Biology Question Bank – 24 MCQs on “General Biology” – Answered!

(b) eugenics

(c) euphenics

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(d) ethnology.

Answer and Explanation:

1. (b): Eugenics is the study of methods of improving the quality of human populations by the application of genetic principles. Euthenics deals with human improvement through altering external factors such as education and the controllable environment. Ethnology compares and analyses the origins, distribution, technology, religion, language and social structure of the racial or national divisions of humanity. Euphenics aims to improve the outcome of a genetic disease by altering the environment.

2. The 1992 Nobel Prize for medicine was awarded to Edmond H. Fischer and Edwin G. Krebs for their work concerning

(a) reversible protein phosphorylation as a biological regulation mechanism

(b) isolation of the gene for a human disease

(c) human genome project

(d) drug designing involving inhibition of DNA synthesis of the pathogen.

Answer and Explanation:

2. (a): Dr Edmond H. Fischer (born April 6, 1920) is a Swiss-American biochemist. He and his collaborator Edwin G. Krebs were awarded the Nobel Prize in Physiology or Medicine in 1992 for describing how reversible phosphorylation works as a switch to activate proteins and regulate various cellular processes.Together Krebs and Fischer decided to see if they could determine the mechanism by which the inactive phosphorylase b was converted to phosphorylase a. Based on the work of Coris, Krebs and Fischer believed that a prosthetic group, which was some form of AMP, was involved in the activation of phosphorylase b. However, they soon discovered that the interconversion of phosphorylase was the result of an enzyme-catalyzed phosphorylation- dephosphorylation reaction.

The discovery of protein kinase established the existence of the first protein kinase cascade in which one kinase activates another kinase. It also stimulated work on the protein phosphorylation process in general. Soon it became evident that reversible protein phosphorylation was a fundamental biological mechanism

3. For the first time, the bacteria were observed by

(a) Robert Koch

(b) A.V. Leeuwenhoek

(c) W.H. Stanley

(d) Louis Pasteur.

Answer and Explanation:

3. (b): Bacteria are moneran prockaryotic microorganisms that are basically unicellular, devoid of chlorophyll a, possess nucleoid attached to mesosome, and food reserve in the form of glycogen.

They were first seen by Dutch merchant and amateur microscopist Leeuvvenhoek (1676) in stored rain water and tartar scraped from teeth. He named them animalcules (small animals). Linnaeus (1758) called them vermes. The term bacterium was coined by Ehrenberg in 1828.

4. The tailed Bacteriophages are

(a) motile on surface of bacteria

(b) non-motile

(c) motile on surface of plant leaves

(d) actively motile in water.

Answer and Explanation:

4. (a): Bacteriophage are the viruses which infect bacteria. The tail plate and the caudal fibres of bacteriophage anchor the phage virion to host cell wall at a specific site.

5. AIDS disease was first reported in

(a) USA

(b) France

(c) Russia

(d) Germany.

Answer and Explanation:

5. (a): Acquired Immune Deficiency Syndrome, or AIDS, was first reported in mid-1981 in the United States; it is believed to have originated in sub-Saharan Africa. The human immunodeficiency virus (HIV) that causes AIDS was identified in 1983, and by 1985 tests to detect the virus were available.

The credit for discovering the AIDS virus is jointly shared by Dr. Robert Gallo, a researcher at the National Cancer Institute, and Luc Montagnier of the Pasteur Institute, France.

6. H.J. Muller had received Nobel Prize for

(a) his studies on Drosophila for genetic study

(b) proving that the DNA is a genetic material

(c) discovering the linkage of genes

(d) discovering the induced mutations by X-rays.

Answer and Explanation:

6. (d): Induced Mutations are mutations that are produced in response to specific external factors and chemicals. Muller (I927) was the first to produce induced mutations in Drosophila by exposing them to X-rays. The specific factors and chemicals of the environment that induce mutations are called mutagens. He got noble prize for this.

7. Passive immunity was discovered by

(a) Jonas E. Salk

(b) A. Flemming

(c) Edward Jenner

(d) L, Pasteur.

Answer and Explanation:

7. (c): When antibodies produced in one body (human or animal) are transferred to another body to induce protection against disease, it is known as passive immunity. Passive immunity was discovered by Edward Jenner when he discovered vaccination for small pox.

8. Maximum absorption of light occurs in the region of

(a) 1000 – 1200 nm

(b) 1500 – 2000 nm

(c) 400 – 700 nm

(d) 700 – 900 nm.

Answer and Explanation:

8. (c): The visible range of light is 400 to 700 nm. The visible light has a wavelength between 390-760 nm. Blue (430-470 nm) and red (660-760 nm) of the light spectrum are the most effective in photosynthesis. Chlorophyll-a exists in two forms, one form with an absorption maximum at 673 nm and the other with an absorption maximum at 703 nm.

9. The term ‘Meiosis’ was given by

(a) A. Flemming

(b) Farme and Moore

(c) Johansen

(d) Knoll and Ruska.

Answer and Explanation:

9. (b): The term meiosis was introduced by J.B. Farme and Moore in 1905. Meiosis (reduction division) is a type of nuclear division that give rise to four reproductive cells (gametes) each with half the chromosome number of the parent cell. Two consecutive divisions occur.

In the first division homologous chromosomes become paired and may exchange genetic material before moving away from each other into separate daughter nuclei. This is the actual reduction division because each of the two nuclei so formed contains only half of the original chromosomes. The daughter nuclei then divide by mitosis and four haploid cells are produced.

Sir Alexander Fleming (6 August 1881 – 11 March 1955) was a Scottish biologist and pharmacologist. His best- known achievements are the discovery of the enzyme lysozyme in 1922 and isolation of the antibiotic substance penicillin from the fungus Pemcilliumnotatum in 1945, for which he shared a Nobel Prize with Florey and Chain.

10. Warm ocean surge of the per current recurring every 5 to 8 years or so in the East Pacific of South America is widely known as

(a) EI Nino

(b) Aye Aye

(c) Magnox

(d) Cull stream.

Answer and Explanation:

10. (a): El Nino is a shift in ocean temperatures and atmospheric conditions in the tropical Pacific that disrupts weather around the world. It is a poorly understood recurrent climatic phenomenon that primarily affects the Pacific coast of South America, but has dramatic impacts on weather patterns all over the world. Pronounced ‘El-Ninyo’, it means ‘the boy’ in Spanish and was named so by Peruvian fishermen after the Christ child since its effects are generally first felt around Christmas.

It is a periodic warming of the Pacific Ocean that leads to terrible extremes of weather. The precise causes, intensity, and longevity of El Nino are not very well understood. The warm El Nino phase typically lasts for 8-10 months or so.

The Aye-aye is a strepsirrhine native to Madagascar that combines rodent-like teeth with a long, thin middle finger to fill the same ecological niche as a woodpecker. It is the world’s largest nocturnal primate, and is characterized by its unique method of finding food; it taps on trees to find grubs, then gnaws holes in the wood and inserts its elongated middle finger to pull the grubs out.

Magnox is a now obsolete type of nuclear power reactor which was designed and used in the United Kingdom, and exported to other countries, both as a power plant, and, when operated accordingly, as a producer of plutonium for nuclear weapons. The name magnox comes from the alloy used to clad the fuel rods inside the reactor.

11. Koch’s postulates are not applicable to

(a) diptheria

(b) cholera

(c) TB

(d) leprosy.

Answer and Explanation:

11. (d): Koch’s postulates (or Henle-Koch postulates) are four criteria designed to establish a causal relationship between a causative microbe and a disease. The postulates were formulated by Robert Koch and Friedrich Loeffler in 1884 and refined and published by Koch in 1890. Koch applied the postulates to establish the etiology of anthrax and tuberculosis, but they have been generalized to other diseases. Koch’s postulates are –

(i) The microorganism must be found in all organisms suffering from the disease, but not in healthy organisms.

(ii) The microorganism must be isolated from a diseased organism and grown in pure culture.

(iii) The cultured microorganism should cause disease when introduced into a healthy organism.

(iv) The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

Koch’s postulates do not apply to viruses because they cannot be cultured in artificial media. Hence leprosy, which is caused by virus, is an exception to Koch’s postulates. This is because the virus is dependent on a live cell for reproduction.

12. Viruses are living, because

(a) they multiply in host cells

(b) carry anaerobic respiration

(c) carry metabolic activity

(d) cause infection.

Answer and Explanation:

12. (a): Virus is a particle that is too small to be seen with a light microscope or to be trapped by filters but is capable of independent metabolism and reproduction within a living cell. Outside its host cell a virus is completely inert. A mature virus (a virion) ranges in size from 20 to 400 nm in diameter.

It consists of a core of nucleic acid (DNA or RNA) surrounded by a protein coat. Some (the enveloped viruses) bear an outer envelope consisting of proteins and lipids. Inside its host cells the virus intiates the synthesis of viral proteins and undergoes replication. The new virions are released when the host cell disintegrates. Viruses are parasites of animals, plants, and some bacteria.

13. During viral infection the protein formed in host cells to resist is

(a) interferon

(b) antitoxin

(c) antibody

(d) histone.

Answer and Explanation:

13. (a): Interferon is any of a number of proteins that increase the resistance of a cell to attack by viruses by unmasking genes that synthesize antiviral proteins. In humans, three groups of interferons have been discovered: a-interferon’s from white blood cell; (3-interferons from connective tissue fibroblasts; and y-interferons from lymphocytes.

14. Due to discovery of which of the following in 1980, the evolution was termed as RNA world

(a) m-RNA, t-RNA, r-RNA synthesise proteins

(b) in some viruses RNA is genetic material

(c) RNA has enzymatic property

(d) RNA is not found in all cells.

Answer and Explanation:

14. (c): RNA world was coined by Walter Gilbert in 1986. He pointed out that RNA could perform as a catalyst. RNA can store information like DNA and catatyze reactions like proteins (enzymes), may have supported cellular or precellular life. RNA enzymes or ribozymes play vital or roles for protein synthesis and catalyze simple chemical reactions.

15. Which one of the following discoveries resulted in a Nobel Prize?

(a) X-rays induce sex-linked recessive lethal mutations

(b) eytoplasmic inheritance

(c) recombination of linked genes

(d) genetic engineering

Answer and Explanation:

15. (a): H.J. Muller for the first time demonstrated X- rays induced sex linked recessive lethal mutations in Drosophila. The method for detecting sex-linked lethal mutation is known as CLB method. This method involves use of CLB stock which carries an/a (i) inversion in heterozygous state to work as crossover suppressor (C),
(ii) recessive lethal (L) on X-chromosome in heterozygous state and (iii) dominant marker, banned eye (B).

16. The term “antibiotic” was coined by

(a) Edward Jenner

(b) Louis Pasteur

(c) Selman Waksman

(d) Alexander Fleming

Answer and Explanation:

16. (c): The term ‘antibiotic’was introduced by Selman Waksman (a Noble Laureate) in 1942. He defined antibiotic to be a substance produced by a micro-organism which in low concentration is antagonistic to the growth of other micro-organism. In 1928, Fleming found destruction of cultures of Staphylococcus aureus in the region of contamination by Penicillium notatum.

Vaccination was introduced by Edward Jenner who found in 1790 that a healthy boy inoculated with mild cow pox could remain protected from small pox. Louis Pasteur (1879) accidentally observed that on inoculation weakened or attenuated pathogen (which could not produce the disease) of cholera produced immunity to the disease.

17. Flagella of prokarvotic and eukaryotic cells differ in

(a) type of movement and placement in cell

(b) location in cell and mode of functioning

(c) microtubular organization and type of movement

(d) microtubular organization and function.

Answer and Explanation:

17. (c): Flagella of prokaryotes and eukaryotes differ in microtubular organization and type of movement. Prokaryotes have simple flagella without microtubules. They are threads of single protein flagella whereas eukaryotes have complex cilia and flagella which consist of microtubules arranged in an outer ring of nine pairs surrounding one central pair (i.e. 9 + 2 arrangements). Microtubules are involved in the movement of cilia and flagella. Microtubules are composed of tubular protein.

18. Recently Govt, of India has followed mixing of alcohol in petrol. What is the amount of alcohol permitted for mixing in petrol?

(a) 2.5%

(b) 10-15%

(c) 10%

(d) 5%.

Answer and Explanation:

18. (d): According to Union Petroleum Minister, Mr. Ram Naik, five percent of ethanol obtained from molasses produced by sugar mills, will be mixed in the petrol for meeting energy needs.

19. The most abundant element present in the plants is

(a) carbon

(b) nitrogen

(c) manganese

(d) iron.

Answer and Explanation:

19. (a): Analysis of plant ash shows that about 92 mineral elements are present in different plants. Out of these, 30 elements are present in each and every plant and rests are in one or other plants. Out of these 30 elements, 16 elements are necessary for plants and are called essential elements, which are as: C, H, O, N, P, S, K, Mg, Ca, Fe, Cu, B, Zn, Mn, Mo and CI. The concentration of C and O is 45%, N is 1.5%, Mn is 0.005% and Fe is 0.01%.

20. Photo synthetically active radiation (PAR) represents the following range of wavelength:

(a) 500- 600 nm

(b) 450-950 nm

(c) 340-450 nm

(d) 400-700 nm.

Answer and Explanation:

20. (d): To understand quantitatively how light affects the rate of photosynthesis, we must first examine how much light energy sunlight provides. At the upper boundary of the atmosphere and at the earth’s mean distance from the sun, the total irradiance is 1360 J m2 s1 (the solar constant), which includes ultraviolet and infrared wavelengths.

As this radiation passes through the atmosphere to the earth’s surface, much energy is lost by absorption and scattering caused by water vapor, dust, CO2, and ozone, so that only about 900 J m-2 s-1 reach plants, depending on elevation, time of day, latitude, and other factors.

Of this, about half is in the infrared, roughly 5 percent in the ultraviolet, and the rest (approximately 400 J m-2s-1) has wavelengths between 400 and 700 nm capable of causing photosynthesis, called photosynthetically active radiation, PAR. The actual amount of radiant energy in the PAR range varies with atmospheric conditions, depending mainly on absorption of infrared radiation by atmospheric water vapor on cloudy days.

21. A self-fertilizing trihybrid plant forms

(a) 8 different gametes and 64 different zygotes

(b) 4 different gametes and 16 different zygotes

(c) 8 different gametes and 16 different zygotes

(d) 8 different gametes and 32 different zygotes.

Answer and Explanation:

21. (a): The genotype of trihybrid self fertilizing plant would be AaBbCc. Now the gametes form will be 2-n = the no. of heterozygosity, which is three in this case. 23 = 8. Hence gametes will be 8. The gametes formed will be ABC, abc, ABc, aBc, Abe, AbC, aBC, abC. The zygotes formed will be gametes = 82 = 64.

22. Evolutionary history of an organism is known as

(a) ontogeny

(b) phylogeny

(c) ancestry

(d) paleontology

Answer and Explanation:

22. (b): Phylogeny is the evolutionary history of an organism or group of related organisms. Ontogeny is the developmental course of an organism from the fertilized egg through to maturity.

It has been suggested that “ontogeny recapitulates phylogeny”, i.e. the stages of development, especially of the embryo, reflect the evolutionary history of the organism. Palaeontology is the study of extinct organisms, including their structure, environment, evolution, and distribution, as revealed by their fossil remains. Ancestry refers to a persons’s ethnic origin or descent.

23. The living organisms can be unexceptional distinguished from the non-living things on the basis of their ability for

(a) interaction with the environment and progressive evolution

(b) reproduction

(c) growth and movement

(d) responsiveness to touch.

Answer and Explanation:

23. (b): Reproduction is the ability of only living organisms to produce offsprings. Their ability is not seen in non-living things.

24. Which of the following is an example of negative feedback loop in humans?

(a) secretion of tears after falling of sand particles into the eye

(b) salivation of mouth at the sight of delicious food

(c) secretion of sweat glands and constriction of skin blood vessels when it is too hot

(d) constriction of skin blood vessels and contraction of skeletal muscles when it is too cold.

Answer and Explanation:

24. (d): Negative feedback is a type of feedback in which the system responds in an opposite direction to the perturbation. It is a process of feeding back to the input a part of a system’s output, so as to reverse the direction of change of the output. This tends to keep the output from changing, so it is stabilizing and attempts to maintain constant conditions.

This often results in equilibrium (in physical science) or homeostasis (in biology) such that the system will return to its original setpoint automatically. Examples of the use of negative feedback to control its system are: thermostat control, phase-locked loop, hormonal regulation, and temperature regulation in animals.