eSaral - JEE | NEET | Class 8-10 Exam Prep App

How is the study of plant anatomy useful to us?

[question] Question. How is the study of plant anatomy useful to us? [/question] [solution] Solution: The study of plant anatomy helps us to understand the structural adaptations of plants with respect to diverse environmental conditions. It also helps us to distinguish between monocots, dicots, and gymnosperms. Such a study is linked to plant physiology. Hence, it helps in the improvement of food crops. The study of plant-structure allows us to predict the strength of wood. This is useful in ut...

Figure 5.17 shows the position-time graph of a body of mass 0.04 kg.

[question] Question. Figure 5.17 shows the position-time graph of a body of mass 0.04 kg. Suggest a suitable physical context for this motion. What is the time between two consecutive impulses received by the body? What is the magnitude of each impulse? [/question] [solution] solution: A ball rebounding between two walls located between at $x=0$ and $x=2 \mathrm{~cm}$; after every $2 \mathrm{~s}$, the ball receives an impulse of magnitude $0.08 \times 10^{-2} \mathrm{~kg} \mathrm{~m} / \mathrm{s...

Name the three basic tissue systems in the flowering plants.

[question] Question. Name the three basic tissue systems in the flowering plants. Give the tissue names under each system. [/question] [solution] Solution: [/solution]...

A guy wire attached to a vertical pole of height 18 m is 24 m long and has a stake attached to the other end.

[question] Question. A guy wire attached to a vertical pole of height 18 m is 24 m long and has a stake attachedto the other end. How far from the base of the pole should the stake be driven so that the wirewill be taut? [/question] [solution] Solution: Let AB be the vertical pole of 18 m and AC be the wire of 24 m. The $\Delta \mathrm{ABC}$, by pythagoras theorem $\mathrm{AC}^{2}=\mathrm{AB}^{2}+\mathrm{BC}^{2}$ $24^{2}=18^{2}+\mathrm{BC}^{2}$ $\mathrm{BC}^{2}=252$ $\mathrm{BC}=6 \sqrt{7} \math...

What is stomatal apparatus?

[question] Question. What is stomatal apparatus? Explain the structure of stomata with a labelled diagram. [/question] [solution] Solution: Stomata are small pores present in the epidermis of leaves. They regulate the process of transpiration and gaseous exchange. The stomatal pore is enclosed between two bean-shaped guard cells. The inner walls of guard cells are thick, while the outer walls are thin. The guard cells are surrounded by subsidiary cells. These are the specialised epidermal cells ...

The mass of an electron is $9.1 \times 10^{-31} \mathrm{~kg}$. If its K.E. is $3.0 \times 10^{-25} \mathrm{~J}$,

[question] Question. The mass of an electron is $9.1 \times 10^{-31} \mathrm{~kg}$. If its K.E. is $3.0 \times 10^{-25} \mathrm{~J}$, calculate its wavelength. [/question] [solution] Solution: From de Broglie’s equation, $\lambda=\frac{\mathrm{h}}{m v}$ Given, Kinetic energy (K.E) of the electron $=3.0 \times 10^{-25} \mathrm{~J}$ Since $\mathrm{K} . \mathrm{E}=\frac{1}{2} m v^{2}$ $\therefore$ Velocity $(v)=\sqrt{\frac{2 \mathrm{~K} \cdot \mathrm{E}}{m}}$ $=\sqrt{\frac{2\left(3.0 \times 10^{-25...

A ladder 10 m long reaches a window 8 m above the ground.

[question] Question. A ladder 10 m long reaches a window 8 m above the ground. Find the distance of the foot of the ladder from base of the wall [/question] [solution] Solution: Let AC = x metres be the distance of the foot of the ladder from the base of the wall. AB = 8 m (Height of window) BC = 10 m (length of ladder) Now, $\quad x^{2}+(8)^{2}=(10)^{2}$ $\Rightarrow x^{2}=100-64=36 \Rightarrow x=6$, i.e., $A C=6 m$ [/solution]...

Why are xylem and phloem called complex tissues?

[question] Question. Why are xylem and phloem called complex tissues? [/question] [solution] Solution: Xylem and phloem are known as complex tissues as they are made up of more than one type of cells. These cells work in a coordinated manner, as a unit, to perform the various functions of the xylem and phloem. Xylem helps in conducting water and minerals. It also provides mechanical support to plants. It is made up of the following components: Tracheids (xylem vessels and xylem tracheids) Xylem ...

If, in Exercise 5.21, the speed of the stone is increased

[question] Question. If, in Exercise 5.21, the speed of the stone is increased beyond the maximum permissible value, and the string breaks suddenly, which of the following correctly describes the trajectory of the stone after the string breaks: (a) the stone moves radially outwards, (b) the stone flies off tangentially from the instant the string breaks, (c) the stone flies off at an angle with the tangent whose magnitude depends on the speed of the particle ? [/question] [solution] solution: Wh...

In figure, O is a point in the interior of a triangle ABC,

[question] Question. In figure, $\mathrm{O}$ is a point in the interior of a triangle $\mathrm{ABC}, \mathrm{OD} \perp \mathrm{BC}, \mathrm{OE} \perp \mathrm{AC}$ and $\mathrm{OF} \perp \mathrm{AB}$. Show that (i) $\mathrm{OA}^{2}+\mathrm{OB}^{2}+\mathrm{OC}^{2}-\mathrm{OD}^{2}-\mathrm{OE}^{2}-\mathrm{OF}^{2}$ $=\mathrm{AF}^{2}+\mathrm{BD}^{2}+\mathrm{CE}^{2}$ (ii)$\mathrm{AF}^{2}+\mathrm{BD}^{2}+\mathrm{CE}^{2}=\mathrm{AE}^{2}+\mathrm{CD}^{2}+\mathrm{BF}^{2}$. [/question] [solution] Solution: (...

The transverse section of a plant material shows the following anatomical features,

[question] Question. The transverse section of a plant material shows the following anatomical features, (a) the vascular bundles are conjoint, scattered and surrounded by sclerenchymatous bundle sheaths (b) phloem parenchyma is absent. What will you identify it as? [/question] [solution] Solution: The monocot stem is characterised by conjoint, collateral, and closed vascular bundles, scattered in the ground tissue containing the parenchyma. Each vascular bundle is surrounded by sclerenchymatous...

The mass of an electron is $9.1 \times 10^{-31} \mathrm{~kg}$.

Prove that the sum of the squares of the sides

[question] Question. Prove that the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals. [/question] [solution] Solution: ABCD is a rhombus in which AB = BC = CD = DA = a (say). Its diagonals AC and BD are right bisectors of each other at O. In $\Delta \mathrm{OAB}, \angle \mathrm{AOB}=90^{\circ}$ $\mathrm{OA}=\frac{1}{2} \mathrm{AC}$ and $\mathrm{OB}=\frac{1}{2} \mathrm{BD}$ By pythagoras theorem, we have $\mathrm{OA}^{2}+\mathrm{OB}^{2}=\mathrm{AB}^...

Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope.

[question] Question. Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or dicot stem? Give reasons. [/question] [solution] Solution: The dicot stem is characterised by the presence of conjoint, collateral, and open vascular bundles, with a strip of cambium between the xylem and phloem. The vascular bundles are arranged in the form of a ring, around the centrally-located pith. The gro...

A batsman deflects a ball by an angle of $45^{\circ}$ without changing

[question] Question. A batsman deflects a ball by an angle of $45^{\circ}$ without changing its initial speed which is equal to $54 \mathrm{~km} / \mathrm{h}$. What is the impulse imparted to the ball? (Mass of the ball is $0.15$ kg.) [/question] [solution] solution: The given situation can be represented as shown in the following figure. Where, AO = Incident path of the ball OB = Path followed by the ball after deflection $\angle A O B=$ Angle between the incident and deflected paths of the bal...

ABC is an equilateral triangle of side 2a.

[question] Question. ABC is an equilateral triangle of side 2a. Find each of its altitudes. [/question] [solution] Solution: Altitude of equilateral triangle $=\frac{\sqrt{3}}{2} \times$ Side $=\frac{\sqrt{3}}{2} \times 2 a=\sqrt{3} a$ [/solution]...

Calculate the wavelength of an electron moving

[question] Question. Calculate the wavelength of an electron moving with a velocity of $2.05 \times 10^{7} \mathrm{~ms}^{-1}$. [/question] [solution] Solution: According to de Broglie’s equation $\lambda=\frac{\mathrm{h}}{m v}$ Where, $\lambda=$ wavelength of moving particle $m=$ mass of particle $v=$ velocity of particle $\mathrm{h}=$ Planck's constant Substituting the values in the expression of $\lambda$ : $\lambda=\frac{6.626 \times 10^{-34} \mathrm{Js}}{\left(9.10939 \times 10^{-31} \mathrm...

Draw illustrations to bring out anatomical difference between

[question] Question. Draw illustrations to bring out anatomical difference between (a) Monocot root and dicot root (b) Monocot stem and dicot stem [/question] [solution] Solution: (a)Monocot root and dicot root (b)Monocot stem and dicot stem [/solution]...

ABC is an isosceles triangle with AC = BC.

[question] Question. $\mathrm{ABC}$ is an isosceles triangle with $\mathrm{AC}=\mathrm{BC}$. If $\mathrm{AB}^{2}=2 \mathrm{AC}^{2}$, prove that $\mathrm{ABC}$ is a right triangle. [/question] [solution] Solution: $\mathrm{As}, \mathrm{AB}^{2}=2 \mathrm{AC}^{2}$ $\mathrm{AB}^{2}=\mathrm{AC}^{2}+\mathrm{AC}^{2}$ $=\mathrm{AC}^{2}+\mathrm{BC}^{2} \quad[\because \mathrm{AC}=\mathrm{BC}]$ As it satisfy the pythagoran triplet So, $\triangle \mathrm{ABC}$ is right triangle, right angled at $\angle \mat...

A shell of mass 0.020 kg is fired by a gun of mass 100 kg.

[question] Question. A shell of mass $0.020 \mathrm{~kg}$ is fired by a gun of mass $100 \mathrm{~kg}$. If the muzzle speed of the shell is $80 \mathrm{~m} \mathrm{~s}^{-1}$, what is the recoil speed of the gun? [/question] [solution] solution: Mass of the gun, M = 100 kg Mass of the shell, m = 0.020 kg Muzzle speed of the shell, v = 80 m/s Recoil speed of the gun = V Both the gun and the shell are at rest initially. Initial momentum of the system = 0 Final momentum of the system = mv – MV Here,...

The electron energy in hydrogen atom is given by

[question] Question. The electron energy in hydrogen atom is given by $E_{n}=\left(-2.18 \times 10^{-18}\right) / n^{2} \mathrm{~J}$. Calculate the energy required to remove an electron completely from the n = 2 orbit. What is the longest wavelength of light in cm that can be used to cause this transition? [/question] [solution] Solution: Given $E_{n}=-\frac{2.18 \times 10^{-18}}{n^{2}} \mathrm{~J}$ Energy required for ionization from n = 2 is given by, $\Delta E=E_{\infty}-E_{2}$ $=\left[\left(...

ABC is an isosceles triangle right angled at C.

[question] Question. $\mathrm{ABC}$ is an isosceles triangle right angled at $\mathrm{C}$. Prove that $\mathrm{AB}^{2}=2 \mathrm{AC}^{2} .$ [/question] [solution] Solution: In $\triangle \mathrm{ABC}, \angle \mathrm{ACB}=90^{\circ}$. We are given that $\triangle \mathrm{ABC}$ is an isosceles triangle. $\Rightarrow \angle \mathrm{A}=\angle \mathrm{B}=45^{\circ}$ $\Rightarrow \mathrm{AC}=\mathrm{BC}$ ... (1) By pythagoras theorem, we have $\mathrm{AB}^{2}=\mathrm{AC}^{2}+\mathrm{BC}^{2}$ $=\mathrm...

Two billiard balls each of mass 0.05 kg moving in opposite directions

[question] Question. Iwo billiard balls each of mass $0.05 \mathrm{~kg}$ moving in opposite directions with speed $6 \mathrm{~m} \mathrm{~s}^{-1}$ collide and rebound with the same speed. What is the impulse imparted to each ball due to the other? [/question] [solution] solution: Mass of each ball = 0.05 kg Initial velocity of each ball = 6 m/s Magnitude of the initial momentum of each ball, $p_{i}=0.3 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ After collision, the balls change their directions of m...

In figure, ABD is a right triangle right angled at A and AC

[question] Question. In figure, $A B D$ is a right triangle right angled at $A$ and $A C \perp B D$. Show that (i) $\mathrm{AB}^{2}=\mathrm{BC} \cdot \mathrm{BD}$ (ii) $\mathrm{AC}^{2}=\mathrm{BC} . \mathrm{DC}$ (iii) $\mathrm{AD}^{2}=\mathrm{BD} \cdot \mathrm{CD}$ [/question] [solution] Solution: In the given figure, we have $\Delta \mathrm{ABC} \sim \Delta \mathrm{DAC} \sim \Delta \mathrm{DBA}$ (i) $\triangle \mathrm{ABC} \sim \Delta \mathrm{DBA}$ $\Rightarrow \frac{\operatorname{ar}(\Delta A ...

Explain the process of secondary growth in stems of woody angiosperm with help of schematic diagrams. What is the significance?

[question] Question. Explain the process of secondary growth in stems of woody angiosperm with help of schematic diagrams. What is the significance? [/question] [solution] Solution: In woody dicots, the strip of cambium present between the primary xylem and phloem is called the interfascicular cambium. The interfascicular cambium is formed from the cells of the medullary rays adjoining the interfascicular cambium. This results in the formation of a continuous cambium ring. The cambium cuts off n...

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