Science & Technology II — SSC Practice Test Review: quick revision, 25 bites

The Central Dogma: DNA → RNA → Protein

One model explains all gene expression.

Francois Jacob and Jacques Monod (1961) proposed the **operon model** explaining how genes are regulated to produce proteins in bacterial cells.

Takeaway. Gene expression flows from DNA to RNA to protein — the foundation of molecular biology.

Glycolysis: The Cytoplasm Connection

Sugar breakdown starts outside the mitochondria.

Takeaway. Glycolysis happens in the cytoplasm — not the mitochondria — making it the first step of respiration.

Energy Flow in a Thermal Power Plant

From fuel to electricity in four steps.

Takeaway. Thermal power plants convert chemical energy → heat → mechanical → electrical energy.

Why Bread Mold Spreads So Fast

Two factors make mold explode overnight.

Takeaway. Abundant spores plus moisture and nutrients are the key drivers of rapid bread mold spread.

Pseudomonas: Nature's Oil Cleaner

Bacteria that eat oil spills.

**Pseudomonas** bacteria are used in bioremediation to break down hydrocarbons and oil pollutants from soil and water.

Takeaway. Pseudomonas is the go-to bacterium for cleaning oil pollutants — a real-world bioremediation application.

Odd One Out: Glucose vs. Breakdown Products

Don't confuse the starting material with the products.

Takeaway. In odd-one-out questions, check whether the item is a reactant or a product — that distinction is the answer.

Carpel: The Female Reproductive Part

One word, one flower function.

Takeaway. Carpel = female reproductive organ of the flower; the statement is True.

Mollusca vs. Arthropoda: Phylum Match-Up

Snail or crab — know the phylum.

Takeaway. Snail : Mollusca :: Crab : Arthropoda — match the phylum by body covering and locomotion.

Meiosis: Four Haploid Cells from One Diploid

One cell becomes four — with half the DNA.

Takeaway. Meiosis is the process that forms four haploid cells from one diploid cell.

Paramoecium vs. Euglena: Reproduction Methods

Two protists, two different strategies.

Takeaway. Both reproduce by binary fission, but the plane of division differs — transverse in Paramoecium, longitudinal in Euglena.

Cockroach: An Arthropoda Classic

Three reasons it's an arthropod.

Takeaway. Cockroach belongs to Arthropoda — justified by jointed legs, exoskeleton, and segmented body.

Peripatus: The Connecting Link

One organism bridges two phyla.

**Peripatus** is considered a connecting link between **Annelida** and **Arthropoda** because it shares characteristics of both phyla.

Takeaway. Peripatus shows annelid-like and arthropod-like features, making it an evolutionary bridge.

Flower: The Structural Unit of Sexual Reproduction

Why flowers matter for plant sex.

Takeaway. The flower is the structural unit of sexual reproduction because it houses both male and female reproductive organs.

Genetic Similarity: Who Decides?

DNA from both parents decides.

New organisms are **not** genetically identical to the parent in sexual reproduction. The **combination of genes from two parents** determines whether offspring are exactly similar or not.

Takeaway. In sexual reproduction, offspring similarity is determined by the gene combination from both parents — not by a single parent.

Biodiversity Conservation: Two Approaches

Save species in place or out of place.

Takeaway. Biodiversity can be conserved through in-situ and ex-situ methods, backed by legal frameworks like the Wildlife Protection Act 1972.

Chordates vs. Non-Chordates

Four features separate them.

Takeaway. Chordates have a notochord, dorsal hollow nerve cord, gill slits, and post-anal tail — non-chordates lack all four.

Mendel to de Vries: The Genetics Chain

One name links to mutation theory.

Takeaway. Gregor Mendel : Modern genetics :: Hugo de Vries : Mutation theory.

Triplet Codon: The Translation Key

Three bases, one amino acid.

Takeaway. RNA synthesis : transcription :: Triplet codon : translation.

Proteins: The Body's Building Blocks

Define proteins in one line.

Takeaway. Proteins are amino acid polymers that carry out structural and functional roles in the body.

Darwin's Natural Selection in Three Lines

Reproduce, compete, survive, evolve.

Takeaway. Natural selection favors organisms with useful modifications, leading to new species over time.

Wildlife Protection Act 1972: Key Clauses

India's legal shield for wildlife.

Takeaway. The Wildlife Protection Act 1972 provides legal protection to wildlife and their habitats in India.

Mollusca: Three Defining Characteristics

Soft body, hard shell, muscular foot.

Takeaway. Molluscs are soft-bodied animals with a muscular foot and often a shell — key features for identification.

Environmental Factors: How They Affect Us

Five factors shape every ecosystem.

Takeaway. Temperature, light, water, soil, and air are the key environmental factors that affect organisms and ecosystems.

Mutation Types: Spot the Change

Small DNA change, big effect.

Takeaway. Mutations are changes in DNA sequence — identify the type by what part of the sequence is altered.

Energy from Carbohydrates, Fats & Proteins

Three fuels, one energy currency.

Takeaway. Carbohydrates, fats, and proteins all feed into cellular respiration to produce ATP — the cell's energy currency.