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

In which the following fish the skin is tough containing minute placoid scales?

In which the following fish the skin is tough containing minute placoid scales?

Say True or False: Cartilage fishes are marine, have placoid scales and homocercal tail fin.

Cartilaginious fishes have I. Scoroll valve " " II. Operculum III. Placoid scale " " IV. Cycloid or ctenoid scales Choose the correct option.

Read the following information and five statements given below it carefully and answer the question which follow : Fortunately, more and more countries are shifting their focus away from industrial development to control of climate these days. A. The countries which focus more on controlling climate changes than industrial development. B. Many countries had once prioritised industrial development which proved to be harmful to the environment in the long run. C. Some experts are of the view that climate changes is not as alarming an issue as it is made to be because it is a natural phenomenon and has been occurring regularly throughout the history of earth. D. If climate changes continues at the present rate, it would bring in large-scale destruction to human habitation in a very short time. E. Industrial development is one of the biggest but definitely not the reason behind global warming. Which of the statements numbered A,C,D and E mentioned above represents a person behind curtailing industrial development by some of the countries ? 1) Either C and E 2) D 3) C 4) Either A or C 5) A