Students can go through AP Inter 2nd Year Botany Notes 6th Lesson Plant Growth and Development will help students in revising the entire concepts quickly.
AP Inter 2nd Year Botany Notes 6th Lesson Plant Growth and Development
→ Growth is one of the most conspicuous events in any living organism. It is an irreversible increase in size, area, length height, volume etc.,
→ Meristems are the sites of Growth.
→ Root, Shoot apical meristems, Intercalary Meristems contribute to the longitudinal growth of plant axis.
→ Growth can be arithmetic or geometrical.
→ Growth Involves three phases, the lag, the log and the senescent phase.
→ When a cell looses capacity to divide leads to differentiation.
→ The development is the Sun of Growth differentiation.
→ Plants exhibit plasticity in development.
→ Plant Growth and development are under the control of both Intrinsic and extrinsic factors.
→ Intrinsic factors are called Plant Growth Regulators.
→ They are Auxins, Gibberellins, Cytokinins, Absicic acid and Ethylene.
→ Plant growth and development is also affected by light, temperature, nutrition, oxygen status, gravity etc.,
→ Auxin was Isolated by F.W. Went from the tips of colebptiles of oat seedlings.
→ The bakane. disease of rice seedlings is caused by a fungus, Gibberella fujikuroi.
→ Skoog and Miller later Identified and crystallised the cytokinesis promoting active substance that they termed kinetin.
→ A B A is a natural anti transplant.
→ Ethylene is a gaseous PGR.
→ IAA, IBA are natural auxins.
→ NAA, 2, 4-D are synthetic auxins.
→ The seed when it is unable to Germinate because favourable external conditions normally required for growth is called quiescence.
→ The seed when it fails to germinate because of internal conditions even though the external conditions are suitable is called dormancy.
→ The flowering response of plants to periods of day/night is termed as photoperiodism.
→ Some plants require the exposure to light for a period exceeding a well defined critical duration are called long day plants.
→ Some plants must be exposed to light for a period less than critical duration before flowering are called short day plants.
→ Some plants do not require exposure to light duration and induction of flowering are called day neutral plants.
→ Method of inducing flowering in plants by pre-chilling treatment is called vernalisation.
→ Growth is an irreversible, permanent increase in the size of an organism or its parts or cells.
→ Animals stop growing after maturity.
→ But in higher plants, roots stems and branches have non-stop growth.
→ While other organs like leaves, flowers and fruits show limited or definite growth.
→ Plant growth and development is affected by light, temperature, nutrition, oxygen etc.
→ Growth can be arithmetical or geometrical based on the cell division in root, shoot. There are three principle phases in growth – lag, log and senescent phases.
→ The flowering response of plants to periods of day/night is called photo periodism. Auxins are powerful growth hormones produced in the stem tips of plants. [IPE]
→ Gibberellins are growth hormones that stimulate fruit repining , stem elongation, termination, flowering, sex expression, enzyme induction, leaf & fruit senescence. [IPE]
→ Cytokinins are a class of plant growth hormones that promote cell divisions in plant roots. Ethylene is a simple gaseous ‘plant growth regulating hormone’. [IPE]
→ The inability or delay of seed to germinate or grow is called seed dormancy. [IPE].
→ Quiescence: It is a delayed seed germination which occurs when a seed fails to germinate because the external environmental conditions are too dry or warm or cold for germination. [IPE]
→ Fruit and leaf drop at early stages can be prevented by the application of auxins. [NEET-2017]
→ Phytochrome is a chromoprotein. [NEET-2016]
→ The avena curvature is used for bioassay of IA A. [NEET-2016]
→ Auxin can be bioassayed by Avena coleoptile curvature. [NEET-2015]
→ Typical growth curve in plants is sigmoid. [NEET-2015]
→ Abscisic acid growth regulator is known as ‘stress hormone’. [NEET-2014]
→ During seed germination its stored food is mobilized by gibberellin. [NEET-2013]
→ One of the commonly used plant growth hormone in tea plantations is indole-3-acetic acid. [2010 PMT]
→ ‘Auxin & Ethylene’ can be applied artificially to induce flowering in pineapple plant throughout the year to increase yield. [NEET-2019]
→ The process of growth is maximum during log phase. [NEET-2020]
→ The plant hormone used to destroy weeds in a field is 2,4-D. [NEET-2021]