A gardener finds some broad-leaved dicot weeds growing
Question: A gardener finds some broad-leaved dicot weeds growing in his lawns. What can be done to get rid of the weeds efficiently? Solution: To get rid of the weeds efficiently, it can be selectively killed using plant growth hormone regulator called auxins....
Read More →While eating watermelons,
Question: While eating watermelons, all of us wish it was seedless. As a plant physiologist can you suggest any method by which this can be achieved? Solution: Parthenocarpy can be done for this. Growth hormones can induce parthenocarpy like Gibberellins and auxins inducing parthenocarpy in tomatoes...
Read More →Define parthenocarpy.
Question: Define parthenocarpy. Name the plant hormone used to induce parthenocarpy. Solution: An artificially induced development of fruit without undergoing any fertilization is known as parthenocarpy. The plant hormone used to induce parthenocarpy is Gibberellin...
Read More →Both animals and plants grow.
Question: Both animals and plants grow. Why do we say that growth and differentiation in plants are open and not so in animals? Does this statement hold for sponges also? Solution: Because the plant growth and differentiation of certain parts like the meristematic tissues of the meristems present in different locations of the plant body is an active site of cell division where growth is indefinite....
Read More →Differentiate
Question: Differentiate $\frac{e^{x}(x-1)}{(x+1)}$ Solution: To find: Differentiation of $\frac{e^{x}(x-1)}{(x+1)}$ Formula used: (i) $\left(\frac{u}{v}\right)^{\prime}=\frac{u^{\prime} v-u v^{\prime}}{v^{2}}$ where $v \neq 0$ (Quotient rule) (ii) $\frac{d e^{x}}{d x}=e^{x}$ (iii) $\frac{d x^{n}}{d x}=n x^{n-1}$ (iv) (uv) = uv + uv (Leibnitz or product rule) Let us take $u=e^{x}(x-1)$ and $v=(x+1)$ $u^{\prime}=\frac{d u}{d x}=\frac{d\left[e^{x}(x-1)\right]}{d x}$ Applying Product rule $(g h)^{\p...
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{\cot x}{\sqrt{\sin x}} d x$ Solution: We know $d(\sin x)=\cos x$, and cot can be written in terms of $\cos$ and $\sin$ $\therefore \cot x=\frac{\cos x}{\sin x}$ $\therefore$ The given equation can be written as $\Rightarrow \int \frac{\cos x}{\sin x \sqrt{\sin x}} d x$ $\Rightarrow \int \frac{\cos x}{\sin ^{3 / 2} x} d x$ Now assume $\sin x=t$ $d(\sin x)=d t$ $\cos x d x=d t$ Substitute values of $\mathrm{t}$ and $\mathrm{dt}$ in above equa...
Read More →A rubber band stretches and reverts to its original position.
Question: A rubber band stretches and reverts to its original position. Bubble gum stretches, but it would not return to its original position. Is there any difference between the two processes? Discuss it with respect to plant growth (Hint: Elasticity (reversible) Plasticity (irreversible)) Solution: A rubber band stretched and reverts to its original position due to the property of elasticity where the form gets reversed. Bubble gum would not return to its original position after getting stret...
Read More →In a slide showing different types of cells can you identify
Question: In a slide showing different types of cells can you identify which type of the cell may be meristematic and the one which is incapable of dividing and how? Solution: On protoplasm, the meristematic cells are rich in and possess large conspicuous nuclei. Their cell wall is thin and comprises cellulose and also has fewer vacuoles....
Read More →To get carpet-like grass lawns are mowed
Question: To get carpet-like grass lawns are mowed regularly. Is there any scientific explanation for this? Solution: The process of Decapitation of plants leads to the inactivation of axillary buds and promotes the growth of lateral buds giving a carpet like an appearance....
Read More →Many discoveries in science have been accidental.
Question: Many discoveries in science have been accidental. This is true for plant hormones also. Can you justify this statement by giving an example? Also what term is used for such accidental findings? Solution: The foolish seedling disease of rice was caused by the fungal pathogen Gibberella fujikuroi. The symptoms of which were first reported by Kurosawa who noticed that uninfected rice developed these symptoms when gibberellins were added....
Read More →Differentiate
Question: Differentiate $\frac{2^{x} \cot x}{\sqrt{x}}$ Solution: To find: Differentiation of $\left(\frac{2^{x} \cot x}{\sqrt{x}}\right)$ Formula used: $(i)\left(\frac{u}{v}\right)^{\prime}=\frac{u^{\prime} v-u v^{\prime}}{v^{2}}$ where $v \neq 0$ (Quotient rule) (ii) $\frac{d \cot x}{d x}=-\operatorname{cosec}^{2} x$ (iii) $\frac{d x^{n}}{d x}=n x^{n-1}$ (iv) $\frac{d a^{x}}{d x}=a^{x} \log a$ (v) $(u v)^{\prime}=u^{\prime} v+u v^{\prime}$ (Leibnitz or product rule) Let us take $u=\left(2^{x} ...
Read More →In animals, there are special glands secreting hormones,
Question: In animals, there are special glands secreting hormones, whereas there are no glands in plants. Where are plant hormones formed? How are the hormones translocated to the site of activity? Solution: Plant hormones are found in the different tissues like the tip of the shoots, the tip of the roots, meristematic tissues, apical buds etc. These hormones are translocate to the site of activity by the vascular bundle tissues like xylem and phloem....
Read More →What is the mechanism underlying the phenomenon by
Question: What is the mechanism underlying the phenomenon by which the terminal/apical bud suppresses the growth of lateral buds? Suggest measures to overcome this phenomenon. Solution: The mechanism underlying the phenomenon by which the terminal/apical bud suppresses the growth of lateral buds is known as apical dominance. To overcome this Decapitation or removal of the apical bud (shoot cutting) that inhibits the growth of the apical bud and promotes the growth of the lateral branches....
Read More →While experimentation,
Question: While experimentation, why do you think it is difficult to assign any effect seen to any single hormone? Solution: It becomes difficult to assign any effect seen to any single hormone because it can be a synergistic or an antagonistic effect as well. The synergistic effect when the two hormones come together and effects combined whereas the antagonistic effect is when hormone counters the effect of each other....
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{1}{\sqrt{1-x^{2}}\left(\sin ^{-1} x\right)^{2}} d x$ Solution: Assume $\sin ^{-1} x=t$ $\Rightarrow \mathrm{d}\left(\sin ^{-1} x\right)=\mathrm{dt}$ $\Rightarrow \frac{\mathrm{dx}}{\sqrt{1-\mathrm{x}^{2}}}=\mathrm{dt}$ $\therefore$ Substituting $t$ and $d t$ in the given equation we get $\Rightarrow \int \frac{1}{\mathrm{t}^{2}} \mathrm{dt}$ $\Rightarrow \int \mathrm{t}^{-2} \cdot \mathrm{dt}$ $\Rightarrow \frac{\mathrm{t}^{-1}}{-1}+\mathrm...
Read More →The role of ethylene and abscisic acid is both positive and negative.
Question: The role of ethylene and abscisic acid is both positive and negative. Justify the statement. Positive Roles of Ethylene : Negative Role of Ethylene : Positive Role of Abscisic acid: Negative Role of Abscisic acid: Solution: (a) Positive Roles of Ethylene: Ripening of fruits When present in low concentration, it stimulates root meristem formation and promotes the growth of lateral roots. (b) Negative Role of Ethylene: Ethylene is responsible for nullifying geotropism. (c) Positive Role ...
Read More →Auxins are growth hormones capable of promoting cell elongation.
Question: Auxins are growth hormones capable of promoting cell elongation. They have been used in horticulture to promote growth, flowering and rooting. Explain the meaning of the following terms related to auxins. a. auxin precursors b. anti-auxins c. synthetic auxins Solution: a. Auxin precursors are responsible for the production of auxins. b. Anti auxin function as an inhibition of the action of auxin by competing for the same receptor. c. Synthetic auxins are some chemical compounds that ha...
Read More →Explain in 2-3 lines each of the following terms
Question: Explain in 2-3 lines each of the following terms with the help of examples taken from different plant tissues a. Differentiation b. De-differentiation c. Redifferentiation Solution: (a) Differentiation: the cell of the apices of roots, apices of shoot and cambium can differentiate and mature so that they can perform specific functions. (b) De-differentiation: A differentiated cell can regain its capacity for cell division when placed under certain conditions (c) Redifferentiation: It i...
Read More →Does the growth pattern in plants differ from that in animals?
Question: Does the growth pattern in plants differ from that in animals? Do all the parts of plant grow indefinitely? If not, name the regions of the plant, which can grow indefinitely. Solution: Yes, the growth pattern in plants differs from that in animals. Only the meristematic tissues can keep on dividing i.e. the meristems are the parts which grow indefinitely throughout the plant life....
Read More →What are the structural characteristics of a?
Question: What are the structural characteristics of a? Meristematic cells near root tip b. The cells in the elongation zone of the root Solution: (a) Meristematic cells near the root tip: -large nucleus -rich protoplasm -vacuoles are less in number (b) The cells in the elongation zone of the root -more number of vacuoles -new cellulosic walls are deposited -there is an increase in size...
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{1+\sin x}{\sqrt{x-\cos x}} d x$ Solution: Assume $x-\cos x=t$ $\Rightarrow \mathrm{d}(x-\cos x)=\mathrm{dt}$ $\Rightarrow(1+\sin x) \mathrm{dx}=\mathrm{dt}$ $\therefore$ Substituting $t$ and dt in given equation we get $\Rightarrow \int \frac{1}{\sqrt{t}} \mathrm{dt}$ $\Rightarrow \int \mathrm{t}^{-1 \backslash 2} \cdot \mathrm{dt}$ $\Rightarrow 2 \mathrm{t}^{1 \backslash 2}+\mathrm{c}$ But $\mathrm{t}=\mathrm{x}-\cos \mathrm{x}$ $\Rightarr...
Read More →Differentiate
Question: Differentiate $\frac{e^{x} \sin x}{\sec x}$ Solution: To find: Differentiation of $\left(\frac{e^{x} \sin x}{\sec x}\right)$ Formula used: (i) $\left(\frac{u}{v}\right)^{\prime}=\frac{u^{\prime} v-u v^{\prime}}{v^{2}}$ where $v \neq 0$ (Quotient rule) (ii) $\frac{d \sin x}{d x}=\cos x$ (iii) $\frac{d \sec x}{d x}=\sec x \tan x$ (iv) $\frac{d e^{x}}{d x}=e^{x}$ (v) $(\text { uv })^{\prime}=u^{\prime} v+u v^{\prime}($ Leibnitz or product rule) Let us take $u=\left(e^{x} \sin x\right)$ an...
Read More →Nicotiana tabacum, a Short Day Plant,
Question: Nicotiana tabacum, a Short Day Plant, when exposed to more than a critical period of light fails to flower. Explain. Solution: A short day plant needs a prolonged dark period to flower because the chemical transformation undergoing this time will flower the plant. So it requires a short day exposure to light....
Read More →The rice seedlings infected with fungus Gibberlla
Question: The rice seedlings infected with fungus Gibberlla fujikuroi is called foolish seedlings? What was the reason behind it? Solution: The property of Gibberellin that causes foolish seedling disease in rice is the elongation of internodes....
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{\left\{e^{\sin ^{-1} x}\right\}^{2}}{\sqrt{1-x^{2}}} d x$ Solution: Assume $\sin ^{-1} x=t$ $\Rightarrow \mathrm{d}\left(\sin ^{-1} \mathrm{x}\right)=\mathrm{dt}$ $\Rightarrow \frac{\mathrm{dx}}{\sqrt{1-\mathrm{x}^{2}}}=\mathrm{dt}$ $\therefore$ Substituting $t$ and dt in the given equation we get $\Rightarrow \int e^{t^{2}} d t$ $\Rightarrow \int e^{2 t} \cdot d t$ $\Rightarrow \frac{\mathrm{e}^{2 t}}{2}+\mathrm{c}$ But $t=\sin ^{-1} x$ $\...
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