Exercise 11.5
In animals, which fertilisation method the gametes are more protected? Animal Fish Frog Lizard Bird egg emergence Exploration|Grade
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
NCERT’s answer
Internal Fertilisation
The gametes are better protected in internal fertilisation.
Fertilisation takes place inside the body of the female, so the gametes and the zygote are never exposed to water currents or to animals that eat them.
In external fertilisation the eggs and sperm are simply released into the water, where many are washed away or eaten.
This is why reptiles, birds and mammals (internal) show moderate to high survival of young from very few eggs, while fish and frogs (external) show low survival from thousands.