Class 11th Biology - Plant Growth and Development Case Study Questions and Answers 2022 - 2023
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Plant Growth and Development Case Study Questions With Answer Key
11th Standard CBSE
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Reg.No. :
Biology
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The diagram given below is a diagrammatic representation of the locations of meristems in the shoot and root of a plant.
Answer the questions that follow.
(a) Identify the letters A, B and C marked in the figure.
(b) What do the arrows indicate?
(c) Which among them is/are involved in
(i) primary growth
(ii) secondary growth?
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The diagram shows the detection of zones of elongation in the primary root. Answer the questions that follow:
(a) Name the technique used to detect the zones of elongation in the root tip.
(b) Name the zones that have elongated the most.
(c) Mention the three characteristics of the cells in the zones of elongation. -
An organism or a part of the organism can produce cells during growth in a variety of ways. The following figure is a diagrammatic representation of two types of growth, A and B.
Identify the types of growth A and B. Differentiate between them with an example of each. -
The above diagram shows. a linear growth curve. Answer the following questions based on it.
(a) What type of growth is exhibited in the above graph?
(b) Give an example where such a curve can be obtained.
(c) How can it be mathematically expressed? -
A sigmoid growth curve is shown above. Answer the following questions based on it.
(a) Name the phases of growth A, Band C in the graph.
(b) What type of growth occurs in phase B?
(c) How can it be mathematically expressed? -
The figure given above is the diagrammatic comparison of the absolute and relative growth rates of two leaves A and B in a given period of time.
(a) What is meant by:
(i) absolute growth rate
(ii) relative growth rate?
(b) Which of them, A or B, shows a higher relative growth rate? Justify your answer. -
There are some plants which can measure the duration of their exposure to light. Such plants require an exposure to light for a period either exceeding or less than a well-defined critical photoperiod before they could flower. There are plants which do not fall into either of the categories mentioned above. Three types of plants A, Band C are shown in the picture given below. Answer the questions that follow.
(a) Name the types of plants A, Band C, with reference to their photoperiodic responses.
(b) Name the part of the plant that perceives the photoperiodic (light) stimulus for flowering.
(c) It has been hypothesised that there is a hormonal substance insolved in this phenomenon. Explain. -
Some varieties of wheat are known as spring wheat and some others as winter wheat. The spring wheat is sown and planted in spring and harvested by the end of the same season. The winter varieties if planted in spring fail to flower or produce grain within the same season; they are sown in autumn and harvested around the next mid-summer.
(a) What could be the probable reason for this?
(b) What term is used for this phenomenon?
(c) Name the plant hormone that can replace the above phenomenon.
Case Study
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Answers
Plant Growth and Development Case Study Questions With Answer Key Answer Keys
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(a) A - Shoot apical meristem.
B - Vascular cambium.
C - Root apical meristem.
(b) The arrows indicate the direction of growth of cells and organs.
(c) (i) Shoot apical meristem and root apical meristem.
(ii) Vascular cambium. -
(a) Parallel line technique.
(b) A, B, C and D.
(c) Characteristics of cells:
(i) Increased vacuolation.
(ii) Deposition of new cell wall.
(iii) Cell enlargement. -
A - Arithmetic growth.
B - Geometric growth.
DifferencesArithmetic growth Geometric growth (a) In this type of growth, one of the two daughter cells formed by mitosis continues to divide. (a) In this type of growth, both the progeny cells formed after mitoses continue to divide (b) It is seen in the elongation of root. (b) It is seen in organs/ tissues in exponential phase of growth. -
(a) Arithmetic growth
(b) A root elongating at a constant rate.
(c) It is mathematically expressed as
L1 = L0 + rt, where
L1 = length at time 't'
L0 = length at time '0'
r = growth rate. -
(a) A - Lag phase
B - Exponential phase
C - Stationary phase
(b) Geometric growth
(c) It is mathematically expressed as
Wt = W0 ert where
Wt = final size (weight, length etc.)
W0 = Initial size (at the beginning)
r = growth rate
e = base of natural logarithm
t = time of growth. -
(a) (i) Absolute growth rate is total growth per unit time.
(ii) Relative growth rate is the total growth per unit time per unit parameter.
(b) Relative growth rate of A = \(\frac{10-5}{5} \times 100\) = 100%
Relative growth rate of B = \(\frac{55-50}{50} \times 100\) = 10%
A shows a higher relative growth rate:. -
(a) A - Long day plant.
B - Short day plant.
C - Day neutral plant.
(b) Leaves
(c) According to the hypothesis, the hormonal substance produced in the leaves after the necessary inductive photoperiod, migrates to the shoot apices and induces flowering. -
(a) The winter wheat requires an exposure to very cold temperature (winter) for phenomenon.
(b) It is called vernalisation.
(c) Gibberellins can substitute the cold temperature (vernalisation).
Case Study
