SSC CGL Biology · Biochemistry
Carbohydrates, Pigments and Proteins
Starch, glycogen, pectin and the sugars with their sources, the plant and algal pigments SSC names, and essential amino acids and milk protein.
Why this matters
Eleven questions in the bank: five from the 2023 shifts, four from the 2024 shifts and two from the 2025 shifts, seven of them MODERATE. Most ask another name or a source, so the two tables are what to learn.
Concept 1 of 2: Carbohydrates and energy molecules
Definition
Stores and fibres:
- Starch (amylum): the plant store, in cereals, potatoes, tubers.
- Glycogen: the animal store, in liver and muscle.
- Cellulose: plant structure; an insoluble fibre, like lignin.
- Pectin: a soluble fibre of fruit walls, built from galacturonic acid; used to thicken jams and jellies.
Sugars: maltose in germinating grains, fructose in fruits such as grapes, lactose in milk, sucrose for transport in plants.
Energy molecules: glucose (fuel), NADH (carrier) and ATP (currency). DNA carries genes, not energy.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 1 · Biochemistry · Carbohydrates, Pigments and Proteins
Starch is for plants
Concept 2 of 2: Pigments, amino acids and milk protein
Definition
Pigments:
- Anthocyanins: water-soluble phenolic pigments of pomegranate, brinjal, black carrot and red cabbage.
- Fucoxanthin: the brown pigment of brown seaweed and diatoms.
- Betalains colour beetroot; astaxanthin colours salmon and shrimp.
Proteins:
- Essential amino acids (nine) must come from food: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine.
- Lysine helps absorb calcium and builds collagen.
- Casein is about 80% of the protein in cow's milk; the rest is whey.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 2 · Biochemistry · Carbohydrates, Pigments and Proteins
Betalains are not phenolic
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (2)
Watch out for (2)
- Starch is for plants→ Carbohydrates and energy molecules
- Betalains are not phenolic→ Pigments, amino acids and milk protein
Test yourself on a real paper
Sit a past SSC CGL paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.