General Science Questions (MCQs) for Competitive Examinations

Notes:
Muscle fatigue refers to the decline in muscle force generated over time. Several factors contribute to muscle fatigue, the most important being lactic acid accumulation. Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2.

Notes:
Sea hares are molluscs. They belong to Phylum Mollusca and Class Gastropoda like snails. Like many other sea slugs (Subclass Opistobranchia), sea hares lack external shells as adults. Sea hares belong to Order Anaspidea.

Notes:
The mitochondria is called the powerhouse of the cell because it is responsible for producing most of the cell’s energy, or adenosine tri-phosphate (ATP). In addition to supplying cellular energy, mitochondria are involved in other tasks, such as signaling, cellular differentiation, and cell death, as well as maintaining control of the cell cycle and cell growth.

Notes:
The first observations of intracellular structures that probably represented mitochondria were published in the 1840s. Richard Altmann, in 1890, established them as cell organelles and called them “bioblasts”. The term “mitochondria” was coined by German microbiologist Carl Benda in 1898.

Notes:
Wolffia is a genus of 9 to 11 species which include the smallest flowering plants on Earth. Commonly called water-meal or duckweed, these aquatic plants resemble specks of cornmeal floating on the water. Wolffia species are free-floating thalli, green or yellow-green, and without roots. The flower is produced in a depression on the top surface of the plant body. It has one stamen and one pistil.

Notes:
Fungi cannot make their own food like plants can, since they do not have chloroplasts and cannot carry out?photosynthesis. Fungi are more like animals because they are?heterotrophs,?as opposed to autotrophs, like plants, that make their own food. Fungi have to obtain their food, nutrients and glucose, from outside sources.

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.

Notes:
In eukaryotic (with nucleus) cells, the vast majority of DNA is found in the nucleus as discrete bodies called chromosomes. The exception to this being the small amount of DNA found in organdies outside the nucleus (mitochondria and chloroplasts). In human cells, more than 99% of the total DNA is nuclear genomic DNA and the remainder mitochondrial.

Notes:
During the process of photosynthesis, light penetrates the cell and passes into the chloroplast. The light energy is intercepted by chlorophyll molecules on the granal stacks. Some of the light energy is converted to chemical energy. During this process, a phosphate is added to a molecule to cause the formation of ATP.

Notes:
Universal donor is a person who is type O in the ABO blood group system and negative for RhD blood group antigen and can donate blood to all recipients. O- blood type doesn’t have antigen for A or B and Rh antigen on the surface of its RBCs. Because of the absence of Rh factor, O- blood type can be given to patients of either Rh type.