Que-Ans (Each of 3 Mark )

Question 13 Marks

Describe the types of connective tissues along with their functions.

Answer

There are five types of connective tissues:-
(i) Areolar connective tissue: It is a loose and cellular connective tissue. It joins skin to muscles, fills spaces inside organs, and is found around muscles, blood vessels, nerve and in the bone marrow.
Functions:
(a) It acts as a supporting and packing tissue between organs lying in the body cavity.
(b) It helps in repair of tissues after an injury.
(c) It also helps in combating foreign toxins.
(d) It fixes skin to underlying muscles.
(ii) Dense regular connective tissue: It is a fibrous connective tissue. It is characterised by ordered and densely packed collection of fibres and cells. Dense regular connective tissue is the principal component of tendons and ligaments.
Functions:
(a) Tendons: Tendons are cord-like, strong, inelastic structures that join skeletal muscles to bones.
(b) Ligament: They are an elastic structure which connects bones to bones.
(iii) Adipose tissue: Adipose tissue is an aggregation of fat globules. The cells that primarily compose adipose tissue are called adipocytes or lipocytes or fat cells. The adipose tissue is abundant below the skin, hetween the internal organs and in the yellow bone marrow.
Functions:
(a) It serves as a reservoir of fat.
(b) It provides shape to the limbs and the body.
(c) It keeps visceral organs in position. It forms shock-absorbing cushions around kidneys and eyeballs.
(d) It acts as an insulator and reduces heat loss from body, i.e. it regulates body temperature.
(iv) Skeletal tissue: The skeletal or supporting tissue includes bone and cartilage which form the endoskeleton of vertebrate body.
(a) Cartilage: The cartilage is a specialised connective tissue which is compact and less vascular. Cartilage can be found in ear, nose tip, epiglottis, inter-vertebral discs, end of long bones, lower ends of ribs and rings of trachea. There are three varieties of cartilage - hyaline, elastic, and fibro-cartilage. The most abundant type is hyaline, found as supportive tissues in the nose, ears, trachea, larynx, and smaller respiratory tubes.
(b) Bone: Bone is very strong and non-flexible tissue. Bone cells are embedded in a hard matrix. Like cartilage, bone is a specialised connective tissue.
Functions:
(a) Cartilage provides support and flexibility to body parts such as ears and nose. It smoothens bone surfaces at the joints.
(b) Bone provides shape and skeletal support to body.
(c) Bone supports and protects vital body organs such as brain, lungs, etc.
(d) Bone anchors the muscles.
(v) Fluid connective tissue: Fluid connective tissue links the different parts of the body and maintains continuity in the body. It includes blood and lymph.
(a) Blood: In this tissue, cells move in a fluid or liquid matrix or medium called plasma. Blood flows in blood vessels called arteries, veins, and capillaries which are connected together to form the circulatory system. Blood contains red blood cells (RBCs), white blood cells (WBCs) and platelets suspended in the plasma.
(b) Lymph: Lymph is a colourless fluid that has filtered out of the blood capillaries.
Functions:
(a) Blood flows and transports gases, nutrients, hormones and vitamins to the tissues, and transports waste products from the tissues to the liver and the kidney.
(b) Lymph transports the nutrients (oxygen, glucose) that may have filtered out of the blood capillaries back into the heart to be recirculated in the body.
(c) Lymph brings $CO _2$ and nitrogenous wastes from tissues to the blood.

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Question 23 Marks

What is the role of ribosmes and golgi body?

Answer

Ribosomes synthesize proteins. Golgi body helps in storage, packaging and dispatch of various substance inside and outside the cell.

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Question 33 Marks

What are the differences between cell wall and cell membrane?

Answer

S.No	Cell Wall	Cell Membrane
1	Cell wall is found in plant cell	Cell membrane is found in animal cells
2	Cell wall is completely permeable	Cell membrane is semi-permeable.
3	The function of the cell membrane is the same as that of the skin.	The function of the cell wall is to provide strength and rigidity to the cell.
4	It is non - living	It is living
5	It is made up of cellulose	It is made up of lipids and proteins

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Question 43 Marks

The velocity$-$time graph of a ball moving on the surface of a floor is shown in the figure. Find the force acting on the ball if the mass of the ball is $50 g$

Answer

The velocity$-$time graph shows that velocity of the ball at $t=0$ is $30\ ms^{-1}$
Initial velocity of the ball, $u =30\ ms^{-1}$
The velocity of the ball at $t=6 s$ is zero.
Final velocity of the ball, $v=0$
Time, $t =6 s$
$\therefore$ Acceleration of the ball,
$a=\frac{v-u}{t}=\frac{0-30\ ms^{-1}}{6 s}$
$=-5\ ms^{-2}$
Negative sign shows that the ball is retarded or decelerated.
Also, mass of ball, $M=50 g$
$=\frac{50}{1000}=\frac{1}{20} \ kg$
Therefore, Force acting on the ball, $F = ma$
$=\left(\frac{1}{20} \ kg\right)\left(-5\ ms^{-2}\right)$
$=-0.25 \ kg\ ms^{-2}$
$=0.25 N\left[1 \ kg\ ms^{-2}=1 N\right]$
Here -ve sign indicates that the force is retarding or stopping force.

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Question 53 Marks

i. The potential energy of a freely falling object decreases progressively. What happens to its
a. Kinetic energy,
b. total mechanical energy?
State the law on which your answer is based.
ii. A household consumes 1 kWh of energy per day. How much energy is this in joules?

Answer

i. a. As potential energy decreases with decreasing height, the speed of the object will increase and hence its kinetic energy will increase.
b. Total mechanical energy will remain constant.
It is based on the law of conservation of energy which states that energy can neither be created nor be destroyed/ It can only be transformed from one form to another.
ii. $1 kWh =3.6 \times 10^6 J$

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Question 63 Marks

Two trains A and B of length 400 m each are moving on two parallel tracks with uniform speed of $72 kmh ^{-1}$ in the same direction with $A$ ahead of $B$. The driver of $B$ decides to overtake $A$ and accelerates by $1 ms^{-2}$. If after 50 s , the guard of B just passes the driver of A , what was the original distance between them?

Answer

Initial speed of each train $u=72 kmh ^{-1}=20 ms^{-1}$
Distance travelled by train $A$ in $50 s=20 \times 50=1000 m$
Distance travelled by train B in 50 s with an acceleration of $1 ms^{-2}$ is $20 \times 50+\frac{1}{2}(1) \times(50)^2=2250 m$ using $S = ut +\frac{1}{2} at ^2$
Therefore the original distance between the trains is $2250-1000=1250 m$

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Question 73 Marks

A train is travelling at a speed of $90 \ kmh ^{-1}$. Brakes are applied so as to produce a uniform retardation of $0.5\ ms^{-}{ }^2$. Find how far the train will go before it is brought to rest.

Answer

Here, initial velocity, $u =90 \ kmh ^{-1}$
$=\frac{90 \ km}{1 / h}$
$=\frac{90 \times 1000 m}{60 \times 60 s}$
$=25 \ ms^{-1}$
Acceleration, $a =-0.5 \ ms^{-2}$
Final velocity $v =0$
From the equation of motion, $2as =v^2-u^2$
$s=\frac{v^2-u^2}{2 a}$
$=\frac{0-\left(25 m s^{-1}\right)^2}{2 \times\left(-0.5 \ ms^{-2}\right)}$
$=\frac{-625 m^2 s^{-2}}{-1.0 \ ms^{-2}}$
$=625 m$
The train will go $625 m$ further, after applying the brakes.

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Question 83 Marks

On the basis of the number of protons, neutrons and electrons in the samples given below identify
i. the cation.
ii. the pair of isobars, and
iii. the pair of isotopes.

Sample	Protons	Neutrons	Electrons
A	17	18	16
B	18	19	18
C	17	20	17
D	17	17	17

Answer

i. Sample A has more protons than electrons. Hence, it is a cation.
ii. Sample B and C have same mass number (Mass number $=$ Number of protons + number of neutrons $=37$ ) but different atomic numbers (i.e. 18 and 17 respectively). Hence, they are a pair of isobars.
iii. Samples C and D have same atomic number but different mass numbers. Hence, they are a pair of isotopes.

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Question 93 Marks

Represent graphically by two separate diagrams in each case
i. Two sound waves having the same amplitude but different frequencies?
ii. Two sound waves having the same frequency but different amplitudes
iii. Two sound waves having different amplitudes and also different wavelengths.

Answer

ii.

iii.

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Science Que-Ans (Each of 3 Mark )

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