Class 9 Biology — Important Questions with Answers

6 concept-first Class 9 Biology questions across 4 chapters — each with a clear model answer, the why behind it, and a memory trick to make it stick. NCERT-aligned and free. Build the base now, and your board exams, NEET and JEE feel a whole lot easier later.

6 questions•4 chapters•Concept-first•NCERT-aligned•For boards, NEET & JEE

The Fundamental Unit of Life (2)Tissues (2)Improvement in Food Resources (1)Natural Resources (1)

The Fundamental Unit of Life2 questions

BiologyProkaryotic and eukaryotic cellsmedium

Give two differences between a prokaryotic and a eukaryotic cell.

Reveal answer▾

What it is

Prokaryotes (bacteria) have no true nucleus; eukaryotes (plants, animals) have a nucleus and organelles.

Answer

A prokaryotic cell has no true nucleus - its genetic material lies free in the cytoplasm - and it lacks membrane-bound organelles like mitochondria; bacteria are examples. A eukaryotic cell has a true, membrane-bound nucleus and membrane-bound organelles; plant and animal cells are examples. Eukaryotic cells are usually larger and more complex.

•Prokaryote: no true nucleus, no membrane-bound organelles (bacteria)
•Eukaryote: true nucleus + organelles (plants, animals)
•Eukaryotic cells are larger and more complex

Why learn this

It's the deepest divide in the living world and why antibiotics can hit bacteria but not your own cells.

💡 Memory trick

PRO = primitive, NO true nucleus; EU = 'true', good nucleus.

BiologyOsmosismedium

What is osmosis? What happens to a cell placed in pure water?

Reveal answer▾

What it is

Osmosis is water moving across a membrane to balance the concentration on both sides.

Answer

Osmosis is the movement of water molecules through a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration. A cell placed in pure water (a hypotonic solution) gains water by osmosis and swells; an animal cell may even burst, while a plant cell becomes firm (turgid) because of its cell wall.

•Water moves across a selectively permeable membrane
•From higher to lower water concentration
•In pure water a cell swells (animal may burst; plant turns turgid)

Why learn this

It's how roots absorb water, how our cells stay hydrated and why salt preserves food.

💡 Memory trick

Water follows the salt. Cell in pure water swells; in salty water it shrinks.

Tissues2 questions

BiologyMeristematic tissuemedium

What is meristematic tissue and where is it found in plants?

Reveal answer▾

What it is

Meristem is a plant's growth tissue - young cells that keep dividing at tips and edges.

Answer

Meristematic tissue is made of small, thin-walled cells that keep dividing to help the plant grow. It is found at the growing regions - apical meristem at the tips of roots and shoots (which increases length) and lateral meristem or cambium (which increases thickness). Because its cells divide actively, they have dense cytoplasm and no large vacuoles.

•Dividing cells responsible for growth
•Apical meristem at root/shoot tips (length)
•Lateral meristem/cambium (thickness)
•Dense cytoplasm, actively dividing

Why learn this

It's why plants grow taller and thicker all their lives, and how grafting and pruning work.

💡 Memory trick

Apical meristem at the tips (length); lateral meristem sideways (girth).

BiologyXylem and phloemmedium

What are xylem and phloem? State the function of each.

Reveal answer▾

What it is

Xylem and phloem are the transport tissues of plants - xylem carries water, phloem carries food.

Xylem carries water up; phloem carries food through the plant

Answer

Xylem and phloem are the two conducting (vascular) tissues in plants. Xylem carries water and dissolved minerals upward from the roots to the leaves. Phloem transports the food (sugar) made in the leaves during photosynthesis to all other parts of the plant. Together they form the plant's transport system.

•Xylem: carries water and minerals up from the roots
•Phloem: carries food from leaves to the whole plant
•Both are conducting (vascular) tissues

Why learn this

They are the plant's plumbing - how water rises from the roots and food reaches every part.

💡 Memory trick

Xylem = water UP from roots; Phloem = Food (from leaves) to the whole plant.

Improvement in Food Resources1 question

BiologyMixed cropping and intercroppingmedium

What is the difference between mixed cropping and intercropping?

Reveal answer▾

What it is

Mixed cropping blends crops with no set pattern; intercropping plants them in definite rows.

Answer

In mixed cropping two or more crops are grown together on the same field at the same time with no fixed pattern, mainly to reduce the risk of total crop failure. In intercropping two or more crops are grown together in a definite row pattern (for example, a few rows of one crop then a few of another) to use nutrients and space efficiently and to help control pests.

•Mixed cropping: crops mixed, no pattern, reduces risk
•Intercropping: crops in a definite row pattern
•Both grown together to improve yield

Why learn this

Farmers use both to raise yield and cut the risk of losing everything to one pest or failure.

💡 Memory trick

Mixed = Muddled together; Inter = In neat rows (a definite pattern).

Natural Resources1 question

BiologyImportance of the atmosphereeasy

Why is the atmosphere important for life on Earth?

Reveal answer▾

What it is

The atmosphere is Earth's protective blanket of air that supplies gases and steadies temperature.

Answer

The atmosphere is a blanket of air that supports life in several ways: it provides oxygen for breathing and carbon dioxide for photosynthesis, keeps the temperature of the Earth steady by preventing sudden day-to-night changes, and shields us from the Sun's harmful ultraviolet rays through the ozone layer. Winds and the water cycle also depend on it.

•Provides oxygen and carbon dioxide
•Keeps temperature steady (day and night)
•Ozone layer blocks harmful UV rays
•Drives winds and the water cycle

Why learn this

It gives us oxygen, blocks harmful UV rays (ozone) and drives weather - no atmosphere, no life.

💡 Memory trick

The air blanket does 3 B's: Breathe, Block UV, Balance temperature.

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