Portal Updates:

18

w w w. s a k s h i e d u c a t i o n . c o m � � �

Engineering Special: Career Guidance on Research and Development in Engineering Useful Study Material for all year Students in Computer Science and Engineering Admissions: Details of PGDM Programme at National Insurance Academy, Pune

Senior Faculty, Hyderabad

UNIT-I, Chapter 6 The 6th and last chapter of Plant Physiology is Plant Growth and Development. Growth is a fundamental aspect of all living organisms yet it is different in plants and animals. This chapter is broadly divided into two main parts. In one part growth is explained and in another part factors responsible for growth is discussed. Both vegetative and reproductive growth is described in this chapter. Very brief mention is made regarding reproductive growth under sub-headings Photoperiodism and Vernalisation. A clear distinction is brought between growth, development and differentiation in the beginning of the chapter. Most part of the chapter is assigned for explaining this with examples. This part of the chapter will make the student understand better what actually growth is and how it different from animals. In plants growth is open or indefinite. When growth is discussed in plants, invariably it should involve the activity of meristems and how it differentiates to form permanent tissues. Anatomy part of the first year should be recollected here briefly. The most important part of the chapter is discovery and physiological aspects of the plant hormones or plant growth regulators. This is not explained clearly. This will leave the student in utter confusion. Student without going into the details of the effects of these regulators, list out the points given in the text book in serial order and develop methods of his own to recollect them better. Only from this part questions will be asked for both IPE and EAMCET. Seed dormancy is brief and one SAQ can be asked on this. In the reproductive growth, very few points has to be remembered on photoperiodism and vernalisation. For the IPE examinations one of the LAQ is from physiology. If the LAQ is given from this chapter, it will be an advantage for the students as it will be the easiest one in entire physiology chapter. In fact the student need not prepare separately for this. One of the SAQ will make the ninety percent of the answer. Only thing that he has to add to the answer is discovery of the regulators. All the important SAQs must be prepared. The physiological effects of the

B¨Ìê»ê§Šæ l Ô¶æ°ÐéÆý‡… l yìlòÜ…ºÆŠæ l 12 l 2015

{Ô¶æ§é®Ð鯌æ Ë¿¶æ™ól gêq¯]l…

Sakshi Bhavita Online Edition www.sakshieducation.com/bhavitha.aspx B. Rajendra

ѧýlÅ

Send your Feedback [email protected]

In plants growth is indefinite growth regulators will be little confusing but not difficult to remember. The student should write point wise, the physiological effects once before going to the exam. Contrasting and complementary nature of these growth regulators, once understood, it will be easy to remember. Student will automatically develop his own way of recollecting. For the EAMCET point of view one question may be given from this chapter. Mostly the question will be of matching type and from plant growth regulators. This part of the chapter i.e. Plant Growth regulators is not easy to remember and recollect. The presentation of this part is confusing without clarity. While preparing for IPE it is advisable to the student to write down all the points in an order that will help the student for the EAMCET also. There is no concept in physiological effects of Growth regulators. These are knowledge based questions. Few points related to first year anatomy to be recollected here. Seed dormany, Photoperiodism and Vernalisation is very brief and easy to remember the points given therein.

LAQ for IPE 1. List five natural plant growth regulators. Write a note on discovery, physiological functions and agricultural/ horticultural applications of any one of them. Only one question is listed for IPE examination from this chapter. This question is having a breakup. Five growth regulators names have to be written and a brief note of their discovery must be mentioned. In text book also it is given very briefly. One of the growth regulators physiological functions have to be mentioned. Regarding all the five growth regulators functions student has to study as five LAQs. Any one he can write here. For preparing this question student may need just 20 minutes.

Important SAQs for IPE 1. Write a note on agricultural / horticultural applications of auxins. 2. Write the physiological responses of gibberellins in plants. 3. Write any four physiological effects of cytokinins in plants. 4. What are the physiological processes that are regulated by ethylene in plants?

5. Write short notes on seed dormany. For all these answers diagrams are not there in the text book. Students can draw on their own some effects of these hormones. It is better to list out the physiological effects rather than writing in a paragraph as given in the text book.

❖

❖

❖

❖

❖

❖

Sr. Inter Botany Botany

Important information for EAMCET ❖

❖

❖

❖ ❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

Growth is irreversible change in the organism or in an individual cell. Growth occurs in living organisms. Swelling of wood cannot be growth as metabolic processes are not involved. In plants growth is indefinite. Continuous addition of cells to the plant body is the open form of growth. Open growth results from activity of the cambium. Secondary growth is also a form of open growth. Growth is measurable. Parameters like dry weight, fresh weight, length, area volume or cell number etc can be considered. Three different phases are observed in plants viz meristematic, elongation and maturation. The three phases can be observed in root apex. Root apex where meristems are present is meristematic phase of growth. Proximal to this is zone of elongation. Further proximal to this is zone of maturation. Meristematic zone is filled with cells rich in protoplasm, elastic primary wall and large conspicuous nucleus. Cells in zone of elongation shows vacuolation, cell enlargement with new cell wall deposition. Large sized cells are present in zone of maturation.

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖ ❖

❖

In arithmetic growth new cells mature to form permanent cells. It is mathematically expressed as Lt = L0+rt. Geometrical growth increases exponentially. Geometrical growth expressed in W1=W0ert. Growth depends on factors like nutrients, water, temperature and other factors. Differentiation is formation of permanent cells from meristems. Dedifferentiation is formation of meristematic cells from permanent living cells. Redifferentiation is meristematic cells formed by dedifferentiation once again giving rise to new differentiated cells. Differentiation examples are xylem, phloem, parenchyma, collenchymas formation. Dedifferentiation examples are formation of vascular cambium and phellogen. Examples of redifferentiation is secondary xylem, secondary phloem, phellum and phelloderm. Development encompasses both growth and differentiation. It is sum total of growth and differentiation. Ability to develop different kinds of structures in response to environment is plasticity. Heterophylly is an example of heterophylly. For differentiation certain chemical are required in minute amounts. These are plant hormones or phytohormones or Plant Growth Regulators (PGR). PGRs involving in growth promotion activities like cell elongation flowering etc are called growth promoters. Auxins, Gibberellins, Cytokinins are growth promoters. Substances involved in growth retarding activities are called growth retarders. Growth retarders are Ethylene and Abscisic acid (ABA). Charles Darwin and Francis Darwin studied phototropism, effect of unilateral light, on canary grass coleoptiles. Auxin was isolated by F.W. Went. In plants naturally occurring auxin is IAA. Auxins are indole compounds. Nitrogen containing. Naphthalenacetic acid(NAA)

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

❖

and 2,4-D(2.4-dichlorophenoxyacetic acid) are synthetic auxins. In plants they are synthesized in apices. Auxins help in root initiation at low concentration levels than apices. Auxins promote xylem differentiation and cell division. Auxins promote flowering in pineapples. In early stages they prevent fruit fall and leaf fall. At mature stages they promote abscission. They are responsible for continuous growth of apical bud and discourage the lateral bud growth. (Apical dominance). Removal of apical bud increases the lateral bud development. 2,4D act as a herbicide. It do not have effect on monocot herbs. Paddy plants with 'bakane' disease found to be infected with a fungus -Gibberella fujikuroi. Kurasawa reported the presence of a substance in fungi responsible for the disease. Sterile fungal filtrate show Gibberellic acids. Chemically this substance is terpenes. More than 100 gibberellins were reported from plants. GA3 is most common and extensively studied.

TSEAMCET-2015 1. Identify the correct pair of combinations I) Zeatin − Adenine derivative − Overcoming apical dominance. II) C2H4 − Indole compound − Effective in fruit ripening. III) ABA − Carotenoid derivative − Induction of parthenocarpy. IV) GA3 − Terpene − Bolting in cabbage. (1) III, IV (2) II, III (3) II, IV (4) I, IV Ans:4

APEAMCET- 2015 1. Induction of cell division and delay in senescence is caused by 1) Cytokinin 2)I.A.A 3) Gibberellins 4) N.A.A Ans:1