Define the terms hybridization and photoperiod.

While studying about irrigation in her textbook,Bhanika read that proper irrigation is very important for the success of crops. Ensuring that the crops get water at the right stages during their growing season can increase the expected yields of any crop. She then thought about how irrigation is necessary in daily life,and considered sources like wells,rivers,and tanks as irrigation systems. She also shared this knowledge about irrigation systems with her friends.
$(a)$ According to you,what kind of qualities are seen in Bhanika?
$(b)$ Explain how rivers are an effective irrigation system.

Based on the kind of biological material used,what are the two kinds of manures? How are they prepared?

During class,Ravi's teacher was teaching about Thomson's model of an atom,stating that an atom is electrically neutral,i.e.,it contains equal positive and negative charges,and that an atom consists of a sphere of positive charge in which electrons are embedded like plums in a pudding. Ravi wondered how his teacher related Thomson's model of an atom to a plum pudding,and he imagined that just as dry fruits are embedded in a Christmas pudding,electrons are embedded in a sphere of positive charge.
$(a)$ According to you,what kind of qualities does Ravi possess?
$(b)$ What are the limitations of Thomson's model?

$(a)$ Distinguish between macronutrients and micronutrients on the basis of $(i)$ their functions and $(ii)$ amount required by plants. $(b)$ Classify the following elements as macro or micronutrients in plants: $(i)$ Nitrogen,$(ii)$ Zinc,$(iii)$ Copper,$(iv)$ Potassium. $(c)$ In what way is the deficiency of these nutrients harmful to crops?

Raman lives in a coastal village. He is the son of a fisherman. Whenever any unwanted animal comes in the net,instead of killing it,he puts it back in the sea.
$(a)$ What would have happened,had he killed those animals?
$(b)$ Give one reason to justify that Raman's action is environment-friendly.
$(c)$ How can you contribute to the preservation of flora and fauna around you? Mention any two steps.