Identify the two components of phloem tissue that help in transportation of food in plants.

1. Phloem parenchyma & sieve tubes
2. Sieve tubes & companion cells
3. Phloem parenchyma & companion cells
4. Phloem fibres and sieve tubes

In the diagram shown below n₁, n₂ and n₃ are refractive indices of the media 1, 2 and 3 respectively. Which one of the following is true in this case?

1. n₁ = n₂
2. n₁ > n₂
3. n₂ > n₃
4. n₃ > n₁

The refractive index of medium A is 1.5 and that of medium B is 1.33. If the speed of light in the air is 3 × 10⁸ m/s, what is the speed of light in medium A and B respectively?

(a) 2 × 10⁸ m/s and 1.33 × 10⁸ m/s

(b) 1.33 × 10⁸ m/s and 2 × 10⁸ m/s

(c) 2.25 × 10⁸ m/s and 2 × 10⁸ m/s

(d) 2 × 10⁸ m/s and 2.25 × 10⁸ m/s

A converging lens forms a three-times magnified image of an object, which can be taken on a screen. If the focal length of the lens is 30 cm, then the distance of the object from the lens is

1. –55 cm
2. –50 cm
3. –45 cm
4. –40 cm