P-2 Cell Biology and Biotechnology — Science STD 10 — Question

i. Which substance is used to produce cheese?
ii. Which enzyme was used earlier for cheese production?
iii. Which enzyme is used to produce vegetarian cheese?

Take a battery, (12V) a variable resistance (or a rheostat), an ammeter (0_5 A), a plug key, needle and a long straight thick copper wire. Take a rectangular cardboard, pass this wire through center. Fix the cardboard and see that it does not slide up or down. Sprinkle iron filings uniformly on the cardboard. Close the key and tap the cardboard gently.

(i) Observe the pattern of iron filings.
(ii) What changes are seen in the magnetic field lines?
(iii) What happens to the magnetic needle of the compass when the compass is brought near the wire, and moved away from the wire? Also observe what happens to the magnetic needle when strength of current is increased.
(iv) What happens to the magnetic needle of the compass when direction of the current is reversed in the straight conductor? State the reasons for your observation.

Define: The Universal law of gravitation and derive mathematically.

At which position will you keep an object in front of a convex lens so as to get a real image of the same size as the object? Draw a figure.

What is meant by dental caries? How are they caused?

What would be the effect on the resistance of a metal wire of:

1. Increasing its length?
2. Increasing its diameter?
3. Increasing its temperature?

Electronic configuration of metal A is 2,8,1. Electronic configuration of metal B is 2,8,8,2. Which of the above metals is more reactive? Explain with reason.

Define principal axis, principal focus and focal length of a convex lens.