1. Consider the following statements related to major ocean currents:
(1) Benguela current is a warm current flowing along west coast of Africa.
(2) Humboldt current is a cold current flowing along east coast of South America.
(3) Canaries current is a cold current flowing along west coast of Africa.
Which of the statements given above is/are correct?
(a) 2 only
(b) 3 only
(c) 1 and 3 only
(d) 1 and 2 only
Ans: (b) Explanation: Ocean currents can be classified based on temperature: as cold currents and warm currents: Warm currents bring warm water into cold water areas and are usually observed on the east coast of continents in the low and middle latitudes (true in both hemispheres). In the northern hemisphere, they are found on the west coasts of continents in high latitudes. Cold currents bring cold water into warm water areas. These currents are usually found on the west coast of the continents in the low and middle latitudes (true in both hemispheres) and on the east coast in the higher latitudes in the Northern Hemisphere. Benguela current is cold current flowing along west coast of Africa. Hence, statement 1 is incorrect. Peruvian current / Humboldt current is cold current flowing along west coast of South America. Hence, statement 2 is incorrect. Canaries current is cold current flowing along west coast of Africa. Hence, statement 3 is correct.
Source: India Physical Environment, Class 11th (NCERT), Page no. 124-125.
2. Consider the following pairs:
Forest : Tree
1. Tropical deciduous forest : Khair, Neem, Khejri
2. Tropical evergreen forest : Rosewood, Mahogany, Aini
3. Tropical thorn forest : Teak, Sal, Shisam
Which of the pairs given above is/are correctly matched?
(a) 1 only
(b) 2 only
(c) 1 and 2 only
(d) 1 and 3 only
Ans: (b) Explanation: The correct pairs are:
1. Tropical deciduous forest : teak, sal, shisam
2. Tropical evergreen forest : rosewood, mahogany, aini
3. Tropical thorn forest : khair, neem, khejri
Value Addition: Tropical Deciduous Forests: They are also called the monsoon forests. They spread over regions which receive rainfall between 70-200 cm.
The Moist deciduous forests are spread in the regions which record rainfall between 100-200 cm Teak, sal, shisham, hurra, mahua, amla, semul, kusum, and sandalwood etc. are the main species of these forests.
Dry deciduous forests spread in the regions where rainfall ranges between 70 -100 cm. As the dry season begins, the trees shed their leaves completely and the forest appears like a vast grassland with naked trees all around. Tendu, palas, amaltas, bel, khair, axlewood, etc. are the common trees of these forests.
Tropical Evergreen Forests: These forests are found in the western slope of the Western Ghats, hills of the north-eastern region and the Andaman and Nicobar Islands. They are found in warm and humid areas with an annual precipitation of over 200 cm and mean annual temperature above 22oC. Tropical evergreen forests are well stratified. Species found in these forests include rosewood, mahogony, aini, ebony, etc. Tropical Thorn Forests: Tropical thorn forests occur in the areas which receive rainfall less than 50 cm. These consist of a variety of grasses and shrubs. It includes semi-arid areas of south west Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh and Uttar Pradesh. In these forests, plants remain leafless for most part of the year and give an expression of scrub vegetation. Important species found are babool, ber, and wild date palm, khair, neem, khejri, palas, etc. Tussocky grass grows up to a height of 2m as the under growth.
Source: Geography Class 11th NCERT, India: Physical Environment, Chapter 5 Page No. 57 and 59.
3. Consider the following statements about ‘Jet streams’ in India:
(1) Westerly jet stream plays a significant role in winter rainfall of North India.
(2) Easterly jet stream steers the temperate depressions into India during south-west monsoon.
Which of the statements given above is/are incorrect?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Ans: (b) Explanation: All of Western and Central Asia remains under the influence of westerly winds along the altitude of 9-13 km from west to east. These winds blow across the Asian continent at latitudes north of the Himalayas roughly parallel to the Tibetan highlands. These are known as jet streams. The western cyclonic disturbances which enter the Indian subcontinent from the west and the northwest during the winter months, originate over the Mediterranean Sea and are brought into India by the westerly jet stream. It brings rainfall in winter which is conducive for rabi crops like wheat, etc. The easterly jet stream steers the tropical depressions into India. These depressions play a significant role in the distribution of monsoon rainfall over the Indian subcontinent. The tracks of these depressions are the areas of highest rainfall in India. The frequency at which these depressions visit India, their direction and intensity, all go a long way in determining the rainfall pattern during the southwest monsoon period.
Source: Geography class XI NCERT India: Physical Environment, Page No. 35, 37.
4. With reference to dry deciduous forests, consider the following statements:
(1) Shedding the leaves completely and appearing as vast grassland in dry season - is the feature of dry deciduous forests.
(2) Dry deciduous forests receive rainfall between 100-200 cm.
(3) Khair trees are commonly found in dry deciduous forests.
Which of the statements given above is/are correct?
(a) 1 only
(b) 3 only
(c) 1 and 2 only
(d) 1 and 3 only
Ans: (d) Explanation: Tropical Deciduous Forests are also called the monsoon forests. On the basis of the availability of water, these forests are further divided into moist and dry deciduous. Statement 1 is correct: As the dry season begins, the trees shed their leaves completely and the forest appears like a vast grassland with naked trees all around. Statement 2 is incorrect: Dry deciduous forests spread in the regions where rainfall ranges between 70 -100 cm. Statement 3 is correct: Tendu, palas, amaltas, bel, khair, axlewood, etc. are the common trees of these forests.
Source: Geography class XI NCERT India: Physical Environment, Chapter 5 Page No. 59.
5. Consider the following events in the evolution of atmosphere:
(1) Degassing
(2) Loss of primordial atmosphere
(3) Modification in the composition of atmosphere through photosynthesis.
Which of the following is the correct sequence of the above events?
(a) 1-2-3
(b) 2-3-1
(c) 2-1-3
(d) 3-1-2
Ans: (c) Explanation: There are three stages in the evolution of the present atmosphere: The first stage is marked by the loss of primordial atmosphere. The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. This happened not only in case of the earth, but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere (degassing). During the cooling of the earth, gases and water vapour were released from the interior solid earth. This started the evolution of the present atmosphere. The early atmosphere largely contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very little of free oxygen. The process through which the gases were outpoured from the interior is called degassing. Continuous volcanic eruptions contributed water vapour and gases to the atmosphere. Finally, the composition of the atmosphere was modified by the living world through the process of photosynthesis. Around 2,500-3,000 million years before the present, the process of photosynthesis got evolved. Life was confined to the oceans for a long time. Oceans began to have the contribution of oxygen through the process of photosynthesis. Eventually, oceans were saturated with oxygen, and 2,000 million years ago, oxygen began to flood the atmosphere. Hence, option (c) is correct.
Source: NCERT- Class XI Fundamental of Physical Geography- Page no. 17.