🧬 Biology · Topic 5 of 10
Start with the study notes on Plants: Structure & Transportation (definitions, examples and a quick revision), then work through 60 practice questions, each with the correct answer and a clear explanation of why it is right. When you are ready, take this topic as an interactive quiz to test yourself.
Topic overview
Root hairs are fine outgrowths that give a large surface area for absorbing water. Water enters them by osmosis.
Examples:
The stem holds the leaves up to the light and carries water and food. A node is where a leaf grows; the part between two nodes is the internode.
Venation is the pattern of veins in a leaf.
Plants have two transport tissues, together called vascular tissue:
Example: Stand a white flower or a celery stalk in coloured water. Coloured streaks appear, showing the path of the xylem.
Remember: Remove a ring of bark (with its phloem) all the way round a tree trunk, and the roots get no food, so the tree slowly dies.
Transpiration is the loss of water as vapour from the leaves, mainly through the stomata.
Examples:
Example: A flower with both stamens and pistil, like mustard or hibiscus, is called bisexual.
Example: Wind-pollinated flowers, such as grass and maize, are small and dull and make lots of light pollen.
Seed dispersal is the scattering of seeds away from the parent plant, so the new plants are not crowded.
Germination is a seed sprouting into a new plant. It needs water, air and a suitable temperature.
Example: Gram has two cotyledons (a dicot); maize has one (a monocot).
Vegetative propagation is growing new plants from roots, stems or leaves instead of seeds. The new plants are identical to the parent.
Examples:
| Misconception | Correct understanding |
|---|---|
| Xylem carries food. | Xylem carries water and minerals; phloem carries food. |
| Transpiration is just a waste of water. | It pulls water up and cools the plant. |
| The flower becomes the fruit. | The ovary becomes the fruit; the ovules become seeds. |
| Seeds need light to germinate. | They need water, air and warmth; light is needed only after the shoot comes up. |
| Pollination and fertilisation are the same. | Pollination moves pollen to the stigma; fertilisation is the joining of male and female cells. |
Which kind of root does maize have?
Fibrous roots.
What do xylem and phloem carry?
Xylem carries water and minerals; phloem carries food.
What is transpiration, and how does it help the plant?
Water vapour lost from the leaves; it pulls water up and cools the plant.
Why do plants wilt on hot afternoons?
They lose water faster than the roots can absorb it.
Which part of a flower makes pollen?
The anther.
What does the ovary become after fertilisation?
The fruit.
How is a coconut dispersed?
By water: its fibrous husk lets it float.
What three things does a seed need to germinate?
Water, air and a suitable temperature.
Key takeaway: Roots absorb water, xylem carries it up, leaves make food, phloem carries the food everywhere, and flowers make seeds for the next generation.
Notes written by Velnov for Class 6–8 students, following the topics of the NCERT science syllabus.
Q1. easy
The two main parts of a plant are the:
Answer: A — Root system (below ground) and shoot system (above ground)
The root system anchors the plant and absorbs water and minerals. The shoot system - stem, leaves, flowers and fruits - carries out photosynthesis and reproduction.
Q2. easy
Which of these is a MAIN function of the root?
Answer: A — Anchoring the plant and absorbing water and minerals
Roots hold the plant firmly in the soil and take in water and dissolved minerals. Some roots also store food, as in carrot and sweet potato.
Q3. medium
A root system with one main thick root and smaller side roots is called a:
Answer: A — Tap root system
Tap roots are found in dicot plants such as mustard, gram, mango and neem. The main root goes deep, with lateral roots branching off it.
Q4. medium
A root system with many thin roots of similar size arising from the base of the stem is called:
Answer: A — Fibrous root system
Fibrous roots are found in monocots such as wheat, rice, maize and grass. They spread near the surface and hold the soil well.
Q6. medium
The arrangement of veins in a leaf is called:
Answer: A — Venation
There are two main patterns: reticulate venation, where veins form a net around the midrib, and parallel venation, where veins run side by side.
Q8. medium
The stalk that attaches a leaf to the stem is called the:
Answer: A — Petiole
The petiole holds the leaf away from the stem so it gets light and air, and carries the vascular tissue that connects the leaf to the plant's transport system.
Q10. medium
Which of these is a function of the STEM?
Answer: A — Holding leaves up to the light and conducting water and food
The stem supports the leaves, flowers and fruits, and its xylem and phloem carry water upwards and food in both directions.
Q12. medium
The tissue that transports food from leaves to other parts is:
Answer: A — Phloem
Phloem carries dissolved sugar from the leaves to growing tips, roots, fruits and storage organs. It can transport in both directions.
Q14. medium
An experiment in which a stem is placed in coloured water shows coloured streaks in the stem. This proves that:
Answer: A — Water travels up the stem through the xylem
Cutting the stem afterwards reveals coloured dots or lines - the xylem vessels stained by the dye - showing the path water takes to the leaves.
Q16. medium
Transpiration helps the plant by:
Answer: A — Cooling the plant and creating a pull that draws water up from the roots
As water evaporates from the leaves, it pulls the column of water in the xylem upwards - the transpiration pull. The evaporation also cools the leaf surface.
Q18. medium
Transpiration increases when:
Answer: A — It is hot, dry and windy
Heat speeds evaporation, dry air accepts more vapour, and wind carries the vapour away from the leaf surface, so all three raise the rate of transpiration.
Q20. medium
The male reproductive part of a flower is the:
Answer: A — Stamen
Each stamen has an anther that produces pollen grains, held up by a stalk called the filament.
Q21. medium
The female reproductive part of a flower is the:
Answer: A — Pistil (carpel)
The pistil has three parts: the sticky stigma at the top, the style below it, and the ovary at the base containing the ovules.
Q23. medium
The part of the flower that develops into a FRUIT after fertilisation is the:
Answer: A — Ovary
After fertilisation, the ovary swells and ripens into a fruit, while the ovules inside it become the seeds. The other floral parts usually wither away.
Q25. medium
The green leaf-like parts that protect a flower bud are the:
Answer: A — Sepals
Sepals form the outermost whorl of a flower, enclosing and protecting the developing bud. Together they are called the calyx.
Q27. medium
The transfer of pollen from the anther to the stigma is called:
Answer: A — Pollination
Pollination may occur within the same flower (self-pollination) or between different flowers of the same kind (cross-pollination), and it precedes fertilisation.
Q29. medium
Wind-pollinated flowers such as those of grasses and maize are usually:
Answer: A — Small, dull-coloured and produce large amounts of light pollen
There is no need to attract insects, so wind-pollinated flowers spend nothing on colour, scent or nectar. Instead they make huge quantities of very light pollen.
Q31. medium
The scattering of seeds away from the parent plant is called:
Answer: A — Seed dispersal
Dispersal prevents overcrowding and competition for light, water and nutrients, and helps plants colonise new areas.
Q33. medium
A coconut is dispersed by water because it:
Answer: A — Has a light fibrous husk that helps it float
The thick fibrous husk traps air, allowing coconuts to float across the sea for long distances and germinate on distant shores.
Q35. medium
The bursting open of pods in castor and balsam scatters seeds. This is dispersal by:
Answer: A — Explosion (the plant's own mechanism)
As the pod dries, tension builds in its walls until it splits suddenly, flinging the seeds several metres away from the parent plant.
Q37. medium
The conditions necessary for a seed to germinate are:
Answer: A — Water, air (oxygen) and a suitable temperature
Water softens the seed coat and activates enzymes, oxygen is needed for respiration, and warmth allows the reactions to proceed. Light is not needed until the shoot emerges.
Q39. medium
The stored food in a seed that nourishes the young seedling is present in the:
Answer: A — Cotyledons
Cotyledons (seed leaves) store food such as starch and protein. A gram seed splits into two cotyledons; a maize grain has only one.
Q41. medium
Reproduction from parts of the plant other than seeds - such as stems, roots and leaves - is called:
Answer: A — Vegetative propagation
Potato tubers, ginger rhizomes, sugarcane stem cuttings and Bryophyllum leaf buds all grow into new plants without seeds.
Q43. medium
Which of these is grown from stem cuttings?
Answer: A — Rose and sugarcane
A cutting with at least one node placed in moist soil develops roots and grows into a new plant identical to the parent - a quick, reliable method for gardeners.
Q45. medium
Which underground stem is used to grow new ginger plants?
Answer: A — Rhizome
Ginger and turmeric are rhizomes - horizontal underground stems with buds. A piece with a bud planted in soil sprouts into a new plant.
Q47. medium
Which type of root helps the banyan tree support its heavy spreading branches?
Answer: A — Prop roots hanging from the branches
Prop roots grow downwards from the branches, reach the soil and thicken into pillar-like supports, letting the crown spread over a huge area.
Q49. medium
Which of these plants has a modified stem that stores food?
Answer: A — Potato
The potato is a stem tuber. Carrot, radish, beetroot and sweet potato are storage roots.
Q51. medium
Roots absorb water from the soil mainly by the process of:
Answer: A — Osmosis through the root hairs
Soil water is more dilute than the cell sap inside root hairs, so water passes in through the cell membrane by osmosis and then moves inwards to the xylem.
Q53. medium
A flower that has both stamens and pistil is called:
Answer: A — A bisexual flower
Bisexual flowers such as mustard, hibiscus and rose contain both reproductive parts. Papaya and cucumber have separate male and female (unisexual) flowers.
Q55. medium
Which part of the plant is usually the site of photosynthesis, gas exchange and transpiration?
Answer: A — The leaf
The leaf carries out all three: chloroplasts photosynthesise, stomata exchange gases, and water vapour is lost through the same stomata during transpiration.
Q57. medium
Which overall statement about plant structure and transport is CORRECT?
Answer: A — Roots absorb water, xylem carries it up, leaves make food, and phloem distributes that food throughout the plant
This sums up the topic: each part of the plant has a role, and the xylem and phloem link them into a single working system - absorption, transport, food-making and distribution.
Q58. medium
Why do gardeners often remove the lower leaves of a stem cutting before planting it?
Answer: A — To reduce water loss by transpiration until the cutting grows roots
A cutting has no roots yet, so it cannot replace lost water. Removing most of the leaves cuts transpiration to a level the cutting can survive while roots develop.
Q60. medium
Which part of a flower is sticky so that pollen grains can be caught on it?
Answer: A — The stigma
The stigma at the top of the pistil has a sticky or feathery surface that traps pollen brought by insects or wind, so the pollen tube can begin to grow down the style.
Q5. hard
Plants with LEAVES having parallel venation usually have:
Answer: A — Fibrous roots
Parallel venation goes with fibrous roots (monocots like grass and maize), while reticulate (net-like) venation goes with tap roots (dicots like mango and hibiscus).
Q7. hard
The broad flat green part of a leaf is called the:
Answer: A — Lamina (leaf blade)
The lamina is where photosynthesis happens. The petiole is the stalk that joins it to the stem, and the midrib is the thick central vein.
Q9. hard
The point on a stem where a leaf arises is called a:
Answer: A — Node
A node is the point of leaf attachment; the length of stem between two nodes is the internode. Buds also arise at nodes.
Q11. hard
The tissue that conducts water and minerals from roots to leaves is:
Answer: A — Xylem
Xylem forms continuous hollow tubes running from root to leaf. Water moves upwards in one direction only, pulled largely by transpiration.
Q13. hard
Xylem and phloem together are called:
Answer: A — Vascular tissue
Vascular tissue forms the plant's transport system, running as bundles through roots, stem and leaf veins.
Q15. hard
The loss of water as vapour from the aerial parts of a plant is called:
Answer: A — Transpiration
Transpiration occurs mainly through the stomata of leaves. It cools the plant, helps minerals move upwards, and creates the pull that draws water from the roots.
Q17. hard
A polythene bag tied over a leafy branch collects water droplets inside. This shows:
Answer: A — Transpiration - the plant is losing water as vapour
Water vapour released by the leaves condenses on the cooler plastic. A bag over a leafless branch collects almost nothing, confirming the leaves are the source.
Q19. hard
Why do plants wilt on a hot summer afternoon?
Answer: A — Water is lost by transpiration faster than the roots can absorb it
When loss exceeds uptake, the cells lose their firmness (turgor) and the leaves droop. They usually recover in the evening as transpiration slows.
Q22. hard
Pollen grains are produced in the:
Answer: A — Anther
The anther is the swollen top of the stamen. When ripe, it splits open and releases pollen grains, which contain the male gametes.
Q24. hard
Ovules develop into:
Answer: A — Seeds
Each fertilised ovule becomes a seed containing an embryo and stored food. A fruit with many seeds simply developed from an ovary with many ovules.
Q26. hard
The brightly coloured parts of a flower that attract insects are the:
Answer: A — Petals
Petals, together called the corolla, are often brightly coloured and scented to attract pollinators such as bees, butterflies and birds.
Q28. hard
Which of these are common agents of pollination?
Answer: A — Insects, wind, water and birds
Insect-pollinated flowers are usually bright and scented with sticky pollen. Wind-pollinated flowers are small and dull with light, abundant pollen.
Q30. hard
The fusion of the male and female gametes is called:
Answer: A — Fertilisation
After pollination, a pollen tube grows down the style to the ovule, where the male gamete fuses with the egg. The resulting zygote develops into the embryo.
Q32. hard
Seeds of the drumstick and maple have wings, which shows they are dispersed by:
Answer: A — Wind
Wings and hairs make seeds light and slow their fall, so the wind can carry them far. Madar (aak) seeds with silky hairs work the same way.
Q34. hard
Seeds with hooks and spines, like those of Xanthium, are dispersed by:
Answer: A — Animals, as the seeds stick to their fur or to clothing
The hooks catch on animal fur or human clothes and are carried away before dropping off elsewhere. Fleshy fruits are also dispersed by animals that eat them.
Q36. hard
The sprouting of a seed into a new plant is called:
Answer: A — Germination
During germination, the seed absorbs water, the seed coat splits, the radicle grows down to form the root and the plumule grows up to form the shoot.
Q38. hard
In a germinating seed, the part that grows into the ROOT is the:
Answer: A — Radicle
The radicle emerges first and grows downwards into the soil. The plumule then grows upwards and becomes the shoot.
Q40. hard
Plants with TWO cotyledons in their seeds are called:
Answer: A — Dicots
Dicots such as gram, pea and mango have two cotyledons, tap roots and reticulate leaf venation. Monocots such as maize and rice have one cotyledon, fibrous roots and parallel venation.
Q42. hard
Bryophyllum reproduces vegetatively through:
Answer: A — Buds on the margins of its leaves
Tiny buds in the notches of Bryophyllum leaves develop into small plantlets. When they fall to moist soil, each grows into a complete new plant.
Q44. hard
An advantage of vegetative propagation is that:
Answer: A — The new plants are identical to the parent and mature faster than from seed
Since the offspring are genetically identical, desirable qualities such as fruit taste are preserved exactly, and plants flower and fruit sooner than seed-grown ones. The drawback is a lack of variation.
Q46. hard
The 'eyes' of a potato are actually:
Answer: A — Buds that can grow into new plants
Each eye is a bud on the underground stem. Planting a piece of potato with an eye produces a whole new plant, using the tuber's stored food.
Q48. hard
Roots that grow from parts of the plant OTHER than the main root are called:
Answer: A — Adventitious roots
Prop roots of the banyan, stilt roots of maize and the roots on a cutting are all adventitious - they arise from stems or leaves rather than from a radicle.
Q50. hard
The tendrils of a pea plant, which help it climb, are modified:
Answer: A — Leaves
In peas, the upper leaflets are modified into thread-like tendrils that coil around a support, holding the weak stem up towards the light.
Q52. hard
Which force helps push water UP a tall tree, together with transpiration pull?
Answer: A — Root pressure and the cohesion of water molecules in narrow xylem tubes
Water molecules stick to one another and to the xylem walls, forming an unbroken column. Transpiration pulls it up while root pressure pushes from below.
Q54. hard
In cross-pollination, pollen is transferred:
Answer: A — From the anther of one flower to the stigma of another flower of the same kind
Cross-pollination brings together material from two plants, producing offspring with more variation - an advantage in a changing environment.
Q56. hard
Why is transpiration sometimes called a 'necessary evil'?
Answer: A — It wastes a lot of water, but it also pulls water up and cools the plant
Most of the water absorbed is lost as vapour, which seems wasteful. But the same process draws water and minerals upwards and prevents the leaves overheating.
Q59. hard
If a ring of bark (containing phloem) is removed all the way round a tree trunk, the tree eventually dies because:
Answer: A — Food made in the leaves can no longer reach the roots
Xylem lies deeper in the wood, so water still rises and the leaves stay alive for a while. But with the phloem cut, the roots are starved of food and finally die, killing the tree.