Chapter 2: Living World

Learn the idea

Living organisms carry out life processes such as nutrition, respiration, growth, response and reproduction. Judge a set of features and evidence over time. A dormant seed can be alive without visibly moving; a moving car is not alive. Respiration releases usable energy in cells and is not the same thing as breathing.

Grouping by evidence

Classification groups organisms by shared characteristics. The book introduces a five-kingdom school model: Monera, Protista, Fungi, Plantae and Animalia. This is a useful introductory model; modern classification systems use further evidence and can organise groups differently. Bacteria lack a membrane-bound nucleus; fungi obtain food from organic material rather than photosynthesising.

Compare plants and animals

Flowering plants form flowers and seeds; mosses and ferns reproduce using spores. A flowering plant may have one seed leaf (monocot) or two (dicot). For animals, a vertebrate has a backbone and an invertebrate does not. Use actual features rather than size or habitat alone: a whale is a mammal, although it lives in water.

Observe without harm

Make a feature table using safe photographs or observations. Record what is visible and mark what is unknown. Do not pick unknown fungi, handle unfamiliar animals or infer every life process from a single picture.

Compare plant groups without mixing models

Mosses have root-like rhizoids rather than true roots. Ferns have true roots, stems, leaves and transport tissue, and form spores. Gymnosperms such as pine produce seeds not enclosed in fruits; they are seed plants but not flowering plants. Angiosperms are flowering plants whose seeds develop enclosed within fruits. Some older school groupings place algae and fungi together as “Thallophyta”; treat that as a historical grouping, not a reason to put fungi in Plantae in the five-kingdom model.

Compare vertebrate classes

Fish commonly have gills and fins. Amphibians include frogs and salamanders; their life cycles and breathing structures vary with stage and species. Reptiles such as lizards and snakes have characteristic scales. Birds have feathers, including birds that cannot fly. Mammals feed their young with milk; whales and bats are mammals despite very different habitats. No single rule such as “lives in water” identifies a whole class.

Invertebrates, food and importance

An invertebrate lacks a backbone, but it may have a shell or an external skeleton: a crab is an example. Adult insects have six jointed legs and three main body regions; spiders have eight legs and are not insects. Decomposers obtain nutrients from dead organic material; a parasite lives on or in a host and gains resources at the host’s expense. Bees can pollinate flowers, earthworms can affect soil structure, and microorganisms can recycle nutrients.

Build and test a feature key

A classification key uses clear alternatives, usually paired yes/no statements, to reach a group or named organism. Use a visible feature such as feathers, not an opinion such as “pretty”. Test every route using the supplied organisms. Record uncertainty when a photograph does not show a feature. Observe from a safe distance and make a poster from drawings or photographs; collecting or harming organisms is unnecessary.

Check a common mistake

A plant takes in oxygen for respiration as well as carbon dioxide for photosynthesis. Do not sort organisms by claiming that only animals respire.

A key for three familiar animals

Has feathers? Yes → pigeon. No → has six legs as an adult? Yes → butterfly. No → fish with fins and gills in this supplied set → rohu. The key is designed for this set; its final branch does not classify every animal on Earth.

Use more than habitat

Both a fish and a whale live in water, but a whale breathes with lungs and feeds its young milk. Shared habitat does not make the whale a fish.

Your written practice

Show your working on paper and enter your answer here. If it does not match, compare the model and try again.