Both lysosomes and vacuoles are endomembrane structures,
[question] Question. Both lysosomes and vacuoles are endomembrane structures, yet they differ in terms of their functions. Comment. [/question] [solution] Solution: Lysosomes are membrane-bound vesicular structures holding a variety of enzymes such as lipases, proteases, and carbohydrases. The purpose of lysosomes is to digest worn out cells. They are involved in the intracellular digestion of foreign food particles and microbes. Sometimes, they also act as suicidal bags. They are involved in th...
Read More →In Rutherford’s experiment, generally the thin foil of heavy atoms, like gold, platinum etc.
[question] Question. In Rutherford’s experiment, generally the thin foil of heavy atoms, like gold, platinum etc. have been used to be bombarded by the α-particles. If the thin foil of light atoms like Aluminium etc. is used, what difference would be observed from the above results? [/question] [solution] Solution: A thin foil of lighter atoms will not give the same results as given with the foil of heavier atoms. Lighter atoms would be able to carry very little positive charge. Hence, they will...
Read More →What are nuclear pores? State their function.
[question] Question. What are nuclear pores? State their function. [/question] [solution] Solution: Nuclear pores are tiny holes present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes. These holes allow specific substances to be transferred into a cell and out from it. They allow molecules such as RNA and proteins to move in both directions, between the nucleus and the cytoplasm. [/solution]...
Read More →Find the area of a rhombus if its vertices are
[question] Question. Find the area of a rhombus if its vertices are (3, 0), (4, 5), (–1, 4) and (–2, – 1) taken in order. [/question] [solution] Solution: Diagonals AC and BD bisect each other at right angle to each other at O. $A C=\sqrt{(-1-3)^{2}+(4-0)^{2}}$ $=\sqrt{16+16}=\sqrt{32}=4 \sqrt{2}$ $B D=\sqrt{(4+2)^{2}+(5+1)^{2}}=\sqrt{36+36}=6 \sqrt{2}$ Then $\mathrm{OA}=\frac{1}{2} \mathrm{AC}=\frac{1}{2} \times 4 \sqrt{2}=2 \sqrt{2}$ $\mathrm{OB}=\frac{1}{2} \mathrm{BD}=\frac{1}{2} \times \mat...
Read More →In Milikan’s experiment,
[question] Question. In Milikan's experiment, static electric charge on the oil drops has been obtained by shining X-rays. If the static electric charge on the oil drop is $-1.282 \times 10^{-18} \mathrm{C}$, calculate the number of electrons present on it. [/question] [solution] Solution: Charge on the oil drop $=1.282 \times 10^{-18} \mathrm{C}$ Charge on one electron $=1.6022 \times 10^{-19} \mathrm{C}$ Number of electrons present on the oil drop $=\frac{1.282 \times 10^{-18} \mathrm{C}}{1.60...
Read More →Cell is the basic unit of life. Discuss in brief.
[question] Question. Cell is the basic unit of life. Discuss in brief. [/question] [solution] Solution: Cells are the basic units of life capable of doing all the required biochemical processes that a normal cell has to do in order to live. The basic needs for the survival of all living organisms are the same. All living organisms need to respire, digest food for obtaining energy, and get rid of metabolic wastes. Cells are capable of performing all the metabolic functions of the body. Hence, cel...
Read More →Find the coordinates of the points which divide the line segment joining
[question] Question. Find the coordinates of the points which divide the line segment joining A (– 2, 2) and B (2,8) into four equal parts. [/question] [solution] Solution: Here, the given points are A(–2, 2) and B(2, 8) Let $P_{1}, P_{2}$ and $P_{3}$ divide $A B$ in four equal parts. $\because \quad \mathrm{AP}_{1}=\mathrm{P}_{1} \mathrm{P}_{2}=\mathrm{P}_{2} \mathrm{P}_{3}=\mathrm{P}_{3} \mathrm{~B}$ Obviously, $\mathrm{P}_{2}$ is the mid-point of $\mathrm{AB}$ $\therefore \quad$ Coordinates o...
Read More →Multicellular organisms have division of labour. Explain.
[question] Question. Multicellular organisms have division of labour. Explain. [/question] [solution] Solution: Multicellular organisms are made up of millions and trillions of cells. All these cells perform specific functions. All the cells specialised for performing similar functions are grouped together as tissues in the body. Hence, a particular function is carried out by a group of cells at a definite place in the body. Similarly, different functions are carried out by different groups of c...
Read More →A certain particle carries $2.5 \times 10^{-16} \mathrm{C}$ of static electric charge.
[question] Question. A certain particle carries $2.5 \times 10^{-16} \mathrm{C}$ of static electric charge. Calculate the number of electrons present in it. [/question] [solution] Solution: Charge on one electron $=1.6022 \times 10^{-19} \mathrm{C}$ $\Rightarrow 1.6022 \times 10^{-19} \mathrm{C}$ charge is carried by 1 electron. $\therefore$ Number of electrons carrying a charge of $2.5 \times 10^{-16} \mathrm{C}$ $=\frac{1}{1.6022 \times 10^{-19} \mathrm{C}}\left(2.5 \times 10^{-16} \mathrm{C}\...
Read More →What are the characteristics of prokaryotic cells?
[question] Question. What are the characteristics of prokaryotic cells? [/question] [solution] Solution: Prokaryotic cell is a unicellular organism lacking membrane-bound organelles. The characteristics of prokaryotic cells are as follows: (i) Most of them are unicellular. (ii) They are generally small in size. The size of a prokaryotic cell varies from 0.5 – 5 µm. (iii) The nuclear region of a prokaryotic cell is poorly-defined because of the absence of a nuclear membrane. Hence, a prokaryotic ...
Read More →The diameter of zinc atom is $2.6 \mathrm{~A}$. Calculate
[question] Question. The diameter of zinc atom is $2.6 \mathrm{~A}$. Calculate (a) radius of zinc atom in $\mathrm{pm}$ and (b) number of atoms present in a length of $1.6 \mathrm{~cm}$ if the zinc atoms are arranged side by side lengthwise. [/question] [solution] Solution: (a) Radius of zinc atom $=\frac{\text { Diameter }}{2}$ $=\frac{2.6 \mathrm{~A}}{2}$ $=1.3 \times 10^{-10} \mathrm{~m}$ $=130 \times 10^{-12} \mathrm{~m}=130 \mathrm{pm}$ (b) Length of the arrangement $=1.6 \mathrm{~cm}$ $=1....
Read More →If A and B are (– 2, – 2) and (2, – 4),
[question] Question. If $\mathrm{A}$ and $\mathrm{B}$ are $(-2,-2)$ and $(2,-4)$, respectively, find the coordinates of $\mathrm{P}$ such that $\mathrm{AP}=$ $\frac{\mathbf{3}}{\mathbf{7}} \mathrm{AB}$ and $\mathrm{P}$ lies on the line segment $\mathrm{AB}$. [/question] [solution] Solution: $\mathrm{AP}=\frac{3}{7} \mathrm{AB}$ $\mathrm{BP}=\mathrm{AB}-\mathrm{AP}=\mathrm{AB}-\frac{\mathbf{3}}{7} \mathrm{AB}=\frac{4}{7} \mathrm{AB}$ $\frac{A P}{B P}=\frac{\frac{3}{7} A B}{\frac{4}{7} A B}=\frac{...
Read More →Find the coordinates of a point A,
[question] Question. Find the coordinates of a point A, where AB is the diameter of a circle whose centre is (2, –3) and B is (1, 4). [/question] [solution] Solution: Here, centre of the circle is O(2, –3) Let the end points of the diameter be A(x, y) and B(1, 4) The centre of a circle bisects the diameter. $\therefore \quad 2=\frac{\mathbf{x}+\mathbf{1}}{\mathbf{2}} \Rightarrow \mathbf{x}+1=4$ or $\mathbf{x}=3$ And $-3=\frac{\mathbf{y}+\mathbf{4}}{\mathbf{2}} \Rightarrow \mathrm{y}+4=-6$ or $\m...
Read More →$2 \times 10^{8}$ atoms of carbon are arranged side by side.
[question] Question. $2 \times 10^{8}$ atoms of carbon are arranged side by side. Calculate the radius of carbon atom if the length of this arrangement is $2.4 \mathrm{~cm}$. [/question] [solution] Solution: Length of the given arrangement = 2.4 cm Number of carbon atoms present $=2 \times 10^{8}$ Diameter of carbon atom $=\frac{2.4 \times 10^{-2} \mathrm{~m}}{2 \times 10^{8}}$ $=1.2 \times 10^{-10} \mathrm{~m}$ $\therefore$ Radius of carbon atom $=\frac{\text { Diameter }}{2}$ $=\frac{1.2 \time...
Read More →If (1, 2), (4, y), (x, 6) and (3, 5) are the vertices of a parallelogram taken in order,
[question] Question. If (1, 2), (4, y), (x, 6) and (3, 5) are the vertices of a parallelogram taken in order, find x and y. [/question] [solution] Solution: Mid-point of the diagonal AC has x-coordinate $=\frac{\mathbf{x}+\mathbf{1}}{\mathbf{2}}$ and $y$-coordinate $=\frac{\mathbf{6}+\mathbf{2}}{\mathbf{2}}=4$ i.e., $\left(\frac{\mathbf{x}+\mathbf{1}}{\mathbf{2}}, \mathbf{4}\right)$ is the mid-point of $\mathrm{AC}$. Similarly, mid-point of the diagonal BD is $\left(\frac{\mathbf{4}+\mathbf{3}}{...
Read More →A body of mass 2 kg initially at rest moves under the action
[question] Question. A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7 N on a table with coefficient of kinetic friction = 0.1. Compute the (a) work done by the applied force in 10 s, (b) work done by friction in 10 s, (c) work done by the net force on the body in 10 s, (d) change in kinetic energy of the body in 10 s, and interpret your results. [/question] [solution] solution: Mass of the body, m = 2 kg Applied force, F = 7 N Coefficient of kineti...
Read More →Name two cell-organelles that are double membrane bound.
[question] Question. Name two cell-organelles that are double membrane bound. What are the characteristics of these two organelles? State their functions and draw labelled diagrams of both. [/question] [solution] Solution: Mitochondria and chloroplasts are the two organelles that are double-membrane-bound. Characteristics of the mitochondria Mitochondria are double- membrane-bound structures. The membrane of a mitochondrion is divided into the inner and outer membranes, distinctly divided into t...
Read More →If the diameter of a carbon atom is 0.15 nm,
[question] Question. If the diameter of a carbon atom is 0.15 nm, calculate the number of carbon atoms which can be placed side by side in a straight line across length of scale of length 20 cm long. [/question] [solution] Solution: $1 \mathrm{~m}=100 \mathrm{~cm}$ $1 \mathrm{~cm}=10^{-2} \mathrm{~m}$ Length of the scale $=20 \mathrm{~cm}$ $=20 \times 10^{-2} \mathrm{~m}$ Diameter of a carbon atom $=0.15 \mathrm{~nm}$ $=0.15 \times 10^{-9} \mathrm{~m}$ One carbon atom occupies $0.15 \times 10^{-...
Read More →Find the ratio in which the line segment joining
[question] Question. Find the ratio in which the line segment joining A(1, – 5) and B( – 4, 5) is divided by the x-axis. Also find the coordinates of the point of division. [/question] [solution] Solution: The given points are : A(1, – 5) and B(–4, 5). Let the required ratio = k : 1 and the required point be P(x, y) Part-I : To find the ratio Since, the point P lies on x-axis, $\therefore$ Its $y$-coordinate is 0 . $x=\frac{m_{1} x_{2}+m_{2} x_{1}}{m_{1}+m_{2}}$ and $0=\frac{m_{1} y_{2}+m_{2} y_...
Read More →Find the ratio in which the line segment joining the points
[question] Question. Find the ratio in which the line segment joining the points (– 3, 10) and (6, –8) is divided by (–1, 6). [/question] [solution] Solution: Let the required ratio be K : 1 [/solution]...
Read More →The sign of work done by a force on a body is important to understand.
[question] Question. The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative: (a) work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket. (b) work done by gravitational force in the above case, (c) work done by friction on a body sliding down an inclined plane, (d) work done by an applied force on a body moving on a rough horizontal plane with uniform velocity, (e) work done by...
Read More →Calculate the energy required for the process
[question] Question. Calculate the energy required for the process $\mathrm{He}_{(\mathrm{g})}^{+} \rightarrow \mathrm{He}^{2+}{ }_{(\mathrm{g})}+\mathrm{e}^{-}$ The ionization energy for the $\mathrm{H}$ atom in the ground state is $2.18 \times 10^{-18} \mathrm{~J}$ atom $^{-1}$ [/question] [solution] Solution: Energy associated with hydrogen-like species is given by, $E_{n}=-2.18 \times 10^{-18}\left(\frac{Z^{2}}{n^{2}}\right) \mathrm{J}$ For ground state of hydrogen atom, $\Delta E=E_{\infty}...
Read More →How do neutral solutes move across the plasma membrane?
[question] Question. How do neutral solutes move across the plasma membrane? Can the polar molecules also move across it in the same way? If not, then how are these transported across the membrane? [/question] [solution] Solution: Plasma membrane is the outermost covering of the cell that separates it from the environment. It regulates the movement of substances into the cell and out from it. It allows the entry of only some substances and prevents the movement of other materials. Hence, the mem...
Read More →What is a mesosome in a prokaryotic cell?
[question] Question. What is a mesosome in a prokaryotic cell? Mention the functions that it performs. [/question] [solution] Solution: Mesosome is a convoluted membranous structure formed in a prokaryotic cell by the invagination of the plasma membrane. Its functions are as follows: (1) These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughter cells. (2) It also increases the surface area of the plasma ...
Read More →What transition in the hydrogen spectrum would have
[question] Question. What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition $n=4$ to $n=2$ of $\mathrm{He}^{+}$spectrum? [/question] [solution] Solution: For $\mathrm{He}^{+}$ion, the wave number $(\bar{v})$ associated with the Balmer transition, $n=4$ to $n$ $=2$ is given by: $\bar{v}=\frac{1}{\lambda}=R Z^{2}\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)$ Where, $n_{1}=2$ $n_{2}=4$ $Z=$ atomic number of helium $\bar{v}=\frac{1}{\lambda}=R(2)^{2}\...
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