Maharashtra Board Class 12 Biology Chapter 1 Reproduction in Lower and Higher Plants Solutions
The Maharashtra Biology Textbook Solutions for Class 12 play a crucial role in helping students grasp complex concepts and prepare effectively for both board examinations and various competitive entrance tests. These solutions allow students to assess their understanding of each topic, helping them identify areas of strength and those that need improvement.
Chapter 1, titled "Reproduction in Lower and Higher Plants", is explained through simple, step-by-step solutions that are easy to follow. These detailed answers are highly appreciated by students as they assist in completing homework efficiently and enhancing exam preparation.
All questions and answers from Chapter 1 of the Class 12 Biology textbook are provided here free of cost. The YBStudy platform makes accessing these solutions enjoyable and convenient. Developed by subject matter experts, these textbook solutions are thoroughly accurate and tailored to support students' academic success.
Class 12 Biology Chapter 1- Reproduction in Lower and Higher Plants Solutions
1. Insect pollinated flowers usually posses ................
a. Sticky pollens with rough surface
b. Large quantities of pollens
c. Dry pollens with smooth surface
d. Light coloured pollens
2. In ovule, meiosis occurs in ..........
a. Integument
b. Nucellus
c. Megaspore
d. Megaspore mother cell
3. The ploidy level is NOT the same in ......
a. Integuments and nucellus
b. Root tip and shoot tip
c. Secondary nucleus and endosperm
d. Antipodals and synergids
4. Which of the following types require pollinator but result is genetically similar to autogamy?
a. Geitonogamy
b. Xenogamy
c. Apogamy
d. Cleistogamy
a. Endosperm
b. Leaf cells
c. Cotyledons
d. Synergids
6. In angiosperms, endosperm is formed by/ due to ..........
a. Free nuclear divisions of megaspore
b. polar nuclei
c. polar nuclei and male gamete
d. synergids and male gamete
7. Point out the odd one ..........
a. Nucellus
b. Embryo sa
c. Micropyle
d. Pollen grain
Q.2: Very Short Answer Questions
1. Name the part of gynoecium that determine the compatible nature of pollen grains.
Answer: Stigma is the part of gynoecium which determine the compatible nature of pollen grains.
2. How many haploid cells are present in a mature embryo ?
Answer: There are 6 haploid cells nd 2 nucleic cells are present in an embryo
3. Even though each pollen grain has 2 male gametes, why atleast 20 pollen grains are required to fertilize 20 ovules in a particular carpel?
Answer: Even though 2 male gametes are there in one pollen grain, 20 pollen grains are required to fertilise 20 ovules. This is due to the presence of double fertilization in angiosperms. For one Zygote to form, One male and one egg is required. The other male gamete fuses with the polar nuclei and forms the primary endosperm nucleus (PEN).
4. Define megasporogenesis.
Answer: Formation of megaspores from megaspore mother cell called megasporogenesis. It occurs inside the nucellus of ovule of angiosperm. The process begins very early then nucellus is not completely surrounded by the integuments.
5. What is hydrophily ?
Answer: Transfer of pollen grains from anther to the stigma through the water is called as hydrophily.
6. Name the layer which supplies nourishment to the developing pollen grains.
Answer: The tapetum is the inner most layer of the microsporangial wall that secretes precursors of sporopollenin which in turn forms sporopollenin as well as provides nourishment to the developing pollen grains.
7. Define parthenocarpy.
Answer: Parthenocarpy is the development of fruit without the formation of seeds due to lack of pollination, fertilization and embryo development.
8. Are pollination and fertilization necessary in apomixis ?
Answer: Apomixis or Agamospermy involves formation of embryos and seeds by asexual methods without involving meiotic gametogenesis and sexual fusion of gametes. Pollination and fertilization are not necessary in apomixis.
9. Name the parts of pistil which develop into fruits and seeds.
Answer: A pistil has three parts , i.e., stigma (receives pollen), which grows down through style to ovary. Ovary contains ovules, which contain an egg. The ovary develops into the fruit and ovule develops into a seeds
10. What is the function of filiform apparatus ?
Answer: The function of filiform apparatus is to guide entry of pollen tube and release of sperm cells.
Filiform apparatus : The synergid cell wall forming an extremely thick structure at the micropylar end is called the filiform apparatus. It bears several finger-like projections into the structure of synergid cytoplasm
Q.3 Short answer questions
1. How polyembryony can be commercially exploited ?
Answer: Polyembryony may be defined as the occurrence of two or more embryos in one ovule which consequently results in the emergence of multiple seedlings.
» It Can be commercially exploited by various ways like
» It can use for disease free plant .
» It can used in horticulture.
» can be used in clones formation.
2. Pollination and seeds formation are very crucial for the fruit formation. Justify the statement.
Answer: pollination and seed formation is very crucial in fruit formation because
Seeds and fruits are formed by fertilization. For fertilization pollination is must. In angiosperms, two structures are formed as a result of double fertilization – a diploid zygote and a triploid primary endosperm cell. The zygote develops into an embryo, whereas, the endosperm cell gives rise to endosperm. It provides nourishment to the growing embryo. Both fruits and seeds are an important part of angiosperms.
3. Incompatibility is a natural barrier in the fusion of gametes. How will you explain this statement?
Answer: In gametic incompatibility, if the sperm and ova are from different species then they do not recognize each other and hence do not fuse to form the zygote. Hence, incompatibility act as a natural barrier for fusion of gametes to prevent reproduction between individuals of different species.
4. Describe three devices by which cross pollination is encouraged in Angiosperms by avoiding self pollination.
Answer: Three outbreeding devices that flowering plants have developed:
1. Self-incompatibility: A genetic method to prevent pollens from fertilizing ovules of the same flower by inhibiting their germination on stigma or pistil.
2. Production of unisexual flowers: So that the male and female parts will be present on different plants i.e., dioecious or on different flowers in the same plant (monoecious). This prevents both autogamy and geitonogamy.
Q.4 Long Answer Questions
Answer :
The process of fusion of male gamete with the female gamete to form the diploid zygote (2n) is known as fertilisation. The fusion of one male gamete with egg and that of another male gamete with a secondary nucleus is called double fertilisation. It is the characteristic feature of only angiosperms. All angiosperms are characterised by a unique process called double fertilisation. Double fertilisation is significant because it involves the use of both the male gametes produced by a pollen grain.
This avoids the chances of polyembryony and increases the chances of survival of the future plant. It consists of two fusions and results in the formation of two products. First fertilisation restores diploidy in the life cycle. The diploid zygote develops into an embryo which subsequently develops into a new plant. Second fertilisation product, triploid PEN (Primary endosperm nucleus) develops to form a nutritive tissue called endosperm for developing an embryo.
Pollen grain marks the begining of male gametophyte. It undergoes first mitotic division to produce bigger, naked vegetative cell and small, thin walled generative cell. The vegetative cell is rich in food and having irregular shaped nucleus. The generative cell floats in the cytoplasm of vegetative cell.
The second mitotic division is concerned with generative cell only and gives rise to two non-motile male gametes. The mitotic division of generative cell takes place either in pollen grain or in the pollen tube. The pollen grains are shed from the anther, at this two- celled stage in most of the angiosperms.
Q.5 Fill in the Blanks
1. The ..................... collects the pollen grains.
Ans: The stigma collects the pollen grain.
- It is the receptive part where pollen pistil interaction is being checked.
- The stigma checks for the intraspecific species.
2. The male whorl, called the ..................... produces ..................... .
Ans: The male whorl, called the Androecium produces male gametes.
- The male gametes are produced by the pollen grain that undergoes unequal mitotic division to form vegetative and generative nuclei simultaneously.
- The generative nucleus is responsible for forming two male gametes.
- The vegetative nucleus contributes to the formation of tube cells.
3. The pollen grains represent the ........................
Ans: The pollen grain represents the male gametophyte.
- It consists of tapetum, endothecium, sporogenous tissue, connective tissue, etc.
4. The .................... contains the egg or ovum.
Ans: The embryo sac contains the egg or ovum in angiosperm. The embryo sac is an 8-celled structure.
5. .................... takes place when one male gamete and the egg fuse together. The a fertilized egg grows into a seed from which the new plants can grow.
Ans: Syngamy takes place when one male gamete and egg fuse together.
6. ......................... is the transfer of pollen grains from the anther of the flower to the stigma of the same or a different flower.
Ans: Pollination is the transfer of pollen grains from the anther of the flower to the stigma of the same or a different flower.
7. Once the pollen reaches the stigma, the pollen tube traverses down the ................... to the ovary where fertilization occurs.
Ans: Once the pollen reaches the stigma, the pollen tube traverses down the stigma to the ovary where fertilization occurs.
8. The ................................ is the base of the flower to which other floral parts are attached.
Ans: The thalamus is the base of the flower to which other floral parts are attached.
9. The whorl ...................... is green that protects the flower until it opens.
Ans: The whorl calyx is green which protects the flower until it opens.
Q.6 Label the part of the Seeds
