Question 1 of 5
Which of the following is a defining characteristic of living organisms?
A. Growth
B. Ability to make body parts
C. Response to external stimuli
D. All of the above
A
Growth
B
Ability to make body parts
C
Response to external stimuli
D
All of the above
Why: All living organisms, from prokaryotes to eukaryotes, show irritability i.e., the ability to sense their environment and respond to it. Plants and animals respond to external stimuli like light, temperature, water, etc. All organisms are conscious of their external environment. Thus, response to external stimuli is a defining property of living organisms. Growth is incorrect as it can occur in non-living things like crystals through increase in mass or number.[1]
Question 2 of 5
Assertion (A): Consciousness is considered as the defining property of living organisms.
Reason (R): All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental stimuli.
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
Why: The assertion is true because consciousness is one of the defining properties of living organisms. The reason is also true and explains the assertion because consciousness is the awareness of surroundings and responding to environmental or external stimuli, making it a defining property.[1]
Question 3 of 5
Plants growing in water are —
A
a) Mesophytes
B
b) Xerophytes
C
c) Hydrophytes
D
d) Epiphytes
Why: **Hydrophytes** are plants that grow in water. These plants are specially adapted to aquatic environments with features like thin cuticles, reduced leaves, and air spaces (aerenchyma) for buoyancy and oxygen transport. Examples include lotus and water lily, which float or are submerged. Mesophytes grow in moderate water conditions, xerophytes in deserts, and epiphytes on other plants.
Question 4 of 5
Animals living in land & water —
A
a) Aerial
B
b) Aquatic
C
c) Amphibians
D
d) Arboreal
Why: **Amphibians** are animals that live both on land and in water. They have a dual life cycle: aquatic larval stage (e.g., tadpole) and terrestrial adult stage. They possess moist skin for respiration and lay eggs in water. Examples: frogs, toads. This classification falls under vertebrates in animal taxonomy.
Question 5 of 5
Xerophytes are —
A
a) Water plants
B
b) Desert plants
C
c) Normal soil plants
D
d) Epiphytes
Why: **Xerophytes** are desert plants adapted to low water availability. Adaptations include thick cuticles, sunken stomata, reduced leaves, deep roots, and water-storing tissues. Examples: cactus, which has spines instead of leaves to reduce transpiration. This is a key classification in plant taxonomy based on habitat.
