General Science Questions (MCQs) for Competitive Examinations

Notes:
Magnetite (Fe3O4) typically contains about 70% iron by weight. It is black in color and strongly magnetic. Hematite (Fe2O3) contains about 60–70% iron. Limonite contains 35–50% iron. Siderite (FeCO3) contains about 48% iron. Magnetite is widely mined due to its high iron concentration compared to other ores.

Notes:
Second statement is wrong because wrought iron is more ductile compared to cast iron

Notes:
The stapes or stirrup is a bone in the middle ear of humans which is involved in the conduction of sound vibrations to the inner ear. The stapes transmits sound vibrations from the incus, another little bone in the middle ear, to the oval window adjacent to the inner ear. The stapes is the smallest bone in the body.

Notes:
Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae (whites of the eyes), and other mucous membranes caused by hyperbilirubinemia. Concentration of bilirubin in blood plasma does not normally exceed 1 mg/dL (>17?mol/L). A concentration higher than 1.8 mg/ dL (>30?mol/L) leads to jaundice. Jaundice is often seen in liver disease such as hepatitis or liver cancer.

Notes:
Veins carry the deoxygenated blood from different parts of the body to the heart. There are two main veins that carry out this job. The superior vena cava carries deoxygenated blood from head, neck, thorax and hands to the right atrium of our heart. The inferior vena cava carries deoxygenated blood from legs, pelvic region and abdominal organs to the right atrium of our heart. Among the veins, only pulmonary vein carries oxygenated blood.

Notes:
Tamarind tree (Tamarindus indica), Ashoka tree (Saraca Indica), Indian Coral tree (Erythrina Indica) have ‘Indica’ common in their botanical names. In biology/taxonomy, if a species originates in India, its scientific name sometimes includes “Indica”.

Notes:
Trypsin is an enzyme that helps us digest protein. In the small intestine, trypsin breaks down proteins, continuing the process of digestion that began in the stomach. It may also be referred to as a proteolytic enzyme, or proteinase. Trypsin is produced by the pancreas in an inactive form called trypsinogen. The trypsinogen enters the small intestine through the common bile duct and is converted to active trypsin.

Notes:
A typical adult human stomach will secrete about 1.5 liters of gastric acid daily. The best-known component of gastric juice is hydrochloric acid, the secretory product of the parietal, or oxyntic cell. It is known that the capacity of the stomach to secrete HCl is almost linearly related to parietal cell numbers.

Notes:
The Theory of Evolution was developed by Charles Darwin (1809-1882). It states that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual’s ability to compete, survive, and reproduce. The theory gained general scientific acceptance after Darwin published On the Origin of Species in 1859.

Notes:
New born babies and children normally breathe faster than older children and adults. Their respiratory rate is about 30-60 breaths per minute. The respiratory rate for the different age-categories of children is:-6-12 months: 24-30; 1-5 years: 20-30; 6-12 years: 12-20.