Crop production and management — Science STD 8 — Question

Name the forces acting on a plastic bucket containing water held above ground level in your hand. Discuss why the forces acting on the bucket do not bring a change in its state of motion.

Out of Amoeba cell and white blood cell, which one is:

1. Eukaryotic cell, and
2. Prokaryotic cell?

Name the point inside the human eye where the image is not visible.

How will you charge an inflated rubber balloon by the method of friction?

If an object is placed at a distance of 7.5cm from a plane mirror, how far would it be from its image?

Why do the shape and size of a balloon change when filled with air or water?

Name the endocrine gland which controls the production of sex hormones ‘testosterone’ and ‘estrogen’.

Why are nerve cells long and have branches?

What is metamorphosis? Give two examples of metamorphosis.

A is an insect which breeds in ponds of stagnant water. The egg of this insect produces a worm like form B which is entirely different in appearance from the adult insects. The form B undergoes a change C and gets converted into insects A. The female of insects A is a carrier of protozoan D which spreads a disease in humans.

1. What are A, B, C, and D?
2. Name another insect which also undergoes change C.