NEET UG
- Which of the following is an example of actinomorphic flower? Answer: 2. Datura Key idea: actinomorphic flowers can be cut into two equal halves in any vertical plane (radial symmetry). Datura is actino... 1
- Bulliform cells are responsible for Answer: 2. Inward curling of leaves in monocots. Key idea: bulliform cells are large colourless cells on the upper epidermis of grass leaves... 1
- In the given figure, which component has thin outer walls and highly thickened inner walls? Answer: 2. C Key idea: in dicot guard cells the wall facing the stomatal pore (inner wall) is thick and the outer wall is thin. In the figur... 1
- Given below are two statements:Statement I : Bt toxins are insect group specific and coded by a gene cry IAc.Statement II : Bt toxin exists as inactive protoxin in B. thuringiensis. However, after ingestion by the insect the inactive protoxin gets co… Answer: 4. Statement I is true but Statement II is false Key idea: Bt toxin is specific to insect groups, and the protoxin is activated in a... 1
- What is the fate of a piece of DNA carrying only gene of interest which is transferred into an alien organism?A. The piece of DNA would be able to multiply itself independently in the progeny cells of the organism.B. It may get integrated into the ge… Answer: 4. B and C only Key idea: a piece of alien DNA without an origin of replication cannot multiply on its own. It either integrates int... 1
- Hind II always cuts DNA molecules at a particular point called recognition sequence and it consists of: Answer: 3. 6 bp Key idea: restriction enzymes such as Hind II recognise a specific palindromic sequence of 6 base pairs. Hind II recognises... 1
- Match List I with List IIList I: A. Clostridium butylicum; B. Saccharomyces cerevisiae; C. Trichoderma polysporum; D. Streptococcus sp.List II: I. Ethanol; II. Streptokinase; III. Butyric acid; IV. Cyclosporin-AChoose the correct answer from the opti… Answer: 4. A-III, B-I, C-IV, D-II Key idea: match each microbe with the product it yields. Clostridium butylicum makes butyric acid (A-III).... 1
- Spindle fibers attach to kinetochores of chromosomes during Answer: 3. Metaphase Key idea: chromosomes line up at the equator in metaphase, with spindle fibres attached to their kinetochores. In metap... 1
- Given below are two statements:Statement I : Chromosomes become gradually visible under light microscope during leptotene stage.Statement II : The begining of diplotene stage is recognized by dissolution of synaptonemal complex.In the light of the ab… Answer: 2. Both Statement I and Statement II are true Key idea: recall what happens in each substage of prophase I. Statement I: In leptoten... 1
- The cofactor of the enzyme carboxypeptidase is: Answer: 2. Zinc Key idea: carboxypeptidase is a metalloenzyme whose cofactor is a metal ion, zinc. Zinc ( Zn²⁺ ) is held in the active site... 1
- These are regarded as major causes of biodiversity loss:A. Over exploitationB. Co-extinctionC. MutationD. Habitat loss and fragmentationE. MigrationChoose the correct option: Answer: 1. A, B and D only Key idea: the "evil quartet" of biodiversity loss is habitat loss and fragmentation, over-exploitation, alien spe... 1
- The equation of Verhulst-Pearl logistic growth isdN/dt = rN≤ft[K-N/K].From this equation, K indicates: Answer: 4. Carrying capacity Key idea: in the Verhulst-Pearl logistic equation, K is the carrying capacity. In dN/dt=rN[K-N/K] , N is popula... 1
- In a plant, black seed color (BB/Bb) is dominant over white seed color (bb). In order to find out the genotype of the black seed plant, with which of the following genotype will you cross it? Answer: 3. bb Key idea: an unknown dominant phenotype is tested by a test cross with the homozygous recessive parent. Cross the black plant... 1
- How many molecules of ATP and NADPH are required for every molecule of CO_2 fixed in the Calvin cycle? Answer: 1. 3 molecules of ATP and 2 molecules of NADPH Key idea: fixing one CO₂ in the Calvin cycle costs 3 ATP and 2 NADPH. One CO₂ joins R... 1
- Auxin is used by gardeners to prepare weed-free lawns. But no damage is caused to grass as auxin Answer: 4. does not affect mature monocotyledonous plants. Key idea: synthetic auxins like 2,4-D kill dicot weeds but not monocot crops or g... 1
- Given below are two statements:Statement I : Parenchyma is living but collenchyma is dead tissue.Statement II : Gymnosperms lack xylem vessels but presence of xylem vessels is the characteristic of angiosperms.In the light of the above statements, ch… Answer: 1. Statement I is false but Statement II is true Key idea: check each statement against tissue properties. Statement I: Parenchyma i... 1
- Identify the correct answer. Answer: 1. Three canonical forms can be drawn for CO₃²⁻ ion. Key idea: check each statement. mathrmCO₃²⁻ : three equivalent canonical forms.... 1
- The rate of a reaction quadruples when temperature changes from 27^°C to 57^°C. Calculate the energy of activation.Given R = 8.314 J K^-1 mol^-1, log 4 = 0.6021 Answer: 2. 38.04 kJ/mol Key idea: logk₂/k₁=E_a/2.303RT₂-T₁/T₁T₂ . T₁=300 K, T₂=330 K, k₂/k₁=4 . E_a=2.303×8.314×0.6021×300×330/30≈38046\ J/m... 1
- The work done during reversible isothermal expansion of one mole of hydrogen gas at 25^°C from pressure of 20 atmosphere to 10 atmosphere is:(Given R = 2.0 cal K^-1 mol^-1) Answer: 3. - 413.14 calories Key idea: for reversible isothermal expansion, w=-2.303 nRTlogP₁/P₂ (work done by the gas is negative in this c... 1
- Given below are two statements :Statement I : [Co(NH_3)_6]^3+ is a homoleptic complex whereas [Co(NH_3)_4Cl_2]^+ is a heteroleptic complex.Statement II : Complex [Co(NH_3)_6]^3+ has only one kind of ligands but [Co(NH_3)_4Cl_2]^+ has more than one ki… Answer: 2. Both Statement I and Statement II are true. Key idea: a homoleptic complex has only one kind of ligand; a heteroleptic complex ha... 1
- The pair of lanthanoid ions which are diamagnetic is Answer: 2. Ce⁴⁺ and Yb²⁺ Key idea: diamagnetic means no unpaired electrons, so 4f⁰ or 4f¹⁴ . mathrmCe⁴⁺ : 4f⁰ ; mathrmYb²⁺ : 4f¹⁴ . Both dia... 1
- Consider the following reaction in a sealed vessel at equilibrium with concentrations of N_2 = 3.0×10^-3 M, O_2 = 4.2×10^-3 M and NO = 2.8×10^-3 M.2NO_(g) ⇌ N_2(g) + O_2(g)If 0.1 mol L^-1 of NO_(g) is taken in a closed vessel, what will be degree of… Answer: 1. 0.717 Key idea: get K_c from the first data set, then use it for the new mixture. K_c=[N₂][O₂]/[NO]²=frac(3.0×10⁻³)(4.2×10⁻³)(2.8... 1
- For the given reaction:[scheme: ring-C(H)=CH-ring KMnO_4/H^+ 'P' (major product), see figure]'P' is Answer: 3. [structure: ring-COOH] Key idea: hot or acidic KMnO₄ cleaves a C=C bond and oxidises each fragment fully to the carboxylic acid.... 1
- Identify the major product C formed in the following reaction sequence :CH_3-CH_2-CH_2-I NaCN A [Partial hydrolysis]OH^- B [Br_2]NaOH C (major) Answer: 2. propylamine Key idea: follow each step. CH₃CH₂CH₂I+NaCN→ CH₃CH₂CH₂CN (A, butanenitrile). Partial hydrolysis with OH^- gives CH₃CH... 1