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The surface features of earth are called Topography.

Raunkiaer classified the world’s vegetation into the following four types. They are megatherms, mesotherms, microtherms and hekistotherms.

The steepness of the mountain or hill allows the rain to run off. As a result the loss of water causes water deficit and quick erosion of the top soil resulting in poor vegetation. On the other hand, the plains and valley are rich in vegetation due to the slow drain of surface water and better retention of water in the soil.

North and south faces of mountain or hill possess different types of flora and fauna because they differ in their humidity, rainfall, light intensity, light duration and temperature regions. The two faces of the mountain or hill receive different amount of solar radiation, wind action and rain. Of these two faces, the windward region possesses good vegetation due to heavy rains and die leeward region possesses poor vegetation due to rain shadows (rain deficit).

Ecotone is the transition zone between two ecosystems.

1. Latitude 

2. Altitude 

3. Direction of mountain and 

4. Steepness of mountain.

Edaphic factors are the abiotic factors related to soil, include the physical and chemical composition of the soil formed in a particular area.

(c) Pyronema

Pyronema confluens is a fungus which grow on the soil of burnt or fire disturbed areas. Hence it is called as indicator of fire.

(b) Anabaena

(a) Statement 1 is correct. Statement 2 is incorrect.

Thermal Stratification is usually found in aquatic habitat. The change in the temperature profile with increasing depth in a water body is called thermal stratification. There are three kinds of thermal stratifications.

1. Epilimnion – The upper layer of warmer water. 

2. Metalimnion – The middle layer with a zone of gradual decrease in temperature. 

3. Hypolimnion – The bottom layer of colder water

1. Fire has a direct lethal effect on plants.

2. It brings out the alteration of light, rainfall, nutrient cycle, fertility of soil, pH, soil flora and fauna

Light, Temperature, Water, Wind and Fire.

1. Temperature affects the enzymatic action of all the bio-chemical reactions in a plant body. 

2. Low temperature with high humidity can spread diseases to plants. 

3. The varying temperature with moisture determines the distribution of the vegetation types.

1. Presence of highly developed root system to absorb water. 

2. Stems and leaves are covered with waxing coating or dense hairs to avoid transpirational loss.

3. Modified leaves generally leathery and shiny to reflect light and heat.

Viviparity is the phenomenon, where the seeds germinate and then starts developing to some extent before they detach from the parent plant body. In plant, it is noticed in Halophytes like Rhizophora.

Submerged plants like Vallisneria receive dim illumination because majority of the light are reflected back by the water surface whereas, the floating hydrophytes receive and absorb maximum light as they are on the water surface.

A statement of equality between two quantities is called Equations.

1. Rice: Tamil Nadu is the India’s second biggest producer of rice. 

2. Banana and Coconut: Tamil Nadu ranks first in production of Banana and coconut. 

3. Cashewnut: Tamil Nadu ranks second in production of cashewnut. 

4. Pepper: Tamil Nadu ranks third in production of pepper. 

5. Sugarcane: Tamil Nadu ranks fourth in production of Sugarcane.

Textile industry in Tamil Nadu: 

1. Tamil Nadu is the largest textile hub of India. 

2. Tamil Nadu is known as the “Yam Bowl” of the country accounting for 41% of India’s cotton yam production. 

3. The textile industry plays a significant role in the Indian economy by providing direct employment to an estimated 35 million people, and thereby contributing 4% of GDP and. 35% of gross export earnings. 

4. The textile sector contributes to 14% of the manufacturing sector. 

5. From spinning to garment manufacturing, entire textile production chain facilities are in Tamil Nadu.

6. About half of India’s total spinning mill capacity is in Tamil Nadu. 

7. The western part of Tamil Nadu comprising Coimbatore, Tirupur, Erode, Dindigul and Karur has the majority of spinning mills manufacturing cotton, polyester, blended yam and silk yam used by garment units in Tamil Nadu, Maharashtra etc.,

8. Yam is also exported to China, Bangladesh, etc. 

9. Tirupur known as “knitting city” is the exporter of garments worth USD (United States Dollar) 3 billion. 

10. Karur is the major home for textile manufacturing (curtain cloth, bed linens, kitchen linens, toilet linens, table linens, wall hangings etc.,) and export hub in India.

11. Erode is the main cloth market in South India for both retail and wholesale readymades.

The Headquarters of Southern Railway is a Chennai.

Marginal revenue (MR) is the addition to the total revenue by the sale of an additional unit of a commodity

MR = ΔTR/ΔQ

MR-Marginal Revenue; ∆TR – Change in total revenue, ∆Q – Change is the total quantity (OR)

MR = TR_n – TR_n-1

TR_n – Total Revenue of n^th item.

TR_n – Total Revenue of n-1 item.

If TR_n-1 = PQ, MR = dTR / dQ = P

Which is equal to AR.

• Perfect competition – price taker 
• Monopoly – price maker 
• Oligopoly – Cournot model

Cost refers to the total expenses incurred in the production of a commodity. Cost analysis refers to the study of behaviour of cost in relation to one or more production criteria, namely size of output, scale of production, prices of factors, and other economic variables.

The point on the supply curve at which a firm earns normal profit is called the break even point. The point of minimum average cost at which the supply curve cuts the LRAC curve is, therefore, the break-even point of a firm.

Shut down point refers to a situation where average revenue is equal to average variable cost. In other words it is the minimum pint of AVC. On the other hand, break even point is the no profit, no loss point. It is the point where TR = TC or AR = AC.

The functional relationship between cost and output is expressed as ‘Cost function’. C= f (Q).

There is a major difference between the short run and long run price under perfect competition. In the short run, price should be equal to or greater than the minimum AVC. If the price falls below this level, the firm will shut down production. On the other hand, the long run price should be equal to or greater than the minimum AC. Below this level, the firm will shut down production.

1. Variable cost

2. Average cost 

3. Marginal revenue 

4. Breakeven point 

5. Constant returns

(d) All the above

Economic profit is TR-TC.

The amount of money that a producer receives in exchange for the sale of goods is known as revenue. Revenue means sales revenue.

Adam Smith regarded pains and sacrifices of labour as real cost of production.

Opportunity cost is the cost of the next best alternative use. It is the value of the next best alternative foregone. (Eg.) A farmer can cultivate both paddy and sugarcane in farmland. If he cultivates paddy, the opportunity cost of paddy output is the amount of sugarcane output given up. Opportunity cost is also called as ‘Alternative cost’ or ‘Transfer cost’.

Revenue received from the sale of an additional unit is termed as Marginal revenue.

(a) perfect competition Question

Profit is the difference between Total Revenue and Total Cost.

Correct Answer is: (b) TC/Q

a. Mobile Phone

b. Coconut The supply of mobile phones are relatively price elastic. This is because the purchase of mobile phones can easily react to a change in price. It is a manufactured good. All the raw materials needed to produce a mobile phone can easily be available. The producers can pile up stock and when price increases they can increase the supply.

The supply of coconut can be price inelastic. This is because the producers cannot easily react to a change in the price of coconut. Years needed for a coconut tree to get mature and start to produce coconuts. It is an agricultural product. The producers cannot hold the stock of coconut for a longer duration.

(a) Out of pocket expenses

Payment made to other for the purchase of factors of production is known as Explicit Costs. It refers to the actual expenditures of the firm to purchase or hire the inputs the firm needs.

Cost refers to Cost of production.

Correct answer is (b) AR = AC

b is the profit maximizing level of output. MR = MC 

At the profit maximizing level of output MC is non decreasing, that is the slope of MC is positive. 

P > AVC.

1. At the production level of 100 units of output, the producer incurs 1500 TC and 1500 TR. So there will be no profit or loss to the producer 

2. When TC =1000 

TR = 750 

Loss = TC-TR 

= 1000-750 = 250

In this diagram, producer’s equilibrium is at point E_r This is because this point satisfies all the conditions of equilibrium.

The conditions for attaining equilibrium are, 

(i) MC = MR 

(ii) MC must cut MR from below These two conditions are satisfied at point E₂