The animal that can regenerate its lost body parts to a remarkable extent is:
A. Cockroach
B. Hydra
C. Earthworm
D. Frog
Answer: Option B
Solution (By JKSSB Mock Tests)
Hydra, a freshwater cnidarian, has extraordinary regenerative ability; even small fragments can regenerate a complete organism. This is due to its high proportion of stem cells. Planarians also show remarkable regeneration. Earthworms can regenerate some posterior segments, but not as extensively as Hydra or Planaria.
Explanation:
Emil Fischer proposed the lock-and-key model in 1894, suggesting that the enzyme's active site is exactly complementary to the substrate, like a key fits a lock. Koshland later proposed the induced fit model, which is more widely accepted. Michaelis and Menten developed enzyme kinetics equations.
Explanation:
Adventitious roots arise from non-root tissues like stems, leaves, or branches. Examples: prop roots of banyan, stilt roots of maize, aerial roots of orchids. Taproot and fibrous roots develop from the radicle.
Consider statements about evolution: 1. Natural selection was proposed by Darwin. 2. Evolution always leads to perfect organisms. 3. Homologous organs indicate common ancestry. Which are correct?
Explanation:
Charles Darwin proposed the theory of evolution by natural selection, where organisms with favorable traits survive and reproduce. Homologous organs share a common structural plan and evolutionary origin, indicating divergent evolution from a common ancestor. Evolution does not lead to perfection; it only results in adaptation to the current environment. Thus, statements 1 and 3 are correct.
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