General Science Questions (MCQs) for Competitive Examinations

Notes:
Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes. They are the only nitrogen-fixing bacteria living in a symbiotic relationship with legumes. Common crop and forage legumes are peas, beans, clover, and soy.

Notes:
Males carry two different types of chromosomes (XY) while the females carry two chromosomes of single type X and (XX). An XY combination produces a boy baby and an XX combination produces a girl baby. Thus, males are responsible for the determination of the sex of the child.

Notes:
The process of photosynthesis occurs when green plants use the energy of light to convert carbon dioxide (CO2) and water (H2O) into carbohydrates. Light energy is absorbed by chlorophyll, a photosynthetic pigment of the plant, while air containing carbon dioxide and oxygen enters the plant through the leaf stomata.

Notes:
Carbon monoxide inhibits the blood’s ability to carry oxygen to body tissues including vital organs such as the heart and brain. When CO is inhaled, it combines with the oxygen carrying haemoglobin of the blood to form carboxy-haemoglobin (COHb). Once combined with the Haemoglobin, that haemoglobin is no longer available for transporting oxygen.

Notes:
The yolk sac is a membranous sac attached to an embryo, providing early nourishment. It functions as the developmental circulatory system of the human embryo, before internal circulation begins. It carries out transfer of nutrients in weeks 2 and 3 when the uteroplacental circulation is established

Notes:
Casein-Lactose protein-sugar pair is present in milk. Normal bovine milk contains 30-35 grams of protein per litre of which about 80 percent is arranged in casein micelles. Casein is present in milk, but it’s not a milk sugar like lactose. Instead, casein is one of the proteins found in milk. Unlike lactose, which causes an intolerance, these proteins in milk are what’s responsible for a milk allergy, according to Food Allergy and Research Education.

Notes:
The main source of atmospheric free oxygen is photosynthesis, which produces sugars and free oxygen from carbon dioxide and water. The organisms that carry out photosynthesis include the plant life of the land areas as well as the phytoplankton of the oceans.
6CO2 + 6H2O + energy —> C6H12O6 + 6O2

Notes:
Pneumonia is a bacterial disease caused by Streptococcus pneumoniae, a Gram-positive bacterium. It lives in the noses and throats of healthy people and can enter lungs through inhalation. Other important Gram-positive causes of pneumonia are Staphylococcus aureus and Bacillus anthracis.

Notes:
Microorganisms or decomposers such as bacteria and fungi help in the process of recycling of nutrients by decomposing various dead organisms such as plants and animals to form humus. Humus is highly nutritious and rich in minerals and microbes vital for healthy plant growth.

Notes:
Fructose, or fruit sugar, is a simple ketonic monosaccharide found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is a 6-carbon polyhydroxyketone with chemical formula of C6H12O6.