Biology

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Classification, plants, hormones and animal facts

⏱ 4 min read🧩 6 question types🎯 19 practice Q

The idea in one minute

This subtopic covers how living things are named and grouped, plant hormones, photosynthesis and which part of a plant we eat. Each item is a one-word pair. Learn the pairs in small groups, such as roots together and stems together.

Classification: the ladder

Carolus Linnaeus is the father of taxonomy. He gave binomial nomenclature, a two-word scientific name of genus plus species, written in italics. Example: Mangifera indica.

R.H. Whittaker (1969) gave the five-kingdom system.

Monera
Protista
Fungi
Plantae
Animalia

Earlier systems used two kingdoms: plants and animals.

Plants divide into two big groups.

Group	Meaning	Examples
Cryptogams	Seedless	Algae, fungi, bryophytes, pteridophytes
Phanerogams	Seed plants	Gymnosperms (naked seed), angiosperms (seed inside fruit)

Monocot and dicot

	Monocot	Dicot
Seed leaves	One	Two
Leaf veins	Parallel	Reticulate (net-like)
Roots	Fibrous	Taproot
Examples	Wheat, rice, maize	Mango, pea, gram

Tip: Parallel veins mean monocot. Net-like veins mean dicot.

Plant hormones

Hormone	Job
Auxin	Cell elongation. Bending to light (phototropism)
Gibberellin	Stem elongation. Seed germination
Cytokinin	Cell division. Delays leaf ageing
Ethylene (gas)	Fruit ripening
Abscisic acid	Stress hormone. Closes stomata. Promotes wilting and dormancy

Photosynthesis and transport

Photosynthesis happens in the chloroplast, which holds the green pigment chlorophyll. Sunlight drives it.

6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2

Rule: The oxygen released comes from water, not from carbon dioxide.

Leaves exchange gases through stomata.
Transpiration pulls water up the xylem.
Phloem carries food.
Excess water vapour escapes mainly through the lower surface of the leaf.

Edible parts of plants

Plant	Edible part
Carrot, radish, beetroot, turnip	Root
Potato, ginger, turmeric, onion (bulb), sugarcane	Stem (modified)
Cabbage, spinach, lettuce	Leaves
Cauliflower, broccoli	Flower
Tomato, brinjal, pumpkin, cucumber	Fruit
Groundnut, gram, mustard, rice, wheat	Seed
Apple, cashew	Fleshy thalamus (accessory fruit)

Watch: Potato, ginger, turmeric and onion grow underground but are stems. Sweet potato is a true root.

Reproduction and scientific names

Vegetative propagation uses runners and bulbs. People add grafting, layering, cutting and tissue culture. Wind pollinates maize and wheat, which have light dry pollen. Insects visit bright petals with nectar.

Organism	Scientific name
Mango	Mangifera indica
Neem	Azadirachta indica
Banyan	Ficus benghalensis
Tamarind	Tamarindus indica
Potato	Solanum tuberosum
Rice	Oryza sativa
Tiger	Panthera tigris
Frog	Rana tigrina

Question types you will see

Each type: how to recognise it, the method step by step, and one question to try.

Type 1very common3 practice Q

Classification history and systems

How to spot it:

'Who gave binomial nomenclature', 'five-kingdom classification', 'which kingdom does a bacterium belong to'.

Method

Linnaeus: binomial names. Whittaker: five kingdoms.
Bacteria go in Monera.
Cryptogams have no seeds. Phanerogams have seeds.

Why it works:

One scientist gave one system.

Try this

The five-kingdom classification was proposed by whom?

Show solution

The five kingdoms are Monera, Protista, Fungi, Plantae, Animalia.
The year was 1969.

Answer

R.H. Whittaker

Type 2very common4 practice Q

Edible part of the plant

How to spot it:

'Potato is a modified', 'carrot is which plant part', 'onion is a modified'.

Method

Name the food.
Find its group in the edible-parts table.
Watch the trap: potato is a stem, sweet potato is a root.

Why it works:

Recall works best by family: roots together, stems together.

Try this

The potato we eat is a modified what?

Show solution

It grows underground.
It has eyes, which are buds.

Answer

Stem (tuber)

Type 3very common3 practice Q

Plant hormones

How to spot it:

'Which hormone ripens fruits', 'bending towards light', 'stress hormone of plants'.

Method

Ripening: ethylene.
Bending to light: auxin.
Wilting and stress: abscisic acid.

Why it works:

Three one-word answers cover most questions.

Try this

Which plant hormone is responsible for fruit ripening?

Show solution

This hormone is a gas.
It is ethylene.

Answer

Ethylene

Type 4common3 practice Q

Photosynthesis and transport

How to spot it:

'Which gas is released in photosynthesis', 'which pigment absorbs light', 'xylem carries', 'stomata'.

Method

Inputs: CO₂ and water. Outputs: glucose and oxygen.
Chlorophyll in chloroplasts absorbs light.
Xylem carries water up. Phloem carries food.

Why it works:

The equation gives every answer.

Try this

In photosynthesis, which gas do plants release?

Show solution

Read the right side of the equation.
The gas comes from water.

Answer

Oxygen

Type 5common2 practice Q

Monocot vs dicot and reproduction

How to spot it:

'Which is a monocot', 'parallel venation', 'pollination by wind', 'grafting'.

Method

Parallel veins and fibrous roots mean monocot.
Wheat, rice and maize are monocots.
Grafting, layering, cutting and tissue culture are vegetative propagation.

Why it works:

Vein pattern separates monocots from dicots.

Try this

A plant shows parallel venation. Which group is it?

Show solution

Parallel veins point to one seed leaf.
Examples are wheat and maize.

Answer

Monocot

Type 6common2 practice Q

Scientific names and firsts

How to spot it:

'The scientific name of mango / neem / rice', match the column of plants and binomials.

Method

Recall the two-word name.
The first word is genus, the second is species.
Both are italic.

Why it works:

Linnaeus set the two-word rule.

Try this

What is the scientific name of mango?

Show solution

Genus is Mangifera.
Species is indica.

Answer

Mangifera indica

Formula sheet

Photosynthesis

6CO_2 + 6H_2O \xrightarrow[\text{chlorophyll}]{\text{sunlight}} C_6H_{12}O_6 + 6O_2

O₂ comes from water. Inputs are carbon dioxide and water. Outputs are glucose and oxygen

Aerobic respiration

C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (ATP)}

The reverse of photosynthesis in terms of matter. It releases energy as ATP

Shortcuts that save time

⚡ Underground but not a root

Potato, ginger, turmeric and onion grow underground but are stems. They have nodes or buds (eyes). Carrot, radish, sweet potato and beetroot are true roots.

Example

The edible part of ginger is?

Show solution

Ginger has nodes and buds.
So it is not a root.

Answer

A modified stem (rhizome)

⚡ Five kingdoms: My Pet Fish Plays Alone

Monera, Protista, Fungi, Plantae, Animalia. Whittaker, 1969.

Mistakes to avoid

Where most students lose marks on this subtopic.

Mistake 01

Calling sweet potato a stem and potato a root.

Potato is a stem. Sweet potato is a root.

Mistake 02

Saying the oxygen from photosynthesis comes from CO₂.

It comes from water.

Mistake 03

Calling the bat a bird or the whale a fish.

Both are mammals.

Mistake 04

Placing bacteria in the kingdom Plantae.

Bacteria belong to Monera.

Mistake 05

Giving Linnaeus credit for the five-kingdom system.

Linnaeus gave binomial names. Whittaker gave five kingdoms.

Quick revision

Read this the night before the exam.

Linnaeus: binomial nomenclature, father of taxonomy. Whittaker: 5 kingdoms (1969).
Monocot: one seed leaf, parallel veins. Dicot: two, reticulate veins.
Auxin: elongation and phototropism. Gibberellin: stem. Cytokinin: division. Ethylene: ripening. ABA: stress.
Carrot root, potato, ginger and onion stem, cabbage leaf, cauliflower flower, tomato fruit, groundnut seed.
Photosynthesis: 6CO₂ + 6H₂O gives glucose + 6O₂. Stomata: gas exchange. Xylem: water. Phloem: food.

Practice: 19 questions

Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.

Topic test · 10 questions

Suggested time 3 min · wrong answers go to your mistake notebook automatically.

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