#neet
- The phenomenon of pleiotropism refers to Answer: 4. a single gene affecting multiple phenotypic expression. Key idea: Pleiotropy is the effect of a single gene on multiple phenotypi... 1
- Identify the pair of heterosporous pteridophytes among the following : Answer: 3. Selaginella and Salvinia Key idea: Heterosporous pteridophytes make two kinds of spores (micro and megaspores). Selaginella and S... 1
- Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R :Assertion A : Late wood has fewer xylary elements with narrow vessels.Reason R : Cambium is less active in winters.In the light of the above statem… Answer: 2. Both A and R are true and R is the correct explanation of A. Key idea: In winter the cambium is less active and forms fewer xylar... 1
- Identify the correct statements :A. Lenticels are the lens-shaped openings permitting the exchange of gases.B. Bark formed early in the season is called hard bark.C. Bark is a technical term that refers to all tissues exterior to vascular cambium.D.… Answer: 3. A and D only Key idea: Check each statement. A is true: lenticels allow gas exchange. B is false: bark formed early in the season... 1
- Match List I with List II :List I | List IIA. M Phase | I. Proteins are synthesizedB. G_2 Phase | II. Inactive phaseC. Quiescent stage | III. Interval between mitosis and initiation of DNA replicationD. G_1 Phase | IV. Equational divisionChoose the c… Answer: 4. A-IV, B-I, C-II, D-III Key idea: Match each phase with its feature. M phase: equational division (IV). G2 phase: proteins are syn... 1
- Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R :Assertion A : In gymnosperms the pollen grains are released from the microsporangium and carried by air currents.Reason R : Air currents carry the… Answer: 4. A is true but R is false. Key idea: In gymnosperms the pollen grains are carried by air currents, but they do form a pollen tube.... 1
- Match List I with List II :List I | List IIA. Iron | I. Synthesis of auxinB. Zinc | II. Component of nitrate reductaseC. Boron | III. Activator of catalaseD. Molybdenum | IV. Cell elongation and differentiationChoose the correct answer from the optio… Answer: 4. A-III, B-I, C-IV, D-II Key idea: Match each element with its role. Iron: activator of catalase (III). Zinc: needed for synthesis... 1
- Which of the following combinations is required for chemiosmosis? Answer: 2. membrane, proton pump, proton gradient, ATP synthase Key idea: Chemiosmosis needs a membrane, a proton pump, a proton gradient an... 1
- Main steps in the formation of Recombinant DNA are given below. Arrange these steps in a correct sequence.A. Insertion of recombinant DNA into the host cell.B. Cutting of DNA at specific location by restriction enzyme.C. Isolation of desired DNA frag… Answer: 2. B, C, D, A or 4. C, B, D, A Key idea: A recombinant DNA is made by cutting the DNA, getting the desired fragment, amplifying it,... 1
- The reaction that does NOT take place in a blast furnace between 900 K to 1500 K temperature range during extraction of iron is : Answer: 2. Fe ₂ O ₃ + CO → 2FeO + CO ₂ Key idea: The blast furnace has temperature zones: the reduction of Fe₂O₃ to FeO by CO takes place in... 1
- Pumice stone is an example of - Answer: 4. solid sol Key idea: Name a colloid by its dispersed phase and dispersion medium. Pumice stone is a solid that traps gas, so gas i... 1
- Which complex compound is most stable? Answer: 4. [CoCl₂(en)₂]NO₃ Key idea: A chelating ligand makes a complex more stable (chelate effect). In [CoCl₂(en)₂]NO₃ , the ligand en (et... 1
- Consider the following compounds/species :i. naphthalene ii. cyclopentadienyl anion iii. cyclobutadiene iv. cyclopropenyl anion v. cyclopropenyl cation vi. cyclooctatetraene vii. anthracene (all drawn as structures)The number of compounds/species whi… Answer: 2. 4 Key idea: Hückel's rule: a planar, cyclic, fully conjugated species with (4n+2) π electrons is aromatic. i. Naphthalene: 10 π e... 1
- The equilibrium concentrations of the species in the reaction A + B ⇌ C + D are 2, 3, 10 and 6 mol L^-1, respectively at 300 K. Δ G^° for the reaction is (R = 2 cal / mol K) Answer: 4. -1381.80 cal Key idea: Δ G^° = -2.303 RTlog K . K = [C][D]/[A][B] = 10 × 6/2 × 3 = 10 , so log K = 1 . Δ G^° = -2.303 × 2 × 300 ×... 1
- On balancing the given redox reaction,a Cr_2O_7^2- + b SO_3^2-(aq) + c H^+(aq) → 2a Cr^3+(aq) + b SO_4^2-(aq) + c2H_2O()the coefficients a, b and c are found to be, respectively - Answer: 2. 1, 3, 8 Key idea: Balance by the ion-electron (or oxidation-number) method. Cr goes from +6 to +3: gain of 3 e ^- per Cr, 6 e ^-... 1
- Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R :Assertion A : The first stage of gametophyte in the life cycle of moss is protonema stage.Reason R : Protonema develops directly from spores produc… Answer: 2. Both A and R are correct and R is the correct explanation of A. Key idea: In mosses the haploid spore germinates into a creeping,... 1
- Cellulose does not form blue colour with Iodine because Answer: 4. It does not contain complex helices and hence cannot hold iodine molecules. Key idea: The blue colour of the starch-iodine test c... 1
- Which micronutrient is required for splitting of water molecule during photosynthesis? Answer: 2. manganese Key idea: Manganese (Mn) is needed for the water-splitting (photolysis) step of the light reaction, which releases O₂ ,... 1
- The thickness of ozone in a column of air in the atmosphere is measured in terms of : Answer: 2. Dobson units Key idea: Ozone thickness in a column of air is measured in Dobson units (DU). Kilobase measures DNA length, decibel... 1
- Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R :Assertion A : ATP is used at two steps in glycolysis.Reason R : First ATP is used in converting glucose into glucose-6-phosphate and second ATP is… Answer: 2. Both A and R are true and R is the correct explanation of A. Key idea: Two ATP molecules are invested in the preparatory phase of... 1
- Upon exposure to UV radiation, DNA stained with ethidium bromide will show Answer: 1. Bright orange colour Key idea: DNA stained with ethidium bromide and exposed to UV light fluoresces as bright orange bands. This... 1
- Among 'The Evil Quartet', which one is considered the most important cause driving extinction of species? Answer: 2. Habitat loss and fragmentation Key idea: Of the four causes in the "Evil Quartet", habitat loss and fragmentation is the most imp... 1
- Which hormone promotes internode/petiole elongation in deep water rice? Answer: 4. Ethylene Key idea: In deep water rice, submergence raises ethylene levels, and ethylene promotes rapid elongation of internodes a... 1
- Frequency of recombination between gene pairs on same chromosome as a measure of the distance between genes to map their position on chromosome, was used for the first time by Answer: 4. Alfred Sturtevant Key idea: Alfred Sturtevant, a student of T. H. Morgan, used the frequency of recombination between gene pairs... 1