Biology MCQs

Notes:
A molecule whose interaction with water and other polar substances is more thermodynamically favorable than its interaction with oil or other hydrophobic solvents is called a hydrophilic molecule. Sugar, salt, starch, and cellulose are examples of hydrophilic molecules.

Notes:
During hibernation in winter, toads or frogs spend the time tucked away deep in the soil, in the mud underwater or hidden amidst foliage or rotting plants. Outside of times of hibernation, they usually take in oxygen via the air, employing their lungs. However, during hibernation, they receive their necessary oxygen through their permeable skin. This is referred to as cutaneous gas exchange.

Notes:
Plant wilting occurs after excessive loss of water by transpiration and lesser absorption. i.e. rate of transpiration exceeds rate of water absorption. On a hot day, plants transpire heavily and cannot absorb water speedily to keep pace with transpiration loss, even when there is enough water.

Notes:
Nitrogen (N), Phosphorus (P) and Potassium (K) are considered as the three essential or primary nutrients for plants. Together they make up the trio known as ‘NPK’. Other important nutrients are Calcium, Magnesium and Sulphur.

Notes:
Gastric acid, gastric juice or stomach acid, is a digestive fluid, formed in the stomach. It is composed of hydrochloric acid (HCl), potassium chloride (KCl) and sodium chloride (NaCl). Gastric acid plays a key role in digestion of proteins, by activating digestive enzymes.

Notes:
The plants, which have hard and thick brown stem and are very tall are called trees. The stems have branches in upper part and much above the ground. For example, mango, neem. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants for sunlight.

Notes:
Cause of night blindness is a deficiency of retinol, or vitamin A, found in fish oils, liver, dairy products, vegetable and fruits yellow in colour. Nyctalopia also called “Night Blindness” is a condition making it difficult or impossible to see in relatively dim light. To over come deficiency of vitamin-A, one needs to feed of food products rich in carotene which is used in synthesis of vitamin-A is liver.

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It is during the pupa or cocoon stage that the silkworm yields the fibre of commercial use. As the silkworm prepares to pupate, it spins a protective cocoon. About the size and color of a cotton ball, the cocoon is constructed from one continuous strand of silk, perhaps 1.5 km long (nearly a mile). The silk cocoon serves as protection for the pupa.

Notes:
Most species of Euglena have photosynthesizing chloroplasts within the body of the cell, which enable them to feed by autotrophy (making energy-containing organic molecules from inorganic raw material through the use of an energy source such as sunlight), like plants. However, they can also take nourishment heterotrophically (making use of food that comes from other organisms in the form of fats, carbohydrates, and proteins), like animals. So Euglena have features of both animals and plants.

Notes:
Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of pathogens, such as viruses, bacteria, parasites, or tumor cells. Interferon synthesis occurs primarily in response to viral single-stranded or double stranded RNA that are either the genetic material of RNA viruses or a product of viral transcription. Interferons are named for their ability to “interfere” with viral replication by protecting cells from virus infections.