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TNPSC botany practice questions: plant physiology and hormones

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

Botany questions in the TNPSC General Science unit stay at the level of the school biology textbook: where photosynthesis happens, how water moves, which hormone does what. The unit carries about 5 of the 75 General Studies questions, so you can expect a botany question in some papers and none in others, which makes a short, sharp revision the right approach. The five questions below cover the chapter's core. The subject guide is TNPSC General Science.

What this topic covers

• Plant cell and tissues: the cell wall, chloroplast, vacuole; xylem, phloem and other tissues.
• Nutrition: photosynthesis, the role of chlorophyll, and how plants obtain nitrogen.
• Water and transport: absorption by roots, transpiration through stomata, translocation.
• Growth regulation: plant hormones.
• Reproduction: pollination, fertilisation, seeds and fruits.

Sample questions

Question 1

The site of photosynthesis in a plant cell is the:

• A. chloroplast
• B. mitochondrion
• C. ribosome
• D. nucleus

Question 2

The loss of water in the form of vapour from the aerial parts of a plant is called:

• A. guttation
• B. respiration
• C. transpiration
• D. germination

Question 3

Water and minerals are carried upward through the plant by the:

• A. phloem
• B. xylem
• C. cambium
• D. cortex

Question 4

The plant hormone that promotes the ripening of fruits is:

• A. auxin
• B. gibberellin
• C. ethylene
• D. cytokinin

Question 5

The nitrogen-fixing bacteria found in the root nodules of leguminous plants are:

• A. Lactobacillus
• B. Salmonella
• C. Vibrio
• D. Rhizobium

Answers and explanations

1. A. Chloroplasts contain chlorophyll and carry out photosynthesis. Mitochondria release energy in respiration, ribosomes make proteins and the nucleus controls the cell.
2. C. Transpiration is the loss of water vapour, mainly through stomata on the leaves. Guttation is the loss of liquid water droplets at leaf margins, usually at night.
3. B. Xylem carries water and minerals upward from the roots, and phloem carries prepared food from the leaves to other parts.
4. C. Ethylene is a gaseous hormone that triggers ripening. This is why a ripe fruit can hasten ripening in the fruits around it.
5. D. Rhizobium lives in the root nodules of legumes such as groundnut and pulses and fixes atmospheric nitrogen into a form the plant can use. This is why legumes enrich the soil.

How to prepare botany

Draw rather than read. A labelled sketch of a leaf cross-section (cuticle, epidermis, palisade layer, spongy layer, stomata and guard cells) and a sketch of a plant cell with its organelles cover most of the chapter. Redraw them from memory until you can label every part.

Learn the processes as equations or flow lines: photosynthesis takes in carbon dioxide and water and releases oxygen and glucose, with light and chlorophyll; respiration is the reverse in terms of the gases. Keep the two processes separate in your head, because options in a question often swap them.

Revise the hormone table above until each hormone has one function. Add a handful of "plants and their special features" facts, such as insectivorous plants (pitcher plant, sundew), parasitic plants (Cuscuta) and plants that fix nitrogen. For the next biology block, go to TNPSC zoology: human body practice.

Take the full topic test on PrepMatic

Since the general science questions are few but quick, a PrepMatic topic test of about 15 questions makes sense once you have covered biology. The free assessment shows your strongest and weakest subjects, which helps you judge whether to spend a day on science or move on to larger units such as Tamil Nadu history and polity.

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