31. What is the body plan of a sea urchin?
a) Bilateral symmetry
b) Radial symmetry
c) Asymmetrical
d) Spherical
Answer: b) Radial symmetry
32. How do sponges reproduce?
a) By laying eggs
b) By live births
c) By budding
d) By pollination
Answer: c) By budding
33. Which of the following is not a characteristic of arthropods?
a) They have jointed appendages
b) They have a segmented body
c) They have an exoskeleton
d) They have a closed circulatory system
Answer: d) They have a closed circulatory system
34. What is the phylum of animals that includes insects and spiders?
a) Porifera
b) Mollusca
c) Arthropoda
d) Echinodermata
Answer: c) Arthropoda
35. How do mollusks respire?
a) Through gills
b) Through lungs
c) Through spiracles
d) Through their skin
Answer: a) Through gills
