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Which of the following statement are not...

Which of the following statement are not true about shark?
a. The skin is tough and covered with placoid scales.
b. They possess a swim bladder which regulates buoyancy.
c. the tail of shark is heterocercal.
d. Ampulla of lorenzini present in the snout of shark is thermoreceptor.
e. it has five pairs of gill slits covered by operculum.

A

a,c,d,e

B

b,c,d,e

C

b and e only

D

c and e only

Text Solution

AI Generated Solution

The correct Answer is:
To determine which statements about sharks are not true, we will analyze each statement provided in the question. ### Step-by-Step Solution: 1. **Statement A: The skin is tough and covered with placoid scales.** - **Analysis**: This statement is true. Sharks, being cartilaginous fish (class Chondrichthyes), have tough skin covered with placoid scales, which are small, tooth-like structures that give the skin a rough texture. 2. **Statement B: They possess a swim bladder which regulates buoyancy.** - **Analysis**: This statement is not true. Sharks do not have a swim bladder; instead, they rely on their large oil-filled liver to maintain buoyancy. Swim bladders are characteristic of bony fish (class Osteichthyes). 3. **Statement C: The tail of shark is heterocercal.** - **Analysis**: This statement is true. Sharks have a heterocercal tail, which means that the tail is asymmetrical, with the upper lobe being larger than the lower lobe. 4. **Statement D: Ampulla of Lorenzini present in the snout of shark is a thermoreceptor.** - **Analysis**: This statement is partially true. The Ampulla of Lorenzini are specialized electroreceptors that help sharks detect electrical fields in the water, and they can also respond to temperature changes, but their primary function is not solely as thermoreceptors. 5. **Statement E: It has five pairs of gill slits covered by operculum.** - **Analysis**: This statement is not true. Sharks have five to seven pairs of gill slits, but they do not have an operculum (a bony cover over the gills), which is found in bony fish. Instead, the gill slits are exposed. ### Conclusion: The statements that are not true about sharks are: - **B**: They possess a swim bladder which regulates buoyancy. - **E**: It has five pairs of gill slits covered by operculum. Thus, the correct answer is **B and E**.
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