Features of organisms Revision Notes

Both animals and plants are multicellular organisms, meaning they are made up of many cells working together.

Animals are heterotrophic: they obtain energy by consuming other organisms.

Plants are autotrophic: they produce their own food through photosynthesis, using sunlight, water, and carbon dioxide.

• Animals consume other organisms for energy (heterotrophic).
• Plants make their own food via photosynthesis (autotrophic).
• Both are multicellular organisms.

Animal cells do not have cell walls, allowing flexibility and a variety of cell shapes.

Plant cells have rigid cell walls made of cellulose, providing structural support and shape.

This difference is a key factor in distinguishing the two kingdoms.

• Animal cells lack cell walls.
• Plant cells have cellulose cell walls.
• Cell walls provide rigidity to plant cells.

Animals have specialized cells and tissues adapted for movement, digestion, and other functions.

Plants have specialized tissues such as xylem and phloem for transport of water and nutrients.

These adaptations reflect their different lifestyles and modes of nutrition.

• Animals have specialized tissues for movement and digestion.
• Plants have vascular tissues for transport.
• Specialization supports their survival strategies.

Vertebrates are animals with a backbone or spinal column.

The five main groups are: mammals, birds, reptiles, amphibians, and fish.

Each group has unique features such as body covering, reproduction, and habitat.

• Mammals have hair/fur and produce milk for their young.
• Birds have feathers and lay hard-shelled eggs.
• Reptiles have scales and lay soft-shelled eggs.
• Amphibians have a life cycle involving aquatic and terrestrial stages.
• Fish live in water and have gills for breathing.

Arthropods have jointed legs and exoskeletons made of chitin.

They are divided into myriapods, insects, arachnids, and crustaceans.

Each group differs in body segments, number of legs, and antennae.

• Myriapods (centipedes, millipedes) have many legs.
• Insects have three body segments and six legs.
• Arachnids (spiders, scorpions) have eight legs and no antennae.
• Crustaceans (crabs, lobsters) have hard exoskeletons and two pairs of antennae.

These characteristics help scientists identify and group animals.

Knowing these groups aids in understanding animal diversity and biology.

• Backbone presence defines vertebrates.
• Leg number and body segments define arthropod groups.
• Reproductive and body features distinguish vertebrate classes.

The kingdom Animalia includes multicellular, heterotrophic organisms without cell walls.

Plantae consists of multicellular, autotrophic organisms with cellulose cell walls.

Fungi are mostly multicellular, absorb nutrients, and have cell walls made of chitin.

Protista includes mostly unicellular eukaryotes with diverse nutrition methods.

• Animalia: multicellular, heterotrophic, no cell walls.
• Plantae: multicellular, autotrophic, cellulose cell walls.
• Fungi: absorb nutrients, chitin cell walls.
• Protista: mostly unicellular eukaryotes, varied nutrition.

Cell structure (presence of nucleus) helps distinguish kingdoms.

Nutrition mode (ingestion, photosynthesis, absorption) is key.

Cell wall composition and multicellularity also guide classification.

• Eukaryotic vs prokaryotic cells.
• Autotrophic vs heterotrophic nutrition.
• Cell wall presence and type.
• Unicellular vs multicellular organization.

By examining these features, organisms can be placed in the correct kingdom.

This helps organize biological diversity and understand evolutionary relationships.

• Identify key traits of an organism.
• Match traits to kingdom characteristics.
• Classify accordingly.

Organisms are grouped into five kingdoms based on cell type, nutrition, and organization.

The kingdoms are: Animalia, Plantae, Fungi, Prokaryotes, and Protoctista.

Each kingdom has unique features that help in classification.

• Animalia: multicellular, ingest food, eukaryotic cells.
• Plantae: multicellular, photosynthesize, cellulose cell walls.
• Fungi: mostly multicellular, absorb nutrients, chitin cell walls.
• Prokaryotes: unicellular, no nucleus, varied nutrition.
• Protoctists: mostly unicellular eukaryotes, diverse nutrition.

Prokaryotes have cells without a nucleus; all other kingdoms have eukaryotic cells.

Animals ingest food; plants photosynthesize; fungi absorb nutrients.

Protoctists have varied nutrition methods, including photosynthesis and ingestion.

• Prokaryotes lack a nucleus.
• Animals ingest food.
• Plants photosynthesize.
• Fungi absorb nutrients.
• Protoctists have diverse nutrition.

Animals, plants, and fungi are mostly multicellular.

Prokaryotes and protoctists are mostly unicellular.

This helps distinguish these kingdoms in classification.

• Multicellular: animals, plants, fungi.
• Unicellular: prokaryotes, protoctists.
• Cell structure and nutrition combined aid classification.

Ferns reproduce by spores instead of seeds or flowers.

They have large divided leaves called fronds, often with spores on the underside.

Ferns do not produce flowers or fruits, distinguishing them from flowering plants.

• Reproduce using spores.
• Have fronds (large divided leaves).
• No flowers or seeds.

Flowering plants produce seeds enclosed within fruits.

They are divided into monocotyledons and dicotyledons based on seed leaves and leaf vein patterns.

These features help in identifying and grouping flowering plants.

• Produce seeds inside fruits.
• Divided into monocots and dicots.
• Classification based on seed leaves and leaf veins.

Monocots have one seed leaf (cotyledon), parallel leaf veins, and flower parts in multiples of three.

Dicots have two seed leaves, net-like leaf veins, and flower parts in multiples of four or five.

These characteristics are used to distinguish between the two groups.

• Monocots: one seed leaf, parallel veins, flower parts in threes.
• Dicots: two seed leaves, net-like veins, flower parts in fours or fives.

Plants can be classified by examining specific features: whether they have vascular tissue (xylem and phloem), produce seeds or spores, and have flowers or cones.

Non-vascular plants like mosses lack vascular tissue and reproduce via spores, limiting their size and habitat.

Ferns have vascular tissue but reproduce by spores, lacking seeds and flowers.

Gymnosperms possess vascular tissue and produce seeds but do not have flowers; their seeds are often on cones.

Angiosperms have vascular tissue, produce seeds, and have flowers, with seeds enclosed within fruits.

• Non-vascular plants: no vascular tissue, reproduce by spores (e.g., mosses).
• Ferns: vascular tissue present, reproduce by spores, no flowers.
• Gymnosperms: vascular tissue, seed production, no flowers.
• Angiosperms: vascular tissue, seed production, flowers present.

Vascular tissue allows efficient transport of water and nutrients, enabling larger plant size and complexity.

Reproductive methods (spores vs seeds) reflect evolutionary adaptations to different environments.

Presence of flowers in angiosperms aids in reproduction through attracting pollinators and protecting seeds.

• Xylem and phloem form vascular tissue for transport.
• Spores are single-celled reproductive units, seeds contain an embryo and food supply.
• Flowers are reproductive structures unique to angiosperms.

By observing vascular tissue, seed presence, and flowers, plants can be categorized into groups.

This classification helps understand plant diversity and evolutionary relationships.

It also aids in identifying plants in practical and exam contexts.

• Check for vascular tissue to separate non-vascular and vascular plants.
• Determine if reproduction is by spores or seeds.
• Look for flowers to distinguish angiosperms from gymnosperms.

Viruses are microscopic infectious agents made up of genetic material, which can be DNA or RNA, enclosed within a protective protein coat called a capsid.

They do not have cellular structures such as membranes, cytoplasm, or organelles.

The protein coat protects the genetic material and helps the virus attach to host cells.

• Genetic material: DNA or RNA, but not both.
• Protein coat (capsid) surrounds and protects genetic material.
• No cell membrane, cytoplasm, or organelles present.

Viruses cannot carry out metabolic processes or reproduce on their own.

They rely entirely on infecting host cells to replicate their genetic material and produce new virus particles.

The protein coat aids in attaching to and entering host cells.

• Viruses lack machinery for independent reproduction.
• They hijack host cell machinery to replicate.
• Attachment to host cells is mediated by the protein coat.

Unlike living cells, viruses do not have a nucleus or cytoplasm.

They cannot metabolize or grow independently, so they are not classified as living organisms.

Understanding virus structure helps in studying infection and disease mechanisms.

• No nucleus or cytoplasm present.
• No metabolic activity outside host cells.
• Classified as non-living infectious agents.