(i) The dorsal and ventral surfaces of a dicot leaf can be clearly distinguished
(ii) The dorsal surface is darker is appearance and the ventral surface is lighter.
(iii) This is due to distribution of palisade parenchyma below the upper epidermis which as rich in chloroplasts.
(iv) Hence the dicot left is described as dorsiventral.

There are companies who are doing e-waste management an a commercial scale. Therefore organizations which generate a lot of e-waste must not throw the same in garbage bins but channelise the e-waste through the organizations meant for the same.

(i) Obesity is the state in which there is an accumulation of excess body fat with an abnormal increase in body weight.
(ii) Obesity occurs if intake of calories is more than the expenditure of energy.
(iii) Overweight and obesity are conditions where the body weight is greater than the mean standard weight for age and height of an individual.
(iv) Body Mass Index (BMI) is an estimate of body fat and health risk. BMI = Weight (kg) / Height (m)²
Causes and risk factors :
(i) Obesity is due to genetic factors, physical inactivity, eating habits (overeating) and endocrine factors.
(ii) Obesity is a positive risk factor in development of hypertension, diabetes, gall bladder disease, coronary heart disease, and arthritis.
Prevention and Control of Obesity :
(i) Diet Management: Low calorie, normal protein, vitamins and mineral, restricted carbohydrate and fat, high fiber diet can prevent overweight.
(ii) Physical exercise: A low calorie diet accompanied by moderate exercise will be effective in causing weight loss. Meditation, yoga and physical activity can also reduce stress related to overeating.

He can adopt clonal selection since banana reproduces asexually from the underground stem.

(i) Pictures and Audio-Visuals give us more understanding than teaching and writing on black board. So, any visual representation of the concepts would help us to understand better and make teaching simple
(ii) Yes. Visual Communication helps us to easily conceptualize complicated theorems and concepts. When the teacher shows pictures / videos that represent the concept, we would easily relate to its application and firmly understand the concept without any mis-perception
(iii) Pictures, Audio-Visuals, animations provide additional information and helps us to easily correlate the concepts. We could easily remember the visuals than black board writing, and visualize it, so that we do not forget and we could easily recollect at the time of examination.

Organic compounds are classified into two types as follows:
(i) Acyclic or Open chain compounds:
These are the compounds in which the carbon atoms are linked in a linear pattern to form the chain. If all the carbon atoms in the chain are connected by single bonds, then the compound is called as saturated. If one or more double bonds or triple bonds exist between the carbon atoms, then the compound is said to unsaturated.

(ii) Cyclic Compounds:
Organic compounds in which the chain of carbon atoms is closed or cyclic are called Cyclic compounds. If the chain contains only carbon atoms, such compounds are called carbocyclic compounds. If the chain contains carbon and other atoms like oxygen, nitrogen, sulphur, etc., these compounds are called heterocyclic compounds. Carbocyclic compounds are further subdivided into alicyclic and aromatic compounds. In alicyclic compounds, the carbon cycle contains only single bonds whereas aromatic compounds contain one or more benzene rings (ring containing alternate double bonds between carbon atoms).
E.g:

The endocrine portion of pancreas is made up of Islets of Langerhans.
Structure of Pancreas:
The Islets of Langerhans consists of two types of cells namely alpha cells and beta cells. The alpha cells secrete glucagon and beta cells secrete insulin.
Functions of Pancreatic hormones:
A balance between insulin and glucagon production is necessary to maintain blood glucose concentration.
Insulin :
(i) Insulin helps in the conversion of glucose into glycogen which is stored in liver and skeletal muscles.
(ii) It promotes the transport of glucose into the cells.
(iii) It decreases the concentration of glucose in blood.
Glucagon:
(i) Glucagon helps in the breakdown of glycogen to glucose in the liver.
(ii) It increases blood glucose levels.
Diabetes mellitus :
The deficiency of insulin causes Diabetes mellitus. It is characterised by
(i) Increase in blood sugar level (Hyperglycemia)
(ii) Excretion of excess glucose in the urine (Glycosuria).
(iii) Frequent urination (Polyuria).
(iv) Increased thirst (Polydipsia).
(v) Increase in appetite (Polyphagia).

Use and disuse theory
(i) Lamarck's Use and Disuse theory states that if an organ is used constantly, the organ develops well and gets strengthened.
(ii) When an organ is not used for a long time, it gradually degenerates.
(iii) The ancestors of Giraffe were provided with short neck and short forelimbs.
(iv) Due to shortage of grass, they were forced to feed on leaves from trees. The continuous stretching of their neck and forelimbs resulted in the development of long neck and long forelimbs which is an example for constant use of an organ.
(v) The degenerated wing of Kiwi is an example for organ of disuse.

Reversible Reactions: A reversible reaction is a reaction that can be reversed, i.e., the products can be converted back to the reactants. A reversible reaction is represented by a double arrow with their heads in the direction opposite to each other. Thus, a reversible reaction can be kept

Explanation: The compound 'AB' undergoes decomposition to form the products 'A' and 'B'. It is the forward reaction. As soon as the products are formed, they combine together to form 'AB': It is the backward reaction
PCl₅(g) ⇌ PCl₃(g) + CI₂(g)
Irreversible Reactions: The reaction that cannot be reversed is called irreversible reaction. Consider the combustion of coal into carbon dioxide and water.
C_(s) + O_2(g) ⟶ CO_2(g)+ Heat
Coal oxygen Carbon dioxide
In this reaction, solid coal burns with oxygen and gets converted into carbon dioxide gas and water. As the product is a gas, as soon as it is formed it escapes out of the reaction container. It is hard to decompose a gas into a solid. Thus, the backward reaction is not possible in this case. So, it is an irreversible reaction

(i) If there is an increase in the area of a solid object due to heating, then the expansion is called superficial or areal expansion.
(ii) Superficial expansion is determined in terms of coefficient of superficial expansion. The ratio of increase in area of the body, per degree rise in temperature to its unit area is called coefficient of superficial expansion. Coefficient of superficial expansion is different for different materials. Its SI unit is also per Kelvin.
(iii) The equation relating to the change in area to the change in temperature is given below:

\(\frac { \triangle A }{ { A }_{ 0 } } \) =α_A ΔT
ΔA  - Change in area
A₀ - Original area
ΔT - Change in area
α_A - Coefficient of superficial expansion

(i) To analyse that the planets are irregular shaped objects, Doppler effect is applied.
(ii) Using Doppler effect, an electromagnetic wave or a high frequency sound wave can be made to incident on different points of planet's surface. By finding the frequency shifts of the reflected waves from different points on planets surface, one can analyse that the planet is made of hills and valleys. From this analysis, we can come to a conclusion the planets are irregularly shaped objects.
(iii) Jagadish Chandra Bose, a famous Indian scientist and Biologist, discovered that plants can feel sadness, happiness, pain etc., for that, he invented device named crescograph. The feelings of sadness, happiness, pain etc.. have different frequencies. When we touch a plant with a lovable thought, the frequency of that thought can be sensed by plants and trees.

Bessemerisation The molten matte is transferred to Bessemer converter in order to obtain blister copper. Ferrous sulphide from matte is oxidized to ferrous oxide, which is removed as slag using silica.
2FeS+3O₂ ⟶ 2FeO+2SO₂ ↑

2 Cu₂S + 3O₂ ⟶ 2 Cu₂O + 2 SO₂

(i) Acquired traits are the characters that cannot be passed from one generation to the next generation.
(ii) Characters which are inherited by the offspring from the parents and carried from one generation to another generation are called Inherited traits.

(i) Kalaivani's mother took a small PVC pipe which has water in it and held in a horizontal position. Water came out drop by drop. When she raised one of the ends of the pipe, the water through the other end came out with a greater speed. She said initially when I was holding the pipe in a horizontal position, pressure at the both the ends are same. So water did not come out. The difference in pressure (Pressure difference) between the two ends is zero. But when I raised one of the ends, the top end has high pressure, and the bottom end has low pressure. Due to this pressure difference, water came out with a faster rate. So compare a conductor or a wire to this PVC pipe The wire is connected to a battery, whose one end has higher potential and the other end has lower potential. Due to this difference in potential, electrons from negative terminal (lower potential end) flow towards the positive terminal (higher potential end). Here electron flow is compared with the water flow and the electric potential is compared with the pressure. Kalaivani felt very happy, after hearing her mother's genius explanation.
(ii) When Kalaivani asked how to understand about the concept of resistance from her mother's scientific explanations, her mother continued. If the water pipe is smooth inside, then there is no charge in the speed of flow of water. i.e., zero resistance. But when the pipe has some blocks inside at different points, the water changes its speed of flow at different points, likewise, whenever electrons flow inside the conductor, they may collide with each other, due to which their speed will be resisted (blocked), which forms as electrical resistance. Her explanation made Kalaivani satisfied.
(iii) When two resistors of resistances, R₁ & R₂ are connected in series to a battery source.
\({ R }_{ s }={ R }_{ 1 }+{ R }_{ 2 }\)
When R₁ & R₂ are connected in parallel,
\(\frac { 1 }{ { R }_{ p } } +\frac { 1 }{ { R }_{ 1 } } +\frac { 1 }{ { R }_{ 2 } } \Rightarrow \frac { 1 }{ { R }_{ p } } =\frac { { R }_{ 2 }+{ R }_{ 1 } }{ { R }_{ 1 }{ R }_{ 2 } } \)
\({ R }_{ p }=\frac { { R }_{ 1 }{ R }_{ 2 } }{ { R }_{ 1 }+{ R }_{ 2 } } \)

A small family is a happy family. If there are one or two children in a family, the parents can afford to give them good education, food, personal care and other facilities required for them to grow into healthy and happy individuals. Thus it is important for parents to plan a small family which will also build a healthy nation.

(i) When birds fly they push the air downwards by their wings (Action).
(ii) The air pushes the bird upwards (Reaction).
(iii) When a person swims he pushes the water using hands backwards (Action), the water pushes the swimmer in forward direction (Reaction).
(iv) Rockets expel gas at high velocity (Action). The downward moving gas pushes the rocket in upward direction (Reaction).
(v) When we fire a bullet, the gun recoils back, Bullet is moving forward (action). The gun equalise this forward action by moving backward (reaction).

Applications of Avogadro's hypothesis
(i) It explains Gay-Lussac's law.
(ii) It helps in the determination of atomicity of gases.
(iii) Molecular formula of gases can be derived using Avogadro's law.
(iv) It determines the relation between molecular mass and vapour density.
(v) It helps to determine Gram molar volume of all gases (i.e. 22.4 lit at S.T.P)

(i) The heart is pear shaped and lies in the thoracic cavity in between the lungs. It is enclosed by pericardium, a double layered membrane.

(ii) The heart is four chambered with two auricles and two ventricles. The right and left auricles are separated by interauricular septum, similarly right and left ventricles are separated by interventricular septum.
(iii) The right auricle opens into the right ventricle by right auriculoventricular aperture, guarded by a tricuspid valve.
(iv) The left auricle opens into the left ventricle by left auriculoventricular aperture guarded by a bicuspid valve or mitral valve.
(v) The opening of the pulmonary artery and aorta are guarded by three semilunar valves.
(vi) The right auricle receives deoxygenated blood through two precaval (superior vena cava) and one postcaval (inferior vena cava) veins from all parts of the body.
(vii) The left auricle receives oxygenated blood from the pulmonary veins from the lungs.
(viii) From the right ventricle arises pulmonary trunk which carries the deoxygenated blood to the lungs and from the left ventricle arises the systemic arch (aorta) which supplies oxygenated blood to all parts of the body.

(i) The main aim of wild life conservation is to preserve the plants and animals from extinction, prevent deforestation, maintain ecobalance, preserve the endangered species and also study the ecological relations of the plants and animals in natural habitat.
(ii) Plantation, cultivation, grazing, felling trees, hunting and poaching are prohibited here

Symptoms: Diabetes mellitus is associated with several metabolic alterations. The most important symptoms are.
(i) Increased blood glucose level (Hyperglycemia)
(ii) Increased urine output (Polyuria) leading to dehydration.
(iii) Loss of water leads to thirst (Polydipsia) resulting in increased fluid intake.
(iv) Excessive glucose excreted in urine (Glycosuria).
(v) Excess hunger (Polyphagia) due to loss of glucose in urine.
(vi) Fatigue and loss of weight.

Green Revolution is the process of increasing food production through high yielding crop varieties and modern agricultural techniques in underdeveloped and developing nations.

The device which helps in explaining the concepts easily through pictures is known as 'Visual Communication Device: For example photos, audio-visuals, drawings, animations all these can be created easily with the help of computer. Cinema is a good example for 'Visual Communication Device'.

(i) Ethylene promotes the ripening of fruits.
Eg : Tomato, Apple, Mango,Banana, etc.
(ii) Ethylene inhibits the elongation of stem and root in dicots.
(ii) Ethylene hastens the senescence of leaves and flowers.
(iv) Ethylene stimulates formation of abscission zone in leaves, flowers and fruits. This leads to premature shedding.
(v) Ethylene breaks the dormancy of buds, seeds and storage organs.

100% pure alcohol is called absolute alcohol.

(i) Astrobiology / Exobiology is the science which looks for the presence of extra terrestrial life in the Universe.
(ii) It deals with the origin, evolution and distribution of life in the Universe and to investigate the possibility of life in other world.
(iii) The major concept is the habitable zone. The theory explains that any planets can support the existence of life, if it fulfills two important criteria, that is :
(a) It must have a right mass to retain an atmosphere.
(b) It must have an orbit at just the right distance from its Star (Sun) that it allows liquid water to exist. Thus, the distance need to be neither too hot or not too cold and is often referred as Goldilock Zone for life.
(iv) In our solar system 'Earth' is the only planet in the Goldilock zone. Since, this zone varies at times as the star evolves, we know that Mars have also been habitable. The life on Mars are likely to be the creatures, we find in extreme environments on earth.

Liquefied Petroleum Gas is a mixture of hydrocarbon gases like propane, butane, propylene etc..

(i) The exposure is 100 R, it may cause fatal diseases like leukemia (death of red blood corpuscle in the blood) or cancer.
(ii) When the body is exposed to about 600 R, it leads to death.
(iii) The safe limit of receiving the radiations is about 100 mR per week.

(i) To see distant objects, the ciliary muscle relaxes and makes the eye lens thinner. This increases the focal length of eye lens.
(ii) Hence, the distant object can be clearly seen. When we look at a closer object, the focal length of the eye lens is decreased by the contraction of ciliary muscle.
(iii) Thus, the image of the closer object is clearly formed on the retina.

(i) It is a genetic condition in which there is an extra copy of chromosome 21 (Trisomy 21).
(ii) Mental retardation, delayed development, behavioural problems, weak muscle tone, vision and hearing disability are some of the conditions seen in these children.

Ions are formed when an atom loses or gains electrons.

(i) Neutrophils
(ii) Eosinophils
(iii) Basophils

(i) When several forces act simultaneously on the same object, then the combined effect of multiple forces can be represented by a single force, which is termed as resultant.
(ii) It is equal to vector sum up (adding the magnitude of forces with direction) of all the forces.

1 Bq = 2.703 x 10^-11 curie
∴ 4.3 x 10³ GBq = 4.3 x 103 x 10⁹ x 2.703 x10^-11
= 11.62 x 10¹
= 116.2 curie

Initial temperature, t₁ = 285 k
Final temperature, t₂ = 363 k
Initial length, I₁ = 6.522 m
Change in length, Δl = 0.576 m
To find: Coefficient of linear expansion α_L=?
α_L =\(\frac { \triangle l }{ l\triangle T } =\frac { ({ l }_{ 2 }-{ l }_{ 1 }) }{ { l }_{ 1 }(t_{ 2 }-{ t }_{ 1 }) } \)
=\(\frac { 6.576-6.522 }{ 6.5222(63-285) } \)
=\(\frac { 0.054 }{ 6.522(78) } =\frac { 0.054 }{ 508.7 } \)
α_L =1.06 x 10^-4 K^-1.

Velocity of light through air, ca = 3 x 10⁸ ms^-1
To find : Speed of light through kerosene,
c_k =?
Refractive index of kerosene, μ_k= 1.44
μ_k=\(\frac { { c }_{ a } }{ { c }_{ k } } \) ⇒ 1.44
μ_k= \(\frac { 3\times 10^{ 8 } }{ { c }_{ k } } \)
=2.083 x 10⁸ ms^-1
Speed of light through kerosene,
c_k = 2 083 x 10⁸ ms^-1

Given 
Frequency g car's distance, n = 800 Hz
Velocity of source, Vs = 120ms^-1
Velocity of sound, v = 340 ms^-1
To find: Frequency emitted by the car, n' = ?
Solution
Apparent frequency, n' =\(\left( \frac { v }{ v-{ v }_{ s } } \right) \times n\)
\(=\frac { 340 }{ 340-120 } \times 800\)
\(=\frac { 340 }{ 220 } \times 80\)
Apparent frequency, n' = 1236 Hz

Force, F = 50 N
Distance, d = 5 cm
To find: Momentum of force= F x d
Momentum of force, 50 x 5 x 10^-2
= 250 x 10^-2
= 2.5 Nm

Electrical energy,
E = 1.2 kwh = 1.2 x 10³ wh
Time, t =30 min\(\frac{1}{2}\) hour
To find: Current drawn by the heater, I = ?
Solution
Energy, E = Vlt \(\therefore I=\frac { E }{ Vt } \)
\(I=\frac { 1.2\times { 10 }^{ 3 }\times 2 }{ 120 } =20A\)
Current, I = 20A

Atomic masses of C= 12, O= 16
Gram molecular mass of CO₂ = 1(C) + 2(O) = 1(12) + 2(16) = 12 + 32 = 44
Gram molecular mass of CO₂ = 44g.

When we are pricked by a cactus, the sensory neurons are activated immediately. They take the message to the brain or spinal cord. The message given by the brain or spinal cord is brought back by the Motor neuron. The motor neuron carries the message to the hand muscles. We immediately pull our hand away from the cactus.

During driving temperature of the gas increases while its volume remains constant. So according to Charles's law at constant V, P α T. ∴ Pressure of gas increases.

The colloidal solution is an example in which solid acts are the dispersion medium while liquid as the dispersed phase. It is also called gel. Reason for the choice. On pressing butter, liquid drops come out of it leaving behind a solid. This clearly shows the butter is a gel.

When sound travels from one medium to other its wavelength and velocity may change, but frequency does not change. So frequency is fundamental property of waves.

Resistance of wire A, \({ R }_{ 1 }=\frac { \rho l }{ A } =\frac { \rho l }{ { \pi r }^{ 2 } } \)
Resistance of wire B, \({ R }_{ 2 }=\frac { \rho l' }{ A' } \)
\(=\frac { \rho \times 2l }{ \pi { (2r) }^{ 2 } } =\frac { \rho l }{ 2\pi { r }^{ 2 } } \)
Total resistance of the series combination, \(\frac { 1 }{ R } =\frac { 1 }{ { R }_{ 1 } } +\frac { 1 }{ { R }_{ 2 } } \)
or \(\frac { 1 }{ R } =\frac { \pi { r }^{ 2 } }{ \rho l } +\frac { 2\pi { r }^{ 2 } }{ \rho l } \)
\(=\frac { 3\pi { r }^{ 2 } }{ \rho l } \)
\(R=\frac { \rho l }{ 3\pi { r }^{ 2 } } \)
\(\therefore \frac { R }{ { R }_{ 1 } } =\frac { \rho l }{ 3\pi { r }^{ 2 } } \times \frac { \pi { r }^{ 2 } }{ \rho l } \)
\(=\frac { 1 }{ 3 } \)

The ovum (egg) lives for about 24 hours. It is not fertilized, it will start disintegrations to take. The uterine lining is also shed as menstrual flow.

Formula of magnesium sulphide = MgS
Ratio by mass of Mg and S = 3:4
Number of atoms in 3 g of Mg = \(\frac { { N }_{ A } }{ 24 } \times 3=\frac { { N }_{ 4 } }{ 8 } \)
Number of atoms in 4 g of S = \(\frac { { N }_{ A } }{ 32 } \times 4=\frac { { N }_{ 4 } }{ 8 } \)
ஃ Ratio of the number of Mg and S is \(\frac { { N }_{ A } }{ 8 } :\frac { { N }_{ 4 } }{ 8 } \) or 1:1