Daily NEET MCQ- June 21, 2022 - NEET MCQ

Blue baby syndrome (methemoglobinemia) is a disease that is caused when the baby consumes drinking water which is rich in nitrates. It is caused when the maximum limit of nitrate in water, i.e. 50ppm, is crossed. When the baby drinks nitrate-rich water, then the nitrates get converted to nitrites and this will go and bind with the haemoglobin present in the blood, forming methemoglobin, which does not have the ability to carry oxygen. This is the reason for the blue color of the skin of the baby.

The maximum prescribed upper limit concentration of lead in drinking water is about 50 ppb. Drinking water gets contaminated with lead when lead pipes are used for the transportation of drinking water. Lead is a harmful substance and can cause damage in kidneys, liver, reproductive system, etc.

The full form of PCB is Polychlorinated biphenyls. It is used as a cleansing solvent. PCBs are also suspected to be carcinogenic (can lead to cancer). Bacteria responsible for degrading biodegradable detergent feed on these and grow rapidly. While growing, they use up all the oxygen dissolved in water. Thus, the lack of oxygen kills all other forms of aquatic life such as fish and plants.

The equation suiting the given conditions will be: y = Asin(kx+wt+a)
At x=0, t=0, velocity is negative, so ‘a’ will be π.
k = 2π/λ = π.
∴ y = 2sin(πx + 2t + π).
At x=20cm & t=10s,
y = 2sin(20.5π + 10π + π)
= 2sin(31.5π)
= -2cm.

In the given equation the phase is 3x-2t+π/2.
This is repeated after every 2π.
∴ sin( 3x-2t+π/2) +2nπ = sin( 3x-2t+π/2).
We can consider the case at t=0, sin(3x+π/2) = sin(3x+π/2+2nπ)
OR cos(3x) = cos(3x+2nπ)
∴ n = 1 for minimum difference.
Minimum distance can be found from kx = 2π
OR x = 2π/k = 2π/3.

The wave number k = 2π/1 = 2π.
The angular frequency w = 2π/1 = 2π.
The particle at x=0, t=0 is moving up from its mean position, & the wave travels towards the positive x-axis so the equation will be:
y = 3sin(2πt – 2πx).

It is in the thylakoid membrane, in which the electron transport system occurs. Each thylakoid membrane is a closed compartment that gets protons from stroma by the b₆ or f complex. Also, thylakoid membrane is impermeable to protons.

The first electron acceptor in photosystem 1 is a Fe-S protein. It is a stable complex of iron and sulfur atoms bonded to a protein. It primarily accepts the electrons and passes onto NADP⁺.

By understanding the photolysis equation, one water molecule gives 2 hydrogen protons. So, 12 water molecules will give 24 hydrogen protons.

The scheme is called Z-scheme. This name was given due to the shape of the sequence. The transfer of electrons from PS II to NADP⁺ produces this scheme when the carries are placed in the order of the redox potential scale.