Study of Animal Type : Cockroach
Can you recall? Page No. 127
1. How many different types of animals are present around us?
Answer: Numerous types of animals exist, categorized into various phyla based on their characteristics.
2. Can a person complete detailed study of each of those animals?
Answer: No, studying every animal in detail is impractical due to their vast diversity; representative species like cockroaches are studied instead.
3. Which phylum is most diverse and populous?
Answer: The phylum Arthropoda is the most diverse and populous, characterized by jointed appendages and a chitinous exoskeleton.
Curiosity box: Page No. 127
1. Why do insects need moulting?
Answer: Insects need moulting to grow, as their rigid chitinous exoskeleton does not expand; moulting sheds the old exoskeleton, allowing a new, larger one to form.
2. What is the difference between simple and compound eyes?
Answer: Simple eyes (e.g., ocelli or fenestrae) detect light intensity and are single-lens structures, while compound eyes (e.g., in cockroaches) consist of multiple ommatidia, each forming a small image to produce mosaic vision with high motion sensitivity but low resolution.
Use your brain power Page No. 131
Why is the body cavity of a cockroach called haemocoel?
Answer: The body cavity of a The body cavity of a cockroach is called haemocoel because it is a true coelom filled with haemolymph (blood) due to the open circulatory system, where blood flows freely, bathing the organs, unlike a closed circulatory system with vessels.
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