Classification & Characteristics of Living Organisms – Revision Flashcards

A comprehensive set of question-and-answer flashcards covering life processes, traditional and modern classification systems, kingdom and phylum characteristics, vertebrate and invertebrate classes, plant groups, and key cellular differences.

What are the seven life processes remembered by the acronym MRS GREN?

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition

Define the life process ‘movement’.

The ability of an organism to change position or travel from one place to another (e.g., animals walking, plants bending toward light).

Define the life process ‘respiration’.

The release of energy from food, usually using oxygen.

Define the life process ‘sensitivity’.

The ability to detect and respond to changes in the environment.

Define the life process ‘growth’.

A permanent increase in size and/or dry mass.

Define the life process ‘reproduction’.

The production of offspring from parent organism(s).

Define the life process ‘excretion’.

Removal of metabolic waste products from the body.

Define the life process ‘nutrition’.

Taking in or making food for energy, growth and repair.

What is biological classification?

The grouping of living organisms based on shared characteristics to make them easier to study and identify.

Who developed the binomial system of nomenclature?

Carl Linnaeus

How many parts are in a binomial scientific name, and what are they called?

Two parts: Genus and species

Write correctly the binomial name for humans.

Homo sapiens (italicised, Genus capitalised, species lowercase)

Why did Linnaeus choose Latin for scientific names?

Latin was no longer spoken, avoiding national bias and remaining constant worldwide.

List the seven main taxonomic ranks in Linnaeus’s hierarchy from largest to smallest.

Kingdom, Phylum, Class, Order, Family, Genus, Species

What taxonomic rank was added above ‘kingdom’ in the three-domain system?

Domain

Name the three domains in Woese’s three-domain system.

Archaea, Bacteria, Eukaryota

Give one biochemical reason Archaea and Bacteria are placed in separate domains.

They have distinct cell-membrane chemistry and ribosomal RNA sequences.

Define a ‘species’.

A group of organisms that can interbreed to produce fertile offspring.

State two traditional methods used to classify organisms before molecular techniques.

Morphology (overall form) and anatomy (internal structure).

What modern techniques have improved classification accuracy?

DNA and amino-acid sequencing, and improved microscopy.

In an evolutionary tree, what does it mean if two species’ branches meet close to the present?

They share a recent common ancestor and are closely related.

Which life process supplies the energy required for all other processes?

Respiration

Why is a growing copper sulfate crystal not considered alive?

Growth is not accompanied by other life processes such as respiration or reproduction.

Which life process do viruses show?

Reproduction (but only inside host cells).

List three life processes viruses cannot perform independently.

Respiration, nutrition, excretion (also growth or movement).

State four key characteristics of the Animal kingdom.

Multicellular, heterotrophic, no cell walls, eukaryotic cells with nuclei.

State four key characteristics of the Plant kingdom.

Multicellular, autotrophic via photosynthesis, cellulose cell walls, eukaryotic.

State three key characteristics of the Fungi kingdom.

Cell walls of chitin, saprotrophic nutrition, most multicellular with hyphae and mycelium.

State two key characteristics of the Protoctist kingdom.

Unicellular or simple multicellular eukaryotes; some autotrophic, some heterotrophic.

State four key characteristics of the Prokaryote kingdom.

Unicellular, no nucleus, circular DNA, cell wall of peptidoglycan.

Give two structural differences between prokaryotic and eukaryotic cells.

Prokaryotes lack a nucleus and membrane-bound organelles such as mitochondria.

Define ‘autotroph’.

An organism that makes its own organic nutrients, usually by photosynthesis.

Define ‘heterotroph’.

An organism that obtains organic nutrients by consuming other organisms.

List the five classes of vertebrates in Phylum Chordata.

Mammals, Birds, Reptiles, Amphibians, Fish

Give three distinguishing features of mammals.

Hair/fur, females produce milk in mammary glands, warm-blooded (endothermic).

Give three distinguishing features of reptiles.

Dry scaly skin, lay shelled eggs on land, cold-blooded (ectothermic).

Give three distinguishing features of birds.

Feathers and wings, beak with no teeth, warm-blooded and lay hard-shelled eggs.

Give three distinguishing features of amphibians.

Moist permeable skin, live part-time in water and on land, lay jelly-coated eggs.

Give three distinguishing features of fish.

Gills for breathing, fins for movement, scales covering body.

What key characteristic unites all arthropods?

Jointed limbs and a segmented body with an external exoskeleton.

Name the four main classes of arthropods.

Insects, Arachnids, Crustaceans, Myriapods

List four features of insects.

Three pairs of legs, two pairs of wings (usually), one pair of antennae, three body regions.

List three features of arachnids.

Four pairs of legs, cephalothorax and abdomen, simple eyes; chelicerae for biting.

List three features of crustaceans.

Five or more pairs of legs, two pairs of antennae, hard carapace (exoskeleton).

List two features of myriapods.

Ten or more pairs of legs, one pair of antennae; body with many similar segments.

Give one key feature of annelids.

Segmented cylindrical body (e.g., earthworms).

Give one key feature of nematodes.

Unsegmented cylindrical body tapered at both ends.

Give two key features of molluscs.

Muscular foot for movement and (usually) a calcium-carbonate shell.

Give one key feature of echinoderms.

Body arranged in five-part radial symmetry (e.g., starfish).

Into which two groups are flowering plants divided?

Monocotyledons and dicotyledons

State three features of monocotyledons.

One cotyledon, parallel leaf veins, flower parts in multiples of three.

State three features of dicotyledons.

Two cotyledons, network (branched) leaf veins, flower parts in fours or fives.

How do ferns reproduce?

By spores produced on the undersides of fronds.

Give two reasons fungi are no longer classified as plants.

They lack chlorophyll/photosynthesis and have chitin cell walls instead of cellulose.

What is saprotrophic nutrition?

Digestion of material outside the body by secreted enzymes followed by absorption of soluble products.

Why aren’t viruses placed in any of the five kingdoms?

They are acellular and can reproduce only inside host cells, lacking other life processes.

Which part of the binomial name Panthera leo is unique to lions?

leo (the species epithet)

Which taxonomic rank shows the most characteristics in common: family or order?

Family (it is lower in the hierarchy).

In the Linnaean system, which two animal phyla exist in the animal kingdom example given?

Chordata and Arthropoda

Name one organ through which mammals excrete waste.

Kidneys (others: lungs, skin).

What type of limbs does a centipede have according to the key provided?

More than five pairs of jointed limbs; first pair modified into poisonous claws (myriapod).

Which plant feature distinguishes liverworts from flowering plants?

They lack roots and flowers; reproduce by spores.

What material strengthens plant cell walls?

Cellulose

What material strengthens fungal cell walls?

Chitin

What is a plasmid?

A small circular piece of DNA found in many prokaryotes in addition to the main chromosome.

Which two structural components are common to all viruses?

Genetic material (DNA or RNA) and a protein coat (capsid).

Which life process is necessary for energy release?

Respiration

Give one example of a warm-blooded vertebrate class.

Mammals (or Birds)

Give one example of a cold-blooded vertebrate class.

Reptiles (or Amphibians or Fish)

What does ‘phototropism’ describe?

Growth of a plant towards light.

Which kingdom contains organisms that may be single-celled, have nuclei, and can be animal-like or plant-like?

Protoctista

Which kingdom contains bacteria?

Prokaryote (Prokaryotae)

What is the purpose of jointed limbs in arthropods?

Flexible movement while protected by exoskeleton segments.

What are cotyledons?

Seed leaves that provide nutrients to the developing plant embryo.

Why was the three-domain system introduced?

Molecular evidence showed fundamental biochemical differences between two groups of prokaryotes and eukaryotes.