NEET UG
- Which of the following is not a feature of the plasmids ? Answer: 4. Single - stranded Key idea: Plasmids are double-stranded, circular, extra-chromosomal DNA. They replicate independently of the ch... 1
- Which of the following features is not present in *Periplaneta americana* ? Answer: 2. Indeterminate and radial cleavage during embryonic development Key idea: Cockroach (Periplaneta) is a protostome arthropod, so it... 1
- Asthma may be attributed to : Answer: 2. allergic reaction of the mast cells in the lungs Key idea: Asthma is an allergic reaction that inflames the bronchi and bronchiol... 1
- Which of the following pairs of hormones are not antagonistic (having opposite effects) to each other ? Answer: 4. Relaxin - Inhibin Key idea: Antagonistic hormones have opposite effects. Parathormone raises blood calcium; calcitonin lowers it.... 1
- Photosensitive compound in human eye is made up of : Answer: 2. Opsin and Retinal Key idea: The photosensitive pigment of the eye, rhodopsin (visual purple), is made of opsin (a protein) and re... 1
- Which of the following approaches does not give the defined action of contraceptive ? Answer: 4. Vasectomy - prevents spermatogenesis Key idea: Vasectomy blocks the transport of sperms; it does not stop spermatogenesis. In vas... 1
- Fertilization in humans is practically feasible only if : Answer: 2. the ovum and sperms are transported simultaneously to ampullary - isthmic junction of the fallopian tube. Key idea: Fertilization... 1
- Select the incorrect statement : Answer: 3. LH and FSH decrease gradually during the follicular phase. Key idea: LH and FSH rise, not fall, during the follicular phase. FSH... 1
- Changes in GnRH pulse frequency in females is controlled by circulating levels of : Answer: 1. estrogen and progesterone Key idea: GnRH pulse frequency in females is controlled by the circulating levels of oestrogen and prog... 1
- A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called : Answer: 1. Ley farming Key idea: Ley farming alternates cereal crops with legume or grass pasture for a few years to restore soil structure... 1
- The two polypeptides of human insulin are linked together by : Answer: 4. Disulphide bridges Key idea: Insulin has two chains, A (21 amino acids) and B (30 amino acids), held together by disulphide bridg... 1
- Mitochondria and chloroplast are :(a) semi-autonomous organelles.(b) formed by division of pre - existing organelles and they contain DNA but lack protein synthesizing machinery.Which one of the following options is correct ? Answer: 3. (a) is true but (b) is false. Key idea: Mitochondria and chloroplasts are semi-autonomous organelles. (a) True. They have their o... 1
- Which of the following statements is wrong for viroids ? Answer: 4. Their RNA is of high molecular weight Key idea: Viroids are infectious agents made only of a small, free RNA with no protein coat... 1
- Gause's principle of competitive exclusion states that : Answer: 3. No two species can occupy the same niche indefinitely for the same limiting resources. Key idea: Gause's principle says that two... 1
- Which of the following most appropriately describes haemophilia ? Answer: 2. X - linked recessive gene disorder Key idea: Haemophilia is caused by a recessive gene on the X chromosome, so it is the most pre... 1
- Emerson's enhancement effect and Red drop have been instrumental in the discovery of : Answer: 2. Two photosystems operating simultaneously Key idea: Red drop and Emerson's enhancement effect showed that two light reactions wor... 1
- In a chloroplast the highest number of protons are found in : Answer: 2. Lumen of thylakoids Key idea: During the light reactions, protons build up inside the thylakoid lumen. They come from water split... 1
- In which of the following, all three are macronutrients ? Answer: Dropped in the official answer key: full marks to every candidate Key idea: Macronutrients are C, H, O, N, P, S, K, Ca and Mg. Micro... 1
- The coconut water from tender coconut represents : Answer: 4. Free nuclear endosperm Key idea: Coconut water is a liquid free nuclear endosperm. In coconut, the triploid primary endosperm nuc... 1
- The correct statement regarding RNA and DNA, respectively is : Answer: 2. The sugar component in RNA is ribose and the sugar component in DNA is 2'-deoxyribose. Key idea: RNA has the sugar D-ribose and D... 1
- Which one given below is a non-reducing sugar ? Answer: 4. Sucrose Key idea: a sugar is non-reducing when both anomeric carbons are tied up in the glycosidic bond, leaving no free hemiacet... 1
- For the following reactions :(a) CH_3CH_2CH_2Br + KOH → CH_3CH=CH_2 + KBr + H_2O(b) (CH3)2CHBr + KOH -> (CH3)2CHOH + KBr (structures shown in figure)(c) cyclohexene + Br_2 -> 1,2-dibromocyclohexane (structures shown in figure)Which of the following s… Answer: 2. (a) is elimination, (b) is substitution and (c) is addition reaction. Key idea: identify what happens to the substrate. (a) CH₃CH... 1
- The correct statement regarding the basicity of arylamines is : Answer: 1. Arylamines are generally less basic than alkylamines because the nitrogen lone-pair electrons are delocalized by interaction with... 1
- At 100°C the vapour pressure of a solution of 6.5 g of a solute in 100 g water is 732 mm. If K_b = 0.52, the boiling point of this solution will be : Answer: 1. 101°C Key idea: use the lowering of vapour pressure to get the mole fraction, and then the boiling point elevation. At 100°C pure... 1