What is apomixis and what is its importance?
Question: What is apomixis and what is its importance? Solution: Apomixis is the mechanism of seed production without involving the process of meiosis and syngamy. It plays an important role in hybrid seed production. The method of producing hybrid seeds by cultivation is very expensive for farmers. Also, by sowing hybrid seeds, it is difficult to maintain hybrid characters as characters segregate during meiosis. Apomixis prevents the loss of specific characters in the hybrid. Also, it is a cost...
Read More →You are given the two circuits as shown in Fig. 14.44.
Question: You are given the two circuits as shown in Fig. 14.44. Show that circuit (a) acts as OR gate while the circuit (b) acts as AND gate. Solution: (a)AandBare the inputs andYis the output of the given circuit. The left half of the given figure acts as the NOR Gate, while the right half acts as the NOT Gate. This is shown in the following figure. Hence, the output of the NOR Gate $=\overline{A+B}$ This will be the input for the NOT Gate. Its output will be $\overline{\overline{A+B}}=A+B$ Y=...
Read More →Find the equation of the line which intersects the x-axis at a distance of 3 units to the left of origin with slope –2.
Question: Find the equation of the line which intersects thex-axis at a distance of 3 units to the left of origin with slope 2. Solution: It is known that if aline with slopemmakesx-interceptd, then the equation of the line is given as y=m(x d) For the line intersecting thex-axis at a distance of 3 units to the left of the origin,d= 3. The slope of the line is given asm= 2 Thus, the required equation of the given line is y= 2 [x (3)] y= 2x 6 i.e., 2x+y+ 6 = 0...
Read More →Explain the role of tapetum in the formation pollen-grain wall.
Question: Explain the role of tapetum in the formation pollen-grain wall. Solution: Tapetum is the innermost layer of the microsporangium. It provides nourishment to the developing pollen grains. During microsporogenesis, the cells of tapetum produce various enzymes, hormones, amino acids, and other nutritious material required for the development of pollen grains. It also produces the exine layer of the pollen grains, which is composed of the sporopollenin....
Read More →Find the equation of the line which passes though
Question: Find the equation of the line which passes though$(2,2 \sqrt{3})$ and is inclined with the $x$-axis at an angle of $75^{\circ}$. Solution: The slope of the line that inclines with the $x$-axis at an angle of $75^{\circ}$ is $m=\tan 75^{\circ}$ $\Rightarrow m=\tan \left(45^{\circ}+30^{\circ}\right)=\frac{\tan 45^{\circ}+\tan 30^{\circ}}{1-\tan 45^{\circ} \cdot \tan 30^{\circ}}=\frac{1+\frac{1}{\sqrt{3}}}{1-1 \cdot \frac{1}{\sqrt{3}}}=\frac{\frac{\sqrt{3}+1}{\sqrt{3}}}{\frac{\sqrt{3}-1}{...
Read More →If one can induce parthenocarpy through the application of growth substances,
Question: If one can induce parthenocarpy through the application of growth substances, which fruits would you select to induce parthenocarpy and why? Solution: Parthenocarpy is the process of developing fruits without involving the process of fertilization or seed formation. Therefore, the seedless varieties of economically important fruits such as orange, lemon, water melon etc. are produced using this technique. This technique involves inducing fruit formation by the application of plant grow...
Read More →What is meant by emasculation?
Question: What is meant by emasculation? When and why does a plant breeder employ this technique? Solution: Emasculation is the process of removing anthers from bisexual flowers without affecting the female reproductive part (pistil), which is used in various plant hybridization techniques. Emasculation is performed by plant breeders in bisexual flowers to obtain the desired variety of a plant by crossing a particular plant with the desired pollen grain. To remove the anthers, the flowers are co...
Read More →In a p-n junction diode, the current I can be expressed as
Question: In a p-n junction diode, the current I can be expressed as $I=I_{0} \exp \left(\frac{\mathrm{eV}}{2 k_{\mathrm{B}} T}-1\right)$ whereI0is called the reverse saturation current,Vis the voltage across the diode and is positive for forward bias and negative for reverse bias, andIis the current through the diode,kBis the Boltzmann constant (8.6105eV/K) and T is the absolute temperature. If for a given diodeI0= 5 1012A and T = 300 K, then (a)What will be the forward current at a forward vol...
Read More →Find the equation of the line which passes though (0, 0) with slope m.
Question: Find the equation of the line which passes though (0, 0) with slopem. Solution: We know that the equation of the line passing through point $\left(x_{0}, y_{0}\right)$, whose slope is $m$, is $\left(y-y_{0}\right)=m\left(x-x_{0}\right)$. Thus, the equation of the line passing through point (0, 0), whose slope ism,is (y 0) =m(x 0) i.e.,y=mx...
Read More →Why is apple called a false fruit? Which part(s) of the flower forms the fruit?
Question: Why is apple called a false fruit? Which part(s) of the flower forms the fruit? Solution: Fruits derived from the ovary and other accessory floral parts are called false fruits. On the contrary, true fruits are those fruits which develop from the ovary, but do not consist of the thalamus or any other floral part. In an apple, the fleshy receptacle forms the main edible part. Hence, it is a false fruit....
Read More →Differentiate between:
Question: Differentiate between: (a)Hypocotyl and epicotyl; (b)Coleoptile and coleorrhiza; (c)Integument and testa; (d)Perisperm and pericarp. Solution: Differentiate between (a) (b) (c) (d)...
Read More →Find the equation of the line which passes through the point
Question: Find the equation of the line which passes through the point$(-4,3)$ with slope $\frac{1}{2}$ Solution: We know that the equation of the line passing through point $\left(x_{0}, y_{0}\right)$, whose slope is $m$, is $\left(y-y_{0}\right)=m\left(x-x_{0}\right)$. Thus, the equation of the line passing through point $(-4,3)$, whose slope is $\frac{1}{2}$, is $(y-3)=\frac{1}{2}(x+4)$ $2(y-3)=x+4$ $2 y-6=x+4$ i.e., $x-2 y+10=0$...
Read More →In an intrinsic semiconductor the energy gap
Question: In an intrinsic semiconductor the energy gapEgis 1.2 eV. Its hole mobility is much smaller than electron mobility and independent of temperature. What is the ratio between conductivity at 600K and that at 300K? Assume that the temperature dependence of intrinsic carrier concentrationniis given by$n_{i}=n_{0} \exp \left[-\frac{E_{g}}{2 k_{\mathrm{B}} T}\right]$wheren0is a constant. Solution: Energy gap of the given intrinsic semiconductor,Eg= 1.2 eV The temperature dependence of the int...
Read More →Write the equations for the x and y-axes.
Question: Write the equations for thexandy-axes. Solution: They-coordinate of every point on thex-axis is 0. Therefore, the equation of thex-axis isy= 0. Thex-coordinate of every point on they-axis is 0. Therefore, the equation of they-axis isx= 0....
Read More →Consider the given population and year graph.
Question: Consider the given population and year graph. Find the slope of the line AB and using it, find what will be the population in the year 2010? Solution: Since line AB passes through points A (1985, 92) and B (1995, 97),its slope is $\frac{97-92}{1995-1985}=\frac{5}{10}=\frac{1}{2}$ Letybe the population in the year 2010. Then, according to the given graph, line AB must pass through point C (2010,y). $\therefore$ Slope of $A B=$ Slope of $B C$ $\Rightarrow \frac{1}{2}=\frac{y-97}{2010-199...
Read More →Why do you think the zygote is dormant for sometime in a fertilized ovule?
Question: Why do you think the zygote is dormant for sometime in a fertilized ovule? Solution: The zygote is formed by the fusion of the male gamete with the nucleus of the egg cell. The zygote remains dormant for some time and waits for the endosperm to form, which develops from the primary endosperm cell resulting from triple fusion. The endosperm provides food for the growing embryo and after the formation of the endosperm, further development of the embryo from the zygote starts....
Read More →The number of silicon atoms per
Question: The number of silicon atoms per m3is 5 1028. This is doped simultaneously with 5 1022atoms per m3of Arsenic and 5 1020per m3atoms of Indium. Calculate the number of electrons and holes. Given thatni= 1.5 1016m3. Is the material n-type or p-type? Solution: Number of silicon atoms,N= 5 1028atoms/m3 Number of arsenic atoms,nAs= 5 1022atoms/m3 Number of indium atoms,nIn= 5 1020atoms/m3 Number of thermally-generated electrons,ni= 1.5 1016electrons/m3 Number of electrons,ne= 5 1022 1.5 1016 ...
Read More →Discuss the continuity of the following functions.
Question: Discuss the continuity of the following functions. (a) $f(x)=\sin x+\cos x$ (b) $f(x)=\sin x-\cos x$ (c) $f(x)=\sin x \times \cos x$ Solution: It is known that ifgandhare two continuous functions, then $g+h, g-h$, and $g . h$ are also continuous. It has to proved first that $g(x)=\sin x$ and $h(x)=\cos x$ are continuous functions. Let $g(x)=\sin x$ It isevident thatg(x) = sinxis defined for every real number. Letcbe a real number. Putx=c+h If $x \rightarrow c$, then $h \rightarrow 0$ $...
Read More →What is triple fusion? Where and how does it take place?
Question: What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion. Solution: Triple fusion is the fusion of the male gamete with two polar nuclei inside the embryo sac of the angiosperm. This process of fusion takes place inside the embryo sac. When pollen grains fall on the stigma, they germinate and give rise to the pollen tube that passes through the style and enters into the ovule. After this, the pollen tube enters one of synergids and releases two...
Read More →If three point (h, 0), (a, b) and (0, k) lie on a line,
Question: If three point (h,0), (a, b) and (0, k) lie on a line,show that $\frac{a}{h}+\frac{b}{k}=1$ Solution: If the points A (h,0), B (a, b), and C (0, k) lie on a line, then Slope of AB = Slope of BC $\frac{b-0}{a-h}=\frac{k-b}{0-a}$ $\Rightarrow \frac{b}{a-h}=\frac{k-b}{-a}$ $\Rightarrow-a b=(k-b)(a-h)$ $\Rightarrow-a b=k a-k h-a b+b h$ $\Rightarrow k a+b h=k h$ On dividing both sides bykh, we obtain $\frac{k a}{k h}+\frac{b h}{k h}=\frac{k h}{k h}$ $\Rightarrow \frac{a}{h}+\frac{b}{k}=1$ H...
Read More →What is bagging technique?
Question: What is bagging technique? How is it useful in a plant breeding programme? Solution: Various artificial hybridization techniques (under various crop improvement programmes) involve the removal of the anther from bisexual flowers without affecting the female reproductive part (pistil) through the process of emasculation. Then, these emasculated flowers are wrapped in bags to prevent pollination by unwanted pollen grains. This process is called bagging. This technique is an important par...
Read More →A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV.
Question: A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV. Can it detect a wavelength of 6000 nm? Solution: Energy band gap of the given photodiode,Eg= 2.8 eV Wavelength, = 6000 nm = 6000 109m The energy of a signal is given by the relation: $E=\frac{h c}{\lambda}$ Where, h= Plancks constant = 6.626 1034Js c = Speed of light = 3 108m/s $E=\frac{6.626 \times 10^{-34} \times 3 \times 10^{8}}{6000 \times 10^{-9}}$ = 3.313 1020J But 1.6 1019J = 1 eV E= 3.313 1020J $=\frac...
Read More →What is self-incompatibility?
Question: What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species? Solution: Self-incompatibility is a genetic mechanism in angiosperms that prevents self-pollination. It develops genetic incompatibility between individuals of the same species or between individuals of different species. The plants which exhibit this phenomenon have the ability to prevent germination of pollen grains and thus, prevent the growth of the pollen tube on the st...
Read More →Two amplifiers are connected one after the other in series (cascaded).
Question: Two amplifiers are connected one after the other in series (cascaded). The first amplifier has a voltage gain of 10 and the second has a voltage gain of 20. If the input signal is 0.01 volt, calculate the output ac signal. Solution: oltage gain of the first amplifier,V1= 10 Voltage gain of the second amplifier,V2= 20 Input signal voltage,Vi= 0.01 V Output AC signal voltage =Vo The total voltage gain of a two-stage cascaded amplifier is given by the product of voltage gains of both the ...
Read More →A line passes through. If slope of the line is m, show that
Question: A line passes through $\left(x_{1}, y_{1}\right)$ and $(h, k)$. If slope of the line is $m$, show that $k-y_{1}=m\left(h-x_{1}\right)$. Solution: The slope of the line passing through $\left(x_{1}, y_{1}\right)$ and $(h, k)$ is $\frac{k-y_{1}}{h-x_{1}}$. It is given that the slope of the line ism. $\therefore \frac{k-y_{1}}{h-x_{1}}=m$ $\Rightarrow k-y_{1}=m\left(h-x_{1}\right)$ Hence, $k-y_{1}=m\left(h-x_{1}\right)$...
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