Biodiversity around us
A school garden has trees, grasses, insects, birds and worms; a rocky roof has hardly any of them.
Biodiversity is the variety of living things in a place. It is high where there are many different plants and animals, like a forest, and low in places like a desert. Each kind of living thing is a species.
In the figure: A forest holds many kinds of living things; a desert holds few.
Rule 1: Where is it high — Count how many different kinds you can find.
- Easy: Rainforests and coral reefs have very high biodiversity.
- Medium: Deserts and polar lands have fewer kinds.
- Exam-type: India is rich in biodiversity.
Rule 2: Why it is important — Living things depend on one another.
- Easy: Plants give us food, wood and medicines.
- Medium: Losing one species can upset others.
- Exam-type: Protecting forests and ponds protects species.
Compare places by counting kinds, not the number of individuals.
Thinking a place with many ants has high biodiversity.
"Many kinds, not many numbers."
Practice questions
- 1What was the Silent Valley forest being threatened by?
- 2Which person is remembered for documenting and protecting India's plant biodiversity?
- 3The variety of plants and animals found in a particular region is called its —
- 4During the nature walk, Dr Raghu said each bird has its own chirp. This is an example of —
- 5What does Maniram chacha do well?
- 6A class lists a few plants on the board, yet many more exist. What does this suggest?
- 7When one kind of living thing in a region is lost, what is a likely effect?
- 8Why should we not pluck leaves and flowers on a nature walk?
Show answers (try them yourself first)
- 1A proposed hydroelectric dam
- 2Janaki Ammal
- 3biodiversity
- 4diversity in nature
- 5Mimic bird calls and identify plants and animals
- 6There are many more varieties than those drawn
- 7Other living things that depend on it may be affected
- 8We should observe nature without disturbing living things
Why and how we group living things
A shopkeeper keeps rice, pulses and oil in separate shelves so that anything can be found quickly.
Millions of kinds of living things exist, so we group them. Grouping makes it easier to study and remember them. We group by a common feature such as body parts, food or where they live. A different feature gives different groups, so first decide the basis of grouping.
In the figure: First split into plants and animals, then use more features to split further.
Rule 1: Basis of grouping — State the rule before you sort.
- Easy: Group by where they live: land, water, air.
- Medium: Group by food: plants eaters and meat eaters.
- Exam-type: Group by body parts: with or without a backbone.
Rule 2: Benefits of grouping — It saves time and shows relations.
- Easy: It is easy to find and name a new organism.
- Medium: It shows which organisms are alike.
- Exam-type: Scientists everywhere can share the same groups.
Pick one clear feature that every item either has or does not have.
Mixing two different rules in the same grouping.
"Pick a basis, then sort."
Practice questions
- 1Which is a basis for grouping animals?
- 2Which feature helps to group the plant seen as 'Tulsi: hard and thin stem'?
- 3Which could be a feature to group animals by?
- 4Which basis would produce the groups 'land animals' and 'water animals'?
- 5Which is the best basis to group plants and animals so as to study them easily?
- 6For grouping plants, which pair of features did the chapter mention?
- 7Which statement about stems helps in grouping plants?
- 8Grouping the cards by 'presence or absence of flowers' is possible for —
Show answers (try them yourself first)
- 1The way they move
- 2Nature of the stem
- 3What they eat
- 4Place where they live
- 5Their similarities and differences
- 6Hard or soft stem and presence of flowers
- 7Stems vary in thickness, height and hardness
- 8plants
Grouping plants
A tulsi plant is small and soft, a rose bush has many woody stems, and a mango tree has one thick trunk.
Herbs are small plants with soft green stems. Shrubs have woody stems branching near the ground. Trees are tall with a thick woody trunk. Climbers need support to climb, while creepers spread along the ground.
In the figure: Herb, shrub and tree differ in height and woodiness of the stem.
Rule 1: Herb, shrub, tree — Look at the stem and the height.
- Easy: Herbs: wheat, tulsi, mint.
- Medium: Shrubs: rose, hibiscus, jasmine.
- Exam-type: Trees: mango, banyan, neem.
Rule 2: Climbers and creepers — Weak stems need help or lie down.
- Easy: Climbers use tendrils or hooks: pea, grape.
- Medium: Creepers spread on the ground: pumpkin, watermelon.
- Exam-type: Both have weak stems that cannot stand alone.
Check three things: height, stem type and need for support.
Calling a big-looking banana plant a tree because it is tall.
"Herb soft, shrub bushy, tree trunk."
Practice questions
- 1A mango tree has a hard, thick, brown stem with branches high up. It is a —
- 2A plant with a small, soft, green stem is a —
- 3The pattern of veins on a leaf is called —
- 4Grass has a bunch of thin, similar roots from the base of the stem. These are —
- 5Generally, plants with reticulate venation have —
- 6A rose plant has many hard stems branching near the ground. It is a —
- 7A plant with a weak stem that needs support to grow upward is a —
- 8The leaves of hibiscus show a net-like pattern of veins. This is called —
Show answers (try them yourself first)
- 1tree
- 2herb
- 3venation
- 4fibrous roots
- 5taproots
- 6shrub
- 7climber
- 8reticulate venation
Grouping animals
A cow, a fish and a butterfly are all animals, yet one has a backbone, one lives only in water and one has six legs.
Animals with a backbone are vertebrates: fish, amphibians, reptiles, birds and mammals. Those without are invertebrates: worms, snails, insects, crabs. We can also group by food: herbivores eat plants, carnivores eat animals and omnivores eat both.
In the figure: Backbone splits animals into two big groups.
Rule 1: With or without backbone — Feel along the back for a bone column.
- Easy: Fish, frog, snake, sparrow and cow are vertebrates.
- Medium: Earthworm, snail, spider and crab are invertebrates.
- Exam-type: Most animals on Earth are invertebrates.
Rule 2: By food — Look at what the animal eats.
- Easy: Herbivores: cow, goat, deer.
- Medium: Carnivores: lion, tiger, frog.
- Exam-type: Omnivores: crow, bear, humans.
Decide first: grouping by backbone, by food or by habitat.
Thinking a whale is a fish because it lives in water.
"Backbone: vertebrate. Food: herb, carni, omni."
Practice questions
- 1An ant has how many legs, as noted in the chapter table?
- 2Which feature is useful for grouping animals?
- 3Which body part do birds mainly use to fly?
- 4Which is a type of movement in animals mentioned in the chapter?
- 5Which animal eats mainly grasses and leaves?
- 6Which group would a butterfly fit when grouping by movement?
- 7Fish move in water mainly with the help of —
- 8A goat moves on the ground using its —
Show answers (try them yourself first)
- 1Six
- 2Where they live
- 3Wings
- 4Hopping
- 5Cow
- 6Animals that fly
- 7fins
- 8legs
Grouping animals
In the app you can move this figure with your finger.
Open in the appHabitat and adaptation
A fish gasps on dry land, and a camel finds a pond heavy to cross: each lives well only where its body suits.
The place where a living thing naturally lives is its habitat. Features of the body or behaviour that help it survive there are adaptations. A fish has gills and a streamlined body for water; a cactus has spines and a thick stem to save water in a desert.
In the figure: Gills and fins suit water; spines and thick stems suit deserts.
Rule 1: Habitats — Land, water and air are the main habitats.
- Easy: Terrestrial animals live on land, aquatic in water.
- Medium: Birds are adapted to the air.
- Exam-type: Some, like frogs, live in both water and land.
Rule 2: Adaptations — Match each feature to its job.
- Easy: Camel stores fat in its hump and can go long without water.
- Medium: Polar bear has thick fur and fat to keep warm.
- Exam-type: Fish breathe with gills.
For any animal, ask: where does it live and which feature helps it there?
Thinking animals change their body quickly to suit a new place.
"Habitat: home. Adaptation: help in that home."
Practice questions
- 1Which feature helps hot-desert camels walk on sand?
- 2Why is a deodar tree conical with sloping branches?
- 3How many humps does a hot-desert camel of Rajasthan have?
- 4Which does a habitat provide?
- 5The place where plants and animals live is called their —
- 6The special features that help a living thing survive in its region are called —
- 7In Shola forests, rhododendrons are shorter with smaller leaves to survive —
- 8Why do camels of the cold desert have shorter legs?
Show answers (try them yourself first)
- 1Long legs with wide hooves
- 2Snow can slide off easily
- 3One
- 4Food, water, air and shelter
- 5habitat
- 6adaptations
- 7heavy winds on mountain tops
- 8Shorter legs help them walk easily on mountainous ground