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16401.

Question : How can a good health maintained ?

Answer»

SOLUTION :BALANCED DIET, Personal hygiene, Regular EXERCISE.
Discussion
16402.

Question : How Biological evolution has taken place ?

Answer»

Solution :Evolution by natural selection in a true sense would have started when cellular forms of life with differences in metabolism capability originated on earth.
The essence of Darwinian THEORY about evolution is natural selection.
The rate of appearance of new forms is linked to the life cycle or the life span.
Microbes that divide FAST have the ability to multiply and become millions of individuals within hours.
A colony of bacteria (say A) growing on a given medium has built in variation in terms of ability to utilise a feed component.
A change in the medium composition would bring out only that part of the population (say B) that can survive under the new conditions.
In due course of time this variant population outgrows the others and APPEARS as new species.
This would happen within days.
For the same thing to happen in a fish or fowl would take million of years as life spans of these animals are in years.
Here we say that fitness of B is better than that of A under the new conditions.
Nature selects for fitness is based on CHARACTERISTICS which are inherited.
Hence there must be a genetis basis for getting selected and to evolve.
Another way of saying the same thing is that some organisms are better adapted to survive in an otherwise hostile environment.
Adaptive ability is inherited.
It has a genetic basis.
Fitness is the END result of the ability to adapt and get selected by nature.
Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution.
Discussion
16403.

Question : How Bacillus thuringiensis provides insect resistance?

Answer»

Solution :During sporulation Bacillus thuringiensis produces CRYSTAL proteins called Delta - endotoxin whichis encoded by CRY genes . Delta -endotoxins have specific activities against the insects of the ORDERS Lepidoptera , Diptera , Coleoptera and Hymenoptera . When the insects ingestthe toxin crystals their alkaline digestive tract denaturesthe INSOLUBLE crystals making them soluble . The cry toxin then gets inserted into the gut CELL membrance and paralyzes the digestive tract . The insect then stops eating and starves to death.
Discussion
16404.

Question : How behavioural responses are achieved by animals during variation in the environment?

Answer»

Solution :(a) Desert lizards are conformer HENCE they cope with the stressful environment by behavioral adaptations:
(b) They bask in the sun and absorb HEAT when their BODY temperature drops below the comfort zone in winter.
(C) They move to shade when the ambient temperature starts increasing.
(d) Some species burrowing into the soil to hide and escape from the above-ground heat.
Discussion
16405.

Question : How are these base pairs held together in a DNA molecule? Explain the base complementarity rules. Name the scientist who framed this rule.

Answer»

Solution :(i) ATCGTACTA.
(II) With the HELP of weak hydrogen bonds.
(iii) Adenine always joins THYMINE A = T and cytosine always joins GUANINE C = G. Erwin Chargaff framed this rule.
Discussion
16406.

Question :How are the two following varieties of sugarcane different from each other'!Saccharum barberi Saccharum officinarum

Answer»

Solution : Saccharum barberi : It has POOR sugar content and YIELD.
Saccharum officiuarum : It has higher sugar contents and STEMS are thicker.
Discussion
16407.

Question : How are the histones attached to DNA molecule removed?

Answer»

Solution :HISTONES are proteins which are removed by APPLICATION of PROTEASE ENZYME.
Discussion
16408.

Question : Howarethe followingformedandinvolvedin DNApackaging in a nucleus of a cell? (i)Histoneoctomer (ii)Nucleosome (iii)chromatin

Answer»

SOLUTION :(i)Histone octamer :Histonesare positively chargedbasicproteins Histonesare rich in basicamino acids lysineandorginineboth ofwhich carry positive charge in their side chains , the Histoneproteinsare arranged to FORM a UNIT of eightmoleculescalledthehistoneoctamer.
(ii)Nucleosome : the negatively chargedDNAmoleculeis wrapped around a positively charged histone octamer to form a nuclesomeA usual nuclesome contains 200 bp of DNAholix.
(iii) chromatin : Nucleosome consitutes therepeating unit FOUND in the necledelous calledchromatin , chromation APPERS as thread- likestainedbodiesbodiesandnucleosomes in chromatin appea asa bead -on- string structurewhen viewed under the electroin microsccopre.
Discussion
16409.

Question : How are the DNA fragments separated through gel electrophoresis ex-tracted ?

Answer»

SOLUTION : The SEPARATED bands of DNA on AGAROSE GEL are cut out from the gel piece and extracted out . This STEP is known as elution. The DNA fragments are purified in this way .
Discussion
16410.

Question : How are the DNA fragments separated by gel electrophoresis visualized and separated for use in constructing recombinant DNA?

Answer»

Solution :The separated DNA fragments stained with ethidium bromide. By EXPOSURE to UV-radiation, the separated DNA become visible as orange-coloured bands. The separated bands of DNA are cut out from the AGAROSE gel and DNA is extracted from the gel PIECE by the PROCESS of elution.
Discussion
16411.

Question : How are synergid cells in chromosomal point of view?(A) Haploid(B) Diploid(C) Triploid(D) Irregular

Answer»

Haploid
Diploid
Triploid
Irregular

Answer :A
Discussion
16412.

Question : How are standing crop and biomass related to each other?

Answer»

SOLUTION :Each trophic level has a CERTAIN mass of living material at a particular time called as the standing crop.
The standing crop is measured as the mass of living organisms (BIOMASS) or the number in a unit AREA. The biomass of a species is expressed in terms of fresh or dry WEIGHT.
Discussion
16413.

Question : What are STD's ? How are they transmitted ?

Answer»

Solution :Sexually transmitted DISEASES (STD) are CALLED as Sexually transmitted INFECTIONS (STI). Normally STI are transmitted. from person to person during INTIMATE SEXUAL contact with an infected partner. Infections like Hepatitis-B and HIV are transmitted sexually as well as by sharing of infusion needles, surgical instruments, etc with infected people, blood transfusion or from infected mother to baby.
Discussion
16414.

Question : How are some microbes able to live in habitats with temperatures exceeding 100^@C ?

Answer»

Solution :• The microbes of HIGH temperature area are known as thermoacidophiles.
• They are able to survive at high temperature by Reduction in the amount of free WATER. Occurrence of branched CHAIN lipids which reduce fluidity of the CELL membrane.
Discussion
16415.

Question : How are seeds advantageous angiosperms ?

Answer»

Solution :Significance of seeds: Seeds offer the following ADVANTAGES to plants:Sincereductive processes such as pollination and fertilization are dependent on water,seed FORMATION is more dependable.
. Seeds have adaptation for dispersal to new habitats and help the species to colonize in other areas Seeds have enough food reserves to nourish seedlings until they are capable of photosynthesis on their own..
• The hard seed coat provides protection to the young embryo.
• Seeds are the product of sexual reproduction, hence they GENERATE new genetic combinations leading to variations.
Seed is the basis of our agriculture. DEHYDRATION and dormancy of mature seeds are crucial for storage of seeds, which can be used as food throughout the year and also raise crops in the next season
Discussion
16416.

Question : How are Rhizobium cultures used as biofertilisers?

Answer»

SOLUTION :By INOCULATING the LEGUME seeds with DIFFERENT stains of Rhizobium in the laboratory.
Discussion
16417.

Question : How are productivity, gross productivity, net primary productivity, and secondary productivity interrelated?

Answer»

Solution :Productivity: It is the rate of production of biomass per unit area over a period of time by plants during photosynthesis. GROSS Productivity: It is the rate of production of organic matter by green plants per unit time per unit area. NET Primary Productivity: Net primary productivity is the AVAILABLE biomass for the consumption of heterotrophs. Net primary Productivity: Gross Primary Productivity-Respiratory losses, `N_(PP) = G_(PP) - R.` Secondary Productivity: It is the rate of formation of NEW organic matter by consumers.
Discussion
16418.

Question : How are primary and secondary immune responses carried out in the human body ? Explain.

Answer»

Solution :The primary and secondary immune RESPONSES are carried out with the help of TWO special types of lymphocytes, the B-lymphocytes and the T-lymphocytes.
B-lymphocytes : These produce an army of proteins in responseto pathogens in blood. These are called antibodies. The different types of antibodies secreted are IgA, IGM, IgE and IgG. This RESPONSE by the immune system is also called the humoral immune response.
T-lymphocytes : These MEDIATE the cell-mediated immunity (CMI).The cell mediated immune response in responsible for the graft refection.
Discussion
16419.

Question : How are pills more effective than other contraceptives ?

Answer»

Solution :The pills are mainly the combination of hormones. These are to be taken daily for a period of 21 days starting within the first five days of menstrual CYCLE. After a GAP of 7 days repeat the same pattern till the female desires to prevent pregnancy. This is EFFECTIVE because of lesser side EFFECTS.
Discussion
16420.

Question : How are non medicated IUDS different from hormone releasing IUDS?

Answer»

SOLUTION :
Discussion
16421.

Question : How are mutations classified based on their effects on translation?

Answer»

SOLUTION :
Discussion
16422.

Question : How are mutations classified?

Answer»

Solution :There are two BROAD types of changes in GENETIC material. They are point mutation and chromosomal mutations. Mutational EVENTS that take place within individual genes are called gene mutations or point mutation, whereas the changes occur in STRUCTURE and number of CHROMOSOMES is called chromosomal mutation.
Discussion
16423.

Question : How are mutations and genetic code related ?

Answer»

Solution :The sudden inheritable change in the genetic material is defined as MUTATION.
It is of the following types :
(i) Point mutation : Mutation in single base pair which is REPLACED by another base pair.
A classical example of point mutation is a change of single base pair in the gene for B globin chain that results in the change of amino acid RESIDUE glulamate to VALINE. It results into a diseased condition called as sickle cell anemia.
(ii) Frameshift mutation : It is a change in the reading frame because of insertion or deletion of base pair, e.g. `"ATC GCT TAT A"`
(a) Insertion : If one or more nucleotides are added in the DNA segment it is called insertion.
If THREE or its multiple bases are added, they will not change the reading frame.
Infact they will form a protein with new amino acids.
(b) Deletion : If one or more nucleotides are removed from the DNA segment it is called deletion.
Here also, if three or its multiple bases are remove one or more amino acid from the polypeptide
Discussion
16424.

Question : How are microbial innoculants used to increase the soil fertility?

Answer»

Solution :Biofertilizers or microbial innoculants are defined perparations containing living cells or latent cells of EFFICIENTS strains of microorganisms that help CROP plants uptake of nutrients by their INTERACTIONS in the rhizosphere when applied through seed and soil. They are efficient in fixing nitrogen, solubilising PHOSPHATE and decomposing cellulose. They are designed to improve the soil fertility, PLANT growth, and also the number and biological activity of beneficent microorganisms inthe soil. They are ecofriendly organic agro inputs and are more efficients and cost effective then chemical fertilizers.
Discussion
16425.

Question : How are microbes useful in industrial production of chemicals, enzymes and other bioactive molecules ?

Answer»

Solution :MICROBES are used for commercial and INDUSTRIAL production of certain chemicals like organic acids, alcohols and enzymes. Examples of acid producers are (i) Aspergillus niger of citric acid (ii) Acetobacter aceti of ACETIC acid (iii) Clostridium butylicum of butyric acid (iv) Lactobacillus of lactic acid. Thus microbes are useful to obtain various types of acids. Yeast is used for commercial production of ethanol. Microbes are also used for production of enzymes. Lipase are used in detergent formulations and are helpful in removing oily stains from the laundry Bottled juices are clarified by the use of pectinase and proteases. Streptokinase produced by the bacterium streptococcus and modified by genetic engineering is used as a clot buster for removing clots from the blood VESSELS of patients Who have undergone myocardial infarction leading to heart attack. Cyclosporine A, that is used as an immunosuppressive agent in organ transplant patients is produced by the fungus Trichoderma polysporum. Statins produced by the yeast MONASCUS purpureus have been commercialised as blood cholesterol lowering cholesterol.
Discussion
16426.

Question : How are microbes useful in household products ?

Answer»

Solution :We use microbes or products derived from them everyday. A common example is the production of curd from milk. Microorganisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) Lactic acid bacteria GREW in milk and convert it to curd. During growth the LAB produce acids that coagulate and partially digest the milk proteins. A small amount of curd ADDED to the fresh milk as inoculum or starter contains millions of LAB. Which at suitable temperatures multiply, thus converting milk into curd which also improves its nutritional quality by increasing vitamin `B_12`In our stomach too, the LAB play very beneficial role in checking disease causing microbes. The dough which is USED for making foods such as Dosa and Idli is also fermented by bacteria. The puffed up appearance of dough is due to the production of `CO_2`gas. Similarly the dough which is used for making bread, is fermented using baker.s yeast. A number of traditional drinks and foods are also made by fermentation by the microbes. .Toddy. a traditional drink of some parts of southern INDIA is made by fermenting sap from palms. Microbes are also used to ferment fish, soyabean and bamboo shoots to make foods. Cheese is one of the oldest food items in which microbes were used. Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity COMING from the microbes used.
Discussion
16427.

Question :How are microbes useful in fermented beverages ?

Answer»

Solution :
Microbes especially yeasts have been used from time immemorial for the production of beverages like wine, BEER, whisky, brandy or RUM. For this purpose the same yeast saccharomyces cerevisiae used for bread making. This is commonly called brewer.s yeast, is used for fermenting malted cereals and FRUIT juices to produce ethanol. Depending on the type of the RAW material used for fermentation and the type of processing (with or without distillation) different types of alcoholic drinks are obtained. Wine and beer are produced without distillation whereas whisky, brandy and rum are produced by distillation of the fermented broth.
Discussion
16428.

Question :How are microbes useful in biofertilisers ?

Answer»

Solution :Environmental pollution is a major cause of concern. The USE of chemical fertilisers to meet the ever increasing demand of agricultural produce has contributed significantly to this pollution There are problems associated with the overuse of chemical fertilisers and there is a large pressure to switch to organic farming. Biofertilisers are organisms that enrich nutrient quality of the soil. The main source of biofertilisers are bacteria, fungi and cyanobacteria. The nodules on the roots of leguminous plants formed by the symbiotic association of Rhizobium. These bacteria fix atmospheric nitrogen into organic farms. Which is used by the PLANT as nutrient. Other bacteria can fix atmospheric nitrogen while free living in the soil (EXAMPLE Azospirillum and Azotobacter) thus enriching the nitrogen content of the soil. Fungi are also known to form symbiotic associations with plants (mycorrhiza). Many members of the genus Glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to ROOT borne pathogens, tolerance to salinity and drought and an overall increase in plant growth and development. Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial ENVIRONMENTS many of which can fix atmospheric nitrogen, e.g. Anabaena, Nostoc, Oscillatoria etc. In paddy fields, cyanobacteria serve as an important biofertiliser. Blue green algae also add organic matter to the soil and increase its fertility. Currently in our country, a number of biofertilisers are available commercially in the market and farmers use these regularly in their fields to replenish soil nutrients and to reduce dependence on chemical fertilisers.
Discussion
16429.

Question : How are homologous organs significant in favour of evolution?

Answer»

Solution :Presence of homologous organs in DIFFERENT groups of ORGANISMS confirms COMMON ancestry and RELATIONSHIP between different groups.
Discussion
16430.

Question : How are fishes helpful in controlling disease like malaria?

Answer»

Solution :Larvivorous FISH such as Panchex, Gambia, Haplochitus, Trichogaster, etc. FEED on the LARVAE of mosquitoes.
Discussion
16431.

Question : How are chromosomes classified based on the position of centromere ?

Answer»

Solution :Based on the position of centromere,the CHROMOSOMES are CLASSIFIED as Telocentric, Acrocentric ,Submetacentric and Metacentric.Telocentric.

Types of chromosomes based on position of centromere
(i)The centromere is found on the proximal end.
(ii)Shape-rod SHAPED .
Acrocentric
(i)Th centromere is found at the one end with a SHORT arm and long arm.
(ii)Shape -rod shaped.
submetacentric
(i)The centromere is found near the centre of the chromosome.Thus forming TWO uneqal arms .
(ii)Shape-J or L shaped.
Metacentric:
(i)The centromere occurs in the centre of the chromosome and form two equal arms.
(ii)Shape -V shaped chromosomes.
Discussion
16432.

Question : How are biofertilisers different from fertilisers such as NPK that we buy from the market? Justify the role of rhizobium as a biofertiliser.

Answer»

Solution :Today environmental pollution is a major threat due to the thoughtless use of chemicals to meet the ever increasing demands of agricultural production. Due to the overuse of chemical fertilizers there is a large-pressure to switch to organic farming using biofertilizers. Biofertilizers are organisms that enrich the nutrient quality of the soil. The main SOURCES of biofertilizers are bacteria, fungi and CYANOBACTERIA. The root nodules of LEGUMINOUS plants are formed by the symbiotic association of Rhizobium. These bacteria fix ATMOSPHERIC NITROGEN into organic forms, which is used by the plant as nutrient.
Discussion
16433.

Question : How are androgenic haploids useful in plant breeding?

Answer»

Solution :Haploids are of great value in agriculture as inbreed lines and they can be DIRECTLY produced by charomosome DOUBLING. They also provide material for genetical STUDIES. Simple segregation process in haploids makes the process EASY for selection of desired TYPES.
Discussion
16434.

Question : How are alleles of particular gene differ from each other ? Explain its significance.

Answer»

Solution :Alleles of a PARTICULAR gene differ from each other on the basis of certain changes (i.e., mutations) in the GENETIC MATERIAL (segment of DNA or RNA). Different alleles of a gene increases the variability or variation AMONG the organisms. These variations are NECESSARY for evolution and adaptations.
Discussion
16435.

Question : How are alleles of particular gene different? Explain its significance.

Answer»

Solution :Alleles of a particular gene differ from each other on the BASIS of CERTAIN changes (i.e., mutations) in the GENETIC material (segment of DNA or RNA). Different alleles of a gene INCREASE the variability or VARIATION among the organisms.
Discussion
16436.

Question : How antibodies are transferred in natural acquired passive immunity?

Answer»

SOLUTION :Antibodies that give NATURAL acquired PASSIVE IMMUNITY are passed on from mother to foetus through the placenta. This transfer is before birth. After birth, the antibodies are passed to the baby through mother's COLOSTRUM.
Discussion
16437.

Question : How and why is the bacterium Thermus aquaticus employed in recombinant DNA technology ? Explain .

Answer»

Solution :The DNA polymerase enzyme ISOLATE from Thermus aquaticus is widely used in PCR for amplification of GENE of INTEREST. This enzyme is heat STABLE and can act under the TEMPERATURE conditions used in PCR maching .
Discussion
16438.

Question : How and where chiasma is formed?

Answer»

Solution :After TETRAD formation, CROSSING over occurs in PACHYTENE stage. The non-sister chromatids of homologous pair make a contact at one or more points. These points of contact between non-sister chromatids of homologouschromosomes are CALLED chiasmata (singular-Chiasma). At chiasma, cross-shaped or X-shaped structure are formed, where breaking and rejoining of two chromatids occure. This results in reciprocal exchange of EQUAL and corresponding segments between them.
Discussion
16439.

Question : How can air pollution be controlled?

Answer»

SOLUTION :Certain measures help to remove pollutants, reduce their PRESENCE or prevent their entry into the atmosphere.
• Trees are the best remedy for urban particulate and gaseoupollution.
• Forests act as carbon sinks and lungs of the planet.
• Catalytic converters in vehicles help to reduce polluting gases DRASTICALLY.
• Diesel exhaust filters in automobiles cuts particulates.
• Electrostatic precipitators reduce release of industrial pollutants.
• Cost effective air pollution treatment SYSTEMS like indoor plants and high performance biofilters can improve indoor air quality.
Discussion
16440.

Question : How AIDS patient fail to develop immunity?

Answer»

Solution :AIDS is caused by HUMAN Immuno Deficiency Virus(HIV).It selectively INFECTS helper T cells.The INFECTED helper T cells will not stimulate antibody production by B-cells resulting in loss of natural defence against viral infection.
Discussion
16441.

Question : How agrochemicals affect ecosystem?

Answer»

Solution :• May kill beneficial bacteria and soil organisms.
• Can cause eutrophication in water BODIES.
• Affect aquatic animals and their productivity.
• Pesticide CONTAINING water, even in trace quantities is unfit for human consumption.
• Particles (aerosols) and residues of these chemicals cause air pollution.
• INHALATION of contaminated air can cause respiratory problems.
• Consumption can lead to poisoning, side effects and after effects.
• Chemicals can cause skin rashes and IRRITATION of eyes.
• Many of these chemicals are reported to be carcinogenic.
• They can trigger hormonal disorders and neurotoxicity.
• Beneficial INSECTS and animals can be affected.
Discussion
16442.

Question : How Agarose Gel Electrophoresis is performed?

Answer»

Solution :Agarose Gel Electrophoresis is used mainly for the purification of specific DNA fragments. Agarose is CONVENIENT for SEPARATING DNA fragments ranging in size from a few hundred to about 20000 base pairs. Polyacrylamide is preferred for the purification of smaller DNA fragments. The gel is complex network of polymeric molecules. DNA molecule is NEGATIVELY charged molecule-under an electric field DNA molecule migrates through the gel. The electrophoresis is frequently performed with marker DNA fragments of Known size which allow accurate size determination of an UNKNOWN DNA molecule by interpolation. The advantages of agarose gel electrophoresis are that the DNA bands can be readily detected at high sensitivity. The bands of DNA in the gel are stained with the dye Ethidium Bromide and DNA can be detected as visible flurescence illuminated in UV light will give organe fluorescense, which can be photographed.
Discussion
16443.

Question : How ADA deficiency cured by gene therapy?

Answer»

Solution :Lymphocytes from the blood of the patient are grown in a culture OUTSIDE the BODY. A functional ADA C-DNA (using a retroviral vector) is then introduced into these lymphocytes which are subsequently returned to the patients. These CELLS are immortal, so the patient REQUIRES periodic infusions of genetically modified lymphocytes.
Discussion
16444.

Question : How a national park can be defined?

Answer»

Solution :ational PARK is a natural HABITAT that is notified by the STATE government to be constituted as a to its cological, faunal, floral, GEOMORPHOLOGICAL, or zoological association want the activities permitted by the Chief WILDLIFE Warden of the state
Discussion
16445.

Question : How 5' of DNA differ from its 3'?

Answer»

Solution :The 5. of DNA refers to the carbon in the sugar to which phosphate `(PO_(4)V)`FUNCTIONAL group is attached. The 3. of DNA referS to the carbon in the sugar to which a HYDROXYL (OH) group is attached.
Discussion
16446.

Question : Houseflies act as mechanical carriers and transmit the parasite from faeces of infected person to food and food products. This results

Answer»

malaria
elephantiasis
amoebiasis
chikungunya

Answer :C
Discussion
16447.

Question : House sparrow can fly for short distances only because of the absence of

Answer»

WHITE muscles
Proper WING span
Pneumatic bones
Red muscles.

Solution :N//A
Discussion
16448.

Question : Hotspots are priority areas for in situ conservation. The key criteria for determining a hotspot is/are

Answer»

location in developed/undeveloped country
vicinity to the sea
to habitat NUMBER of endemic SPECIES and DEGREE of threat
all of these

Answer :C
Discussion
16449.

Question : Hot spots of Biodiversity are area :

Answer»

where MAXIMUM number of,FAUNA is found.
where maximum number of FLORA is found.
where maximum diversity is found.
where maximum natural RESOURCES is found.

Answer :C
Discussion
16450.

Question : Hot spots are the regions of exceptionally high biodiversity. But they have become regions of accidental habitat loss too. Name the three hotspots of our country. Why are they called 'biodiversity hotspots' ?

Answer»

Solution :Western Ghats and SRI lanka, Indo-Burma, Himalaya CALLED .biodiversity hot SPOTS. as they show
(i) High level of species richness
(ii) High degree of ENDEMISM
(iii) Under constant threat of extinction.
Discussion