NDA Biology · Teaching notes
Plant Biology — NDA Biology
Plant Biology is a 29-PYQ chapter spanning 2017–2026 — mostly EASY and MODERATE, with one HARD transpiration experiment. Unlike pure-recall chapters, it leans 'Apply': you trace mechanisms (how water splits in photosynthesis, why a shoot grows up, which embryo part becomes the root) as much as you memorise named facts. The chapter teaches in five movements, building from the plant's raw building blocks up to how it grows and reproduces: (1) Plant tissues and meristems — the dividing tissues that drive growth, the simple permanent tissues (parenchyma, collenchyma, sclerenchyma), and the conducting tissues (xylem, phloem); (2) Photosynthesis — how a leaf turns light, water and CO₂ into food and releases oxygen, plus a few high-yield crop facts; (3) Plant processes — the photosynthesis-respiration gas link, transpiration, and tropisms (the directional growth responses); (4) Seed, fruit and embryo development — the radicle and plumule, true vs false fruit, and the parts of the ovule; (5) Vegetative propagation — growing new plants without seeds. Every PYQ is tagged. Watch the mechanism questions — a few statement items reward knowing the SEQUENCE, not just a single fact.
Subtopic notes
Plant Tissues and Meristems
11 PYQsPlants grow at meristems (regions of dividing cells), which mature into permanent tissues — simple ones (parenchyma, collenchyma, sclerenchyma) for packing and support, and complex conducting tissues (xylem, phloem) that carry water and food.
Open note
Photosynthesis
10 PYQsPhotosynthesis is how green plants use light, water and CO₂ to make glucose and release oxygen; the light reaction splits water (giving the O₂) and the dark reaction fixes CO₂ into sugar.
Open note
Plant Processes — Gas Exchange, Transpiration and Tropisms
3 PYQsPhotosynthesis and respiration are linked by oxygen; transpiration is water loss mostly through the lower-surface stomata; and tropisms are directional growth responses (shoots up = negative geotropism).
Open note
Seed, Fruit and Embryo Development
4 PYQsThe seed embryo has a radicle (becomes the root) and a plumule (becomes the shoot); a false fruit like apple develops from the thalamus; and the ovule's nucellus stores reserve food.
Open note
Vegetative Propagation
1 PYQsVegetative propagation is growing a new plant from a vegetative part (root, stem, leaf) without seeds — potato propagates through its eye buds.
Open note
PYQ weightage by concept
18 concepts · 29 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
18 concepts · 29 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Simple permanent tissues — parenchyma, collenchyma, sclerenchyma | 4 | 14% |
| Types of meristem — apical, lateral, intercalary | 3 | 10% |
| Conducting tissues — xylem and phloem | 2 | 7% |
| Differentiation — meristem cells become permanent tissue | 1 | 3% |
| Which organisms have vascular tissue | 1 | 3% |
| Plant tissues — meristematic vs permanentfoundation | — | — |
| Concept | PYQs | Share |
|---|---|---|
| Crop and botany facts — golden rice, sugarcane, cropping, nettle | 4 | 14% |
| Photosynthesis — requirements, equation and products | 2 | 7% |
| The light reaction — splitting water releases oxygen | 2 | 7% |
| Chlorophyll and why leaves look green | 1 | 3% |
| Meristematic tissue drives plant growth | 1 | 3% |
| Concept | PYQs | Share |
|---|---|---|
| The oxygen link — photosynthesis feeds respiration | 1 | 3% |
| Tropisms — directional growth responses | 1 | 3% |
| Transpiration — water loss through lower-surface stomata | 1 | 3% |
| Concept | PYQs | Share |
|---|---|---|
| True vs false fruit, and the inflorescence | 2 | 7% |
| The seed embryo — radicle and plumule | 1 | 3% |
| Parts of the ovule — where reserve food is stored | 1 | 3% |
Formula & revision sheet
2 formulas · 8 reference tables · 23 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
2 formulas · 8 reference tables · 23 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (4)
Types of meristem — apical, lateral, intercalary3 rows
| Meristem | Where | Causes growth in |
|---|---|---|
| Apical | Root and shoot tips | Length / height (primary growth) Damage to the apical meristem reduces the LENGTH of the plant (NDA 2018). |
| Lateral (cambium) | Sides of the stem | Girth / thickness (secondary growth) Increase in girth of the stem is due to lateral meristem ONLY (NDA 2021). Cambium = a lateral meristem (NDA 2025). |
| Intercalary | Base of leaves / internodes | Length (regrowth, e.g. grasses) |
Simple permanent tissues — parenchyma, collenchyma, sclerenchyma3 rows
| Tissue | Living / dead | Role + key fact |
|---|---|---|
| Parenchyma | Living | Basic packing + storage; found in xylem and phloem; forms aerenchyma (air sacs) in aquatic plants Parenchyma is the 'basic packing tissue' found in xylem and phloem (NDA 2021); aerenchyma buoyancy sacs are parenchyma (NDA 2022). |
| Collenchyma | Living | Thickened walls give flexibility to the plant |
| Sclerenchyma | DEAD | Lignified walls; rigid support; no protoplast at maturity Sclerenchyma is the simple tissue made of DEAD cells (NDA 2020, 2026). |
Conducting tissues — xylem and phloem3 rows
| Tissue | Carries | Components |
|---|---|---|
| Xylem | Water + minerals | Tracheids, vessels, xylem parenchyma, xylem fibres Xylem = tracheids + vessels + xylem parenchyma + xylem fibres (NDA 2019). |
| Phloem | Food (sucrose) | Sieve tubes, sieve plates, companion cells, phloem parenchyma, fibres |
| Pericycle | NOT conducting | A parenchyma layer outside the vascular bundle — a distractor Pericycle is NOT a component of conducting tissue (NDA 2019). |
Which organisms have vascular tissue4 rows
| Organism | Group | Vascular tissue? |
|---|---|---|
| *Marsilea* | Fern (pteridophyte) | YES — true xylem + phloem |
| *Cladophora* | Green alga | No |
| *Penicillium* | Fungus | No |
| *Anabaena* | Cyanobacterium | No |
Watch out for (7)
- Apical = length, Lateral = girth — don't swap them→ Types of meristem — apical, lateral, intercalary
- Differentiation ≠ division→ Differentiation — meristem cells become permanent tissue
- Sclerenchyma is the DEAD one→ Simple permanent tissues — parenchyma, collenchyma, sclerenchyma
- Parenchyma hides inside the conducting tissues→ Simple permanent tissues — parenchyma, collenchyma, sclerenchyma
- Pericycle is NOT a conducting component→ Conducting tissues — xylem and phloem
- Sieve plates and companion cells are PHLOEM, not xylem→ Conducting tissues — xylem and phloem
- Spot the plant among the non-plants→ Which organisms have vascular tissue
Formulas (2)
Reference tables (1)
Crop and botany facts — golden rice, sugarcane, cropping, nettle4 rows
| Fact | Answer | Note |
|---|---|---|
| Golden rice produces | Vitamin A (beta-carotene) | GM crop targeting vitamin-A deficiency Golden rice = Vitamin A, NOT omega-3 or vitamin B/C (NDA 2017). |
| Sugarcane is grown for | Sucrose | The cash-crop sugar; not glucose/fructose/starch |
| Two+ crops grown together | Intercropping | Same land, same time, defined rows Intercropping = simultaneous; crop rotation = in sequence (NDA 2020). |
| Nettle sting injects | Methanoic (formic) acid | Through hollow stinging hairs |
Watch out for (8)
- Oxygen is a PRODUCT, not a requirement→ Photosynthesis — requirements, equation and products
- Only ~1% of sunlight is used→ Photosynthesis — requirements, equation and products
- Released O₂ comes from WATER, not CO₂→ The light reaction — splitting water releases oxygen
- Water splits in the LIGHT reaction→ The light reaction — splitting water releases oxygen
- Leaves look green because chlorophyll REFLECTS green→ Chlorophyll and why leaves look green
- Meristem is LIVING and dividing — not dead wood→ Meristematic tissue drives plant growth
- Golden rice = Vitamin A→ Crop and botany facts — golden rice, sugarcane, cropping, nettle
- Intercropping (simultaneous) vs crop rotation (sequential)→ Crop and botany facts — golden rice, sugarcane, cropping, nettle
Watch out for (3)
- Photosynthesis + Oxygen is the linked pair→ The oxygen link — photosynthesis feeds respiration
- Shoot up = NEGATIVE geotropism (not negative phototropism)→ Tropisms — directional growth responses
- Lower surface coated = dries up LAST→ Transpiration — water loss through lower-surface stomata
Reference tables (2)
True vs false fruit, and the inflorescence2 rows
| Structure | What it is | Example |
|---|---|---|
| False fruit (apple) | Fleshy part from the thalamus, not the ovary | Apple, pear (pseudocarps) Apple's edible part = thalamus / receptacle (NDA 2026), not petal/sepal/stamen. |
| Inflorescence | A cluster of many florets on one axis | Sunflower, marigold (Asteraceae) The colourful sunflower/marigold 'flower' is an INFLORESCENCE (NDA 2017). |
Parts of the ovule — where reserve food is stored4 rows
| Ovule part | Role |
|---|---|
| Nucellus | Nutritive tissue holding the reserve food The ovule part with reserve food = nucellus (NDA 2026). |
| Integument | Outer protective layer (→ seed coat) |
| Funicle | Stalk attaching the ovule |
| Chalaza | Base where integument meets the nucellus |
Watch out for (4)
- Radicle = Root, Plumule = shoot→ The seed embryo — radicle and plumule
- Apple flesh = thalamus, not petal/sepal/stamen→ True vs false fruit, and the inflorescence
- Sunflower = inflorescence, not a single flower→ True vs false fruit, and the inflorescence
- Reserve food = nucellus (not integument or funicle)→ Parts of the ovule — where reserve food is stored
Reference tables (1)
Vegetative propagation — the organs that do it4 rows
| Plant | Propagating part |
|---|---|
| Potato | Eye buds (on the tuber) Vegetative propagation through eye buds = potato (NDA 2024). |
| Ginger | Rhizome (underground stem) |
| Onion | Bulb |
| Sugarcane | Stem cuttings (nodes) |
Watch out for (1)
- Eye buds = potato→ Vegetative propagation — the organs that do it