Daily NEET MCQ- June 10, 2022 - NEET MCQ

At the contact surface of two bodies (here, fluid layers) molecular bonds are formed. When there is relative motion between them these bonds try to oppose it. This is how friction works. Therefore we can say it is an electromagnetic force as molecular bonds are considered to be electromagnetic forces.

Resistance force by a fluid on a body = 6πηrv, where η is coefficient of viscosity, r is radius of body & v is its velocity. This doesn’t depend on density.
Another way to think of this is to imagine a hollow and solid sphere of the same radius falling through air at the same speed. The resistance offered by air will be the same on both as they have the same surface area exposed and are moving at the same speed.

At terminal velocity, Mg = viscous force. Therefore, 0.001*10^-3*10 = 6πηrv ∴ v = 10^-5/ 6πηr = 10^-5 / ( 6π*1.8 X 10^-5*0.001) = 29.47 m/s.

At normal temperature and pressure, there is no force of attraction between the gas particles. So they expand and occupy the space that is available. This statement supports the assumption.

As the particles of gas travel in straight lines and move in a random motion and collide with each other and also collide with the walls of the container, the pressure is exerted on the walls of the container in all directions.

The total energy of molecules before the collision is equal to the total energy after the collision. That means there may be an exchange of energy between the molecules but the total energy does not change, so the collisions of gas molecules are elastic.

The strategy that the plant cell uses is to catabolise the glucose molecule in such a way that not all the liberated energy goes out as heat. The key is to oxidise glucose, not in one step but several small steps.

During the process of respiration, oxygen is utilised and carbon-dioxide, water and energy are released as products. The combustion reaction requires oxygen.

The first cells on this planet lived in an atmosphere that lacked oxygen. Even among present-day living organisms, we know of several organisms that are adapted to anaerobic conditions.

 In any case, all living organisms retain the enzymatic machinery to partially oxidise glucose without the help of oxygen. This breakdown of glucose to pyruvic acid is called glycolysis.