$(a)$ Give two examples of shellfishes.
$(b)$ Mention the names of four marine fish of high economic value.

$(a)$ What is lactation period? Name two breeds of cattle which are selected for their long lactation period. Why are they crossed with local breeds?
$(b)$ What are roughage and concentrates?

Raman along with his family visited the Dead Sea. There,his father observed a lady lying on her back in the sea and reading a newspaper. This astonished Raman's father,who thought the lady might be practicing black magic. Raman explained to his father why the lady was not drowning.
$(a)$ What,according to you,is the reason the lady is not drowning in the Dead Sea?
$(b)$ What value is exhibited by Raman?

Two average students, Ram and Shyam, were discussing the following graphs in the class:
[Image: $1158-196$]
The question relating to the graphs was to identify which one of them was not possible. Ram and Shyam agreed that graphs $A, B$ and $C$ were not possible. But Shyam said that graph $D$ is possible, while Ram said that it is also not possible. Since their teacher was on leave, they could not ask her. Seeing this, Ratan, who was very intelligent, came to their rescue. He told Shyam that graph $D$ was also not possible.
$(a)$ Do you think that Ratan is right? If so, why is graph $D$ not possible?
$(b)$ What values are imbibed by Ratan?

Which of the following are exotic breeds of cattle?

Write four methods of weed control.