General Science Questions (MCQs) for Competitive Examinations

Notes:
Bulbs are modified stems of some plants. The stem is modified to be a storage organ where the plant stores its reserve materials which it would use in times of need. It has a modified flower bud or other growth point that is surrounded by modified, fleshy leaves that are referred to as scales. Onion is the best example of bulb.

Notes:
Frogs that spend the coldest times of the year inside of the mud or within rotten heaps of leaves during hibernation receive their necessary oxygen through their skin. This is referred to as cutaneous gas exchange. They use their skin to soak in the oxygen their bodies require. Outside of hibernation period, frogs usually respire using their lungs.

Notes:
Water is transported through the plant in Xylem vessels, these begin in the roots and end in the leaves of the plant. Water is transported through a combination of “Transpirational pull” and capillary action that produces root pressure.

Notes:
Buccal cavity (oral cavity) refers to the mouth cavity: the beginning of the alimentary canal, which leads to the pharynx and (in vertebrates) to the oesophagus. It is part of the digestive system. In mammals it contains the tongue and teeth, which assist in the mechanical breakdown of food, and the openings of the salivary glands.

Notes:
Fermentation is the process by which complex organic compounds, such as glucose, are broken down by the action of enzymes into simpler compounds in the absence of oxygen (anaerobic). Yeasts can convert sugars to alcohol and carbon dioxide by fermentation. Fermentation is used to produce wine, beer, yogurt and other products.

Notes:
Alveoli are an important part of the respiratory system whose function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream. These tiny, balloon-shaped air sacs sit at the very end of the respiratory tree and are arranged in clusters throughout the lungs. Alveoli are tiny balloon shaped structures and are the smallest passageway in the respiratory system.

Notes:
Potatoes are examples of tubers : the swollen ends of stolons that may store starch. It is a stem because it has many nodes called eyes with spaces between eyes known as internodes. Potato tubers develop at the end of swollen underground stem structures, rhizomes.

Notes:
Babies breathe much faster than older children and adults. A newborn’s normal breathing rate is about 30-60 times each minute. This may slow to 20 to 40 times per minute when the baby is sleeping. The pattern of breathing in a baby may also be different. A baby may breathe fast several times, then have a brief rest for less than 10 seconds, then breathe again.

Notes:
Technically, the largest organ in the body is the liver. Liver is also the heaviest organ, with an average of 1.6 kilograms (3.5 pounds). The largest organ ‘of’ the body is the skin (the skin is ‘outside’ the body).

Notes:
An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. When excessive amounts of acids are produced in the stomach the natural mucous barrier that protects the lining of the stomach can damage the esophagus in people with acid reflux. Antacids contain alkaline ions that chemically neutralize stomach gastric acid, reducing damage and relieving pain.