🌸 Chapter 1
Sexual Reproduction in Flowering Plants
(2 Marks )
Part A – Flower Structure & Introduction
1.
What is the function of the flower in plants?
→ The flower is the reproductive organ of angiosperms; it produces male and
female gametes and is the site for pollination and fertilization, resulting in
seed and fruit formation.
2.
Name the four whorls of a typical flower.
→ Calyx, Corolla, Androecium, and Gynoecium.
3.
What is the difference between bisexual and unisexual flowers?
→ Bisexual flowers contain both stamens and carpels (e.g., Hibiscus).
Unisexual flowers have either stamens or carpels, not both (e.g.,
Papaya).
🌿 Part B – Androecium & Microsporogenesis
4.
Define microsporogenesis.
→ Microsporogenesis is the process of formation of haploid microspores (pollen
grains) from diploid microspore mother cells (MMC) by meiosis in the anther.
5.
What is the role of tapetum in the anther?
→ The tapetum nourishes the developing pollen grains and contributes to pollen
wall formation by secreting enzymes and precursors for sporopollenin.
6.
Mention the layers of a microsporangium.
→ From outside to inside: Epidermis, Endothecium, Middle layers, and Tapetum.
7.
What is sporopollenin?
→ It is a highly resistant organic material forming the outer wall (exine) of
pollen grains; it resists acids, alkalis, and enzymes, ensuring pollen
preservation.
8.
State the functions of vegetative and generative cells in pollen grain.
→ Vegetative cell forms the pollen tube; generative cell divides to produce two
male gametes.
🌼 Part C – Gynoecium & Megasporogenesis
9.
Define megasporogenesis.
→ The process by which a diploid megaspore mother cell (MMC) in the ovule
undergoes meiosis to form four haploid megaspores, of which one is functional.
10.
Describe the structure of a mature embryo sac.
→ It is a 7-celled, 8-nucleate structure with an egg apparatus (1 egg + 2
synergids) at the micropylar end, 3 antipodal cells at the chalazal end, and 2
polar nuclei in the central cell.
11.
Name the parts of an ovule.
→ Funicle, Hilum, Integuments, Micropyle, Nucellus, and Embryo sac.
🌺 Part D – Pollination
12.
What is pollination? Mention its types.
→ Transfer of pollen from anther to stigma.
Types: (1) Self-pollination (Autogamy, Geitonogamy)
(2) Cross-pollination (Xenogamy).
13.
What are cleistogamous flowers? Give one example.
→ Flowers that never open and are always self-pollinated. Example: Viola
or Oxalis.
14.
Name any two agents of pollination and one example for each.
→ Wind – Maize (Anemophily); Water – Vallisneria (Hydrophily).
15.
What are the advantages of cross-pollination?
→ It promotes genetic variation, increases adaptability, and helps evolution by
combining genes from different plants.
16.
What adaptations are seen in insect-pollinated flowers?
→ Bright color, fragrance, nectar, sticky pollen, and sticky stigma to trap
pollen brought by insects.
🌾 Part E – Fertilization & Double Fertilization
17.
What is double fertilization?
→ In angiosperms, one male gamete fuses with egg (syngamy) and the other fuses
with polar nuclei (triple fusion). Both events together are called double
fertilization.
18.
Who discovered double fertilization and in which plant group does it occur?
→ Discovered by Nawaschin in Lilium; it occurs only in angiosperms.
19.
What is triple fusion?
→ The fusion of one male gamete with two polar nuclei in the central cell to
form the primary endosperm nucleus (PEN).
20.
Mention the products of syngamy and triple fusion.
→ Syngamy → Zygote (2n); Triple fusion → Primary Endosperm Nucleus (3n).
21.
What is the function of the endosperm?
→ It provides nourishment to the developing embryo during seed development.
🌱 Part F –
Post-Fertilization Changes
22.
List the post-fertilization changes in a flower.
→ Ovule → Seed; Ovary → Fruit; Integuments → Seed coat; Zygote → Embryo;
Primary endosperm nucleus → Endosperm.
23.
Distinguish between true fruit and false fruit.
→ True fruit: Develops from ovary only (e.g., Mango).
False fruit: Develops from ovary and other floral parts (e.g., Apple).
24.
What is parthenocarpy? Give one example.
→ Formation of fruit without fertilization; such fruits are seedless (e.g.,
Banana).
25.
What is a seed? State its major parts.
→ A mature ovule after fertilization; consists of seed coat, embryo, and stored
food (endosperm or cotyledons).
🌾 Part G – Apomixis & Polyembryony
26.
Define apomixis.
→ Production of seeds without fertilization, where embryos arise from diploid
cells like nucellus or integument.
27.
How is apomixis useful to plant breeders?
→ It helps in producing hybrid seeds without repeated crossing, ensuring
genetically uniform progeny.
28.
Define polyembryony. Give one example.
→ Occurrence of more than one embryo in a single seed; e.g., Citrus or Mango.
29.
How can polyembryony arise naturally?
→ By development of additional embryos from nucellar cells or from multiple
fertilized eggs in the same ovule.
30.
Mention two differences between apomixis and parthenocarpy.
|
Feature |
Apomixis |
Parthenocarpy |
|
Result |
Seed without fertilization |
Fruit without fertilization |
|
Example |
Citrus,
Grasses |
Banana,
Pineapple |
