wHAT IS ECOLOGY?
Ecology, also called ‘bioecology’, ‘bionomics’, or ‘environmental biology’ is the scientific study of interactions among organisms and between organisms and their environment.
"The word ecology was coined by the German zoologist Ernst Haeckel, who applied the term oekologie to the “relation of the animal both to its organic as well as its inorganic environment.” The word comes from the Greek oikos, meaning “household,” “home,” or “place to live.”" Thus, ecology deals with the organism and its environment. [Source: britannica.com]
EXCRETION AND HOMEOSTASIS - KCSE BIOLOGY NOTES, AUDIOVISUALS, SCHEMES, QUESTIONS, ANSWERS AND OBJECTIVES
GASEOUS EXCHANGE IN PLANTS AND ANIMALS - KCSE BIOLOGY NOTES, AUDIOVISUALS, SCHEMES OF WORK, QUESTIONS AND ANSWERS
Transport in Animals - kcse biology notes, videos, objectives, schemes of work, questions and answers
NUTRITION IN PLANTS AND ANIMALS - KCSE BIOLOGY NOTES, SCHEMES OF WORK, OBJECTIVES, QUESTIONS AND ANSWERS
classification 1 - kcse biology notes, syllabus, objectives, schemes OF WORK, questions, answers and others
By the end of the topic, the learner should be able to:
topics / sub-topics breakdown
Classification is putting organisms into groups.
Classification is based on the study of external characteristics of organisms.
It involves detailed observation of structure and functions of organisms.
Organisms with similar characteristics are put in one group.
Differences in structure are used to distinguish one group from another.
The magnifying lens is an instrument that assists in the observation of fine structure e.g. hairs by enlarging them.
Using a Magnifying Lens
A specimen is placed on the bench or held by hand,
Then the magnifying lens is moved towards the eye until the object is dearly focused and an enlarged image is seen.
The magnification can be worked out as follows:
Note: magnification has no units.
Necessity/need for Classification
To be able to identify organisms into their taxonomic groups.
To enable easier and systematic study of organisms.
To show evolutionary relationships in organisms.
Major Units of Classification (Taxonomic Groups)
Taxonomy is the study of the characteristics of organisms for the purpose of classifying them.
The groups are Taxa (singular Taxon).
The taxonomic groups include:
Living organisms are classified into five kingdoms namely;
Some are unicellular while others are multicellular.
They have no chlorophyll.
Most are saprophytic e.g. yeasts, moulds and mushrooms.
A few are parasitic e.g. Puccinia graminae.
Kingdom Monera (Prokaryota)
These are very small unicellular organisms.
They lack a nuclear membrane
do not have any bound membrane organelles.
Hence the name Prokaryota.
They are mainly bacteria, e.g. Vibrio cholerae.
They are unicellular organisms.
Their nucleus and organelles are surrounded by membranes (eukaryotic).
They include algae, slime moulds - fungi-like and protozoa
They are all multicellular.
They contain chlorophyll and are all autotrophic.
They include; Bryophyta (moss plant), Pteridophyta (ferns) and Spermatophyta (seed bearing plants).
These are all multicellular and heterotrophic.
Examples are annelida (earthworms), mollusca (snails),athropoda, chordata .
Example of Arthropods are ticks, butterflies.
Members of Chordata are fish, frogs and humans.
External Features of Organisms
In plants we should look for:-
Spore capsule and rhizoids in moss plants.
Sori and fronds in ferns.
Stem, leaves, roots, flowers, fruits and seeds in plants.
In animals, some important features to look for are:
Segmentation, presence of limbs and, number of body parts, presence and number of antennae. These are found in phylum arthropoda:
Visceral clefts, notochord, nerve tube, fur or hair, scales, fins, mammary glands, feathers and wings.
These are found in chordata.
Organisms are known by their local names.
Scientists use scientific names to be able to communicate easily among themselves.
This method of naming uses two names, and is called Binomial nomenclature.
The first name is the name of the genus: (generic name) which starts with a capital letter.
The second name is the name of the species (specific name) which starts with a small letter.
The two names are underlined or written in italics.
Man belongs to the genus Homo, and the species, sapiens.
The scientific name of man is therefore Homo sapiens.
Maize belongs to the genus Zea, and the species mays.
The scientific name of maize is Zea mays.
Use of Collecting Nets, Cutting Instruments and Hand Lens.
Forceps are used to collect crawling and slow moving animals.
Sweep nets are used to catch flying insects.
Cutting instrument like scapel is used to cut specimen e.g. making sections.
Hand lens is used to magnify small plants and animals.
Drawing of the magnified organism are made and the linear magnification of each calculated.
Collection and Detailed Observation of Small Plants and Animals
E.g. moss, ferns, bean.
Look for the following:
Moss plants: Rhizoids and spore capsules.
Fern plants: Rhizomes with adventitious roots; large leaves (fronds) with Sori (clusters of sporangia).
Seed plants: Tree/shrub (woody) or non-woody (herbs) e.g. bean.
Root system - fibrous, adventitious and tap root.
Stem - position and length of internodes.
Type of leaves - simple or compound; arranged as alternate, opposite or whorled.
Flower - colour, number of parts, size and relative position of each:
Fruits - fleshy or dry; edible or not edible.
Seeds - monocotyledonous or dicotyledonous.
Small animals e.g. earthworms, tick, grasshopper, butterfly, beetles.
Observe these animals to see:
By the end of the topic, the learner should be able to:
INTRODUCTION (5 LESSONS)
Introduction to Biology
Biology derived from Greek words
Biology is therefore the study of living things/organisms.
Branches of Biology
Importance of Biology
Characteristics of Living Things
Life defined through observations of activities carried out by living things;
Nutrition is the processes by which food/nutrients are acquired/made and utilized by living organisms.
Green plants and certain bacteria make their own food.
All other organisms feed on complex organic materials.
This is the breakdown of food to provide energy.
The energy released is used for various activities in the organism.
Process through which respiratory gases (CO2 & O2) are taken in and out through a respiratory surface.
Excretion is the removal of metabolic wastes from the body.
Substances like urea, carbon dioxide (Carbon (IV) oxide).
These substances are poisonous if allowed to accumulate in the body.
Growth and Development
Growth means irreversible change in size.
All organisms increase in size that is, they grow.
Development is irreversible change in complexity.
As they do so, they also become differentiated in form.
Reproduction is the formation of new individuals of a species to ensure continued existence of a species and growth of its population.
The ability of organisms to detect and respond to changes in the environment. This is of great survival value to the organism.
This the progressive change in position from one place to another.
Some organisms are sessile (i.e. fixed to the substratum).
The majority of plants move only certain parts.
Collection and Observation of Organisms
Biology as a practical subject is learnt through humane handling of organisms.
Materials needed for collection of organisms include:-
Observation of Organisms
Presenting the Results of Observations
Organisms are observed and important features noted down: colour, texture hard or soft; if hairy or not. Size is measured or estimated.
Biological DrawingsIt is necessary to draw some of the organisms.
In making a biological drawing, magnification (enlargement) is noted.
Indicate the magnification of your drawing, i.e. how many times the drawing is larger/smaller than the actual specimen MG=length of drawing/length specimen
How to Draw
Collection, Observation and Recording of Organisms
Plants and animals collected from the environment, near school or within school compound using nets, bottles and gloves.
Animals collected include:-
arthropods, earthworms and small vertebrates like lizards/chameleons/ rodents.
Place in polythene bags and take to the laboratory.
Stinging/poisonous insects killed using ether.
Other animals are observed live and returned to their natural habitat.
Plant specimen collected include: -
leaves, flowers and whole plants.
Observations are made to show the following:-
The differences between animals and plants collected.
COMPARISON BETWEEN PLANTS AND ANIMALS