMEMBER

Autogamy : When pollen grains of a flower are transferred from anther to stigma of the same flower.

Coleorhiza : A protective sheath of radicle in monocot seed.

Coleoptile : A protective sheath of plumule in monocot seed.

Endothecium : A fibrous layer in the anther next to epidermis.

Geitonogany : Self pollination between flowers of the same plant.

Micropyle : A small pore in the ovule through which the pollen tube enters.

Nucellus : Multicellular tissue in the centre of ovule where embryo sac is present.

Tapetum : Inner most layer of cells in pollen sac which provide nutrition to developing pollen grains

Viability of Seed : Ability of seed to retain the power of germination.

1. Microsporangium (Pollen sac) :
Outermost layer = Epidermis
Second layer = Endothecium
Middle layer = 2 – 4 layers of cells
Innermost layer = Tapetum [Nourishes the developing Pollen grains
(Microspores)]

2. Microsporogenesis : Process of formation of microspores from a pollen mother cell

QUESTIONS

VSA (1 MARK)

Question 1. In a young anther, a group of compactly arranged homogenous cells were observed in the centre of each microsporangium. What is the name given to these cells?
Answer: Sporogenous tissue
In simple words: The central homogenous cells in a young microsporangium form the sporogenous tissue, which gives rise to microspores.

Exam Tip: Remember that sporogenous tissue occupies the center of each microsporangium when the anther is young.

Question 2. Give the scientific name of a plant which came to India as a contaminant with imported wheat and causes pollen allergy.
Answer: Parthenium (Carrot grass)
In simple words: Parthenium hysterophorus entered India as a wheat contaminant and is a major cause of pollen allergy and asthma.

Exam Tip: Always underline binomial nomenclature names or write them correctly; Parthenium is a classic example of an alien invasive weed.

Question 3. Pollen grains of water pollinated species have a special characteristics for protection from water. What is that?
Answer: Presence of a mucilaginous covering
In simple words: Hydrophilous plants have pollen grains coated with mucilage to prevent them from getting wet and decayed in water.

Exam Tip: Mention 'mucilaginous envelope' or 'covering' specifically to secure full marks.

Question 4. Why are pollen grains produced in enormous quantity in Maize?
Answer: To ensure pollination because Maize is pollinated by wind (anemophily).
In simple words: Wind pollination is a very uncertain process with huge wastage of pollen grains, so plants produce them in massive numbers to guarantee fertilization.

Exam Tip: Link the high quantity of pollen directly to the randomness and inefficiency characteristic of wind pollination.

Question 5. In same species of Asteraceae and grasses, seed are formed without fusion of gametes. Mention the scientific term for such form of reproduction.
Answer: Apomixis
In simple words: Apomixis is asexual reproduction that mimics sexual reproduction by producing seeds without fertilization.

Exam Tip: Do not confuse apomixis with parthenocarpy; apomixis refers to seed formation without fertilization, whereas parthenocarpy refers to fruit formation without fertilization.

Question 6. Arrange the following in correct developmental sequence : Male gamete, Potential pollen mother cell, sporogenous tissue, Pollen grains, Microspore tetrad.
Answer: Sporogenous tissue \(\rightarrow\) Potential pollen mother cell \(\rightarrow\) Microspore tetrad \(\rightarrow\) Pollen grain \(\rightarrow\) Male gamete
In simple words: Development starts from internal sporogenous cells, which differentiate into pollen mother cells, undergo meiosis to form tetrads, develop into pollen grains, and finally produce male gametes.

Exam Tip: Pay close attention to biological sequences; always trace the pathway from vegetative/meristematic tissue down to the gametic stage.

Question 7. If the diploid number of chromosomes in an angiospermic plant is 16. Mention number of chromosomes in the endosperm and antipodal cell.
Answer: Number of chromosomes in endosperm = 24, and in antipodal cell = 8.
In simple words: Since diploid number \(2n = 16\), the haploid number \(n = 8\). Antipodal cells are haploid (\(n\)), so they have 8 chromosomes. Endosperm is triploid (\(3n\)), so it has \(3 \times 8 = 24\) chromosomes.

Exam Tip: Always determine the haploid number \(n\) first from the given diploid value before calculating ploidy levels like \(3n\) (endosperm) or \(2n\) (embryo).

SA-II (2 MARKS)

Question 8. In angiospermic plant before formation of microspore sporogenous tissue undergo cell division (a) Name the type of cell division. (b) What would be the ploidy of the cells of tetrad?
Answer: (a) Meiosis division (Meiotic cell division).
(b) Haploid (\(n\)).
In simple words: Microspore mother cells undergo meiosis to yield haploid microspore tetrads.

Exam Tip: Clearly label parts (a) and (b) as presented in the question paper to ensure accurate evaluation.

Question 9. Outer envelop of pollen grain made of a highly resistant substance. What is that substance? At which particular point the substance is not present?
Answer: Sporopollenin; at the germ pore, sporopollenin is absent.
In simple words: The outer exine layer contains sporopollenin, which withstands harsh environments, but leaves tiny gaps called germ pores for pollen tube emergence.

Exam Tip: Sporopollenin is one of the most resistant organic materials known; it cannot be degraded by enzyme, high temperature, or strong acid.

Question 10. Fruits generally develops from ovary, but in few species thalamus contributes to fruit formation. (a) Name the two categories of fruits. (b) Give one example of each.
Answer: (a) The two categories are True fruits and False fruits.
(b) True fruit example: Mango; False fruit example: Apple.
In simple words: Fruits developing solely from the ovary are true fruits, whereas those where other floral parts like the thalamus contribute are false fruits.

Exam Tip: Mentioning the exact botanical definition along with common examples like apple, strawberry, or cashew for false fruits fetches full credit.

Question 11. Among the animal, insects particularly bees are the dominant pollinating agents. List any four characteristic features of the insect pollinated flower.
Answer: 1. Flowers are large.
2. Colorful petals of flowers.
3. Presence of fragrance.
4. Rich in nectar.
In simple words: Insect-pollinated flowers are showy, fragrant, and nectar-rich to attract visiting pollinators.

Question 12. Differentiate between geitonogamy and xenogamy.
Answer:

In simple words: Geitonogamy happens on the same plant, while xenogamy happens between different plants of the same species.

Exam Tip: Use a comparative table format for clear differentiation questions.

Question 13. In the given figure of a dicot embryo, label the parts (A) and (B) and give their function.
Answer: A = Plumule - To form the shoot system.
B = Cotyledons - Storage of food.
In simple words: Plumule develops into the shoot, while cotyledons store reserve nutrients for the growing embryo.

Question 14. Name the parts A, B, C and D of the anatropous ovule (Figure 2) given above.
Answer: A = Micropyle
B = Outer integument
C = Nucellus
D = Embryo sac
In simple words: These are the core structural zones of a standard anatropous ovule from tip to center.

Exam Tip: Practice drawing a standard anatropous ovule diagram clearly labelling integuments, micropyle, nucellus, and embryo sac.

Question 15. Given below is an incomplete flow chart showing formation of gamete in angiospermic plant. Observe the flow chart carefully and fill in the blank A, B, C and D.
Answer: A = Ovule/Megasporangium
B = Megaspore mother cell
C = Tapetum
D = Pollen grains
In simple words: Blanks correspond to key anatomical structures and cell types in the male and female reproductive pathways of flowering plants.

Exam Tip: Trace both megasporogenesis and microsporogenesis pathways mentally to verify gamete formation flow charts.

Question 16. Name the blank spaces a, b, c and d is the table given below :
Item: (i) Pericarp | What it represents in the plant: a
Item: (ii) b | What it represents in the plant: Cotyledon in seeds of grass family
Item: (iii) Embryonal axis | What it represents in the plant: c
Item: (iv) d | What it represents in the plant: Remains of nucellus in a seed.
Answer:
a = Wall of fruit
b = Scutellum
c = Shoot and root tip
d = Perisperm
In simple words: These terms match specific seed and fruit structures with their respective botanical definitions.

Exam Tip: Memorize terms like perisperm (persistent nucellus) and scutellum (grass cotyledon) as they are frequently tested.

Question 17. Even though each pollen grain has two male gametes. Why are at least 10 pollen grains and not 5 pollen grains required to fertilise 10 ovules present in a particular carpel?
Answer: Because only one male gamete is involved in syngamy (fusion of male gamete with the egg cell) for each ovule, and each pollen grain's two male gametes participate in double fertilization within the same single ovule (one fuses with the egg, and the second fuses with the polar nuclei). Thus, to fertilize 10 separate ovules, 10 individual pollen grains are required.
In simple words: Both male gametes from a single pollen grain fuse inside the same ovule during double fertilization; they cannot fertilize separate ovules.

Exam Tip: Emphasize that one pollen grain's gametes both act on the same embryo sac, making one pollen grain per ovule mandatory for separate fertilization events.

SA-I (3 MARKS)

Question 18. Continued self pollination lead to inbreeding depression. List three devices, which flowering plant have developed to discourage self pollination?
Answer: (a) Release of pollen and stigma receptivity is not synchronized (Dichogamy).
(b) Anther and stigma are placed at different positions/heights to avoid contact (Herkogamy).
(c) Self-incompatibility, a genetic mechanism that prevents self-pollen from germinating or growing on the stigma.
In simple words: Plants prevent self-pollination by timing pollen release differently from stigma readiness, placing them at different heights, or through genetic self-incompatibility.

Exam Tip: Mentioning dichogamy, herkogamy, and self-incompatibility covers all major outbreeding devices.

Question 19. What will be the fate of following structures in the angiospermic plant? Ovary wall, Ovule, zygote, outer integument Inner integument and primary endosperm nucleus.
Answer:
- Ovary wall = Pericarp
- Ovule = Seed
- Zygote = Embryo
- Outer integument = Testa
- Inner integument = Tegmen
- Primary endosperm nucleus = Endosperm
In simple words: Post-fertilization, flower parts transform into fruits and seeds with protective seed coats and nutrient tissue.

Exam Tip: This is a high-yield post-fertilization transformation list; commit testa, tegmen, and pericarp conversions to memory.

Question 20. Differentiate between microsporogenesis and megasporogenesis. What type of cell division occurs during these events. Name the structure formed at the end of these two events.
Answer:
- Microsporogenesis is the process of formation of microspores from a pollen mother cell.
- Megasporogenesis is the process of formation of megaspores from a megaspore mother cell.
- Meiotic division occurs in both events.
- Microsporogenesis results in the formation of pollen grains (microspores), while megasporogenesis results in the formation of megaspores.
In simple words: Both processes use meiosis to create spores, but microsporogenesis produces pollen grains while megasporogenesis produces megaspores.

Exam Tip: Explicitly state that meiosis occurs in both, and clearly distinguish between the resulting microspores and megaspores.

LA (5 MARKS)

Question 21. Draw the embryo sac of a flowering plants and label : (a) (i) Central Cell (ii) Chalazal end (iii) Synergids (b) Name the cell that develops into embryo sac and explain how this cell leads to formation of embryo sac. (c) Mention the role played by various cells of embryo sac. (d) Give the role of filiform apparatus.
Answer:
(a) Embryo sac structural layout features a 7-celled and 8-nucleate arrangement with antipodals at the chalazal end, synergids and egg cell at the micropylar end, and central polar nuclei.
(b) Functional Megaspore: The functional megaspore nucleus undergoes three successive mitotic divisions to form an 8-nucleate stage, followed by cell wall formation resulting in a typical 7-celled, 8-nucleate female gametophyte.
(c) Role of cells: Egg fuses with male gamete to form the zygote; synergids guide the pollen tube and absorb nutrients; central cell fuses with the second male gamete to form primary endosperm cell; antipodals degenerate after fertilization.
(d) Role of filiform apparatus: Located at the micropylar tip of synergids, it guides the entry of the pollen tube.
In simple words: The functional megaspore divides mitotically to form the embryo sac, where each cell plays a specific role in fertilization, nourishment, and pollen tube guidance.

Exam Tip: For 5-mark long answers, break your response into clear sub-headings (a, b, c, d) matching the prompt parts to score maximum marks.