Question Discussion & Solution

The correct answer is Deforestation.

• Deforestation is not related to conservation of land resources.

Key Points

• The felling and clearing of forest cover or tree plantations to accommodate agricultural, industrial or urban use is Deforestation.
• Deforestation can also be seen as removal of forests leading to several imbalances, both ecologically and environmentally.
• According to the Global Forest Resources Assessment 2020 (FRA 2020) report, the rate of forest loss has declined in the period of 1990-2020.
• The world’s total forest area is 4.06 billion hectares (bha), which is 31% of the total land area.

Additional Information

• The FRA is released by the United Nations Food and Agriculture Organization (FAO).
• Restriction on overgrazing is done to reduce Negative effects of grazing which include overgrazing, increased soil erosion, compaction and degradation, deforestation.
• Land reclamation is the process of creating new land from oceans, seas, riverbeds or lake beds.
• Regulated use of fertilizer controls the movement of water and nutrients within the plant.

The correct answer is Bone.

• Bone:
  • Bone is living, growing tissue. It is made mostly of collagen, a protein that provides a soft framework, and calcium phosphate, a mineral that adds strength and hardens the framework.
  • Osteoporosis, or porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased risk of bone fractures.

Additional Information

• Heart:
  • A large proportion of cardiovascular disease is due to atherosclerosis.
  • In atherosclerosis, the walls of your arteries become thick and stiff because of the build up of fatty deposits called plaques. 
• Glomerulonephritis is a group of diseases that injure the part of the kidney that filters blood.
• Asthma, Chronic obstructive pulmonary disease (COPD), Pneumonia are common lung diseases.

CONCEPT:

• Power: The rate of work done is called power.
  • It is denoted by P.
  • Mathematically it is written as

\(Power\;\left( P \right) = \frac{{\;W}}{{t}}\)

CALCULATION:

Given - mass of 1^st person (m₁) = 80 kg, mass of 2^nd person (m2) = 60 kg, time (t₁) = 12 sec, and time (t2) = 11 sec​

• The power to take an object to a certain height in 12 sec by 1^st person is 

\(\Rightarrow P_1 = \frac{mgh}{t}=\frac{80gh}{12}\)       ----(1)

• The power to take an object to a certain height in 11 sec by 2^nd person is 

\(\Rightarrow P_1 = \frac{mgh}{t}=\frac{60gh}{11}\)       ----(2)

On dividing equations 1 and 2, we get

\(\Rightarrow \frac{P_1}{P_2} =\frac{\frac{80gh}{12}}{\frac{60gh}{11}}=\frac{11}{9}\)

The pattern followed here is:

In every alternative, the numbers at the 2^nd and the 3^rd position are exactly divisible by the number at the 1^st position, while in (8, 801, 624), 801 is not exactly divisible by 8.

The correct answer is Potato.

Modifications of Root

1. For storage of food
   • Roots are modified in some plants for storing reserve food materials.
   • These modified roots usually are swollen and assume different forms such as spindle-shaped, e.g., radish; top-shaped, e.g., beet, turnip; cone-like, e.g., carrot; indefinite shape, e.g., sweet potatoes.
   • Dahlia, Asparagus, Portulaca are some other examples of plants with modified roots for food storage.
2. Nodulated roots
   • The roots of pea and other leguminous plants have numerous swollen nodules on fine branches of roots.
   • These nodules are formed due to the symbiotic association of Rhizobium (bacterium) that live inside the root cortical cells of the roots.
   • They fix nitrogen and an active nodule is pink in colour.
3. For mechanical support
   • Roots are modified to provide mechanical support as seen in a banyan tree which has roots growing vertically/obliquely downwards (prop roots); sugarcane/maize in which roots arise from the nodes in the cluster at the base of the stem (stilt roots) and betel/black pepper in which nodes and internodes bear roots which help in climbing.
4. For gaseous exchange
   • Pneumatophores or breathing roots are found in plants growing in mangroves or swamps with saline water for exchange of gases.
   • They are erect peg-like structures with numerous pores through which air circulates e.g., Rhizophora mangle.

• Modifications of Stem

1. For storage of food
   • Stems get modified into underground structures for storage of food as seen in potato (tuber), ginger (rhizome), garlic (bulb), yam (corm).
   • Presence of an eye (node) in potato, distinct nodes with internodes and scaly leaves in ginger/yam, a cluster of roots at the base of the reduced stem in garlic/ onion, all indicate that these underground plant parts are modified stem.
2. For vegetative propagation
   • Plants besides reproducing sexually also propagate through vegetative parts.
   • For this purpose, stems may be modified into a runner (Cyanodon dactylon, Oxalis). Runners are slender prostrate branches arising from axillary buds;
   • stolon (e.g., mint, strawberry) which is a slender lateral branch arising from the base of the stem grows upward and then down to develop new daughter plants;
   • offset having a single long horizontal internode growing up to some distance and producing a tuft of leaves above and a cluster of roots below at the apex (Eichornia, Pistia) and
   • sucker, which arises from the underground part of the stem, grow obliquely and gives rise to a new shoot. (Chrysanthemum, Banana, Pineapple).
3. For protection
   • Some modified stem provides protection as thorns which are hard, pointed structures each representing a branch that arises from the axil of a leaf.
   • Thorns are found in plants like Duranta, Pomegranate, Acacia, Ber, Prosopis, Bougainvillea, Citrus, etc.
4. For support
   • Tendrils are modifications of the stem to provide support to plants, e.g., Vitis, passionflower, Bignonia etc.
5. For photosynthesis
   • Stems are also modified into Phylloclade, to facilitate photosynthesis.
   • Phylloclades are flattened/cylindrical stem or branches of unlimited growth (Cactus).