In Class 11 Final Exams there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Download of CBSE Class 11 Biology Chapter 15 Case Study and Passage Based Questions with Answers were Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 11 Biology Plant Growth and Development to know their preparation level.

In CBSE Class 11 Biology Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Plant Growth and Development Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 11 Biology Chapter 15 Plant Growth and Development

Case Study/Passage-Based Questions

Case Study 1:

Plant growth regulators are the chemical substances which govern all the factors of development and growth within plants. Some other names used to refer to it are phytohormones and plant growth hormones. Phytohormones are organic compounds which are either synthesized in laboratories or produced naturally within the plants. They profoundly control and modify the physiological processes like the growth, development, and movement of plants. Based on their actions, plant growth regulators are broadly classified into two major groups: Plant growth promoters

Plant growth inhibitors.

Auxins, Gibberellins, and Cytokinins are grouped into Plant growth promoters while Abscisic acid and Ethylene are grouped into Plant growth inhibitors. Ethylene can be grouped either into the promoters or into the plant inhibitors.

Auxins was first isolated from human urine. The term ‘auxin’ is applied to the indole-3-acetic acid (IAA), and to other natural and synthetic compounds having certain growth regulating properties. They are generally produced by the growing apices of the stems and roots, from where they migrate to the regions of their action. Auxins like IAA and indole butyric acid (IBA) have been isolated from plants. NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic) are synthetic auxins. All these auxins have been used extensively in agricultural and horticultural practices. They help to initiate rooting in stem cuttings, an application widely used for plant propagation. Auxins promote flowering e.g. in pineapples. They help to prevent fruit and leaf drop at early stages but promote the abscission of older mature leaves and fruits. In higher plants, the growing apical bud inhibits the growth of the lateral (axillary) buds, a phenomenon called apical dominance. Removal of shoot tips (decapitation) usually results in the growth of lateral buds. It is widely applied in tea plantations, hedge-making. Auxins also induce parthenocarpy, e.g., in tomatoes. They are widely used as herbicides. 2, 4-D, widely used to kill dicotyledonous weeds, does not affect mature monocotyledonous plants. It is used to prepare weed-free lawns by gardeners. Auxin also controls xylem differentiation and helps in cell division.

1.) Identify the incorrect statement about PGR.

• Statement 1 – 2, 4-dichlorophenoxyacetic is natural auxins.
• Statement 2 – Auxin controls xylem differentiation and helps in cell division.
• Statement 3 – Auxins was first isolated from human urine.
• Statement 4 – Indole acetic acid are isolated from plants.

Ans: Statement 1 – 2, 4-dichlorophenoxyacetic is natural auxins.

2.) ___________________ is synthetic auxins

• a) Indole butyric acid
• b) 2, 4-dichloroethynoxyacetic
• c) Naphthalene acetic acid
• d) 4, 2-dichlorophenoxyacetic

Ans:c) Naphthalene acetic acid

3.) Name the plant growth regulator was first isolated from human urine?

Ans: Auxin was the first plant growth regulator isolated from human urine.

4.) Define phytohormones.

Ans: Phytohormones are organic compounds which are either synthesized in laboratories or produced naturally within the plants. They profoundly control and modify the physiological processes like the growth, development, and movement of plants.

5.) Explain apical dominance. Name the hormone that controls it.

Ans: Apical dominance is defined as phenomenon in which the apical bud become dominant and suppresses the growth of lateral buds into branches. Auxin is the plant growth regulator that controls apical dominance.

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