Characteristics of living beings
A puppy eats, grows and plays, while a stone lying beside it stays the same for years.
Living beings need food and air, grow, take in oxygen for respiration, respond to changes around them, remove waste (excretion), reproduce and finally die. Non-living things show none of these. Most living things are made of tiny units called cells.
In the figure: A living being passes all the tests; a stone fails them all.
Rule 1: The checklist — Test with each characteristic one by one.
- Easy: Food, growth and breathing: all living things need them.
- Medium: Response: a dog turns to a sound; a plant bends to light.
- Exam-type: Reproduction keeps a kind of living thing from dying out.
Rule 2: Not every sign shows in all — Use all signs together.
- Easy: Plants do not walk, yet they are alive.
- Medium: A seed looks still but is alive and can sprout.
- Exam-type: A moving car or a flowing river is not alive.
Never decide life only from movement; check food, growth and reproduction too.
Believing a thing that moves is always alive.
"Eat, grow, breathe, respond, remove waste, reproduce."
Practice questions
- 1Which of these is a living being?
- 2A shell found on the beach may actually be —
- 3Needing food for growth and development is called —
- 4Producing new ones of one's own kind is called —
- 5A living being that cannot show any of the life characteristics even when food, air and water are available is said to be —
- 6A car moves on the road but is non-living because it —
- 7Which set lists characteristics of all living beings?
- 8The process of taking air in and out is part of —
Show answers (try them yourself first)
- 1Pigeon
- 2part of the body of a living snail
- 3nutrition
- 4reproduction
- 5dead
- 6does not grow, respire or reproduce
- 7Move, need food, grow, respire, excrete, respond to stimuli, reproduce
- 8respiration
Plants as living beings
A potted plant left in a dark cupboard turns yellow, while one placed by a window stays green and bends towards the glass.
Plants make their own food in leaves by photosynthesis, using sunlight, water and carbon dioxide, and give out oxygen. They also respire, grow, respond to stimuli, excrete and reproduce. Roots take in water and minerals; the stem carries them upwards.
In the figure: Leaves use sunlight, water and CO2 to make food and release oxygen.
Rule 1: Making food — Green leaves are the kitchen of the plant.
- Easy: Chlorophyll gives leaves the green colour and traps light.
- Medium: Plants give out oxygen that we breathe.
- Exam-type: Without light a plant cannot make food.
Rule 2: Other life signs — Plants respond slowly.
- Easy: Sunflower turns towards the Sun.
- Medium: Touch-me-not folds its leaves when touched.
- Exam-type: Plants also breathe, day and night.
Name the three raw materials for plant food: sunlight, water and carbon dioxide.
Believing plants take in food from the soil like animals eat.
"Light + water + CO2 in the leaf: food + oxygen."
Practice questions
- 1Does a plant show growth?
- 2Which living characteristic is shown by a plant producing seeds that grow into new plants?
- 3Which scientist built the crescograph to measure plant growth and responses?
- 4Plants do not move from place to place but still show —
- 5Insectivorous plants depend on insects for —
- 6Climbers show movement when they —
- 7The touch-me-not (chhui-mui) plant folds its leaves when —
- 8All living beings respire. This includes —
Show answers (try them yourself first)
- 1Yes, plants also grow
- 2Reproduction
- 3Jagadish Chandra Bose
- 4movements such as opening of flowers
- 5nutrition
- 6wind around objects placed near them
- 7we touch them
- 8plants as well as animals
Germination of seeds
Soaked chana in a damp cloth shows small white tails in two days.
Germination is the start of a new plant from a seed. A seed needs water, air (oxygen) and a suitable temperature. The seed swells, the root (radicle) comes out first and goes down, and then the shoot (plumule) grows up with the first leaves.
In the figure: The root comes out first, then the shoot with leaves.
Rule 1: Conditions needed — Test by removing one condition at a time.
- Easy: A dry seed does not sprout; it needs water.
- Medium: A seed under deep water lacks air and may not sprout.
- Exam-type: Very cold or very hot places stop germination.
Rule 2: Stages — Follow the order of events.
- Easy: Seed takes in water and swells.
- Medium: The seed coat splits and the root grows down.
- Exam-type: The shoot grows up and green leaves open.
Keep soil or cotton damp but not flooded when sprouting seeds.
Thinking a seed needs sunlight to germinate.
"Water, air, warmth: root first, shoot next."
Practice questions
- 1In Activity 10.2, which pot was kept in the dark with moist soil?
- 2In Activity 10.2, which pot received no water?
- 3In Activity 10.2, which pot was moist and in sunlight?
- 4In Activity 10.2, which pot had excess water above the soil?
- 5Which seeds need light to germinate?
- 6When a seed turns into a sprout, it is said to have —
- 7The outer covering of a seed is called the —
- 8Seeds use the air present in —
Show answers (try them yourself first)
- 1Pot C
- 2Pot A
- 3Pot D
- 4Pot B
- 5Coleus and Petunia
- 6germinated
- 7seed coat
- 8the spaces between soil particles
Growth, movement and life cycle of a plant
A mango seed becomes a sapling, then a tree that flowers and gives fruits with new seeds.
A plant grows as its roots go down and its shoot goes up. Parts move slowly: shoots bend to light, and roots grow towards water. The life cycle runs from seed to seedling, to a grown plant, to flower and fruit, which holds new seeds. Plants live different lengths of time.
In the figure: The cycle goes on: new seeds start new plants.
Rule 1: Growth and movement — Look for slow changes over days.
- Easy: Height and number of leaves increase with time.
- Medium: A plant by a window bends towards light.
- Exam-type: Flowers of some plants open at day and close at night.
Rule 2: Plant life cycle — Seed to seed.
- Easy: Flowers make fruits and fruits hold seeds.
- Medium: Annuals live one season; trees live for many years.
- Exam-type: Seeds spread by wind, water or animals.
Start the life cycle at the seed and end at the new seed.
Leaving out the flower stage between plant and fruit.
"Seed, seedling, plant, flower, fruit, seed."
Practice questions
- 1What does the crescograph of J. C. Bose show?
- 2In an upright plant, the root grows —
- 3In an upright plant, the shoot grows —
- 4When light comes only from one direction, the shoot —
- 5The entire process from seed to plant to the next generation of seeds is called the —
- 6The fruit of a bean plant is a —
- 7When a plant is kept inverted, the root —
- 8When a plant is kept inverted, the shoot —
Show answers (try them yourself first)
- 1How fast plants grow
- 2downwards
- 3upwards
- 4grows towards the light
- 5life cycle of a plant
- 6pod with seeds
- 7bends and grows downwards
- 8bends and grows upwards
Life cycles of animals
A caterpillar eating leaves is not a butterfly yet; it changes shape completely before it flies.
Every animal passes through stages from birth to adulthood. A butterfly goes through egg, larva (caterpillar), pupa and adult. A frog goes through egg, tadpole, young frog and adult. Some animals, like cats and humans, give birth to young that look like the adult.
In the figure: Butterfly and frog change shape greatly; chickens only grow bigger.
Rule 1: Butterfly and frog — Each stage looks different from the next.
- Easy: Butterfly: egg, larva, pupa, adult.
- Medium: The larva eats a lot and grows; the pupa rests.
- Exam-type: Frog: egg, tadpole with a tail, young frog, adult.
Rule 2: Other animals — Some young look like small adults.
- Easy: Chicken: egg, chick, hen or cock.
- Medium: Cockroach: egg, nymph, adult.
- Exam-type: Mammals give birth to babies and feed them milk.
Write the stages in order and say which one eats and which one rests.
Thinking a tadpole is a different animal from a frog.
"Egg, larva, pupa, adult."
Practice questions
- 1Mosquitoes pass through how many stages in their life cycle?
- 2The silk moth has how many life stages?
- 3The correct order of mosquito life stages is —
- 4Kerosene oil is sprayed on stagnant water because it —
- 5Female mosquitoes can transmit diseases such as —
- 6A white jelly-like cluster of eggs at the edge of a pond is called —
- 7Mosquito larvae and pupae live in —
- 8Mosquito larvae and pupae come to the water surface to —
Show answers (try them yourself first)
- 1four
- 2four
- 3egg, larva, pupa, adult
- 4forms a layer that stops larvae and pupae from breathing air
- 5malaria, dengue and chikungunya
- 6spawn
- 7water
- 8get air to respire