Dichotomous Keys in Taxonomy

Study Notes

Animals

Multicellular organisms that can be divided into two main groups: vertebrates and invertebrates

Vertebrates

Phylum Chordata
Include mammals, birds, reptiles, amphibians, and fish
Have a backbone

Invertebrates

No backbone
Include many groups, such as arthropods, insects, crustaceans, arachnids, and myriapods

Mammals

Habitat: land and water
Physical features: hair or fur for insulation, constant internal body temperature
Fertilization: internal, with eggs fertilized by sperm inside the female's body
Give birth to live young, which develop inside the mother's body supported by a placenta
Young are fed on milk by mammary glands
Some species display extensive parental behavior

Birds

Habitat: almost every environment and across every continent
Physical features: feathers, wings, well-developed circulatory system, modified bones
Fertilization: internal, with eggs fertilized by sperm inside the female's body
Lay hard-shelled eggs, which develop outside the parent's body
Significant parental behavior to protect the eggs and young

Reptiles

Habitat: marine, freshwater, and dry desserts
Physical features: thick, dry scaly skin, varies with environmental temperature
Fertilization: internal, with eggs fertilized by sperm inside the female's body
Lay eggs, which are protected by leathery shells
Young develop outside the parent's body

Amphibians

Habitat: spend part of their life in water and part on land
Physical features: two pairs of legs, gills and tails in tadpoles
Body temperature: cold-blooded, relies on the environment to maintain body temperature
Fertilization: external, with males shedding sperm over eggs released by the female
Young develop from eggs

Fish

Habitat: marine, freshwater, and river water bodies
Physical features: streamlined body, fins and tail, swim bladder, scales, operculum
Body temperature: cold-blooded, relies on the environment to maintain body temperature
Fertilization: external, with males shedding sperm over eggs released by the female
Young hatch from eggs and fend for themselves

Ferns

Physical features: broad, divided leaves called fronds
Grow as clumps of fronds from the ground
Some species have a thick trunk
Method of reproduction: release spores into the air from spore cases under the leaves

Flowering Plants

Physical features: central stem, side branches, leaves, roots
Method of reproduction: depends on flowers, male gametes in pollen grain, female gamete in ovule
Fertilization results in seeds, which are produced in fruits that aid in dispersal or protection

Monocotyledons vs Dicotyledons

Monocotyledons: single cotyledon, long strap-leaves, parallel veins
Dicotyledons: two cotyledons, broad leaves, branching veins

Fungi

Physical features: single-celled or multicelled, hyphae, no chlorophyll
Obtain nutrients through saprotrophic nutrition, secreting digestive enzymes outside the cells

Prokaryotes

Physical features: single-celled, microscopic, cells smaller than plants and animals
No nucleus, genetic material lies free in the cytoplasm
Examples: bacteria like Salmonella and Mycobacterium

Insects

Physical features: three body regions, six jointed legs, pair of wings, exoskeleton made of chitin
Head has sense organs: compound eyes, antennae, chemical detectors
Some insects have complex social structure with intricate behavior patterns

Protoctists

Physical features: single-celled, microscopic, eukaryotes
Have features of animal and plant cells
Examples: various single-celled organisms

Description

Explore the concept of dichotomous keys used in taxonomy to identify organisms based on their features. Learn how to navigate through a series of questions leading to the name of the organism by choosing between two descriptions at a time.