Biology: Pathways, Genetics and Precise Terminology
Biology in MHT-CET covers Botany and Zoology from the Maharashtra State Board Class 11–12 syllabus: plant morphology and anatomy, photosynthesis, respiration, genetics, molecular biology, biotechnology, ecology, human physiology, reproduction and evolution. MCQs test precise terminology, pathway sequences and diagram-based recall.
Core rules and concepts
- Photosynthesis: light reactions in thylakoids produce ATP and NADPH; the Calvin cycle in the stroma fixes CO₂ via RuBisCO.
- Respiration: glycolysis in the cytoplasm, Krebs cycle in the mitochondrial matrix, electron transport on the inner membrane.
- Genetics: Mendel's law of segregation; a dihybrid cross of heterozygotes gives a 9:3:3:1 phenotypic ratio.
- Molecular biology: DNA replication is semi-conservative; transcription uses RNA polymerase; translation occurs on ribosomes.
- Ecology: energy flow is unidirectional; pyramids of energy are always upright.
Worked example
Two pea plants heterozygous for two independently assorting genes (AaBb × AaBb) are crossed. What fraction of offspring shows both recessive traits? Each gene gives a 1/4 chance of the recessive phenotype (aa or bb). Independent assortment gives 1/4 × 1/4 = 1/16.
Traps that cost marks
- Mixing mitosis and meiosis: meiosis has two divisions and produces four haploid cells.
- Confusing the roles of DNA and RNA in transcription and translation.
- Misreading "not" or "except" in negative questions.
- Forgetting that the Calvin cycle occurs in the stroma, not the thylakoid.
- Naming hormones or enzymes imprecisely.