Shankar IAS MCQs: Plant Diversity of India | Famous Books for UPSC Exam (Summary & Tests) PDF Download

Q1: Statement 1: Deciduous trees shed their leaves during autumn in cold climates.
Statement 2: Evergreen trees retain leaves throughout the year, shedding them gradually as new ones grow.
(a) Both statements are true.
(b) Statement 1 is true, but Statement 2 is false.
(c) Statement 1 is false, but Statement 2 is true.
(d) Both statements are false.
Ans: (a)
Deciduous trees indeed shed their leaves for part of the year, typically during autumn. Evergreen trees, on the other hand, retain leaves throughout the year and gradually shed old leaves as new ones grow.

Q2: Assertion (A): Epiphytes are plants that grow on other plants for support and access to light but do not derive nourishment from them.
Reason (R): Epiphytes have roots that serve two functions—changing roots for anchoring to the host and aerial roots for extracting moisture from the air.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) Both A and R are false.
Ans: (a)
The assertion correctly defines epiphytes and the reason explains their unique root functions.

Q3: Arrange the following effects of abiotic components on plants in the order of their occurrence under high light intensity:
1. Increased transpiration
2. Short stem development
3. Production of smaller, thicker leaves
(a) 1, 2, 3
(b) 2, 3, 1
(c) 3, 1, 2
(d) 2, 1, 3
Ans: (b)
Under high light intensity, the development of the root system is favored, leading to a short stem, which then results in increased transpiration and the production of smaller, thicker leaves.

Q4: Statement 1: Trees grow from the top, not from the bottom.
Statement 2: Frost causes the freezing of water in the intercellular spaces of plants, leading to the dehydration of cells.
(a) Both statements are true.
(b) Both statements are false.
(c) Statement 1 is true, but Statement 2 is false.
(d) Statement 1 is false, but Statement 2 is true.
Ans: (a)
Statement 1 is true as trees grow from the top. Statement 2 correctly describes the effect of frost on plants.

Q5: Statement 1: Pneumatophores are spike-like projections of roots above the ground to obtain sunlight.
Statement 2: Haustorial roots are the roots of parasitic plants that can absorb water and nutrients from another plant.
(a) Both statements are true.
(b) Statement 1 is true, but Statement 2 is false.
(c) Statement 1 is false, but Statement 2 is true.
(d) Both statements are false.
Ans: (b)
Pneumatophores are spike-like projections of roots above the ground, but their purpose is to help submerged roots obtain oxygen, not sunlight. Haustorial roots are indeed the roots of parasitic plants that absorb water and nutrients from another plant.

Q6: The decline of insectivorous plants is primarily due to ________, ________, and ________.
(a) Overharvesting, habitat destruction, pollution
(b) Climate change, urbanization, deforestation
(c) Pesticides, overwatering, soil erosion
(d) Invasive species, natural disasters, overgrazing
Ans: (a)
Explanation: Overharvesting, habitat destruction, and pollution are the major threats to insectivorous plants.

Q7: Assertion (A): Biological invasion by alien species is a major threat to native species and ecosystems.
Reason (R): Alien invasive species often lack natural predators in new environments, leading to uncontrolled population growth.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) Both A and R are false.
Ans: (a)
The assertion correctly identifies the threat of biological invasion, and the reason explains a key factor contributing to this threat.

Q8: Which of the following is NOT an invasive plant species in India?
(a) Lantana camara
(b) Blue Vanda
(c) Water Hyacinth
(d) Parthenium
Ans: (b)
Blue Vanda is a native orchid of India, not an invasive species, unlike the others listed.

Q9: Statement 1: Medicinal plants like Sarpagandha are used for treating central nervous system disorders.
Statement 2: The Prosopis juliflora is a native tree of India that aids in preventing soil erosion.
(a) Both statements are true.
(b) Both statements are false.
(c) Statement 1 is true, but Statement 2 is false.
(d) Statement 1 is false, but Statement 2 is true.
Ans: (c)
Statement 1 is true regarding the medicinal use of Sarpagandha. Statement 2 is false as Prosopis juliflora is an invasive species, not native to India.

Q10: Statement 1: Closed canopy classification indicates a density of 0.50 to 0.75.
Statement 2: Etiolation refers to the pale yellowing of plants due to excessive light exposure.
(a) Both statements are true.
(b) Statement 1 is true, but Statement 2 is false.
(c) Statement 1 is false, but Statement 2 is true.
(d) Both statements are false.
Ans: (c)
Closed canopy classification indicates a density of 1.0, not 0.50 to 0.75. Etiolation refers to the pale yellowing of plants due to insufficient light, not excessive light exposure.

Q11: Statement 1: Bamboo gregarious flowering is followed by plant death.
Statement 2: Sal trees are absent in Deccan trap but are replaced by teak.
(a) Both statements are true.
(b) Statement 1 is true, but Statement 2 is false.
(c) Statement 1 is false, but Statement 2 is true.
(d) Both statements are false.
Ans: (a)
Bamboo gregarious flowering is indeed followed by plant death. Sal trees are absent in Deccan trap and are replaced by teak.

Q12: Statement 1: Red and blue light are the most efficient for plant photosynthesis.
Statement 2: Ultraviolet light promotes normal growth in plants.
(a) Both statements are true.
(b) Both statements are false.
(c) Statement 1 is true, but Statement 2 is false.
(d) Statement 1 is false, but Statement 2 is true.
Ans: (c)
Red and blue light are crucial for photosynthesis, but ultraviolet light does not promote normal growth in plants.

Q13: What is the primary cause of dieback in plants?
(a) Excessive sunlight
(b) Nutrient-rich soil
(c) Inadequate light and dense growth
(d) High temperature
Ans: (c)
Dieback is often triggered by lack of sufficient light and dense growth patterns.

Q14: Statement 1: The inner bark (Phloem) of a tree transports sap full of sugar.
Statement 2: The Cambium is a thin layer of living cells just inside the bark that produces new cells, allowing the tree to grow wider each year.
(a) Both statements are true.
(b) Statement 1 is true, but Statement 2 is false.
(c) Statement 1 is false, but Statement 2 is true.
(d) Both statements are false.
Ans: (a)
The inner bark (Phloem) of a tree indeed transports sap full of sugar. The Cambium is a thin layer of living cells just inside the bark, responsible for producing new cells and allowing the tree to grow wider each year.

Q15: What is the primary effect of invasive alien species on ecosystems?
(a) Increased biodiversity
(b) Habitat improvement
(c) Loss of biodiversity
(d) Enhanced agricultural productivity
Ans: (c)
Invasive alien species often lead to the loss of biodiversity in ecosystems.

Q16: Assertion (A): Trees prevent soil erosion by trapping soil that would otherwise become silt.
Reason (R): Trees have extensive root systems that stabilize the soil.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (a)
Trees do prevent soil erosion through their root systems, which stabilize the soil.

Q17: Statement 1: The world’s tallest tree is a coast redwood in California.
Statement 2: The world’s oldest trees are Bristlecone pines in the USA, aged over 4,600 years.
A. Both statements are true.
B. Both statements are false.
C. Statement 1 is true, but Statement 2 is false.
D. Statement 1 is false, but Statement 2 is true.
Ans: (a)
Both statements are true regarding the tallest and oldest trees.

Q18: Which of the following are characteristics of a tree?
1. Tall stature
2. Well-defined trunk
3. Multiple stems from the base
4. Higher longevity compared to shrubs and herbs
(a) 1 and 2 only
(b) 1, 2, and 4
(c) 2, 3, and 4
(d) All of the above
Ans: (b)
Characteristics of a tree include a tall stature, well-defined trunk, and higher longevity compared to shrubs and herbs.

Q19: Match the following root types with their descriptions:

(a) 1-A, 2-B, 3-C
(b) 1-C, 2-B, 3-A
(c) 1-A, 2-C, 3-B
(d) 1-B, 2-C, 3-A
Ans: (a)
Each root type is correctly matched with its botanical description.

Q20: What is the primary function of the cambium in a tree?
(a)Transporting water and nutrients
(b) Producing new cells for growth
(c) Protecting the tree from external damage
(d) Converting energy into food
Ans: (b)
The cambium is a thin layer of living cells just inside the bark that produces new cells, allowing the tree to grow wider each year.