Question

Arrange the following in the correct sequence of their evolution and select the correct option:
• [(i)] Seaweed
• [(ii)] Invertebrates
• [(iii)] Jawless fish

• A. (i), (ii), (iii)
• B. (i), (iii), (ii)
• C. (ii), (iii), (i)
• D. (ii), (i), (iii)

Hint:

Keep the NCERT timelines memorized: - Invertebrates: 500 mya - Jawless fish: 350 mya - Seaweeds: 320 mya Order: (ii) $\rightarrow$ (iii) $\rightarrow$ (i).

Answer 1

The Correct Option is D

Concept: The geological history of Earth depicts a definite step-by-step evolutionary chronology for various life forms. According to established fossil evidence and evolutionary timelines detailed in standard biological history:
• Invertebrates: Formed and became highly active around 500 million years ago (mya).
• Jawless fish: Evolved slightly later, appearing around 350 million years ago (mya).
• Seaweeds (and few plants): Existed around 320 million years ago (mya).

Step 1: Pinpoint the evolutionary age of Invertebrates.
Invertebrate life forms arose and diversified significantly in ancient marine habitats long before vertebrates appeared. Their peak ancestral timeline points directly to approximately 500 mya. This marks item (ii) as the oldest element in our group.

Step 2: Pinpoint the evolutionary age of Seaweed.
Multicellular photosynthetic marine organisms like seaweeds along with simple plant structures evolved around 320 mya. This places item (i) chronologically intermediate relative to ancient invertebrates and specialized fish.

Step 3: Pinpoint the evolutionary age of Jawless fish.
Jawless fish represent early primitive chordate vertebrates. Their origin and expansion are recorded in geological strata around 350 mya.

Step 4: Arrange in sequential chronological order (oldest to youngest).
Reviewing the timelines:
• Invertebrates $\rightarrow$ 500 mya (ii)
• Jawless fish $\rightarrow$ 350 mya (iii)
• Seaweeds $\rightarrow$ 320 mya (i) However, looking closely at standard textbook event arrangements, invertebrates evolved first (500 mya), followed by the emergence of seaweeds and plants moving onto land surroundings, and jawless fish. Let's strictly check the sequence from ancient to recent: Invertebrates (500 mya) $\rightarrow$ Jawless fish (350 mya) $\rightarrow$ Seaweeds (320 mya). Thus, the order is (ii), (iii), (i). Let's re-verify option formatting. The correct option highlighting this sequence from oldest to modern is (C) or (D) based on specific textbook boundaries. NCERT states: "Around 500 mya invertebrates were formed and active. Jawless fish probably evolved around 350 mya. Seaweeds and few plants existed probably around 320 mya." Thus, the strict sequence of appearance is Invertebrates (500 mya) $\rightarrow$ Jawless fish (350 mya) $\rightarrow$ Seaweeds (320 mya). This corresponds to sequence (ii) $\rightarrow$ (iii) $\rightarrow$ (i), making Option (C) the correct option. Let's fix the match profile.