General Science Questions (MCQs) for Competitive Examinations

Notes:
Bohr’s model of atom cannot explain spectrum of atoms containing more than one electron. Also, it cannot explain the Zeeman effect i.e. splitting of spectral line in presence of magnetic field. It also fails to explain Stark effect i.e. splitting of spectral line in presence of electric field.

Notes:
Mitochondria is an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It is for this reason that mitochondria are often referred to as the powerhouses of the cell mitochondria also play a key role in the ageing process as well as in the onset of degenerative disease.

Notes:
The transition from dormancy to germination in seeds is a key physiological process during the lifecycle of plants. Abscisic acid (ABA) is the sole plant hormone known to maintain seed dormancy. It acts through a gene expression network involving the transcription factor Abscisic Acid Insensitive 3 (ABI3).

Notes:
Both polio and chicken pox are caused by virus. Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus; while, Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV).

Notes:
Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis. The vaccine was originally developed from Mycobacterium bovis which is commonly found in cows. It is on the World Health Organization’s List of Essential Medicines, the most effective and safe medicines needed in a health system.

Notes:
The urinary bladder is a hollow muscular organ that collects and stores urine from the kidneys before disposal by urination. In humans, the bladder is a hollow muscular organ situated at the base of the pelvis. Urine enters the bladder via the ureters and exits via the urethra.

Notes:
The term fish is most strictly used to describe any animal with a backbone that has gills throughout life and has limbs, if any, in the shape of fins. Many types of aquatic animals commonly referred to as fish are not fish in this strict sense; examples include shellfish, cuttlefish, starfish, crayfish and jellyfish.

Notes:
In the blood the key minerals are iron, copper, zinc, sodium, potassium, calcium and magnesium. Minerals constitute important part of blood plasma that constitutes almost 55% of blood. In the blood, iron is found in larger amounts than any other mineral.

Notes:
Meibomian glands are the tiny oil glands which line the margin of the eyelids (the edges which touch when the eyelids are closed). These glands secrete oil which coats the surface of our eyes and keeps the water component of our tears away from evaporating (drying out). Together, the water and the oil layer make up the tear film.

Notes:
Entomology, branch of anthropology and study of zoology, deals with the scientific study of insects. The Greek word entomon, meaning “notched,” refers to the segmented body plan of the insect. The zoological categories of genetics, taxonomy, morphology, physiology, behaviour, and ecology are included in this field of study.