(BSEB, 2017 C)
Ans. Parthenogenesis is the development of an unfertilized ovum into a fully formed haploid organism. It is monoparental i.e. honey bees, wasps, aphids. The offsprings thus produced are exactly similar to the parents. It permits triploid and aneuploid chromosomal combination. At the same time it stops the chances of new combinations of genes.
2. Define buds and bulbils with the help of suitable examples.
[BSEB, 2022 A)
Ans. Buds-A small lateral or terminal protuberance on the stem of a plant that may develop into a flower, leaf or shoot. Example an incompletely opened flower, apical bud, axilary bud. Bulbils-Tiny secondary bulb that forms in the angle between a leaf and stem or in place of flowers on certain plant is called bulbils. It is also called secondary bud. Formation of bulbils is a form of asexual reproduction. Examples: anions and lilies.
5.Describe the ecological adaptations of plants. hydrophytic
(BSEB, 2023 A)
Ans. Hydrophytes are plants growing in or near water. These plants have following merits for adaptation:
(i) Hydrophytes are adapted to survive in excess of water in their surroundings.
(ii) They fix sunlight and ensures the survival of an aquatic ecosystem.
(iii) The leaves of hydrophytes are thin, flat and have large air spaces inside to give them buoyancy.
(iv) Only small roots are required as they can also extract nutrients from the surrounding water through their tissues.
6. Why is endosperm in angiospermic ovule considered as more efficient?
Ans. In angiosperms, the cells of endosperm are triploid-due to double fertilization. Thus they are considered more efficient in supplying food materials to the developing embryo.
7. Why is the process of fertilization in a flowering plant referred to as double fertilization?
Ans. Fertilization in flowering plants is referred to as double fertilization because two male gametes from the same microspore takes part in fusion. One male gamete fuses with the egg to form a diploid zygote and the other male gamete fuses with the two polar nuclei or secondary nucleus to form the triploid primary endosperm nucleus.
8. Name any four plants with the animals which facilitate pollination in them. Ans. Clover-Bee, Butterfly, Milkweed-Bee [BSEB, 2017 C] Mint-Bee, Lupine-Bee, Butterfly.
9. Define: (1) True Fruit (II) Parthenogenic Fruits (1) Polyembryony (BSEB, 2018 AJ Ans. (1) True Fruit-True fruit is develop only from the ovary are called true fruit. e.g.: Tomato. (1) Parthenocarpic fruits-Fruits develop without fertilisation is called parthenocarpic fruits, e.g.: Banana. (ill) Polyembryony-Occurence of more than one embryo in a seed is called polyembryony. c.g.: Citrus. 10. What do you understand by budding? Write with examples. [BSEB, 2014) Ans. Budding-Budding is a form of asexual reproduction in which a new organism develops from on outgrowth or bud on another one due to cell division at one particular site. The new organism remains attached as it grows, separating from the parent organism only when it is mature, leaving behind scar tissue. Since the reproduction is asexual, the newly created organism is a clone and is genetically identical to the parent organism Ex-(Hydra).
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