• Food web is a network of food chains where all the chains are naturally interconnected.
• Each organism is generally eaten by two or more kinds or organisms which are again eaten by several other organisms and so instead of straight line food chain, the series of organisms dependent on one another food can be shown by branched lines which is called as a food web.
• Flow of energy in a food chain is unidirectional, once it reaches the next tropic level it does not come back again.
• For example- energy which passes to the herbivores does not come back again to autotrophs.

Non-biodegradable substances do not break down or dissolve for many years. Because of that, they can be recycled and reused. So, instead of throwing wastes in the garbage, it can be dumped in a proper recycling place making it useful for other purposes.

Apparent flattening of the sun’s disc at sunrise and sunset is due to atmospheric refraction. The density and the refractive index of the atmosphere decreases with altitude, so the rays above and below the sun on the horizon are refracted by different degrees. This causes the apparent flattening of the sun. But the rays from the sides of the sun on a horizontal plane are generally refracted by the same amount, hence the sun still appears circular along its sides.

The rays of light from the bottom of the sun are refracting more than those from the top, flattening the sun's circular shape. “Flattened sun” can also refer to the Sun appearing in an oval shape close to the horizon during sunrise or sunset. The lower half of the sun appears darker in colour than the top half. At sunrise and sunset, the sun is near the horizon. The rays of light from the upper part and lower part of the periphery of the sun bend unequally on travelling through earth's atmosphere. That is why the sun appears oval or flattened at the time of sunrise and sunset.

Sustainable development is the organizing principle for meeting human development goals while simultaneously sustaining the ability of natural systems to provide the natural resources and ecosystem services on which the economy and society depend.

(i) Democracy is a rule of the majority means that rule by majority views.

(ii) Rule by majority does not mean rule by majority in terms of religion, race, linguistic groups, poors or rich.

(iii) It means that in case of every decision or in case of every election, different persons and groups may and can form majority.

• So, to say that democracy must be a rule of the poor will give rise to a further division of society on a different line and lead to conflict.

• Democracy remains democracy only as long as every citizen has a chance of being in majority at some point of time

(i)   Democracy is a rule of the majority means that rule by majority views.

(ii)  Rule by majority does not mean rule by majority in terms of religion, race, linguistic groups, poors or rich.

(iii) It means that in case of every decision or in case of every election, different  persons and groups may and can form majority.

•  So, to say that democracy must be a rule of the poor will give rise to a further division of society on a different line and lead to conflict.

• Democracy remains democracy only as long as every citizen has a chance of being in majority at some point of time. 

Vegetative propagation is practiced for growing some types of plants because of the following advantages: It helps to introduce plants in new areas where seed germination fails to produce mature plants due to changes in environmental factors and the soil. It is a more rapid, easier, and cheaper method. 

Vegetative propagation methods include: • rooting of cuttings, • layering or marcotting, • grafting, • micropropagation. Propagation is the natural mechanism by which plants regenerate. Propagation by seeds is the main method by which plants reproduce in nature.

Reproduction through spores gives several advantages to an organism. ... Spores can remain dormant till favourable conditions become available. Spores help an organism to tide over the bad phase. Spores can be spread through water, air, or animals and thus is good for the spread of an organism to more places.

Reproduction through spores gives several advantages to an organism. Some of them are as follows:
a. Spores can remain dormant till favourable conditions become available.
b. Spores help an organism to tide over the bad phase.
c. Spores can be spread through water, air or animals and thus is good for the spread of an organism to more places.

Variation beneficial to the species
Even so, for factors beyond the control of the species, such locations will alter, and can even destroy the entire species. If any differences in all of these species were to be found in a few individuals, they would have a chance of surviving.

Variations can be beneficial or harmful according to the ecological niche of the organism.
A variation suitable for the particular niche is selected by nature in evolution. Thus variations are necessary for the survival of the species.
Variation is important for the evolution of the species.
Example
A population of heat resistant bacteria in the temperature of the water survives if the temperature of water increases by global warming but most other bacteria would die.

DNA determines the body design of an individual. The DNA that gets transferred from parents to offsprings makes them look similar. DNA copying is important for reproduction. Additional copies of DNA are made during replication which is necessary for the new cells formed after cell division. Moreover, some minor alterations during DNA replication are responsible for bringing variations in the long run.

YES I COMPLETELY ABREE ON THIS POINT.

Annea was only 12 years ols and she was too young to understand what was going around her.`The Diary of Anne Frank’ and the given extract is one of the most authentic works describing the atrocities committed on the Jews during the Nazi’s occupation of the Netherlands in the 1940s. It also provides an intimate account of daily life that her small groups led in hiding in Amsterdam. Her frankness, honesty and sincerity of description of her parents, friends and teachers make her writing the most important document of the Holocaust period.

Carbon form large number of compounds due to the following properties:

         (a) Catenation → Carbon shows the property of catenation that is the ability to form bonds with other carbon atoms forming long chains both branched and unbranched chains, and even rings.

         (b) Tetravalency → Carbon has valency 4, it is capable of bonding with 4 other carbon atoms or atoms of other non-covalent elements, giving rise to compounds with specific properties depending on the elements present in the compound.

         (c) Isomerism → Carbon compounds show the property of isomerism that is compounds having same molecular formula but different structural formula.

Width of the track = 10 m

Distance between two parallel lines = 60 m

Length of parallel tracks = 106 m

DE = CF = 60 m

Radius of inner semicircle, r = OD = O’C

= 60/2 m = 30 m

Radius of outer semicircle, R = OA = O’B

= 30+10 m = 40 m

Also, AB = CD = EF = GH = 106 m

Distance around the track along its inner edge = CD+EF+2×(Circumference of inner semicircle)

= 106+106+(2×πr) m = 212+(2×22/7×30) m

= 212+1320/7 m = 2804/7 m

Area of the track = Area of ABCD + Area EFGH + 2 × (area of outer semicircle) – 2 × (area of inner semicircle)

= (AB×CD)+(EF×GH)+2×(πr²/2) -2×(πR²/2) m²

= (106×10)+(106×10)+2×π/2(r²-R²) m²

= 2120+22/7×70×10 m²

= 4320 m²

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In this lesson, Griffin is showcased as a selfish scientist who first leaves his mentor to be able to get credit for something he and his mentor had been planning together. He then steals his father's money to be able to finance himself. His father commits suicide because of this. He then creates his invention if invisibility formula and becomes invisible. Next he sets fire to a building in which his neighbor's cat was annoying him. This man used a scientific invention for his own satisfaction. He scared off people and stole things like clothes and bandages to cover himself. He comes across a school friend and asks to do bad deeds. To destroy the city and bring down a reign on nuisance on the people. However, Griffin's friend reports him and he gets beaten to death by navvies.

This all showcases how his invention brought down problems for other people but in the end he died due to his bad deeds.

Science is power. Scientific discoveries are assets. If they come in contact with wrong people they can cause much damage.

Valli (Valiyammai) is a very intelligent, sensitive, clever, self-respecting, fast-forward and courageous girl. She is only eight years old but looks more mature than her age. She has curiosity about things. Due to this curiosity, she starts traveling alone by bus.

She has a passion to fulfill her desire, so she saves money by reducing her daily expenses to raise the bus fare. It was not an easy task for an eight-year-old girl to control his small desires of eat and drink.

She is also self-respecting and hence pays the full fare of the bus and refuses to get help from the bus conductor. She is fast-forward and clever, so she also argues with the conductor of the bus.

She also has sensations and gets depressed upon seeing the dead calf and forgets her happiness and becomes calm.

She has courage so that only eight year old girl left the house for travelling alone without telling her mother.

Thus we can say that Valli (Valiyammai) is an intelligent, sensitive, clever, self-respecting, fast-forward and courageous girl.

It is because resources are in limited amount in the world and we should be aware of reducing the wastage of resources. For example the prices of petrol and diesel are increasing, prices of gold and silver are increasing, advertisement are made for reducing wastage of electricity.