the human eye and the colourful world — Science STD 10 — Question

Which substances are selectively reabsorbed from initial filtrate in the tubular part of nephron?

What makes an object visible?

How is the product formed during the chemical reaction?

What are the characteristics of respiratory surface?

Choose the correct option :
The magnetic field inside a long straight solenoid carrying current...
(a) is zero.
(b) decreases as we move towards its end.
(c) increases as we move towards its end.
(d) is the same at all points.

An eye camp was organised by the doctors in a village. They found that the eyes of aged people in the village have the near point receded and the far point also gets reduced. Often aged people suffer from both myopia and hypermetropia. Doctors (opthalmologists) provide these people spectacles of bi-focal lenses to correct the defects. The people were happy and grateful to the doctors.
(1) Name the eye defect from which the people were suffering.
(2) Give any two causes of this defect.
(3) What were benefits to organise such camps in rural areas? Give two suggestions.

What is meant by olfactory indicator? Give examples.

Which among the following possess the highest biological magnification?
Grasshopper, frog, snake and peacock.

Why all food chains begin with organisms that contain chlorophyll?

If a number of bulbs of different wattages are joined in parallel with a voltage source, which bulb will glow with maximum brightness?