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What are not true? a. Dermal scales of...

What are not true?
a. Dermal scales of fishes form the exoskeleton
b. cycloid and ctenoid scales have distinct lines of growth which aid in determining the age of the fish.
c. Fish scales are never shed.
d. The skin in elasmobranchs is covered with placoid scales.
e. The development of a placoid sale is not like the development of a tooth

A

a,b,c and e

B

b,cand e

C

c,d and e

D

only e

Text Solution

AI Generated Solution

The correct Answer is:
To determine which statements about fish scales and their characteristics are not true, we will analyze each option step by step. ### Step-by-Step Solution: 1. **Option A: Dermal scales of fishes form the exoskeleton.** - **Analysis:** Dermal scales are indeed part of the fish's protective covering. They provide structural support and protection, similar to an exoskeleton. - **Conclusion:** This statement is **true**. 2. **Option B: Cycloid and ctenoid scales have distinct lines of growth which aid in determining the age of the fish.** - **Analysis:** Cycloid and ctenoid scales do have growth rings that can be used to estimate the age of fish, much like tree rings. - **Conclusion:** This statement is **true**. 3. **Option C: Fish scales are never shed.** - **Analysis:** Fish scales can be shed and replaced throughout a fish's life, especially during growth or in response to injury. - **Conclusion:** This statement is **not true**. 4. **Option D: The skin in elasmobranchs is covered with placoid scales.** - **Analysis:** Elasmobranchs, such as sharks and rays, do have skin covered with placoid scales, which are tooth-like structures. - **Conclusion:** This statement is **true**. 5. **Option E: The development of a placoid scale is not like the development of a tooth.** - **Analysis:** Placoid scales are indeed modified forms of teeth, sharing similar developmental pathways. - **Conclusion:** This statement is **not true**. ### Final Conclusion: The statements that are **not true** are: - **Option C**: Fish scales are never shed. - **Option E**: The development of a placoid scale is not like the development of a tooth. ### Summary of Incorrect Statements: - C and E are incorrect.
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