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• Biology


  The area of science dealing with living things. It includes biological concepts and process skills, technology and attitudes and values for addressing the needs and problems of society. In recent years, the development of techniques in genetic engineering and increased understanding of the molecular basis of cellular processes have led to the emergence of a new and exciting field of scientific research called biotechnology.
• Organic compounds


  • Carbohydrates
  • Lipids
  • Proteins
  • Enzymes
  • Nucleic Acids
  • Vitamins
• Carbohydrates


  Made up of carbon, hydrogen, and oxygen. Their sizes range from the small simple sugars like glucose and fructose to the large and complex forms like starch and glycogen. Only the simple sugars (monosaccharides) can easily pass across cell membranes. Most carbohydrates serve as energy molecules or energy reserves in living organisms.
• Cellulose


  Gives strength and protection to plant cells.
• Lipids


  Macromolecules such as fats, oils and waxes. They are made up of carbon, hydrogen, and oxygen. The building blocks used to form fats are fatty acids and glycerol. Some excess food in the body is stored as fats. Lipids that are liquid at room temperature are known as oils. Waxes serve as protective body covering to organisms. They make plant and animal tissues water-resistant.
• Proteins


  Made up of repeating units of amino acids. They are a component of the muscles and all other tissues. In the form of enzymes, they control the rate of chemical reactions inside the cell. Without the enzymes, such chemical processes hardly occur.
• Enzymes


  Proteins that act as catalysts (substances that can increase or speed up chemical reaction). Enzymes are specific in their actions. They are not used up in the reaction.
• Nucleic Acids


  Carriers of hereditary information in living organisms. What an organism looks like, and what it can do, are controlled by nucleic acids.
• Vitamins


  Substances necessary in very small amount for body growth and activity. They are also needed to prevent certain diseases. Vitamins are organic substances essential to life but not required as energy sources. The sources of most Vitamins are plants and bacteria.
• Inorganic compounds


  • Water
  • Carbon dioxide
  • Minerals
• Water


  The most abundant inorganic compound. About 65% to 95% of the substances of every living thing is water. It is the medium of transport for food, minerals and other substances in living system.
• Carbon dioxide


  Supplies the carbon found in substances made by living things.
• Minerals


  Chemical elements or compounds occurring naturally. They may come from the soil maybe dissolved in water, or maybe found as salt in seawater. Minerals are absorbed by plant roots in the form of ions.
• Life functions


  • Nutrition
  • Transport
  • Metabolism
  • Homeostasis
  • Digestion
  • Absorption
  • Behavior
  • Excretion
  • Reproduction
• Nutrition


  The process of ingesting and absorbing food to provide the energy for life, promote growth, and repair or replace damages tissues.
• Transport


  Involves movement of nutrients water, ions, and other materials into and out of the various cells and tissues of organisms. This process includes absorption of small molecules across cell membranes and secretion of biochemicals such as enzymes, mucous, and hormones. In many species, the circulatory system plays an important role in transport.
• Metabolism


  Includes the process by which nutrients and simple molecules are used to form more complex molecules for growth, repair, and reproduction (anabolism). Metabolism also includes the process of breaking down complex molecules to release energy from chemical bonds (catabolism) and to provide small molecules such as simple sugars and amino acids as budding blocks for more complex molecules (anabolism).
• Homeostasis


  An internal balance in all aspects of metabolism and biological function.
• Digestion


  A special form of catabolism that breaks food down into smaller molecules and releases energy.
• Absorption


  Allows small molecules to pass through cell membranes throughout the body tissues. This allows for a gas exchange and in some species such as plants and fungi nutrients are obtained by absorption from soil and water.
• Behavior


  The response of living things to stimuli in the environment. These stimuli may include things such as light, chemical signals, noise, or a change in the seasons.
• Excretion


  The elimination of waste products.
• Reproduction


  The process by which an organism produces offspring either sexually or asexually. Its main purpose is for the perpetuation of species.
• Types of reproduction


  • Asexual
  • Sexual
• Asexual reproduction


  Reproduction without the use of gametes or sex cells. One parent organism can reproduce by itself.
• Types of asexual reproduction

  • Fission
  • Budding
  • Sporulation
• Fission


  The splitting of the body of an organism into two identical parts.
• Budding


  The growing of a bud out of the parent cells or bodies which when detached can grow into another organism that resembles the appearance of the parent.
• Sporulation


  Spore formation as in fern plants and mushrooms.
• Sexual reproduction


  Requires the union of male and female gametes called "fertilization". Male gametes are called sperm cells and female gametes are called egg cells.
• Types of sexual fertilization

  • External
  • Internal
• External fertilization


  The union of sperm cells and egg cells happen outside the body of the female organisms.
• Internal fertilization


  The union of sperm cells and egg cells happen inside the body of a female organism.
• Cells


  The smallest structures capable of basic life processes, such as taking in nutrients, expelling waste, and reproducing. All living things are composed of cells. Some microscopic organisms, such as bacteria and protozoa, are unicellular, meaning they consist of a single cell. Plants, animals, and fungi are multicellular; that is, they are composed of a great many cells working in concert.
• Prokaryotic cell


  Found only in bacteria and archaebacteria, all the components, including the DNA, mingle freely in the cell's interior, a single compartment. They are among the tiniest of all cells, ranging in size from 0.0001 to 0.003 mm (0.000004 to 0.0001 in) in diameter. They can be rod like, spherical, or spiral in shape, are surrounded by a protective cell wall. They live in a watery environment, whether it is soil moisture, a pond, or the fluid surrounding cells in the human body. Tiny pores in the cell wall enable water and the substances dissolved in it, such as oxygen, to flow into the cell; these pores also allow wastes to flow out.
• Anatomy of a simple bacterium

  • Cell wall
  • Cell membrane
  • Cytoplasm
  • DNA
  • Ribosomes
  • Pilus
  • Flagellum
  • Plasmid
  • Capsule
  • Mesosomes
• Plasma membrane


  A thin membrane pushed up against the inner surface of the prokaryotic cell wall. The plasma membrane, composed of two layers of flexible lipid molecules and interspersed with durable proteins, is both supple and strong. Unlike the cell wall, whose open pores allow the unregulated traffic of materials in and out of the cell, the plasma membrane is selectively permeable, meaning it allows only certain substances to pass through. Thus, the plasma membrane actively separates the cell's contents from its surrounding fluids.
• Cytoplasm


  The semifluid that fills the cell enclosed in the plasma membrane. Composed of about 65 percent water, the cytoplasm is packed with up to a billion molecules per cell, a rich storehouse that includes enzymes and dissolved nutrients, such as sugars and amino acids. The water provides a favorable environment for the thousands of biochemical reactions that take place in the cell. Within the cytoplasm of all prokaryotes is deoxyribonucleic acid (DNA), a complex molecule in the form of a double helix, a shape similar to a spiral staircase.
• Ribosomes


  The only organelles in prokaryotic cells—tiny bead-like structures. These are the cell's protein factories. Following the instructions encoded in the DNA, ribosomes churn out proteins by the hundreds every minute, providing needed enzymes, the replacements for worn-out transport proteins, or other proteins required by the cell.
• Eukaryotic animal cells


  Typically about ten times larger than prokaryotic cells. In animal cells, the plasma membrane, rather than a cell wall, forms the cell.