Virtual Kollage: Introduction to Science - Biology

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Introduction to Science - Biology



INTRODUCTION IN SCIENCE
Learning objectives:
                After going through this chapter, the student should have an in-depth knowledge on the subject.
                Distinguish between fundamental units and derived units
                Understand the basic components of each of the four areas under the subject

WHAT IS SCIENCE?
Science is defined as the knowledge acquired through systematic observation, experimentation and evaluation of information gained in relation with other bodies of knowledge.

INTRODUCTION TO BIOLOGY
Biology is the scientific study of living things and their relationship with the environment. The environment is made up of living and non-living things.
Non- living things are the things that do not have life in them. Thus they cannot carry out life processes, example, stone, book, television, among others.
Living things on the other hand are things that have life in them and can carry out life processes. Living things are made up of plants and animals, example, human being, fishes, timber, among others.

WHAT ARE LIFE PROCESSES?
They are characteristic processes that all living organisms carry out. Life processes of living things include the following

                MOVEMENT/LOCOMOTION
                REPRODUCTION
                NUTRITION
                EXCRETION
                RESPIRATION
                GROWTH
                SENSITIVITY

MOVEMENT/LOCOMOTION: This may include the whole organism moving from one place to another (locomotion). Plants do not loco mote, however their parts example, root move from one place to another.

RESPIRATION
It is defined as the chemical process through which food substances are broken down within the cell of an organism to release energy with or without the use of oxygen. Respiration occurs in two forms; that is exchange of gases or internal respiration.
Respiration that takes place in the presence of oxygen is known as AEROBIC RESPIRATION while the respiration that occur in the absent of oxygen is called ANAEROBIC RESPIRATION.

NUTRITION
It is the process by which living things obtain and use food. Nutrition provides the energy needed by an organism to carry out other life processes. Animals and plants under go this process of feeding in different ways. Plants take theirs by a process known as PHOTOSYNTHESIS while animals eat PLANTS AND 
 OTHER ANIMALS.

EXCRETION
It is the process whereby metabolic wastes are removed from the body of living organism. Metabolic wastes are poisonous, harmful, useless substances which when accumulated within the cell or an organism causes other malfunctioning and diseases.

REPRODUCTION
It is the process by which living things give rise to new individuals of their own kinds. Reproduction is very important because it present organism from extension. There are two types of respiration, SEXUAL AND ASEXUAL RESPIRATION.

GROWTH
This is the ability of an organism to increase in size or weight due to increase in the cytoplasm of the cell. Growth brings changes to the body either in shape or size.

SENSITIVITY/ IRRITABILITY
This is the ability of an organism to respond to stimulus (changes in the environment). Stimulation can be favourable or unfavourable.
                                           
BIOLOGICAL CLASSIFICATION
Classification refers to the sorting out of living things and putting them into groups, based on certain features.

REASON FOR CLASSIFICATION
                Easy identification
                To enhance research
                To place a rank in organism
                Permit description of organisms using one or few words
                Forms a common pool of knowledge
                Permits new organisms to be identified and classified

 HISTORY OF CLASSIFICATION
Aristotle a Greek (382-322) classifies organisms based on their ability and inability to fly. But in 1707, Carolous Linnaeas (1707-1778) did not agree to this rather, he classify organism based on SEVEN (7) RANKS as

KINGDOM→PHYLUM/DIVISION→CLASS∩→ ORDER→ FAMILY→ GENUS→SPECIES
(KING PHAROH CALLS ORDER FOR GENERAL SCIENCE)
We will now focus on the KINGDOM classification of organisms.

KINGDOM ORGANISM:
All organisms are put under five (5) kingdoms. These are:

KINGDOM ANIMALIA: The members in this group include man, fish, monkeys, birds, insects, toads, among others.

Characteristics:
                They have nucleus enclosed by nuclear membranes
                They have no cell walls
                They are multi-cellular
                They rely on external sources for food
                They reproduce by the fusion of the male and female gametes.
                KINGDOM PLANTAE: Members of this group have chlorophyll and include mango, maize, mosses, ferns, flowers, among others.

Characteristics:
                They are multi-cellular
                They have chlorophyll to manufacture their own food
                They have cell walls made up of cellos
                They have nucleus enclosed by nuclear membranes
                KINGDOM PROKARYOTAE / MONERA: They include bacteria and blue-green algae

Characteristic:
                They are microscopic
                They are unicellular
                They have no definite nucleus
                They have no membrane bound organelles
                KINGDOM PROTOCTISTA/ PROTISTA: They include protozoa, paramecium, plasmodium, trypanosome, green algae, etc.

Characteristics:
                Many of them are unicellular although a few are multi-cellular
                They have normal cell organelles but no tissues
                They have nucleus
                KINGDOM FUNGI: They include mushroom, moulds, parasitic fungi, ringworm, etc.

Characteristics:
                They are non-mobile multi-cellular
                They have no chlorophyll
                They have no stems, roots or branches
                They have cell walls but it made of chitin.

BINOMIAL SYSTEM OF NAMING ORGANISM
This involves the use of the Genus and Species to give organisms two names known as SCIENTIFIC NAMES in animals and BOTANICAL NAMES in plants. The scientific name for man is Homo-Sapien and the botanical name of maize is ZeaMays.

VIRUSES
Viruses do not fall under any of the ranking above. Viruses are very tiny organism and cannot be seen under light microscope except an electric microscope.
Characteristics:
                They are made up of Deoxyribonucleic acid (DNA)
                They have no nucleus, cytoplasm or cell membrane
                They are not cells but particles
                They are capable of producing a new generation of viruses when in living organisms
                They cannot grow unless attached to living cells
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