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#mutations

28 public questions tagged with this topic.

BOTANY

Which of the following statements about genetic mutations is incorrect?

Silent mutations do not change the amino acid sequence, as the altered codon still codes for the same amino acid. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Botany section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Botany portion (Latest NCERT Textbooks for Academic Session 2026-27 -

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BOTANY

Which of the following statements about mutations is correct?

Silent mutations do not change the amino acid sequence due to the redundancy of the genetic code. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.

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BOTANY

Which of the following statements about mutations is incorrect?

Point mutations do not always cause frameshift mutations; they can also be silent or missense mutations. This follows from NCERT principle where relation explains outcome clearly for students.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.

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BOTANY

Which of the following statements about genetic mutations is incorrect?

Point mutations do not always cause frameshift mutations; they can be silent or missense mutations. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.

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BOTANY

What is the genetic cause of sickle-ll anemia?

Sickle-ll anemia is caused by a single base substitution in the β-globin gene, leading to the replacement of glutamic acid with valine. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Cell Structure and Function, Cell Cycle and Biomolecules, Topic: Cell organelles and biomolecular structure.

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C-Elegans Development-l

Which of the following mutations leads to a Multivulva (Muv) phenotype?

LIN-12 encodes Notch family transmembrane receptor regulating temporal, somatic gonad, and vulval fates through lateral signaling feedback. Gain-of-function alleles cause constitutive Notch intracellular domain signaling independent of LAG-2 ligand due to missense in extracellular EGF repeats or intracellular PEST degradation domain. In VPCs, ectopic LIN-12 drives excessive secondary fate adoption, antagonizing MAPK primary induction feedback leading to multiple ventral invaginations or multivulva phenotype with extra pseudovulvae expressing 2° markers. Conversely, loss yields two anchor cells, demonstrating dosage sensitivity of Notch balancing 1° versus 2° outcomes.

Ref: Sternberg, WormBook Vulval development: Gain-of-function LIN-12 causes multivulva via ectopic secondary fate induction.

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Elegans -ll

Which of the following mutations leads to excess uterine tissue formation?

LIN-12 Notch controls binary decision between anchor cell and ventral uterine precursor within gonad. During L2 stage, Z1.ppp and Z4.aaa express both LAG-2 ligand and LIN-12 receptor. Lateral interaction amplifies slight difference so cell with higher LIN-12 becomes ventral uterine precursor continuing division, while other with lower LIN-12 becomes anchor cell. Gain-of-function lin-12 mutants with constitutively active NICD cause both Z1.ppp and Z4.aaa to adopt ventral uterine fate, producing two ventral uteri, loss of anchor cell, extra uterine tissue and failure to induce vulva. Thus excess LIN-12 activity leads to duplication of uterine lineage at expense of AC.

Ref: Greenwald et al. 1983; Sternberg Vulval Chapter: Gain-of-function lin-12 leads to excess uterine tissue formation.

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Eye Lens Induction -ll

Which condition is caused by mutations in Pax6?

Mutations in PAX6 transcription factor cause aniridia, congenital absence or severe hypoplasia of iris, accompanied by corneal opacification, cataracts, foveal hypoplasia, and nystagmus. Pax6 continues expression in iris, cornea, retina throughout development maintaining ocular progenitor gene networks. Dominant haploinsufficiency reduces DNA binding to target promoters. Cataract alone typically results from crystallin mutations, retinal detachment from other causes, myopia polygenic. Aniridia represents classic dosage-sensitive phenotype of PAX6 linked to 11p13 deletion, demonstrating pleiotropic eye regulatory role beyond lens induction and corneal maintenance.

Ref: NCBI Bookshelf, Molecular Biology of Eye: PAX6 mutations causing aniridia and ocular anomalies.

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