Introduction to biology test

INTRODUCTION TO BIOLOGY

Definition

Biology is the scientific study of living things. Biology is one of many sciences. It is classified as a natural science. Other natural sciences include Chemistry, Physics, Geology, Astronomy, Earth Science, Meteorology, Oceanography, as well as a number of others.

Subdivisions of biology pertinent to this course

Biochemistry – the study of chemical substances found in living organisms and the chemical reactions that they undergo. The reactions include metabolic pathways that break down large molecules to produce energy or that synthesize carbohydrates, lipids, proteins, and nucleic acids.

Molecular Biology – The study of the synthesis, structure, and function of biologically important macromolecules such as DNA, RNA, and proteins. It investigates genetics at the molecular level and includes the study of the replication, transcription, and translation of nucleic acids. It is also concerned with the sequencing of DNA, the manipulation of DNA, and the control of genes.

Bioinformatics – The application of techniques from applied mathematics, informatics, statistics, computer science, and chemistry, especially biochemistry to solve biological problems usually on the molecular level.

Cell Biology – the study of the structure and functions of the cell.

Genetics – the study of heredity and variation.

Developmental Anatomy – the study of growth and development during the entire life of the organism.

Embryology – the study of the origin and development of the organism from the egg to birth.

Anatomy – the study of the structure of living things.

Comparative Anatomy – the comparative study of the structure of vertebrates. It is closely related to evolutionary biology and phylogeny. Phylogeny – the origin, evolutionary development, and genealogical history of a taxonomic group of organisms, both living and extinct.

Physiology – the study of the functioning of living things.

Comparative Physiology – the comparative study of the function of vertebrate cells, tissues, organs, and systems.

Taxonomy – the study of the classification of living things.

Microbiology – the study of microorganisms, including bacteria, viruses, protists, and fungi.

Botany – the study of plants.

Zoology – the study of animals.

Parasitology – the study of parasites (organisms that live at the expense of other organisms), their hosts, and the relationship between them.

Marine Biology – the study of ocean life.

Evolution – the change in the genetic makeup of a population with time.

Behavior – the study of the activities of animals and their response to stimuli in their environment, including how they interact with one another, find and defend resources, establish territories, choose mates and reproduce, and care for their young.

Ecology –the study of the relationship between living things and their environment.

Subdivisions Based Upon the Kind of Organism Being Studied

Examples: Entomology – the study of insects, Ornithology – the study of birds, etc.

Characteristics of living things

What is life? No satisfactory definition exists. However, we can approach the problem by comparing living and nonliving things and by establishing the characteristics of living things.

Living and nonliving things compared

Some characteristics which may be used to distinguish living from nonliving things are as follows:

I. Organization

Chemical Organization

Living things are composed primarily of carbon, hydrogen, oxygen, nitrogen, and phosphorous, organized into complex, high molecular weight molecules.

Enzymes mediate chemical reactions in living things.

The same and other chemical elements occur as compounds in nonliving materials but their molecular weights are small (below 2,000) and they are not highly organized.

Deoxyribonucleic acid (DNA) is uniformly present in all living things.

Protoplasmic Organization

The material of which living matter is made is known as protoplasm.

Cellular Organization

Cellular organization is characteristic of all living things. (Viruses – an exception)

Cells are organized into tissues and organs in higher forms.

Morphological Organization

Living things have a characteristic form and size and are arranged as definite individuals.

II. Life Processes

1. Metabolism

Metabolism includes the physical and chemical changes by which materials derived from the environment are transformed and utilized for energy production on one hand and synthesis on the other.

The process by which energy is produced is a process of breakdown and is known as catabolism .

The building up process or synthesis is called anabolism .

Energy production involves a series of reactions termed Glycolysis and the Citric Acid Cycle . Although certain of the reaction steps may differ in certain organisms, these reactions are found generally in all living things.

A good deal of the energy that is produced is trapped and stored in the form of a molecule known as ATP or Adenosine Triphosphate .

Synthesis in living organisms is under genetic control and components are built according to a specific pattern found originally in the DNA characteristic of that organism.

Processes Related to Metabolism

Nutrition – the intake and transformation of food so that it can be utilized.

Living things seek out raw materials and/or energy necessary for life.

Absorption – the taking in of solids.

Secretion – the process by which something is compounded in one part of the body that can be used in another.

Respiration – the intake of O2 and discharge of CO2.

Circulation or Transport – the movement of materials throughout the organism.

Excretion – the giving off of waste material.

Other Life Processes

2. Irritability and Conductivity (Response)

Living things respond to changes in the environment. These changes are known as stimuli. The ability to respond to a stimulus is known as irritability .

Irritability is also known as responsiveness. We can say that living things respond to stimuli.

Conductivity is the ability to conduct an electrical impulse. Although all protoplasm can conduct an impulse, this ability is especially well-developed in nerve cells.

3. Movement

Movement is characteristic of living things. Movement is change of place or position.

Living things move volitionally (of their own will).

4. Growth and Life Cycle

A living organism grows by divisions of cells.

Living organisms grow by development of new parts between or within older ones.

Living things have the capacity to repair or to replace protoplasm.

Each kind of organism has a definite life cycle: birth, growth, maturity, and death.

If nonliving things increase, they do so by external addition, as with crystals, and there is no orderly cycle of change.

Living things do not merely accrete through external addition (like e.g. crystals).

5. Reproduction

Living things have the ability to reproduce themselves in kind.

The continuation of the species depends on reproduction.

Genetic and hereditary characteristics are transmitted through DNA.

Nonliving things cannot reproduce.

6. Adaptability

Adaptation – Any characteristic of living organisms, which in the environment they inhabit, improves their chances of survival and ultimately of leaving descendants, in comparison with the chances of similar organisms, without the characteristic; natural selection therefore tends to establish adaptations in a population (Abercrombie, et al., A Dictionary of Biology, 1951).

Homeostasis

Living matter shows homeostatic responses to the environment.

Homeostasis – the maintenance of constant conditions within the internal environment of the body.

Homeostasis is a central concept in the field of human physiology.

The term was coined by the eminent United States Physiologist, Walter Cannon. The concept is generally accredited to the great French scientist, Claude Bernard.

The word is derived from the Greek words homios, meaning “like” or “similar”, and stasis, “a standing still”.

Examples of Homeostasis

Man is capable of remaining active and typically retaining a remarkably constant body temperature under an imposing variety of temperature extremes, ranging from intense desert heat to extreme arctic cold. Even though external temperature may vary widely, man’s internal body temperature remains constant at 98.6( F. When the temperature varies, even a degree or two, we realize we are “sick”, that something is wrong.

Concentration of respiratory gases in the Body Fluids

O2 and CO2 levels within the body must be maintained within close limits. A constant supply of O2 is essential for living cells. CO2 a waste product must not be allowed to build up. If the CO2 level rises, this stimulates the brain and structures known as chemoreceptors. The nervous system then signals the respiratory system to bring about an increase in the rate of respiration. This eliminates the excess CO2, brings about an increase in O2 and restores homeostasis.

pH of body fluids

The pH of the arterial blood remains constant at pH 7.4. If the pH of the arterial

drops to pH 7.0 and remains there for longer than a few minutes, the person will go into a coma and die. If the pH rises to pH 7.8 and stays there for more than a few minutes the person will go into convulsions. Even in disease conditions the pH of the arterial blood almost never becomes more acidic than 7.0 or more basic than 7.8.

Special chemicals in the blood known as buffers maintain constant blood pH by neutralizing excess acid or base. The urinary and respiratory systems also have important roles in the regulation of acid base balance.

Evolution

Living things are undergoing evolution.

Evolution – the change in the genetic makeup of a population with time.

Introduction to Biology Study fall 2021