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Let S = {1, 2, 3, ...., n} and A = {(a, b) | 1 ≤ a, b ≤ n} = S × S. A subset B of A is said to be a good subset if (x, x) ∈ B for every x ∈ S. Then, the number of good subsets of A is
Number of elements in B for a good set = n So, number of good subsets of B = 2n - 1
Let ao = 0 and an = 3an - 1 + 1 for n ≥ 1. Then, the remainder obtained after dividing a2010 by 11 is:
an = 3an - 1 + 1 a2010 = 3a2009 + 1 = 3(3a2008 + 1) + 1 = 32 a2008 + 3 + 1 = 33 a2007 + 3 + 3 + 1 . . . = 32010 a0 + (3 + 3 + ... + 3) + 1 (2009 times) = 0 + 6027 + 1 = 6028 Remainder = (6028/11) = 0
A uniform non-deformable cylinder of mass m and radius R is rolling without slipping on a horizontal rough surface. The force of friction
There is no slide. So, V = ωR at the point of contact. Because of this, there will be no relative motion at this contact point. So, frictional force would be zero.
A piece of hot copper at 100oC is plunged into a pond at 30oC. The copper cools down to 30oC, while the pond, being huge, stays at its initial temperature. Then,
Using theory of entropy, as the temperature increases, randomness decreases.
Doping silicon with boron produces a/an
As boron is trivalent impurity, it will produce p-type semiconductor.
The concentration of a substance undergoing a chemical reaction becomes one-half of its original value after time t regardless of the initial concentration. The reaction is an example of a
For a first order reaction, half life period is independent of initial concentration of the reaction.
An ionic compound is formed between a metal M and a non metal Y. If M occupies half the octahedral voids in the cubic close packed arrangement formed by Y, the chemical formula of the ionic compound is
For CCP (cubic close packed arrangement): Number of atoms per unit cell (Z) = 4 As we know, if total number of atoms = N Then, number of tetrahedral voids = 2N Number of octahedral voids = N Hence, according to the question, metal M occupies half of the octahedral voids. Then, the chemical formula is: M2Y4 or MY2.
Plants are attracted to light through the hormonal action of which of the following?
The plant hormone auxin is responsible for a plant's ability to grow towards the light. The cells on the plant that are the farthest from the light have a chemical called auxin, that reacts when phototropism occurs. This causes the plant to have elongated cells on the farthest side from the light.
Nucleotides are monomers of DNA. Each nucleotide consists of a
DNA is a polymer. The monomer units of DNA are nucleotides and the polymer is known as a "polynucleotide". Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the sugar and a phosphate group.
Earthworms are bisexual but still cross-fertilisation is common. This is because
Earthworms are bisexual but still cross-fertilisation is common. This is because spermatozoa and ova mature at different times in the same earthworm.
Wooden doors and windows swell up in the rainy season by
The process of adsorption of water by solid particles of a substance, without forming a solution, is called 'imbibition'. Wooden doors and windows adsorb water in humid rainy season and increase in their volume so that they are hard to open or close. This occurs by the process of imbibition.
Peptic ulcers are caused by
Helicobacter pylori (H. pylori) is a bacteria that can cause a stomach infection and inflammation. This is the main organism that causes peptic ulcers.
By which of the following mechanisms is glucose reabsorbed from the glomerular filtrate by the kidney tubule?
Glucose is present in blood plasma and glomerular filtrate, but not present in urine (normally). This is because glucose is selectively reabsorbed in the proximal convoluted tubule. It is reabsorbed from the filtrate into the blood by active transport (symport with Na+ ions).
Plant roots are usually devoid of chlorophyll and cannot perform photosynthesis. However, three are exceptions. Which of the following plant roots can perform photosynthesis?
Tinospora has long, slender and hanging aerial adventitious roots. These roots are green and photosynthetic.
In a food chain such as grass → deer → lion, the energy cost of respiration as a proportion of total assimilated energy at each level would be
With increase in every trophic level, the amount of energy decreases. Hence, the energy cost of respiration will increase with every trophic level.
If the total number of photons falling per unit area of a leaf per minute is kept constant, then which of the following will result in maximum photosynthesis?
Rate of photosynthesis is fastest in blue and red lights.
When a person is suffering from high fever, it is sometimes observed that the skin has a reddish tinge. Why does this happen?
This happens because of higher blood circulation to the skin. This helps to release more heat from the body.
Conversion of the Bt protoxin produced by Bacillus thuringiensis to its active form in the gut of the insects is mediated by
Bt crystal toxins include the Cry proteins (crystal toxins) and Cyt proteins (cytolytic toxins). When these crystal proteins are exposed to the alkaline environment of the gut of susceptible larvae, the crystals are solubilised and proteolytically processed at the N-terminus and/or the C-terminus by mid-gut proteases to yield the active protease-resistant toxin.
Estimate the order of the speed of propagation of an action potential or nerve impulse.
The mean conduction velocity of an action potential ranges from 1 metre per second (m/s) to over 100 m/s, and in general, increases with axonal diameter.
The Na+/K+ pump is present in the plasma membrane of mammalian cells where it
The sodium-potassium pump works by pumping two potassium ions into the cell and pumping out three sodium ions using the energy from an ATP molecule.
Patients who have undergone organ transplants are given anti-rejection medications to
Immunosuppressive therapy used in transplantation prevents activation and proliferation of alloreactive T-lymphocytes.
The process of organogenesis starts as soon as the three germ layers are formed in a developing embryo. The human brain is formed from the
Organogenesis begins with the process of neurulation. This neurulation begins with the formation of primitive streak in epiblast (ectoderm), which leads to the formation of neural tube (nerve cord).
An electrode is placed in the axoplasm of a mammalian axon and another electrode is placed just outside the axon. The potential difference measured will be
When a nerve or muscle cell is at "rest", its membrane potential is called the resting membrane potential. In a typical neuron, this is about –70 millivolts (mV).
Genetic content of a cell reduces to half during
The process of meiosis involves two divisions of the genetic material. The first division is called the reduction division – or meiosis I – because it reduces the number of chromosomes from 46 chromosomes or 2n to 23 chromosomes or n (n describes a single chromosome set).
The two enzymatic activities associated with RuBisCo are
RuBisCo is a bifunctional enzyme. It possesses both carboxylase and oxygenase activities. Both the activities are found on the same active site. The enzyme acts as an oxygenase during photorespiration and as a carboxylase during photosynthesis.
In orange and lemon, the edible part of the fruit is
The outer ovary wall in citrus fruits becomes the thick spongy layer of the rind, while the inner ovary wall becomes very juicy with several seeds.
In vertebrates, 'glycogen' is stored chiefly in
Glycogen is a readily mobilised storage form of glucose. The two major sites of glycogen storage are the liver and skeletal muscles.
A polynomial P(x) with real coefficients has the property that P''(x) ≠ 0 for all x. Suppose P(0) = 1 and P'(0) = -1. What can you say about P(1)?
Since P''(x) ≠ 0 ⇒ a ≠ 0 P(x) = ax2 + bx + c P'(x) = 2ax + b P''(x) = 2a P(0) = c = 1 P'(0) = b = -1 Therefore, P(x) = ax2 - x + 1 P(1) = a - 1 + 1 = a ≠ 0
Suppose m, n are positive integers such that 6m + 2m+n.3W + 2n = 332. The value of the expression m2 + mn + n2 is
6m + 2m+n.3w + 2n = 332 Maximum possible value of m is 3 because if m = 4, then 6m exceeds 332. Checking for m = 3, 2 and 1, we get m = 2, n = 3, w = 2 m2 + mn + n2 = 4 + 6 + 9 = 19
Emulsification of 10 ml of oil in water produces 2.4 × 1018 droplets. If the surface tension at the oil – water interface is 0.03 Jm-2 and the area of each droplet is 12.5 × 10 -16 m2, then the energy spent in the formation of oil droplets is
Total droplets = 2.4 x 1018 Total area = total droplets x area of one drop = 2.4 x 1018 x 12.5 x 1016 = 12.5 x 2.4 x 102 m2 Energy consumption = 0.03 x 12.5 x 2.4 x 102 = 90 Joule
E. coli has an optimal temperature of 37°C. Which of the following is an INCORRECT explanation for this?
Cell membrane becomes more permeable at high temperature. E. coli has an optimal temperature of 37°C. At this temperature, all the processes required for synthesising new cells occur at maximal rate.
Energetically unfavourable reactions occur in human cells through
Cells use a strategy called reaction coupling, in which an energetically favourable reaction (like ATP hydrolysis) is directly linked with an energetically unfavourable (endergonic) reaction. The linking often happens through a shared intermediate, meaning that a product of one reaction is "picked up" and used as a reactant in the second reaction.
The restriction endonuclease EcoR-I recognises and cleaves DNA sequence as shown below: 5' - G A A T T C – 3' 3' – C T T A A G – 5' What is the probable number of cleavage sites that can occur in a 10 kb long random DNA sequence?
Let's start with 10 kb fragment, and go through from one end to the other, and mark every time a 'G' occurs. Theoretically those could all be the beginning of EcoRI sites. There will be approximately 2500 such 'G's. Now to match the pattern, we need an 'A' in the second position, so mark all those sites that contain the dinucleotide 'GA', there will be about 2500 x 0.25 = 625 of them. The next match we need is position 3, another 'A', so in a similar fashion, let's go through the positions of all those GA dinucleotides, and just mark the ones that have an 'A' at the next position. So that will be about 625 x 0.25, or approximately 156 'GAA's distrubuted randomly along the 10 kb fragment. If we continue, essentially filtering out more and more of those 'G' sites in our initial list, then we will find that on average, there are: 39 sites with GAAT. 10 sites with GAATT. 2 sites with GAATTC.
Insects constitute the largest animal group on earth. About 25-30% of the insect species are known to be herbivores. In spite of such huge herbivore pressure, globally, green plants have persisted. One possible reason for this persistence is that
Change in preference of herbivores for plants has enabled the survival of plants for long.
You mark two ink-spots along the height at the base of a coconut tree and also at the top of the tree. When you examine the spots next year when the tree has grown taller, you will see that
Tree trunk growth is coordinated with the increase of tree height and width. When buds begin opening in the early Spring, cells in the trunk and limbs get the signal to increase in girth by dividing and in height by elongating.
E.coli was pulsed with tritiated thymidine for 5 min and then transferred to normal medium. Which of the following observations would be correct after one cell division?
DNA replication is semi conservative. Hence, when DNA is transferred to the normal medium, only one strand will be radioactive.
The length of one complete turn of a DNA double helix is
One complete 360 degree turn of the DNA helix covers 10 base in length and a physical distance of 34 angstrom.
Presence of plastids in plasmodium suggests it is a
An apicoplast is a derived non-photosynthetic plastid found in most Apicomplexa, including malaria parasites such as Plasmodium falciparum. It originated from an alga through secondary endosymbiosis.
Lions in India are currently restricted to Gir, Gujarat. Efforts are being made to move them to other parts of the country. This is because they are most susceptible to extinction due to infectious diseases under the following conditions when present as
Animals present as one large population are most susceptible to extinction due to infectious diseases.
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