Biology

Introduction to Ecology:

Ecology is the study of organisms and their environment.
All organisms show interdependence on one another.
Organisms are affected by their environment, and they in turn affect the environment.
Green plants manufacture food by photosynthesis which other organisms obtain directly or indirectly.

Bees are important in pollination i.e. in production of honey Members of the phylum have a notochord in early stages of development. They have visceral clefts – which are slits perforating the body wall at the pharynx. In fish these slits become gills while in higher chordates these slits are only present in embryo. They

Leaves Type of leaf (a) Compound leaves. (b) Type of venation. Simple leaf Trifoliate Pinnate Type of leaf margin. Type of leaf arrangement on stem. The colour of leaf. The texture ofleaf; whether hairy or smooth. Shape of the leaf e.g. palmate. Stem Type of stem – woody or herbaceous. Shape of stem – cylindrical

Most animals move from place to place in search of food. Major phyla are: Platyhelminthes (Tapeworm). Nematoda (Ascaris). Annelida (Earthworm). Mollusca (Snails). Arthropoda Chordata Phylum Arthropoda Distinguishing Characteristics of Phylum Arthropoda They have jointed appendages, which are specialised for various functions. Their body is covered by a hardened exoskeleton made of chitin. It is shed

General Characteristics of Kingdom Plantae They are multicellular and eukaryotic. They are photosynthetic and have pigment chlorophyll. Their cells have cellulose cell walls. They reproduce sexually, others asexually. Kingdom Plantae has three major divisions: Bryophyta, Pteridophyta Division Bryophyta These include mosses and liverworts. Plant body is not differentiated into root, stem and leaves. They have

Multicellular fungi are made of thread-like structures called hyphae (singular hyphae) that form a mycelium. e.g. Saccharomyces cereviseae (bread yeast). Others include Penicillium, Rhizopus, and edible mushroom Economic Importance of Fungi Beneficial Effects of Fungi Some fungi are used as food e.g. mushrooms. Some are decomposers which enhance decay to improve soil fertility – recycling

KINGDOM PROTOCTISTA Examples include; Algae such as spirogyra, Chlamydomonas, euglena, Sargassum And protozoa such as amoeba, paramecium and Trypanosoma. General Characteristics They are said to be eukaryotic since their nucleus is bound by a membrane Most are mobile, and use flagella, cilia and pseudopodia. Some are sessile. They reproduce mainly asexually, by binary fission, fragmentation

General Characteristics Unicellular and microscopic Some single cells ,others colonial Nuclear material not enclosed within nuclear membrane-prokaryotic Have cell wall but not of cellulose. Have few organelles which are not membrane bound Mitochondria absent Mostly heterotrophic, feeding saprotrophically or parasitically,some are autotrophic. Reproduction mostly asexual through binary fission Most of them are anaerobes but others

Classification is the science that puts organisms into distinct groups to make their study easy and systematic. Modern scientific classification is based on structure and functions. Organisms with similar anatomical and morphological characteristics are placed in one group while those with different structures are grouped separately. Modern studies in genetics and cell biochemistry are used

What is growth? Growth is the irreversible increase in dry mass, size and complexity of an organism brought about by the synthesis of new protoplasm. For growth to be effective, building up of materials (anabolism) must exceed the rate of breaking down (catabolism). In plants, growth is indefinite and apical while it is definite and

CELLULAR (INTERNAL/TISSUE) RESPIRATION The oxidation of glucose in the cell to release energy is known as cellular respiration and it occurs in the mitochondria of all living cells. There are two types of cellular respiration i.e. aerobic and anaerobic respiration AEROBIC RESPIRATION When cellular respiration takes place in the presence of oxygen is known as

AUTOTROPHIC NUTRITION Plants are referred to as autotrophs, i.e. being able to manufacture their food (Organic compound from inorganic materials such as water, carbon dioxide) Autotrophs generally have two modes of nutrition which are chemosynthesis and photosynthesis (holophytic). HETEROTROPHIC NUTRITION This is a type of nutrition in which organisms depend directly or indirectly on autotrophs

Environment/Nature and State of Matter Living cells are known to be surrounded by a watery environment. This may include: Fresh/salt water in which the unicellular organisms live, Intercellular fluid that bath the bodies of cells of higher animals. The nature of states of matter makes diffusion and osmosis possible. Matter can be defined as any

DEFINITION AND FORMS OF CELLULAR EXISTENCE The cell is the simplest, smallest, basic, structural and functional unit of life. The cell can carry out all life activities such as growth, respiration e. t. c. Cells can exist in various forms which include As a single cell (unicellular forms) g. Amoeba, Chlamydomonas, Chlorella, Euglena Chlamydomonas(Chlamydomonas rivalries)

MODERN CLASSIFICATION OF LIVING ORGANISMS All organisms cannot be suitably classified as either plants or animals based on CarolusLinneaus classification. Therefore five kingdoms have been generally accepted for all living organisms, these include Monera, Protista, fungi, plantae and animalia. KINGDOM MONERA (Prokaryotes) This group consists of simplest living organisms (bacteria, blue-green anabaena). They are microscopic

THE VERTEBRATES (PHYLUM CHORDATA) All vertebrates have the following features: A bilaterally symmetrical body which is divided into a head, trunk and a tail with a neck joining the head to the trunk in most vertebrates. An internal skeleton (endoskeleton) Well developed central nervous system and sense organs. A closed blood system Skin covered with

All living organisms can be generally classified as plants or animals. However, plants can be distinguished from animals in the following ways: PLANTS ANIMALS 1. Undergo passive movement. Undergo free or active movement with well developed organs of locomotion. 2. Gaseous exchange takes place through the entire body. Gaseous exchange is through special organs. 3.

Everything in nature can be classified into two groups: living and non -living things. The living things can be distinguished from their nonliving counterparts through the following characteristics observable in all living things: MOVEMENT: Animals can move from place to place on their own in search of food. Higher plants move certain parts of their

A microscope is an instrument used in magnifying and viewing organisms smaller than 0.1mm that is too tiny to be seen by the human eyes. A compound light microscope consists of the following parts: Revolving nose piece: it is used for selecting lens to be used and to be in line with the eye Objective

This is a systematic approach used to investigate enquiries arising from any observation made in nature. Therefore, the scientific method is the tool used to unravel the mysteries of life. The scientific methods include the following steps: Observation Classification Inference Measurement and Identification Hypothesis Experiment Control or Conclusion Theory or Law The starting point of