The density of a population in a given habitat during a given period fluctuates due to changes in :
(A) Natality
(B) Emigration
(C) Immigration
(D) Mortality
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Read the following paragraph carefully and answer the given questions.
Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer (type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes. For determining the cause of allergy, the patient is exposed to or injected with very small doses of possible allergens, and the reactions studied. The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy. Heroin, commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound. This is obtained by acetylation of morphine. Techniques like radiography (use of X-rays), CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs. Different species of Plasmodium (P. vivax, P. malaria and P. falciparum) are responsible for different types of malaria. Of these, malignant malaria caused by Plasmodium falciparum is the most serious one and can even be fatal.
Which of the following cells are involved in phagocytosis and destruction of microbes?

The number of trophic levels in the grazing food chain are restricted because of the:

Arrange the steps of agarose gel electrophoresis in a correct sequence :
(A) Visualisation of DNA fragments under UV light
(B) Movement of the DNA fragments under electric field towards anode
(C) Loading the DNA in the wells
(D) Staining of DNA fragments with ethidium bromide
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Which of the following acts as bio fertilizer in paddy field?

Match List I with List II.

LIST I	LIST II
A. Dodo	I. Australia
B. Quagga	II. Mauritius
C. Thylacine	III. Africa
D. Stellar's Sea cow	IV. Russia

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Clot buster produced from Streptococcus is:

Biofertilizers enrich the nutrient quality of the soil. Which of the following is not a source of biofertilizer?

Microbes in human welfare Microbes are a very important component of life on earth. we use microbes and microbially derived products almost every day, like LAB to make curd, yeast to make bread, adding flavor and texture to cheese, producing antibiotics etc. The addition of LAB, improves the milk quality by increasing vit. B12. Cheese is one of the oldest food items in which microbes are used. For example, large holes in Swiss cheese are due to CO2 produced by the bacterium Propionibacterium sharmanii. The BOD test measures the rate of uptake of oxygen by microorganisms in a sample of water and thus, indirectly, BOD is a measure of the organic matter present in the water. The greater the BOD of waste water, the more is its polluting potential. In anaerobic sludge digesters, bacteria produce a mixture of gases like methane, hydrogen sulphide and carbon dioxide. These gases form biogas and can be used as a source of energy. Biofertilisers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilisers are bacteria, fungi and cyanobacteria. You have studied about the nodules on the roots of leguminous plants formed by the symbiotic association of Rhizobium. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as a nutrient. Other bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter).
In anaerobic sludge digesters, the biogas produced by the bacteria, is composed of -

If \(\vec{a}=2 \hat{i}-3 \hat{j}+\hat{k}\) and \(\vec{b}=2 \hat{i}+\hat{j}-\hat{k}\), then which of the following statements is/are correct?
(A) \(\vec{a}\) and \(\vec{b}\) are collinear
(B) \(\vec{a}\) and \(\vec{b}\) are perpendicular
(C) Angle between \(\vec{a}\) and \(\vec{b}\) is \(\frac{\pi}{4}\)
(D) \(|\vec{a}+\vec{b}|=2 \sqrt{5}\)
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If the function \(f(x)=x^2+k x+7\) is strictly increasing in the interval [-2, 2], then

A proton and an alpha particle accelerated through different potential differences have the same de-Broglie wavelength. The ratio of their respective accelerating potentials is

In class XII, suppose \(5 \% \) of boys and \(0.25\%\) of girls are physically fit for a game.
A fit student is selected at random from this class having same number of boys and girls.
If the probability that the selected student is a girl is \(\frac{m}{n}\), \(\operatorname{gcd}(m, n)=1\), then \(m+n\) is equal to