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Biology

Biology is derived from two Greek words, that is, bios which means life and logos or logia which means study or knowledge.

So biology can be defined as a branch of science which deals with the study of life. The term biology can also be defined as a branch of science which deals with the study of living things or organisms.

Biologist

A person specialized in the study of biology

Life

Life means being alive or existing. Something is alive or existing if it possesses life processes. The life processes are growth, movement or locomotion, respiration, excretion, reproduction, sensitivity and nutrition.

Organism

Organism is anything which has life. It is the other name of a living thing. Organisms are made up of cells.

Cell

A cell is a basic unit of living things. The cell has three main parts, cell membrane, cytoplasm and nucleus. Cells which make up plants are called plant cells and those which make up animals are called animal cells.

Some organisms are made up of one cell. They are called unicellular or single-celled organisms e.g. amoeba, euglena and yeast. Some organisms are made up of many cells, they are called multi cellular organisms e.g. animals, plants, and most fungi.

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The Meaning of the Term GeographyDefine the term geography

The term "geography" comes from the ancient Greeks, who needed a word to describe the writings and maps that were helping them make sense of the world in which they lived. It is a combination of two Greek words: "geo" and "graphia". In Greek, "geo" means “Earth” and "graphia" means “to write, draw or describe”.

These two words together form geography, which means to draw, write about or describe the Earth. These meanings led to the development of the early definition of geography which referred to description of the Earth by words, maps and statistics and included both the physical Earth and everything found on it such as plants, animals and people. Therefore, geography is the study of the distribution and interrelationship of phenomena in relation to the Earth’s surface. Alternatively, geography can be described as the study of the Earth and its environment.

Geographers explore both the physical properties of Earth’s surface and the human societies spread across it. They also examine how human culture interacts with the natural environment and the way locations and places can have an impact on people. Geography seeks to understand where things are found, why they are there, and how they develop and change over time.

There are two branches of geography, namely physical geography, and human and economic geography:

1. Physical geography - mainly concerned with the study of Earth’s seasons, weather, climate, soil, streams, landforms, and oceans. All of these features form the physical environment which includes all natural features found on the Earth’s surface such as water bodies, mountains, rivers, plains, natural forests, etc.
2. Human and economic geography - involves the study of human activities on the Earth's surface. Human activities include farming, trade, mining, transportation, settlement, tourism, etc.

Fig 1.1 A section of Uluguru Mountain Ranges showing physical features (mountains) and man-made or human features (buildings)

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Inter-relationship between different geographical phenomena

There exist interrelationships between different geographical phenomena. Physical environment interacts with living organisms in a number of ways. For example, land resources provide soil that supports plant growth.

Sun rays generate heat which leads to the evaporation of water; then water vapour forms clouds and eventually rain. The rainfall feeds plants, i.e., it supports plant growth. Plants are food for herbivores and omnivores such as human beings.

Climate determines the types of plant and animal species that can survive in a particular geographical area and influences human population distribution. Climate also determines human activities like farming, tourism, and settlement. On the other hand, human activities can lead to modification of physical environments, for example, soil degradation, land reclamation, and forest conservation

Fig 1.2 Human activities such as quarrying can lead to soil degradation

The Importance of Studying Geography

Geography answers questions about the natural and human worlds. The following are some of the reasons for studying geography:

1. To develop knowledge of places and environments throughout the world. This will help in solving issues about the environment and sustainable development.
2. Geography serves as an important link between the natural and social sciences. As you study geography, you encounter different societies and cultures. This helps you realize how nations rely on each other.
3. To help us understand basic physical systems that affect everyday life. For instance, how water cycles and ocean currents work are all explained with geography. These are important systems to monitor and predict in order to help lessen the impact of disasters.
4. To learn the location of places and the physical and cultural characteristics of those places in order to function more effectively in our increasingly interdependent world.
5. To enable us explore the methods and strategies used by other nations for economic developments and how Tanzania can borrow and employ the same for a similar purpose.
6. To be able to make sensible judgement about spatial distribution of human settlements in relation to physical environment.
7. To gain knowledge about the available, finite resources that the Earth has been endowed with and how to manage and use them sustainably.
8. To help us take care of the world around us by understanding others better and knowing the limitations of the Earth. This enable us make our planet a more liveable one.
9. To understand various types of natural environments and how to harness them for equitable use by the present and future generations.
10. To gain positive attitudes and values which enable one become a responsible and successful member of the society.
11. To serve as the basis for further studies in specialized fields such as cartography (the science of map making), land survey, meteorology (the study of weather and weather forecasting), climatology (study of climate), seismography (the scientific measuring and recording of the shock and vibrations of Earthquakes), teaching, aviation and research.

Fig 1.3 A cartographer at work

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Components of the Solar SystemName the Components of the Solar System

When we look at the sky at night we see thousands of bright bodies. These are stars and planets. Our Earth is one of the planets. Sometimes we can see a group of stars which form patterns called constellations. In some occasions we can see bright, moving objects. These are called meteorites.

The arrangement of the planets in relation to the position of the sun is called the solar system. The name is derived from a Latin word sol which means sun. The solar system is made up of the sun, planets, moons, natural satellites, asteroids, meteors, comets, dust, ice, and interplanetary space (it contains interplanetary dust and interplanetary gas).

All planets and other bodies revolve around the sun. The sun is the central body of the solar system, and it is the only body that generates its own heat. Bodies that revolve around the sun are kept in their orbits (paths) by the sun’s powerful force of gravity.

There are eight known planets in the solar system. The planets, starting from the one closest to the sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

The four innermost planets in the solar system, Mercury, Venus, Earth and Mars are also called terrestrial planets. They are called terrestrial because they have a compact, rocky surface like the Earth's.

Jupiter, Saturn, Uranus, and Neptune are known as the Jovian (Jupiter-like) planets, because they are all gigantic compared with Earth, and they have a gaseous nature like Jupiter's. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores.

Fig 1.4 The solar system

You grew up learning that the solar system consists of nine planets, including Pluto as one as those planets. However, the International Astronomical Union (IAU) stripped Pluto of this status in 2006.

When Pluto was discovered in 1930, it was hailed as the ninth planet in the solar system based on an overestimation of its size. But it looked out of place among the larger planets following the discovery of swarms of ‘ice dwarfs’—icy rocks in the Kuiper Belt, at the very edge of the solar system billions of miles from the sun. This prompted some astronomers to suggest that Pluto could be just another Kuiper Belt Object (KBO), disappointing generations of schoolchildren who grew up learning that Pluto was the smallest planet in the solar system.

On the other hand, this was also a question of meaning or definition of the term ‘planet’. Pluto is clearly big enough for gravity to give it a round shape like any planet (unlike KBOs that tend to be misshapen). It revolves around the sun like other planets. It has an atmosphere and seasons, too.

When the IAU demoted Pluto to a “dwarf planet”, it spelt out three conditions that a celestial body must meet to qualify as a planet: 1) it must be round; 2) it must orbit the sun; and 3) it must have “cleared the neighbourhood” of its orbit (a planet’s gravity sweeps and clears the space around it of other objects). Pluto follows the first two rules, but it hasn’t cleared the neighbourhood of its orbit—which put it in the category of “dwarf planets”. (Of the five known dwarf planets, Pluto, Makemake, Haumea and Eris are located beyond Neptune. The fifth, Ceres, is located in the asteroid belt between Mars and Jupiter.).

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Importance of the Components of Solar SystemDescribe the importance of the components of solar system

Though the solar system has many components, the two most important components of the solar system are the Earth and the sun. The Earth sustains lives of a diversity of living organisms (plants and animals). The Earth contains numerous resources that enable living organisms to thrive in it. The Earth’s atmosphere contains water and air (a mixture of several gases that are used by living organisms for survival). In general, the Earth is the only planet known to sustain life.

The sun is the source of all energy that supports life on Earth. The sun is responsible for water cycle and it is responsible for weather conditions and climate. The moon lights the Earth on some days of the month, though it gets its light from the sun.

The following is an outline of some importance of the sun:

1. The sun is very important in the plants’ growth. The sun helps the plants to make their own food by the photosynthesis process.
2. The sun is very necessary for the other living organisms, that is, it provides us with light for the vision and to do our work.
3. The sun provides us with the heat to warm our bodies.
4. The sun provides some animals and humans (that feed on plants) with food as it helps the plants to make its own food by the photosynthesis process.
5. The sun is used in heating water and warming houses by the solar heater which changes the solar energy of the sun into the heat energy. The heat energy is used in warming houses and heating water.
6. The sun is very important in the formation of the clouds, rain, and winds. The sun evaporates the water in the seas, lakes and oceans into water vapour. When the water vapour rises in the sky, it cools and condenses forming the clouds, which eventually forms rain.