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Ncert Solutions For Class 12 Biology Chapter 2_40.1

 

Ncert Solutions For Class 12 Biology Chapter 2 in English

Adda 247 provides NCERT Solutions for Class 12 Biology Chapter 2 which is for the students who want to go ahead in life and achieve great marks in their examinations. The NCERT Solutions for class 12 chapter 2 are provided by the teachers who are experts of their subjects. The solutions are set according to the rules formulated by the NCERT class 12 biology and in the language that can be understood by every student. By these reading the solutions students can build up a strong base easily. The NCERT class 12 Biology solutions covers the chapters 1 to 16 with the important questions and the answers in a detailed way.

Examinations can be threatening for some people, a proper learning of the concepts is the key to crack the examination. Students rely on the solutions of the NCERT provided by Adda 247. The solutions are formulated by the experts of the subjects who have tremendous knowledge in their subjects.

These NCERT Solutions of class 12 help the students to get familiarized with the textbooks. The students can access the solutions anywhere while browsing the web easily. The solutions are very precise and accurate.

 

NCERT Solutions for Class 12 Biology Chapter 2 – Sexual Reproduction in Flowering Plants

 

The chapter provides information about Sexual reproduction in flowering plants. Events that take place before fertilization are termed as Pre-fertilization events. Following events would occur before actual fertilization takes place in a plant: Gametogenesis-Development of male & female reproductive structures. Formation of male & female gametes. Gamete transfer-Bringing together male & female gamete. Pollination occurs in plants to facilitate gamete transfer.



Download Full PDF of Class 12 Biology Chapter 2

Features of the NCERT Solutions for Class 12 Biology Chapter 2 – Sexual Reproduction in Flowering Plants

 

NCERT Solutions of class 12 have been answered based on the important information on the question.

  • The columns are used wherever necessary.
  • Solutions are solved point wise and accurately answered point to point.

 

Important Question of Ncert Solutions Class 12 Biology Chapter 2

Question 1. Name the parts of an angiosperm flower in which the development of male and female gametophyte take place.

 

Answer:  The male gametophyte or the pollen grain develops inside the pollen chamber of the anther, whereas the female gametophyte (also known as the embryo sac) develops inside the nucellus of the ovule from the functional megaspore.

 

Question 2.  Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.

 

Answer:

Character Microsporogenesis Megasporogenesis
1. Definition This is the formation of microspores in sporogenous tissue (microspore mother cell) due to meiosis. This is the formation of megaspores in megaspore mother cell due to meiosis.
2. Number of spore mother cells involved Many. One.
3. Fate of spore Microspore leads to development of male gametophyte. Leads to formation of female gametophyte (embryo sac).
4. Site of occurrence Pollen sacs (microsporangia) in anther lobes. In nucellus of ovule.

 

Type of cell division during microsporogenesis and megasporogenesis meiosis.

Structure formed — (a) Due to microsporogenesis. Microspores (pollen grains) are formed which lead to development of male gametophyte.(b) Due to megasporogenesis. Megaspores are formed. Out of them one megaspore leads to development of female gametophyte (embryo sac).

 

Question 3. Arrange the following terms in correct developmental sequence:Pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes

 

Answer:   The correct development sequence is as follows:

Sporogenous tissue – pollen mother cell – microspore tetrad – Pollen grain – male gamete

During the development of microsporangium, each cell of the sporogenous tissue acts as a pollen mother cell and gives rise to a microspore tetrad, containing four haploid microspores by the process of meiosis (microsporogenesis). As the anther matures, these microspores dissociate and develop into pollen grains. The pollen grains mature and give rise to male gametes.

 

Question 5. What is meant by monosporic development of female gametophyte?

Answer:  Megaspore is the first cell of the female gametophyte. Depending upon the number of megaspores the development of female gametophyte is termed as monosporic, bisporic or tetrasporic. Monosporic development starts with meiosis in megaspore mother cell to form a dyad and then tetrad of megaspores. Out of four, one is functional that undergoes the three simultaneous divisions to form 2-, 4- and finally 8-nucleate and 7-celled embryo sac.

 

Question 7.  What are chasmogamous flowers? Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.

 

Answer: There are two types of flowers present in plants namely Oxalis and Viola − chasmogamous and cleistogamous flowers.

Chasmogamous flowers have exposed anthers and stigmata similar to the flowers of other species.

Cross-pollination cannot occur in cleistogamous flowers. This is because cleistogamous flowers never open at all. Also, the anther and the stigma lie close to each other in these flowers. Hence, only self-pollination is possible in these flowers.

 

Question 8. Mention two strategies evolved to prevent self-pollination in flowers.

 

Answer:    The strategies evolved to prevent self-pollination in flowers are:

1) Dichogamy- The maturation of anthers and stigma at different time in a bi-sexual flower which prevents self-pollination.

2) Self-incompatibility: The pollen grains of a flower are not capable of completing growth on the stigma of the same flower.

 

Question 9. What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?

 

Answer: Self incompatibility is also called self-sterility. It is the natural inability to prevent self-pollination in which pollen grains from the same flower is unable to fertilize ovules of same flower or plant.

It happens due to several complex mechanisms. These could be saprophytic or gametophytic incompatibility. Prevent of pollen germination, retardation of growth, reorientation of pollen tube, failure of nuclear fusion could be one of the reason.

 

Question 10. What is bagging technique? How is it helpful in a plant breeding programme?

 

Answer:

i)In the flowers with both anther and stigma, the anther is removed before maturation carefully using forceps.

ii)The flower is then covered with a bag made up of butter paper.

iii)The covering of emasculated flowers with a bag of suitable size, generally made up of butter paper, to prevent contamination of its stigma with unwanted pollens is called bagging technique.

  1. iv) When the stigma matures, the pollens from desired flower are dusted on the stigma with the help of pre-sterilized brush and the flower is re-bagged until the fruit is developed.
  2. v) This technique is called artificial hybridization. Plant breeders often use this method to prevent the contamination of stigma of flowers from unwanted pollens. This technique is also helpful is developing the plant of desired variety.

 

Question 11. What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.

Answer: Triple fusion is the fusion of the male gamete with two polar nuclei inside the embryo sac of the angiosperm.

This process of fusion takes place inside the embryo sac.

When pollen grains fall on the stigma, they germinate and give rise to the pollen tube that passes through the style and enters into the ovule. After this, the pollen tube enters one of synergids and releases two male gametes there. Out of the two male gametes, one gamete fuses with the nucleus of the egg cell and forms the zygote (syngamy). The other male gamete fuses with the two polar nuclei present in the central cell to form a triploid primary endosperm nucleus. Since this process involves the fusion of three haploid nuclei, it is known as triple fusion. It results in the formation of the endosperm.

One male gamete nucleus and two polar nuclei are involved in this process.

 

Question 12. Why do you think zygote is dormant for sometime in a fertilized ovule?

 

Answer:  Further development of zygote into embryo and subsequent development of embryo need food resources. The food is provided by endosperm. Hence, endosperm needs to develop to ensure development of embryo. Hence, zygote remains dormant for some time till endosperm develops

 

Frequently Asked Questions on NCERT Solutions for Class 12 Biology Chapter 2

 

What are the advantages of referring NCERT Solutions for class 12 Biology chapter 2?

 

Students referring the NCERT Solutions of class 12 by Adda 247 find the solutions helpful during the exams. The solutions are prepared by the experts in an interactive manner keeping in mind the students. The students’ perspective is kept in mind while preparing the solutions. It helps in completing the syllabus on time and also provides notes for the revision prior to the exam.

 

What are the advantages of referring NCERT in competitive exams like JEE and AIPMT?

 

Most of the competitive exams like NEET, JEE etc. follow the basic NCERT books for designing their question papers. NCERT serves as the base for every book prepared for NEET and JEE. The competitive exams are based on the CBSE syllabus applied in XI and XII classes and NCERT books strictly follow CBSE syllabus. In addition to this, NCERT books play an important role in clearing out the theoretical concepts. Every topic given in NCERT books is explained in such a way to help students make their basics and fundamentals strong and clear.

 

How to read NCERT books more efficiently?

 

Given below are the important points which must be followed while reading the NCERT books in an efficient manner:

Go through each topic thoroughly by understanding the meaning and significance of each line mentioned in that particular topic.

Ask your teacher if any doubts.

Note down the important topics to revise at the time of examination.

Solve all the exercise questions given at the end of each chapter. These questions are important for understanding the concepts in a better way.

 

Is it mandatory to solve all the NCERT questions mentioned at the end of each chapter?

 

The questions and answers mentioned in NCERT textbooks at the end of each chapter are quite important not only for examination but also for understanding the concepts in a better way. These questions aim to test the students’ understanding and learning over the topics that they have learned in the chapter.

Solving the NCERT exercise problems will help to

  • clear all the concepts and formulae you learned in a chapter
  • get comfortable with different types of questions that might be asked in exams
  • get enough practice which is key to succeed in Mathematics exam
  • improve your accuracy and speed

 

What are the important concepts covered in the Chapter 2 of NCERT Solutions for Class 12 Biology?

 

The concepts involved in the chapter 2 of NCERT Solutions are –

1.1 – Flower

1.2- Pre-fertilization-Structure and Events

1.3- Double fertilization

1.4- Post-fertilization

1.5- Apomixis and Polyembryony

 

These concepts are created by the faculty at Adda 247. The solutions are available at Adda 247 in the PDF format which can be downloaded by the students.

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